Abstracts from the 26th Annual Meeting of the Engineering and Urology Society May 14,2011 Washington,DC

Objective: TURP before HIFU is mandatory in order to adjust each prostate to the maximum penetration depth (30mm) and for movement of the longitudinal transrectal applicator. Only a prostate volume of <25 cc can be treated completely. We studied the influence of immediate or delayed (1 month) HIFU after TURP. HIFU application dose, treatment time, and side effect induction, as well as changes in TURP technology (mono-/bipolar), were analyzed.

Material and Method: A total of 1,529 patients have been treated with TURP & HIFU since 2000; 1,346 of these patients were included into the analysis with their complete data set. Our prospective data collection includes 140 data points/HIFU treatment since 1996, subgrouped into annual cohorts. TURP from 2000–2007 was performed as monopolar, and since 2008 as bipolar resection. The HIFU device used was Ablatherm^® (EDAP-TMS,Lyon).

Results: In 2001, only 10% delayed treatments were performed; in 2010 54% HIFU treatments were performed with a one month delay. Treatment time was not influenced by this strategy: 1,105 combined TURP & HIFU lasted 94 minutes (range of 72–115 minutes), with a month delay the HIFU treatment lasted 92 minutes (range 65–119 minutes). HIFU dose showed equal data: 562 (433–682) lesions applied in the combined and 549 (391–717) lesions applied in the split group. Resected tissue was 53% (range 48%–63%) until 2006 and increased by 25% to 66% (range 63%–70%) by introduction of bipolar TURP. Side effect analysis clearly showed that HIFU one month after TURP reduces typical side effects by 50%. Efficacy (PSA Nadir) did not show differences between the two groups.

Conclusion: Since the treatment goal is complete prostate coagulation by HIFU, neoadjuvant TURP is necessary in order to increase efficacy and to minimize side effects. Whether TURP and HIFU are performed in one or two sessions does not influence efficacy (according to Nadir), but side effects decreased by 50% with delayed treatment.

Source of funding:

Harlachinger Krebshilfe e.V.; Lingen Stiftung

Thanks to Ms. Regina Nanieva for database management and analysis.

7. Robotic Radical Prostatectomy Using A 3-Dimensional Flat-Screen Monitor for the Surgical Assistants

Objectives: 3-Dimensional (3-D) visualization for the surgeon is considered to be one of the major advantages of robotic prostatectomy. Paired optical systems and cameras provide the surgeon at the console with a 3-D perspective of the field. However, the assistants working on the side of the patient still have to depend upon 2-D images projected onto a flat-screen monitor. On this monitor, they often have to rely on motion parallax and judge depth by observing the spatial relationship of objects in the field of vision. We created a new 3-D system on a flat screen for the da Vinci Robot System. We undertook this study to see if passing on this technology to surgical assistants would improve their efficiency.

Materials and Methods: The da Vinci stereoscopic visualization system has a custom-designed endoscope with two separate optic channels; thus, it recreates the most important aspect of stereopsis: binocular disparity. The image is displayed on the surgeon's console through the Vision cart. We made a control box that can convert the da Vinci 3-D signals to 3-D signals on a flat screen. It is connected to the da Vinci system and a 3-D monitor. We receive a 3-D view though polarized 3-D glasses. The study was conducted with patients undergoing robotic radical prostatectomy in Kobe University Hospital. The assistant wore polarized glasses for a flat screen 3-D monitor and used the 3-D system throughout the entire procedure. The efficiency of the 3-D system for assistance was evaluated on a scale of 0 to100 subjectively.

Results: All 13 cases were achieved with 3-D assistance. The polarized glasses were comfortable to wear, and direct vision seldom was influenced. Overall satisfaction was scored +94. Vision provided by the 3-D flat screen monitor was described to be “as good as the surgeon's console.”

Conclusion: The use of 3-D visualization seems to improve the efficiency of assistance during robotic radical prostatectomy. Vision provided by the 3-D flat screen with special glasses is very similar to the robot's console.

9. The Fibre Tow Technique: A Novel Maneuver to Retrieve Ureteric Calculi

Introduction: Retrograde stone migration during ureteroscopic lithotripsy poses a problem. We describe the “Fibre Tow technique,” a novel maneuver to retrieve such stones in order to facilitate pulverization.

Methods: The technique can be described in the following steps

• Step 1: Patient position: Reverse Trendelenberg

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FIG. 1.

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FIG. 2.

Results: The calculus cannot slide down the ureteral mucosa due to high inertia of the stone at rest. It has to be lifted off the ureteral mucosa in order for it to move down the ureter. The technique prevents the repeated exchange of stone retrieval devices, reduces cost of the accessories, and saves time as the same fibre is used for to tow the stone as well as pulverization. It is easily reproducible and can be used in any part of the ureter.

Conclusion: The “Fibre Tow” allows fast and safe manipulations of calculi during ureteroscopy. It is cost effective, saves time, is easily reproducible, and can be used for any ureteric stone.

Introduction: The advent of fluoroscopically-guided interventional procedures has resulted in dramatic rise in radiation exposure for both patients and interventionalists with their distinct occupational health hazards. Radiation safety measures such as ALARA or “As Low As Reasonably Achievable” principles of reducing exposure time, maximizing distance, and shielding have been recommended to reduce radiation exposure to patients and operating room personnel. Shielding consists mainly of wearing heavy, lead-impregnated chest and pelvic aprons, in addition to thyroid shields, lead-impregnated glasses, and gloves. Exposure to radiation and subsequent orthopedic complaints secondary to heavy radiation protection measures are important occupational hazards that endourologists face. The aim of the present study was to assess the compliance of endourologists with radiation safety measures and determining the prevalence of orthopedic complaints among practicing endourologists.

Methods: An internet-based survey was sent to all members of the Endourological Society. The website remained open for six weeks (November 1^st till December 15^th, 2010) to allow members an opportunity to visit and complete the online survey. Baseline characteristics on practice pattern (geographical region, age, years of practice, days per week of endourology, and number of cases in the previous year), compliance with various radiation protection measures (thyroid, chest and pelvic aprons, gloves, glasses, and dosimeters), and prevalence of various orthopedic complaints (neck, back, hand and joint problems) were assessed. Furthermore, open-ended questions assessed reasons for non-compliance.

Results: Out of 160 surveys returned, 24 were excluded because of incomplete data. There was good compliance with chest and pelvic shields, with 97% of endourologists reported wearing these; however, compliance with thyroid shields was only 68%. Furthermore, only 34.3%, 17.2%, and 9.7% of endourologists reported using dosimeters, lead-impregnated glasses, and gloves, respectively. Overall, 86 (64.2%) respondents complained of orthopaedic problems. Specifically, 51 (38.1%) complained of back problems, 37 (27.6%) complained of neck problems, 23 (17.2%) complained of hand problems, and 19 (14.2%) complained of hip and knee problems. Furthermore, the prevalence of orthopaedic complaints were significantly higher among African endourologists, older endourologists (>40 years), longer duration of practice (>10 years), and combined annual caseload of ureteroscopies (URS) and percutaneous nephrolithotomies (PCNL).

Conclusion: There was lack of compliance among endourologists in the use of certain radiation protection measures, such as thyroid shield, dosimeter, lead-impregnated glasses, and gloves. Orthopaedic complaints among practicing endourologists are common and correlate with the annual caseload of combined URS and PCNL.

Introduction: Contributing agents in the fragmentation of stones by extracorporeal shockwave lithotripsy (SWL) are ureteral stents, which allow for better fragmentation of ureteral calculi and assistance of passing those fragments, as well as avoiding ureteral obstruction. Variable length ureteral stents have the luxury of one size fits all. The object of this study was to determine whether removal of the renal portion of the stent in a variable length device would naturally recoil in the bladder, which in turn can be utilized to motivate stone fragment passage actively when incorporated with a partially occlusive proximal device.

Methods: Utilizing the Cook Sof-Flex multiple length stent 4.7Fr, the renal portion of the stent was removed. The stent then was inserted to its maximum length, with a small coil remaining in the bladder, and monitored under direct observation via the cystoscope.

Results: Direct observation of the bladder portion of the multi-length stent revealed a natural tendency for the stent to actively migrate caudally in the ureter and recoil to its natural pre-insertion form in the bladder. This migration was assisted during respiratory motion. Speed of the migration was variable, but motion was persistent.

Conclusion: Distally coiled stents have the capability to be an active assistant in the progression of ureteral calculus or fragments when incorporated with a cephalad semi-occlusive device. Further studies are warranted to convert double-J stents from a static stone passage device to an active assistant in the management of ureteral calculi disease.

Introduction: Digital light processing (DLP^®) hyperspectral imaging is a non-invasive means of visualizing the chemical composition of in vivo tissues using reflectance spectroscopy. It is able to provide a real-time map of surface tissue oxygenation. Using a CoolSNAP HQ₂™ CCD camera (Photometrics, Tucson, AZ), we have previously used this system to characterize renal ischemia during open partial nephrectomy in pigs and humans. By incorporating a light guide, 0⁰ laparoscope, and a DVC 1200M CCD camera (DVC, Austin, TX), DLP^® hyperspectral imaging was adapted for use during laparoscopic surgery.

Methods: Two adult female pigs underwent DLP hyperspectral imaging using the laparoscopic system, before, during, and after clamping the renal hilum for 90 minutes. Imaging during ischemia was obtained at several intervals. The relative percentage of oxygenated hemoglobin (relative %HbO₂) was determined at each imaging interval using previously described methodology. Data were compared to those for 3 pigs imaged over a similar interval using the open HQ₂™ camera.

Results: For Lap vs. Open, relative %HbO_2, was 68.7 vs. 72.9% pre-clamp respectively, dropping by an average of 27% vs. 26% within 10 minutes after clamping, and rapidly rising to baseline after clamp removal, with similar trends for the two imaging systems.

Conclusion: The laparoscopic DLP hyperspectral imaging system performs similarly to the open system and has excellent spectral imaging capabilities.

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FIG. 1.

Laparoscopic HSI camera.

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FIG. 2.

%HbO₂ versus time.

Introduction: Aim of this study was to describe initial laboratory experience using the SPIDER™ platform for LESS urologic procedures and to report its first clinical application.

Methods: The SPIDER system was tested in a laboratory setting and used for a clinical case of renal cyst decortication. Three tasks were performed during the dry lab session, and different urologic procedures were conducted in a porcine model. The time to complete the tasks and penalties was registered during the dry lab session. Perioperative outcomes and subjective assessment by the surgeons were registered.

Results: The surgeons had a positive experience with the SPIDER system, with a mean overall score of 3.6 (on a scale of 1–5), and they were able to gain proficiency in performing tasks regardless of their level of expertise. The highest scores recorded were for ease of device insertion, instrument insertion and exchange, and triangulation. During the clinical case, the platform provided good triangulation without instrument clashing. However, retraction was challenging because of the lack of strength and precise maneuverability with the tip of the instruments fully deployed.

Conclusion: The SPIDER™ surgical system represents a new concept in the field of the LESS armamentarium, offering intuitive maneuverability of instruments in the abdominal cavity, restored triangulation without external instrument clashing, and no significant gas leakage. Drawbacks of the first generation system include its challenging clinical application, and further refinements are awaited to define the role of the system.

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18. Ball-Tip Holmium:Yag Optical Fiber

Introduction: The holmium:YAG optical laser should be advanced through the working channel of a flexible endoscope in a straight (i.e., non-deflected) configuration. The fiber usually will not pass through the channel with the scope deflected and damage to the working channel may occur as the sharp tip cuts into it and lead to leaks and costly repair. We tested the hypothesis that a ball-tipped fiber allows for safer passage through a flexible ureteroscope in the deflected configuration.

Methods & Results: A 240 μm core sized holmium: YAG optical laser fiber (Boston Scientific, Natick, MA) was prepared with a ball-tip and passed through the working channel of seven flexible ureteroscopes (Wolf Viper, Stryker U-500, Olympus URF-V x2, Olympus URF-P5, ACMI Dur-8 Elite, Storz Flex-X2). The following measurements were recorded: pre- and post-visual assessment of the screen image, resistance to passing fiber in both a 180 degree and maximally deflected configuration (Scale 1- 5), visualization of aiming beam (Scale 1 – 3), and visualization of the stone before and during ablation (1.0J 10z, Scale 1 – 3). Three different fibers were tested for each ureteroscope.

Conclusion: The ball-tipped fiber passed through all scope channels but required greatest force in the two ureteroscopes that had active secondary deflection (DUR-8 Elite, U-500). No visible damage to the ureteroscopes occurred. The ball-tip allowed the fiber to pass through a deflected ureteroscopy and may reduce endoscope damage during holmium: YAG laser lithotripsy.

Introduction: While typically reserved for poor surgical candidates, percutaneous cryoablation (PCA) is emerging as a safe and effective alternative to partial nephrectomy for treating the small renal mass (SRM). PCA poses a risk of thermal injury to adjacent tissues, limiting its application. Various protection techniques aimed at minimizing this risk have been described without widespread success or acceptance. We describe pneumodissection (PD), a novel technique for preventing unintended thermal tissue injury during PCA. We present our initial experience with 3 patients.

Methods: Using a Yueh needle, a sufficient quantity of air was injected into the perirenal space under CT guidance until the resulting air pocket separated the kidney mass from the adjacent bowel. PCA was completed as previously described. Safety was evaluated by analyzing post-procedural and follow-up CT imaging for bowel injury and by clinical assessment.

Results: Three patients with SRMs with overlying bowel, with a mean age of 65 years, mean tumor size of 1.8cm, and with tumors located in the right (2) or left (1) kidney, and being lateral (2) or medial (1), were studied. PD mechanically separated the bowel from tumor (mean distance 1.3cm), permitting successful PCA. There were no immediate or late complications (median follow up 7 months) by CT imaging or clinical assessment.

Conclusion: We have shown that PD is a safe and effective technique for preventing bowel injury in patients undergoing PCA. PD physically separates and thermally insulates vulnerable structures from the ice ball, making previously inaccessible tumors amenable to PCA. Unlike other dissection techniques, PD employs room air, an excellent thermal insulator, which does not freeze or conduct thermal energy as readily as water. Since room air is available widely and is dispensed easily, PD requires no special equipment. Given our success, we support the widespread adoption of PD. In the future, PD may broaden the application of PCA and revolutionize therapy for the SRM. Further study is needed to validate these results.

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FIG. 1.

CT images pre- (A) and post- (B, C) PD.

Introduction: Prolonged warm ischemia time (WIT) is associated highly with renal damage during partial nephrectomy. Recently, the RENAL nephrometry score (RNS) was developed to standardize the description of renal tumor anatomy in a quantifiable manner. We analyzed preoperative factors as well as individual categories of the RNS to identify those predicting a longer WIT and affecting postoperative renal function.

Methods: Medical records and imaging exams of 187 consecutive patients who underwent robotic partial nephrectomy at our institution were reviewed. Total RNS and its individual categories were determined. Multivariable linear regression analysis was performed to identify factors significantly associated with WIT and late postoperative glomerular filtration rate (GFR).

Results: Mean patient age, body mass index (BMI), and tumor size were 59.6 years, 30.6 Kg/m², and 3.15 cm, respectively. The overall RNS was categorized as low complexity (4–6) in 84 patients (45%), moderate complexity (7–9) in 80 (43%), and high complexity (10–12) in 23 (12%). There was no association between gender (p=0.6), BMI (p=0.3), or anterior/posterior location (p=0.8) with WIT. A longer WIT was associated with tumor size >4cm (p<0.0001), entirely endophytic properties (p=0.005), tumor ≤4mm near the collecting system/sinus (p<0.0001), and location of the tumor >50% across the polar line, or crossing the axial renal midline, or entirely between the polar lines (p=0.004). The total RNS and WIT correlated highly (Spearman correlation coefficient=0.54, p<0.0001). There was a very significant trend of higher WIT by the increase of the complexity of the renal tumor (p for trend <0.0001). Late postoperative GFR could be predicted by the following equation: GFR_L=36+0.7×GFR_pre−0.6×WIT−0.2×age+0.4×RNS, where GFR_L: late postoperative GFR and GFR_pre: preoperative GFR.

Conclusion: WIT is affected highly by the RNS and its categories, except anterior/posterior location. Increased complexity of the tumor leads to a very significant trend of higher WIT. Prediction of late postoperative renal function could help in the decision-making process for nephron sparing surgery. Further validation of our late postoperative equation is warranted.

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FIG. 2.

Performance of the equation to predict GFR. *The dots represent the actual values, while the 45^o line represents what would be the perfect model.

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FIG. 3.

Equation predictive of late postoperative GFR.

Introduction: Prostate biopsy typically is performed under transrectal ultrasound (TRUS) guidance. In clinical practice, it is difficult to determine the accuracy of the geometric distribution of TRUS-guided sextant biopsy within the gland.

Methods: A biopsy simulation system was built to measure in vitro biopsy locations accurately. This system consists of a custom-made pelvic mockup with precisely defined geometry and an optical tracking system (Polaris^®, NDI, Ontario, Canada) used to measure the relative location of the mockup, TRUS probe, and biopsy needle (Figure 1). The pelvic mockup includes a prostate model and rectal cavity. Special molds were made for building the mockup so that the geometry, size, and position of the prostate within the mockup is consistent and invariant from one mockup to another. An active (6-DOF) optical tracking marker was assembled precisely on the mockup box. Since the location of the prostate within the box is known, this marker can be used to measure the exact location of the prostate. Two other active markers were mounted on the handle of the TRUS probe to measure its location. Finally, a point (3-DOF) marker was mounted on the shaft of the biopsy needle to measure the depth of needle insertion. Overall, this system measures the locations where biopsies are sampled. Calibration and verification tests showed that the measurement errors of the instrument are within 1 mm. We defined the gold standard using a common 12-core sextant biopsy plan, and then determined how closely an experienced urologist can perform a biopsy compared to the gold standard.

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FIG. 1.

Optical tracking of probe and prostate mockup

Results: A preliminary result from a simulated biopsy is represented graphically in Figure 2. The simulated biopsy cores are clustered and a large portion of the prostate gland remains under-sampled. Targeting errors are defined as the distance from the gold standard to the core center of each sample. The average error was 8.86 mm.

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FIG. 2.

Gold standard biopsy locations (green marks) and actual center of core samples acquired (red marks) in three orthogonal views of the prostate.

Conclusion: TRUS-guided prostate biopsies may not closely follow sextant biopsy plans. A study with multiple experienced urologists is in progress.

Acknowledgement: Study partially supported by the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Award CA141835 from the National Cancer Institute, Award PC101984 form the Prostate Cancer Research Program (PCRP), and Hitachi Medical Systems America.

Objective: In 8% of the patients who undergo TURP because of symptomatic BPH, histological examination shows PCa. Consequently, these patients need a therapeutic approach for their PCa. We treated these patients with HIFU as a local therapy and analyzed efficacy and side effects.

Material and Methods: Since 2000 we identified 65 patients with incidental PCa out of our prospective monocentric HIFU database (n=2,300). Their mean age was 70 years (range 57–87 years), the mean PSAi was 4.9 ( range 1–32), mean prostate volume 39 cc (range 16–130 cc), and a median of 20 grams (range 1–95 g) had been resected. Histology showed median 5% (5–50%) positive chips and a Gleason of 5 (3–9). Patients were treated completely with transrectal HIFU (robotic Ablatherm^® integrated imaging, EDAP-TMS, Lyon) in spinal anesthesia in a single session.

Results: A PSA Nadir of 0.07 (0–3.67) was measured after 1.8 months (range 0.7–5.9 months), including 62%<0.1/81%<0.5 ng/ml). A median PSA of 0.13 (0–8.3), equivalent to a median PSA velocity of 0.01 ng/ml/year, was found after a mean follow-up of 48 months (range of 3–110 months).

Intra- and post-operative side effects were minimal– Clavien: <15% I-III. Long-term follow-up showed 45% of secondary obstructions caused by necrotic tissue or bladder neck stenosis. Other long- term side effects were mild: intermediate urinary stress incontinence Grade I (11%), and UTI (14%). Median disease-free survival was 31 months in a median 33 month follow-up. There was no cancer- specific mortality.

Conclusion: The PSA nadir of 0.07 ng/ml, as well as the PSA velocity of 0.01 ng/ml/year, indicates that HIFU can be used as a curative therapy for patients with incidental PCa. The psychological burden of the patients who are confronted either with untreated cancer disease in cases of “wait & see,” or with fear of significant side effects in cases of radical surgery or radiation, can be avoided by this non-invasive transrectal therapy with High Intensity Focused Ultrasound.

Source of Funding:

Harlachinger Krebshilfe e.V, Lingen Stiftung.

Thanks to Ms. Regina Nanieva for HIFU database management and analysis.

24. Robotic Versus Laparoscopic Partial Nephrectomy for Bilateral Synchronous Kidney Tumors: Comparative Analysis at a Single Institution

Introduction: Robotic Partial Nephrectomy (RPN) is emerging as an attractive minimally invasive nephron-sparing approach for renal tumors. The aim of this study was to compare intra-operative and early post-operative outcomes of RPN to Laparoscopic Partial Nephrectomy (LPN) outcomes in patients with bilateral synchronous renal tumors.

Methods: Our ongoing IRB-approved prospectively maintained kidney cancer database was used to identify the study population. Medical records of patients who underwent minimally invasive nephron-sparing surgery at our institution from January 2001 and March 2010, were used. A cohort of 9 patients undergoing bilateral RPN was identified and compared to 17 consecutive patients who underwent sequential bilateral LPN. Demographic, intra-operative, post-operative, and short-term renal functional data were retrospectively compared between the 2 groups.

Results: A total of 18 procedures were performed in the RPN group and 32 procedures in the LPN group. Mean warm ischemia time was shorter in the RPN group than the LPN group (23 vs. 29.5 minutes, respectively; p=0.059). Median tumor size was 3.7 cm and 2.7 cm in the RPN and LPN groups, respectively (p=0.03). Final post-op GFR mean was 68.7±9.8 and 51.2±6.6 in the RPN and LPN groups, correspondingly (p=0.004). No difference was found in terms of complications in the RPN group (n=2) versus the LPN group (n=4).

Conclusion: RPN is a safe and effective minimally invasive nephron-sparing treatment for bilateral synchronous kidney tumors. There is a trend towards shorter warm ischemia time and less impact on postoperative renal function compared to the laparoscopic approach.

Introduction: Approximately 500,000 vasectomies are performed annually in the United States, making it the most common urological procedure in the U.S. Although more effective and less likely to have complications than tubal ligation, the number of men undergoing surgical sterilization is approximately three-fold less than women. A safer, less invasive approach to vasectomy may eliminate male fears associated with surgery and reverse these trends. Our laboratory has recently demonstrated successful noninvasive laser coagulation and thermal occlusion of the canine vas deferens, ex vivo and in vivo, with the goal of developing a completely noninvasive vasectomy procedure. During conventional surgical vasectomy, occlusion of the vas is confirmed visually. However, during noninvasive laser vasectomy, a noninvasive diagnostic method may be helpful to confirm successful targeting and closure of the vas to insure consistent and reproducible results. High frequency ultrasound (HFUS) imaging has been shown previously to quantify the anatomical dimensions of the human vas accurately, in vivo. The objective of this study was to use HFUS to confirm successful targeting and thermal coagulation of the canine vas during noninvasive laser vasectomy.

Methods: Bilateral noninvasive laser coagulation of the vas deferens was performed in a total of 6 dogs using an Ytterbium fiber laser with a wavelength of 1075 nm, output power of 9.0 W, 500 ms pulse duration, pulse rate of 0.5 Hz, and 3 mm diameter spot. A cryogen spray cooling device was used to cool the treatment area during the procedure and prevent the formation of scrotal skin burns. A standard clinical US system with 13.2 MHz transducer was used to image the canine vas before and after the procedure. Simultaneous application of Doppler US at a frequency of 6.15 MHz helped to distinguish between the vas and the spermatic cord. Burst pressure measurements were recorded for the excised thermally coagulated vas samples to quantify the degree of closure.

Results: Acute burst pressures averaged 291±31 mmHg, significantly greater than previously reported normal ejaculation pressures of 136±29 mmHg. Representative HFUS images of the canine vas deferens both before and after the procedure are shown in Figure 1, demonstrating the ability to distinguish native from thermally coagulated vas. Doppler US indicated normal blood flow through the testicular artery and no detectable collateral damage to proximal structures.

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FIG. 1.

Representative ultrasound images showing (A) native vas before the procedure and (B) thermal lesion in vas after the procedure.

Conclusion: High frequency ultrasound can be used as a diagnostic method to confirm successful targeting and thermal coagulation of the canine vas during noninvasive laser vasectomy.

Introduction: Despite the positive clinical outcomes (greater than 90% success rate) of early electro-hydrodynamic lithotripters (EHLs), such as the Dornier HM3, the use of shock wave lithotripsy (SWL) has decreased in the last 20 years. This is attributable to several factors, including the short lifetime of sparker electrodes in the HM3, which prompted a move to non-sparker shock-wave sources in 2^nd and 3^rd generation lithotripters. As a result, the success rate of SWL has decreased to less than 50% in recent years, while the success rate of invasive techniques, such as flexible ureteroscopy, have success rates greater than 90%. We have developed a new shock wave source using an array of small sparker sources for use in SWL that can resolve lifetime and other issues of sparker based SWL.

Methods: Two arrays of 7 sparkers were built and operated simultaneously, with the sparkers arranged along the circumference of a circle in a single plane (Figure 1). The pressure field was measured with PVDF hydrophones (Onda HGL-0400 at low pressure and Onda HNS-0500 at higher levels) both at focus and along three axes around focus. The pressure field from a single sparker also was measured and used in a simulation to estimate the pressure field from different array configurations and operating conditions. The sparker arrays also were used to break artificial stones made with Ultracal-30 gypsum.

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FIG. 1.

Seven element sparker array.

Results: The sparker array produced a pressure pulse that delivered a peak pressure of 40 MPa with a pulse width of 0.7 μsec to the focus. The planar sparker array produced a pressure field with a focal spot (50% of peak) that is 38 mm long the direction normal to the plane of the array, but narrow, only 2.5 mm, within the plane of the array and perpendicular to the direction of propagation and 15 mm long in the direction of propagation. Simulation of the pressure field reproduced this, and also predicted a more symmetric focal region for a compact 3-dimenstional arrangement with the sparkers on a spherical surface. The model predicts that this configuration will produce a focal region between 4.2 and 6.4 mm in the plane perpendicular to propagation and 50 mm long in the direction of propagation. The simulations also suggest that the physical pulse width is proportional to the temporal pulse width of the pulse, which provides greater flexibility in the design of the pressure field.

The sparker array was used to break artificial stones in 7 tests using 2400 shock wave pulses in each test. Additional testing resulted in the array delivering more than 20,000 pulses without a decrease in output pressure.

Conclusion: The sparker array provides a consistent, configurable electro-hydrodynamic shock wave source for use in shock wave lithotripsy.

Introduction and Objectives: To verify the ability of identifying the layered structures of ureteral wall and imaging a segment of ureter in three dimensions with a high speed endoscopic optical coherence tomography (EOCT).

Methods: We imaged a porcine ureter ex vivo using a spectral domain EOCT with an optimally designed circumferential scanning fiber catheter. The images were correlated with the histological images to identify corresponding structures. Three-dimensional images and enface images at different radical depths were reconstructed from the multiple cross-sectional images to show the layered structure of a segment of the ureter from different views.

Results: EOCT images can clearly reveal all layers of the ureteral wall, as shown in the histological images. Especially with the optimally designed fiber catheter, the light beam was well centered during the rotation and pull back, which allowed constant acquisition of high fidelity images and unambiguous identification of the smooth muscle layers in all images. With significantly improved imaging speed, a segment of ureter (20 mm) can be imaged in a short period of time.

Conclusions: With its capability to image all layers of the ureteral wall, EOCT offers the potential to stage urothelial cancers that have infiltrated the muscular wall (stage T2). This information will be complimentary to the diagnostic information obtained through ureteroscopic biopsy and CT urogram.

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FIG. 1.

Introduction: A key challenge for prostate cancer therapy is to diagnose tumor lesions precisely. Here we describe a novel stereotactic prostate biopsy system which integrates preinterventional MRI with peri-interventional ultrasound for perineal prostate biopsies.

Methods: 50 men with suspicion of prostate cancer underwent multiparametric 3T-MRI (median age 67 years, mean PSA 8.9 ng/ml, mean prostate volume 51 ml). Suspicious lesions were marked before the obtained data were transferred to the stereotactic biopsy system. Using a custom-made biplane TRUS probe mounted on a stepper, 3D-ultrasound data were generated and fused with the MRI. As a result, suspicious MRI-lesions were superimposed onto the TRUS-data. Next, 3D biopsy planning was performed including systematic biopsies from the peripheral and transition zones of the prostate. Perineal biopsies were taken under live US imaging, and the location of each biopsy was documented in 3D. Feasibility, safety, target registration error and cancer detection were evaluated.

Results: Prostate cancer was detected in 27 out of 50 patients (54%). A positive correlation between MRI findings and histopathology was found in 72%. In MRI-lesions marked as highly suspicious, the detection rate was 100% (13/13). Target registration error of the first 1159 biopsy cores was 1.7 mm. Regarding adverse effects, one patient experienced urinary retention and one patient a perineal hematoma. Urinary tract infections did not occur.

Conclusion: Perineal stereotactic prostate biopsies guided by the combination of MRI and ultrasound allow effective examination of suspicious MRI-lesions. Each biopsy core taken is documented accurately for its location in 3D enabling MRI-validation and tailored treatment planning. The morbidity of the procedure was minimal.

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30. Jackhammer Nephroscopy (JN): An AID to Fragment Evacuation During Percutaneous Nephrolithotomy

Objective: Evacuation of small fragments poses a problem during Percutaneous nephrolithotomy (PCNL). We describe and evaluate an innovative “Jackhammer nephroscopy” to overcome this problem.

Methods: Jackhammer nephroscopy (JN) was designed and the safety, advantages and weaknesses evaluated in 15 cases.

Steps of JN:

1. Trap fragments in the sheath holding the sheath against the pelvic wall, creating a closed water column in the sheath.

Results: The JN was used for all punctures, stones, JN DATA renal anatomies, and for second time surgeries. JN helps fast and easy extraction of the stone fragments. We never had to abandon the technique. No intra-operative or post-operative complications were observed. Larger fragments need accessory devices. Collecting evacuated fragments may need a sieve drape. Some learning curve should be expected.

Conclusion: We recommend the Jackhammer nephroscopy as safe, fast, effective and cheap technique to evacuate small fragments during percutaneous nephrolithotomy.

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FIG. 1.

31. In Vivo Evaluation of a Novel Bipolar Radiofrequency Ablation Device in Patients Undergoing Laparoscopic Partial Nephrectomy: A Pilot Study

Introduction: Ablative therapies have become increasingly attractive in the treatment of small renal masses (SRMs). Radiofrequency ablation (RFA) is a well-established technology routinely employed in ablative treatment of hepatic and pulmonary masses. Traditional RFA is performed using monopolar probes inserted into targeted tissue that conduct energy through a circuit completed by a grounding pad. This approach has several limitations, most notable for small ablative zones with irregular shapes and borders, skip lesions of viable tissue within targeted ablation zones, and skin burns at the grounding pad sites. These problems may be avoided by using bipolar RFA probes, which have been successfully tested in animal in vivo and ex vivo models.

Methods: We evaluated a novel bipolar RFA device (Encage™, Trod Medical^®) which employs a probe within coil technique to contain all ablative energy within the margins of the outer coil (Figure 1). In an IRB-approved study, we used this to ablate renal masses in 10 patients undergoing laparoscopic partial nephrectomy. The probe was placed percutaneously and laparoscopically guided into the tumor after laparoscopic exposure. Electrical current was adjusted continuously by the generator to overcome disruption from increasing impedance created from desiccated tissue. The specimens then were excised in routine fashion of laparoscopic partial nephrectomy, and analyzed by a single pathologist. We recorded lesion size, shape, and size of transition zone to viable tissue (via NADH staining).

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FIG. 1.

Bipolar RFA probe.

Results: Ablation was successful in all 10 patients. Duration of ablation was 200 seconds. Average time to set up and place probe was between 2 and 4 minutes. All ablated tissue showed no sign of viable cells as per histologic examination and NADH staining. Size of ablation zone averaged 6.26 cm³, with regular borders and a tapered cylindrical shape similar to the shape of the outer coil (Figure 2). The width of the transition zone, or area spanning complete tissue ablation to the first viable cells, ranged from 10 to 60 microns. There were no complications during the ablations.

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FIG. 2.

Ablation zone in RCC.

Conclusion: This pilot study demonstrates the safety and efficacy of a novel bipolar RFA device. The area of ablated tissue not only exhibits completely devitalized cells, but also a very precise target zone. With these characteristics, potential advantages of this new technology during RFA ablation of SRMs include less collateral damage, more complete ablation without skip lesions leading to lower rates of local recurrence, and reduced incidence of skin burns. Although successful with laparoscopic guidance, further studies are needed to evaluate image-guided percutaneous application of this device.

Objective: The purpose of this article is to establish the validity of fractal analysis in the evaluation of capsular invasion of small RCC based on contrast enhanced computed tomographic (CT) images.

Materials and Methods: Between January 2007 and January 2011, 183 consecutive patients (age range, 19–95 years; 102 men, 81 women) with small renal masses <4cm considered T1a and T3a respectively, underwent total or partial nephrectomy. The pattern and degree of enhancement, lesion contour and calcifications were evaluated on the preoperative renal CT. Renal capsule contour was extracted by removing the interior points of the object during each phase of the CT scan and analyzed by estimating the global fractal dimension, the local fractal dimension and local connected fractal dimension using a box counting algorithm. T3a stage was considered to be a reduction of more than 0.2 units in the global fractal dimension. The imaging stage and fractal analysis results were compared to the histological results using Fisher tests, Pearson χ² tests, multivariate logistic regression and Wilcoxon rank sum tests.

Results: Of the 183 renal tumors (median size, 3.4 cm; range,1.1–4.0 cm) included in this study, 98 (54%) were clear cell renal cell carcinomas (RCCs); 20 (11%), papillary RCC; 24 (13%), chromophobe RCC; 21 (12%), oncocytomas; six (3%), lipid-poor angiomyolipomas; and 14 (8%), other or unclassified renal tumors. Clear cell RCC most commonly manifested with a mixed enhancement pattern of both hypervascular soft-tissue components and low-attenuation areas that corresponded to necrotic or cystic changes. The imagistic parameters suggesting clear RCC were correspondent to 88% of all clear cell tumors, while the fractal analysis was correspondent to 79% respectively. The sensibility of the imaging parametres and global fractal dimension in predicting T3a stage were 67% and 89% respectively, when compared to the histological result. Even more, the fractal dimension seems to slightly variate between the CT evaluations of oncocytomas (1.30±0.1), suggesting a non aggressive pattern of extension characteristic for benign lesions.

Conclusions: The fractal analysis improves the accuracy of preoperative staging in RCC and can be a useful tool in diagnosing benign lesions that require active surveillance.

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FIG. 1.

Right T1a RCC (corticomedular phase).

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FIG. 2.

The time (spatial) series - x(t) - is generated by computing either the mean value or the maximal (dominant) value of each columns of pixels within the strip.

Introduction: The aim of this study is to evaluate effective prognostic factors in the evolution of patients with retroperitoneal fibrosis and to establish the validity of fractal analysis in determining the disease severity in these patients.

Material and Methods: This study included 19 patients (M/F: 5/14) treated for idiopathic retroperitoneal fibrosis and bilateral obstructive renal failure between Jan 2004-Dec 2008. Patients were identified retrospectively, searching for patients diagnosed with IRF, after retroperitoneal biopsy or, in most cases the diagnosis rested on radiological findings, especially CT, with identification of a retroperitoneal mass, the absence of other demonstrable renal or ureteric disease or any other pathology that could explain the findings. CT was useful in describing the retroperitoneal mass around the aorta and inferior vena cava, the extent of the lesion and for monitoring the response to surgical treatment during the follow-up. The data were evaluated about medical history, physical examination findings, laboratory tests (serum urea and creatinine, blood sugar, sodium, potassium, bicarbonate levels, serum pH, uric acid, haematocrit, white blood cell count), imaging methods (renal echography, abdominal CT-scan, MRI). At admission, all patients had active disease with obstructive renal failure and underwent bilateral ureteric stenting in order to normalize the BUN levels. After normalizing of BUN levels, ureterolysis and omental wrapping was performed. Postoperatively, ureteric stents were removed after 1 month and remission of renal disfunction was obtained in approximately 5 months (range 2–10 months). All patients were followed for at least 1 year. Patients were checked regularly every 3 months.

Results: Of the 19 patients, there were 5 men and 14 women. The median age at diagnosis of RF was 50 years (range 42–64 years). The most frequent presenting symptoms were back or abdominal pain, weakness, weight loss, oligoanuria, arterial hypertension and mild fever. The duration of symptoms before diagnosis ranged from 6 to 18 months. At presentation all patients had active disease, presenting renal dysfunction with a median serum creatinine of 5,18 mg/dl (range 1–15.4 mg/dl). Most of the patients had moderate bilateral hydronephrosis (2^nd degree hydronephrosis). In our study, all patients had excellent prognosis, with full recovery of renal function in 15 patients (78%). The fractal dimension of the fibrosis mass contour correlates with level of renal function impairment. Even more, the fractal dimension seems to variate slightly between CT evaluations (1.30±0.1), suggesting a non-aggressive pattern of extension of the fibrotic mass characteristic for benign lesions.

Conclusions: The imaging parameters did not predict the disease severity, except the increase in fractal dimension of fibrosis surface area. Efficacy of bilateral ureteric stenting in improving renal function is limited in most of the cases. Despite the level of renal function impairment at admission, full recovery can be achieved after bilateral ureteric stenting/nephrostomy and ureterolysis.

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FIG. 1.

Retroperitoneal fibrotic mass involving the 2 ureters+ureteral stents (native CT scan).

Introduction: The lower urinary tract is controlled by the central and peripheral nervous systems. We have designed a well-controlled animal model to investigate the effects of repetitive compression on the amplitude and velocity of nerve conduction in the pudendal and pelvic nerve using the femoral nerve as a model.

Methods: New Zealand Rabbits were used in our animal experiments. All animals were managed in accordance with Institutional Animal Care and Use committee (IACUC) within the University of Minnesota. Each rabbit was anesthetized and its thigh was cut open to expose the femoral nerve. A balloon-sleeve compression system (Fig. 1(a)) was used to generate pressure on the femoral nerve. A stimulus isolator was employed to stimulate the nerve and a needle electrode was used to capture the compound nerve action potentials (CNAPs). Compression pressure was increased gradually and the amplitude of CNAPs was recorded. The nerve conduction velocity (NCV) was calculated as, where d is the distance between the electrodes, and the latency was recorded from the onset of the stimulus to the peak of the major deflection of the CNAPs.

Results: The commercially available software Chart Scope 7 (AD Instruments, Bella Vista, N.S.W., Australia) was set to deliver a single square wave pulse with stimulus duration of 0.1 millisecond (msec) and a stimulus intensity of 3 mA. The amplitude of CNAPs was recorded at different compression pressure levels. Fig. 2 summarizes the results obtained from which we can see that the amplitude of CNAPs goes down remarkably in 4 out of 6 experiments as the compression pressure goes up.

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FIG. 1.

(a) the diagram and (b) the photo of the balloon-sleeve compression system.

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FIG. 2.

Curve of amplitude of CNAPs as the compression pressure goes up.

Conclusion: Preliminary results show the amplitude of CNAPs decreases as the compression pressure is increased in most of the cases that demonstrates the feasibility of using the balloon-sleeve system to perform the designed nerve compression study. Future studies will demonstrate the relationship between repetitive compression and amplitude/velocity of nerve conduction.

Introduction: Numerous holmium:YAG optical laser fibers are available commercially for flexible ureteroscopy. Fiber performance and durability can vary widely among different manufacturers and their product lines. Differences in performance characteristics with a single product line have been reported. We sought to determine the performance characteristics of a newly developed non-tapered, single-use 240 micron fiber, the Flexima (Boston Scientific, Natick, MA), during both clinical use and in a bench-test model.

Methods: One hundred single-use fibers were used in 100 consecutive ureteroscopy procedures. Pulse energy, frequency, and total energy delivered were recorded. The amount of fiber burn back from the tip was measured with a digital micrometer. Following their use in clinical cases, the fibers were evaluated for energy transmission in both straight and 180° bent configuration using an energy detector with settings of 400 mJ at 5Hz. Fifty pulses were recorded for each trial. Failure threshold was evaluated by bending the fibers to 180° with an initial bend radius of 1.25 cm. The laser was activated with a setting of 1200 mJ at 10Hz for 30 seconds. If the fiber did not break, the radius was reducing in 0.25 cm increments and the testing repeated until a radius of 0.5 cm was reached. Three trials for each fiber were performed.

Results: The mean energy transmitted was 451 mJ and 441 mJ in a straight and 180° bend configuration, respectively. 80% of fibers transmitted at least 400 mJ; 13% of fibers fractured at a bend radius of 0.5 cm with energy transmission. No fibers failed at larger bends. No fibers failed at the connector end. During clinical use, fiber tips burnt back an average length of 1.664 mm, but the amount of burn back was highly variable. No correlation with laser settings or total energy transmission was identified. 67% of fibers had greater than half of the maximal tip length remaining following their clinical use. No fibers fractured during clinical use.

Conclusion: Fiber performance between fibers was consistent in terms of energy transmission and resistance to fracture when activated in a bent configuration. Fiber burn back during clinical use showed significant variation amongst the fibers that did not correlate with settings used or energy delivered. This suggests possible mechanical damage to the fiber tip during manufacturing. The lack of fiber fracture during clinical use may reduce the risk of flexible endoscope damage.

36. Novel Instrumentation for Davinci™ Robotic Laparoendoscopic Single-Site Surgery: Early Laboratory Experience

Introduction: Herein we describe our initial laboratory experience with VeSPA robotic instruments and assess their feasibility and efficiency for urological application.

Methods: The VeSPA surgical instruments (Intuitive Surgical, Sunnyvale, CA) were designed to be used with the daVinci Si surgical system. A multichannel port and curved cannulae were inserted through a single 3.5-cm umbilical incision. The port allowed 1 scope, 2 robotic instruments, and a 5- to 12-mm assistant instrument. Four pyeloplasties (right 2, left 2), 4 partial nephrectomies (right 2, left 2), and 8 nephrectomies (right 4, left 4) were performed in 4 female farm pigs (mean weight, 34.5 kg). Technical feasibility and efficiency were assessed in addition to perioperative outcomes.

Results: All 16 R-LESS procedures were performed successfully without the addition of laparoscopic ports or open conversion. There were no intraoperative complications. No robotic system failures occurred, and robotic instrument clashing was found to be minimal. One needle driver malfunctioned and assistant movement was limited.

Conclusion: R-LESS kidney surgery using the VeSPA instruments is feasible and efficient in the porcine model. The system offers a wide range of motion, instrument and scope stability, improved ergonomics, and minimal instrument clashing. Although preliminary experience is encouraging, further refinements are expected to optimize urological applications of this robotic technology.

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FIG. 1.

37. Laser Probe for Laparoscopic Nephron Sparing Surgery

Introduction: Laparoscopic partial nephrectomy typically requires clamping the renal vessels to prevent hemorrhage during excision of the renal masses. This warm ischemia time may damage healthy renal tissue during surgery and contribute to postoperative decline in glomerular filtration rate. Laser technologies may improve renal functional outcomes and reduce operating time by eliminating the need to clamp the renal vessels. Also, intraoperative bleeding may be reduced by the known coagulative benefits of laser technology.

Methods: To employ lasers in laparoscopic partial nephrectomy, the vaporized kidney must be evacuated from the abdomen to maintain surgeon's view of the kidney, and a support of the slender fiber must be provided to use it as a laparoscopic instrument. Also, the probe must not outpace the CO₂ used to distend the abdomen or the abdomen will collapse. A laparoscopic probe adapter for a side-fire GreenLight™ laser was designed and built. This type of laser is used frequently in laser prostate photovaporization.

Results: The probe presents a slender tubular construction through which the laser fiber is placed and securely attached at its head, as shown in the Figure 1. The side-fire tip of the fiber protrudes at the tip of the probe. The diameter of the fiber, inner, and outer diameters of the probe are 1.7 mm, 4 mm, and 5 mm respectively. The length of the probe under its handle is 283 mm. A guide is placed at the tip of the probe to center the fiber. A connection attaches the GreenLight™ at the head of the probe. To provide suction to extract the vaporized kidney tissue concurrently while lasing, several orifices are provided at the probe tip, right next to the side-fire laser output. To maximize airflow, these are built within the tip guide and also laterally within the barrel of the probe next to the tip. Two valves and corresponding buttons are placed at the head of the probe. One is connected to a vacuum source, and the other could be used for irrigation, as needed. To operate the laser probe the surgeon uses the GreenLight as usual but simultaneously depresses the vacuum valve to evacuate vapors during and after lasing. The direction of the side-fire laser can be adjusted relative to the probe from a knob behind the connection.

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FIG. 1.

Laser probe with GreenLight™ laser

Bench tests of the probe show that components can easily be assembled for the procedure. Fume suction experiments show that the vacuum extraction is functioning well. The balance between the flow of CO₂ and the outflow of the suction will be addressed in animal experiments to determine if the vapors can be effectively eliminated without collapsing the abdomen. The tip guide is expected to concentrate suction at the place where kidney vapors are produced, thus extracting with low vacuum flow. Institutional Animal Care and Use Committee protocols are approved, and porcine experiments are expected to commence soon.

Conclusion: A new probe adapter was designed and built to use a GreenLight laser for laparoscopic laser vaporization of renal tissue. We believe this strategy may be a useful adjunct for nephron sparing surgery.

Introduction: Transurethral resection (TUR) with a resectoscope (rTUR), the gold standard of bladder tumor management for 80 years, is flawed. rTUR violates the cardinal oncologic principle of en bloc resection, scattering and potentially seeding tumor throughout the bladder. This shortcoming may explain the high rate of tumor recurrence after rTUR. We describe endoscopic snare resection of bladder tumors (ESRBT), a safe en bloc method of TUR, and specimen retrieval using an electrosurgical colonic polypectomy snare and endoscopic net. We present our initial experience with 9 patients.

Methods: Under cystoscopy, a colonic snare was lassoed around the tumor base. Cutting current was applied to the snare, severing the tumor at its base and achieving hemostasis. The tumor was secured in the snare or in a mesh net and then removed. Deep resection of the tumor base was performed. Efficacy of the snare resection was evaluated by pathologic assessment. Safety was evaluated by clinical assessment.

Results: 11 bladder tumors in 9 patients (mean age: 65 years) were treated, with tumor sizes of: 2 small, 6 medium, and 3 large. All papillary TCC tumors were non-muscle-invasive, including 5 high-grade, 2 low-grade, and 1 nondiagnostic. Location: 6 lateral wall, 2 dome, 2 trigone, and 1 posterior wall. All tumors were resected en bloc. Muscle was present in 50% of specimens. There were no immediate or early post-operative complications at 2-week follow up.

Conclusion: We have shown that ESRBT is a technically easy, safe, and effective technique for TUR of pedunculated bladder tumors using currently available equipment. ESRBT limits tumor dispersal and provides excellent pathologic specimens. ESRBT may decrease morbidity and lower recurrence rates. Given our promising initial results, we foresee ESRBT as an emerging alternative treatment modality for the TUR of certain bladder tumors.

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FIG. 1.

The bladder tumor was identified (A), encircled with the snare (B, C) and resected en bloc with cutting current, leaving a small electrocautery footprint (D) with excellent hemostasis. The specimen was retrieved en bloc within an endoscopic net, preserving tumor architecture and limiting tumor dispersal (E, F).

Introduction: Image-guided prostate biopsy through fusion of multi-parametric MRI with real-time transrectal ultrasound (TRUS) offers the promise of improved cancer diagnosis. Accurate image registration of MR and TRUS is necessary to target areas of suspected cancer reliably. We performed preliminary clinical validation of the MR-TRUS registration accuracy in a 3D imaging and biopsy-tracking device (Artemis, Eigen). Prior validation of MR-TRUS registration has been performed only on phantoms.

Methods: Five patients with internal gold bead fiducials (3 per patient), previously inserted to guide radiation therapy, were imaged using multi-parametric MRI and 3D transrectal ultrasound. The fiducial locations were identified by a uro-radiologist and imaging scientists on MRI and TRUS. Prostates were then outlined using a semi-automatic segmentation method in both modalities. For each case, three users (SN, RN, DK) performed manual alignment and automatic registration independently. Segmentations in TRUS and MRI were kept constant across users per study. Registration was performed on both segmented surfaces with a user defined rigid alignment followed by an automatic non-rigid surface registration of corresponding segmentations from MR and TRUS followed by elastic interpolation. Target registration error (TRE), i.e., the distance between corresponding points on MR and TRUS, was averaged across users and fiducials in a study. The error associated with selecting a fiducial, or fiducial localization error (FLE), was normalized across users, and calculated as the mean norm of the resulting error vectors.

Results: 10 of the 15 fiducials were found with certainty on both modalities. We found an average target registration error (TRE) of 3.23 mm, with a fiducial localization error (FLE) of 0.53 mm in TRUS and 0.44 mm in MRI. When all observers agreed upon an alignment for registration, a TRE of 3.08 mm was found.

Conclusion: Registration accuracies in men agreed with values previously obtained in phantoms (Narayanan et al, IEEE Biomed Imag, 2009). FLE contributions to TRE were minimal. Increases in both the dataset size and TRUS scan quality are necessary for improved estimation of error. Segmentation variability in TRUS and MR and its contribution to TRE are also necessary for an accurate measure of error sources. These preliminary data indicate that MR-TRUS fusion, for the purpose of targeted prostate biopsy, may be performed with accuracy.

40. Ex Vivo Model for Renal Fracture in Cryoablation

Introduction: Renal fracture is a recognized complication of cryoablation. In some series it comprises 4% of the complications associated with the procedure. Factors that have been associated with the occurrence of parenchymal fracture include the usage of larger cryoprobes and the use of the guillotine technique. Several investigators have proposed different mechanisms for the formation of these fractures. Our objective was to demonstrate in a controlled lab setting the formation of fractures due to cryoablative therapy.

Methods: Endocare Perc-17 probes and Galil 17 gauge IceRod probes were selected because they are of similar diameter (1.7 mm and 1.47 mm respectively) and reported ice ball size. Cryoablation was performed with one or two probes of either Galil 1.47 mm IceRods or Endocare Perc-17. Freezes were first done in water and subsequently in the ex vivo renal model. The ex vivo model used here is a kidney obtained at the butcher or supermarket which was subsequently bivalved. One kidney that was used was fresh harvested and had a capsule. However this proved not to be essential for modeling renal fractures. The cryoprobe or probes are placed parallel and just underneath the cut surface, inserted through the lateral surface of the kidney towards the medial surface of either upper or lower pole to avoid the pelvis and major calyces and involve the most parenchyma. Freeze-thaw-freeze cycles of various durations were performed. Two IceRods and two Perc-17s were frozen individually and parallel to each other at a distance of 3 cm. Freezing was done in normal saline solution, ultrasound gel, and kidney obtained from butcher shop. These kidneys are readily available, however they are provided with the renal capsule removed.

Results: No fractures were noted in the IceRod freezes. Fractures were noted in the Perc-17 freezes, either singly or together forming one large iceball. A popping sound was noted during thaw both in the saline model and in the ex vivo hemisected porcine kidney. When there was audible cracking sound during thaw, a visible crack became evident during the second freeze in the kidney (Figure 1). Cracks were noted to extend from the probe through parenchyma. In multiple probe freezes the zone of merging of two ice balls has smooth ice and the fractures that appear there originate at the probe and extend through this area. We only observed fracture formation with the Endocare probes. We also observed more effective, faster ice ball formation with the Endocare probes.

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FIG. 1.

Fracture in the model with Perc-17 second freeze.

Conclusion: Of the proposed mechanisms of fracture generation, thermal shock fit our data best. The bivalved ex vivo kidney is a good model for study of fracture during cryoablation.

Introduction: Despite advantages of better cosmesis and potentially less surgical trauma, concerns have arisen about oncological efficacy of LESS. Our objective was to evaluate the oncological outcomes of Laparoendoscopic single-site surgery (LESS) for renal tumors in the short to mid-term.

Methods: At our center, since 2007, 34 patients have undergone LESS procedures for renal tumor, including partial nephrectomy (PN) (11), radical nephrectomy (17), cryoablation (5), and metastectomy (1). Articulating and straight laparoscopic instruments were used for standard LESS procedures (22) and the da Vinci system for robotic LESS procedures (12). Surgical, functional, and oncological outcomes were evaluated.

Results: Mean operative time was 189±51.8 minutes and mean blood loss was 252±305 milliliters. Tumors for PN procedures had median PADUA and RENAL nephrometry scores of 7 and 6, respectively; with a mean warm ischemia time of 20.2±7.1 minutes. Overall, mean visual analog pain scale at discharge was 1.5 (1–10). Mean length of stay was 3.4 days. One focally positive margin was noted after a PN, with negative intraoperative frozen section. Mean decrease of glomerular filtration rate was 15.9%. Postoperative complications included retroperitoneal abscess (Clavien IIIa) in 1 patient, and bleeding (Clavien II) in 6 patients, treated conservatively. Most of the transfusions occurred in the PN subgroup. There were 2 conversions to standard laparoscopy and 2 to open surgery. Overall, recurrence-free, and cancer specific survival were 98%, 100%, and 100%, respectively, with a mean follow-up of 26 months.

Conclusion: LESS is feasible for treatment of renal cancer in selected patients. Initial results of oncological adequacy are similar to published standard laparoscopy series; however, longer follow up is awaited.

Introduction: Recently, the RENAL nephrometry score (RNS) was developed to standardize the description of renal tumors anatomy in a quantifiable manner. The aim of this study was to evaluate the RNS as a predictor of postoperative complications related to robotic partial nephrectomy (RPN).

Methods: We reviewed the image exams of 187 consecutive patients who underwent RPN at our institution. For each patient RNS was determined. RNS consists of R: radius (tumor size), E: exophytic/endophytic properties of the tumor, N: nearness of the tumor to collecting system/or sinus, A: anterior/posterior location, L: location relative to polar lines. We evaluated the relation between the complication rate and each component of the RNS using logistic regression analysis.

Results: Mean patient age, body mass index (BMI), and tumor size were 59.6 years, 30.6 Kg/m2, and 3.15 cm, respectively. Tumor was located in the upper pole in 22%, interpolar or hilar region in 46%, and lower pole in 32% of the patients. The mean warm ischemia time was 18.3 min. The overall RNS was categorized as low complexity (4–6) in 84 patients (45%), moderate complexity (7–9) in 80 (43%), and high complexity (10–12) in 23 (12%). Larger tumors were associated with a higher frequency of complications (Chi-square test p=0.005). Forty six percent of the patients with tumors >4 cm had complications, against 21.3% of the patients with tumors ≤4 cm (Fisher exact test, p=0.0021). There was no relation between E (p=0.8), N (p=0.2), A (p=0.8), L (p=0.3) components and complications. Complications were significantly associated with more complex tumors, according to the total RNS (Chi-square test p=0.003). There was no correlation between grade of complications and complexity of the tumor, according to RNS (Chi-square test p=0.252).

Conclusion: Higher RNS is associated with increased risk of perioperative complications. Of all RNS categories, larger tumor size has the highest correlation with complication incidence.

Introduction: Successful noninvasive laser thermal coagulation of the canine vas deferens, in vivo, has been reported previously both with and without the use of optical clearing agents (to make the scrotal skin more transparent). However, there are significant differences between the tissue properties of canine and human skin. Since the matrix of laser and cooling parameters is too large to completely explore in experiments, it is important to use computer simulations to predict the optimal set of treatment parameters. In this study, a standard three-stage (optical, thermal, and tissue damage) computer model was used to explore the feasibility of noninvasive laser vasectomy in humans.

Methods: Part 1 (optical) of the model consists of a Monte Carlo model of light transport in tissue to determine the spatial distribution of absorbed photons in the major tissue layers (epidermis, dermis, and vas). The scrotal fold anatomy in the vas ring clamp makes it necessary to include skin layers on the top and bottom of the model. An index of refraction, absorption and scattering coefficient, and anisotropy factor (direction of scattering) was assigned to define the optical properties of each tissue layer. Part 2 (thermal) of the model consisted of using the MC results as the spatial heat source for the heat transfer model. Each tissue layer was assigned a value for the density, specific heat, and thermal conductivity. Part 3 (tissue damage) of the model used the temperature-time data from Part 2 as the input in a standard Arrhenius integral model for irreversible thermal tissue denaturation. In this model, tissue damage is treated as a first order rate process (based on chemical reaction kinetics) that is exponentially dependent on temperature and linearly dependent on time. Tissue damage is defined by a single parameter (Ω), where a value of Ω >1 results in irreversible tissue damage. Multiple treatment parameters were studied, including laser output power (5–9 W), cryogen pulse duration (60–100 ms), cryogen cooling rate (0.5–1.0 Hz), and increase in optical transmission (0–50 %) through skin due to application of optical clearing agents. The parameters were chosen based on those used successfully in a canine model.

Results: After application of an optical clearing agent to increase skin transmission by 50%, an average laser power of 6 W, cryogen pulse duration of 60 ms, and cryogen cooling rate of 1 Hz, resulted in vas wall temperatures of approximately 58 ^oC, sufficient for thermal coagulation (Ω >1), while 1 mm of the skin surface remained at a safe temperature of approximately 45 ^oC with Ω <1 (Figure 1). A critical temperature above 52 ^oC would result in undesirable thermal coagulation of skin.

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FIG. 1.

Map of accumulated thermal damage after 60 sec of laser irradiation and 6 W of average laser power. The vas wall is thermally coagulated (Ω >1) while the skin remains undamaged (Ω <1).

Conclusion: A computer model including Monte Carlo, heat transfer, and thermal damage simulations, indicates that it is possible to noninvasively thermally coagulate the human vas deferens without adverse side-effects (e.g., scrotal skin burns) if an optical clearing agent is applied to the skin prior to the procedure.

Introduction: Laparoscopic surgery and the ability of the surgeon to focus are benefited by a clear and uninterrupted view of the patient's anatomy. However, laparoscopic video images often are obscured and/or interrupted by the accumulation of debris on the end of the laparoscope or condensation. This is particularly true with smoke or plume from modern energy coagulation techniques. This study examines the use of FloShield™, a novel device that uses insufflation airflow to prevent debris accumulation on the end of the laparoscope, to decrease operative interruption during laparoscopic cholecystectomy.

Methods: 28 consented patients scheduled to undergo laparoscopic cholecystectomy were randomized to have their surgery performed with or without the FloShield device. An observer in the room was tasked with recording how many times during each procedure the surgeon interrupted surgery to clean the end of the laparoscope in order to restore adequate vision. These results were tabulated and compared.

Results: In the 14 laparoscopic cholecystectomy cases not using FloShield, surgery was interrupted an average of 2.96 times per case. In the 14 procedures using FloShield, surgery was interrupted an average of 0.26 times, a 90% reduction.

Conclusion: FloShield is a novel device that fits over the shaft of the laparoscope and utilizes principles of fluid dynamics to flow CO2 over the end of the laparoscope to prevent debris from attaching to the surface of the lens. FloShield prevents condensation and “spins” particulate matter away from the optics of the laparoscope. This study supports the observation in over 2,000 cases since commercial launch that FloShield significantly reduces the need to interrupt surgery to clean the laparoscope.

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FIG. 1.

Demonstrated is a smoke tube (bottom part of screen) blowing onto a 30-degree laparoscope that has the FloShield™ sheath over it. When CO2 is blowing through FloShield™ (left), the smoke is pushed away from the lens. When CO2 is not flowing through FloShield™ (right), smoke contacts the lens.

Introduction: To evaluate feasibility and diagnostic performance of submillisievert computed tomography (CT) examinations reconstructed with iterative reconstruction (IR) techniques in patients with urinary stone disease.

Methods: 26 patients (mean age 38 years) with diagnosed urolithiasis, treated and on follow-up underwent submillisievert dose unenhanced scan on 64 MDCT (Discovery CT750 HDCT, GE Healthcare) and 128 MDCT (Somatom Definition Flash, Siemens Health care) for evaluation of stone disease. The scan protocol included 80 kV, auto mA 75–150 or Ref mA - 80, slice thickness 5mm for <200 lbs and 100 kV, auto mA 75–150 or Ref mA - 80, slice thickness 5mm for >200 lbs. Images were reconstructed using filtered back projection (FBP) and IR [ASIR(GE) 60% & 80% and IRIS (Siemens)]. Images of 2–3 mm were reconstructed in the coronal and sagittal planes in all cases. All the image data set axial (FBP, IR) coronal and sagittal images were reviewed for image quality (scale 1–5), noise (scale 1–3), number & size of calculi and confidence in diagnosis of urolithiais as well as urologic or non-urologic diagnosis (scale 1–3) other than calculi on PACS work station. Comparison was made with the prior low dose FBP baseline CT scan. The radiation dose (CTDI, DLP and mSv) were recorded and compared with baseline CT studies. Analysis of data was performed by using Wilcoxon signed rank sum test and Student's t-test.

Results: All 34 stones, mean size 6.4 mm (range 4–15 mm), were diagnosed confidently by two readers, yielding 100% sensitivity and accuracy. In 8 patients, stones had passed/resolved after treatment. In giving a differential diagnosis, IR images were rated better than FBP (2.8 vs. 1.7). The mean CTDI, DLP and mSv for submillisievert protocol was 1.2, 65.3, and 0.86, respectively, in comparison to 10.6, 363.4, and 5.4, respectively for our baseline low dose exam, with 82–88% dose reduction (p=0.0013).

Conclusion: Submillisievert unenhanced CT is feasible clinically for diagnosis of urinary tract stone disease with 82% to 88% dose reduction. This study suggests that submillisievert dose CT with new iterative reconstruction technique is adequate in the assessment of urinary tract stone and enables significant reduction in radiation dose when compared with the standard, low-dose stone protocol CT.

50. The Spear-Headed Lithotriptor: An Inexpensive Alternative for Hard Stones

Objectives: To describe a novel modification of the lithotriptor head in order to make intracorporeal lithotripsy for hard calculi fast, safe, and inexpensive.

Methods: The “Spear-headed lithotriptor” was fabricated, patented, and used for percutaneous nephrolithotripsy at the Institute of Urology. It has a pointed tip in contrast to the flat disc-shaped tip of a conventional probe (Figure 1).

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FIG. 1.

Results and Discussion: Although conventional probes are excellent for stone fragmentation, they are not universally fast and efficient, especially in the setting of hard urinary stones. Another disadvantage in these clinical scenarios is stone chipping and tangential probe slippage, making it difficult to pin down the stone. This results in involuntary application of excessive axial pressure on the probe with the possible potential of renal trauma. The impact pressure generated at the tip of the probe is directly proportional to the pressure transferred along the shaft of the probe from the lithotriptor handpiece and inversely proportional to the area of the tip of the probe. At the generator settings of 4 bars; the probe tip impact pressure is 16 bars when the probe tip diameter is 3 mm (a conventional probe). On reducing the tip diameter to 0.5 mm (the Spear-headed lithotriptor) the probe tip impact pressure increases to 575 bars. Thus at the “First Hit” (i.e., on point contact of the probe with the stone), a highly focused impact force is generated (Figure 2). As fragmentation progresses, cracks and uneven surfaces cause more area of the probe tip to come into contact with the stone (Figure 3), increasing the effective probe tip area and causing a drop in the impact pressure of subsequent strikes. This creates the graduated impact force. The lateral vectors of force and mechanical separation also come into play at this stage (Figure 4) leading eventually to bivalving of the stone; the end point of the fragmentation process. The safety profile of the spear- headed lithotripter is likely to be similar to that of other pneumatic devices. As a universal precaution it should be used only under direct vision, keeping away from the mucosa. One should judge the depth of the stone to avoid injuries caused by the tip boring through the distant end of the stone. It should be fairly easy to learn and master, but it may be difficult to pin down a stone at the contact hit (i.e., prior to the creation of the first dent).

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FIG. 2.

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FIG. 3.

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FIG. 4.

Conclusions: The Spear-head creates highly focused impact forces, graduated impact forces, centrifugal vectors of force, larger stone fragments, augmented mechanical separation of the fragments, decreased lateral displacement of probe, decreased stone migration, and reduced generator pressure settings, thus improving stone pulverisation.

Introduction: Since its invention, shock wave lithotripsy (SWL) remains one of the first line options for management of upper urinary tract calculi. However, the latest generation of electromagnetic (EM) shockwave lithotripters with smaller focal areas and higher peak pressures has been criticized for lower stone-free rates and higher retreatment rates due to difficulty in keeping the stone in the smaller focal zone. Whereas the Efficiency Quotient (EQ) of the original electrohydraulic (EH) Human Model 3 (HM3) lithotripter is between 0.64 and 0.67, there is a wide variation among the reported EQs of the latest generation of EM Storz Modulith lithotripters (0.57–0.67). Therefore, the objectives of the present study was to calculate the EQ of the latest fourth generation mobile Storz Modulith SLX-F2 lithotripter and to determine factors affecting stone-free rate.

Methods: A retrospective review of a prospectively collected database of the first consecutive 533 patients undergoing SWL between June 2009 and February 2010. A total of 16 patients with radiolucent stones and 46 patients with incomplete follow-up were excluded. To minimize radiation, patients were followed with plain radiography to assess stone-free status. While success was defined as absence of residual fragments or presence of fragments <4 mm, stone-free was defined as complete absence of radio-opaque stone fragments. Retreatment was considered when a repeat SWL was performed for the same stone. Patients requiring post-SWL curative auxiliary procedures, such as ureteroscopy, were considered SWL failures and were not included in the stone-free rate. Univariate and multivariate analyses were performed to identify factors determining stone-free rates.

Results: Follow-up was complete for 474 patients with a mean age of 54.2±14.5 years. Mean stone size was 9.51±3.87 mm, with 248 (52.3%) being left-sided and 270 (57.0%) located in the kidney. Renal stones were significantly larger than ureteral stones (10.5±3.5 vs. 8.7±1.62 mm, p=0.001). Overall success rate after a single SWL session was 82.7% (renal 82.2% and ureteral 83.3%; p=0.81). Retreatment rate was 14.7% (renal 15.2% and ureteral 14.2%; p=0.79). Stone-free rate was 77% (renal 74.1% and ureteral 80.9%; p=0.10). Forty-three patients had pre-SWL ureteral stents, whereas 13 patients required post-SWL ureteral stenting. Thirty-five patients required post-SWL curative procedures. The EQ was 0.66 and the modified EQ was 0.62. On multivariate analysis, stone-free patients were associated with significantly smaller stone size (9.5 vs. 10.3 mm, p=0.02), younger age (53.1 vs. 58.0 yrs; p=0.002), right-sided stones (83.6% vs. 71.0%; p=0.001) and absence of a ureteral stent (78.7% vs. 64.3%; p=0.001).

Conclusions: The mobile Storz Modulith SLX-F2 lithotripter has an acceptable EQ of 0.66. In the present study, smaller stones (<10 mm), younger age, right-sided stones, and absence of ureteral stents were associated with significantly higher stone-free rates.

Introduction: Rapid assessment of microbial activity in a urine sample is critical in the care of medicine in the 21^st century. Over or inappropriate antibiotic use is a major factor in the cost of medical management of urinary tract symptoms and will lead to an increase in super-resistant bacterial populations. Therefore, an office-based mechanism that evaluates the potential for an active urinary tract infection would greatly enhance office-based management of this disease entity. Using the MicroBionetics CultureStat Urinary Detection System, a physician should be able to determine the potential of an active UTI or the success of a previously treated UTI within 30 to 150 minutes.

Methods: Thirty (30) patients were evaluated with lower urinary tract symptoms or a recently suspected UTI with antibiotic therapy already initiated, pending culture results. Using the CultureStat aspiration tube, 7ml of freshly collected urine is allowed to incubate for 30 minutes, followed by a spectroscopy reading looking for both turbidity (cell mass) and increased metabolic activity causing a change in TTC Level (bacterial respiration). Suspicious specimens were incubated an additional two hours to plot bacterial activity.

Results: CultureStat was able to identify 100% of the appropriately treated urinary tract infections, and was 85% accurate in identifying those patients where symptoms would require antibiotic therapy immediately.

Conclusion: Urinary tract infections are a log phase bacterial event. An increase in turbidity (cell mass) and bacterial respiration allows for a rapid assessment of active bacterial growth in the collected specimen. When incorporated with the clinical history, this can either confirm appropriate treatment of an already treated patient, or the need to start antibiotic therapy in those with a high level of bacterial activity. In an era of cost containment and efficient use of antibiotic therapy, this office-based test mechanism deserves further evaluation.

56. Cost Analysis of Metal Ureteral Stents with 12 Months of Follow-Up

Introduction: The metallic ureteral stent was developed for patients with ureteral obstruction related to malignant disease, but it can be used in all patients requiring chronic indwelling ureteral stents for ureteral obstruction. The traditional method of polymer stent management requires 3 to 6 exchanges per year depending upon patient and logistical factors. This has significant direct financial cost associated with it. We report our experience with the placement of the Resonance metallic stent for benign and malignant ureteral obstruction focusing on comparative hospital charges to polymer based ureteral stents.

Methods: A prospective database of patients undergoing metal stent placement from February 2008 to present was reviewed. Mean charges for a single, traditional non-metal and metal stents insertion was calculated. Cost was based on direct hospital charges related to stent cost and surgery.

Results: 21 patients underwent metal stent placement at our institution. Of these, 3 traditional stent placements were omitted from analysis due to charges for ureteroscopy at the same setting. Mean charges per single traditional and metal stent placement was $6,853.16 and $9,699.73, respectively. The estimated annual cost of traditional stents (3–6 exchanges) would be $18,218.25 to $36,436.50. Based on three, four, or six polymer stent exchanges per year, the annual cost reduction compared to a metal stent would then be 48.02%, 61.02% and 74.01%. No patient required early discontinuation of his or her metal stent due to LUTS or gross hematuria.

Conclusions: For patients not fit for definitive surgical intervention regarding their ureteral occlusive disease the metal stent is a financially advantageous and well-tolerated option. Compared to traditional polymer stents, the metal stent has a significant financial benefit, with an estimated cost reduction of 48% to 74%.

Introduction: A variety of minimally invasive, energy-based modalities has been and continues to be investigated for the treatment of renal tumors. The goal of any such technique is definitive destruction of the lesion, preservation of the normal surrounding parenchyma, and minimal morbidity. It is the intent of this study to determine the optimal dose and safety of radiosurgical ablation of renal tumors.

Methods: Patients who were considered to be poor surgical candidates were offered radiosurgical ablation of the renal tumor. Patients underwent renal biopsy and fiducial marker placement under computed tomography (CT) guidance with local anesthesia. A CT and/or magnetic resonance imaging (MRI) were obtained and the tumor and surrounding structures were contoured. The physicists then determined the ideal number of radiosurgical beams that would be needed to ablate the tumor and the direction of the beam. Escalating doses from 2400 cGy up to 4800 cGy were used. Patients were monitored for any adverse events; a follow-up biopsy was performed at 6 months, and serial imaging performed at 6-month intervals.

Results: A total of 19 patients have been treated to date, with a mean age of 80 years. The mean tumor size was 3.42 cm and all patients were stage T1a. Four patients received 600 cGy×4 fractions, 4 patients received 800cGy×4 fractions, 4 patients received 1000 cGy×4 fractions, and 7 patients received 1200 cGy×4 fractions. Of the patients treated, 1 patient reported a grade 2 serious adverse event (nose bleed) and there was 1 death from lung cancer, both of which were determined to be unrelated to treatment.

Conclusion: In our initial dose escalation study to determine ideal dosing and toxicity, we reached no dose limiting toxicities. We intend to extend our study with a dose escalation over 3 fractions. Once we reach the optimum ablative dose regarding toxicities, we plan to determine the efficacy. We anticipate that radiosurgical ablation of renal tumors will prove to be a safe and efficacious non-invasive option for the management of renal masses.

Introduction: Laparoendoscopic Single Site Surgery (LESS) has been applied to several urologic procedures. However, currently available systems are somewhat limited in their utility. The Single Port Instrument Delivery Extended Reach (SPIDER) surgical system was developed by TransEnterix Inc. (Durham, NC) for improved ergonomics and instrument control during LESS. The flexible design of the SPIDER system allows for continuous instrument triangulation and eliminates instrument collision during LESS. We present our initial clinical experience performing a LESS Pyeloplasty (LESS-Pp) with the SPIDER surgical system.

Methods: Following informed consent, a 40-year-old female underwent a right-sided dismembered LESS-Pp using the SPIDER surgical system for the management of a urinary obstruction. All portions of the procedure were performed using the SPIDER system with the aid of a 5-mm assistant port entering the skin <1 cm away from the SPIDER entry site.

Results: The case was completed without an intraoperative complication. The length of surgery was 423 minutes and the length of hospital stay was 4 days. An elevated JP creatinine on post-op day #2 was managed conservatively and resolved.

Conclusion: LESS-Pp with the SPIDER surgical system can be safely performed following careful patient selection. This system allows for excellent surgical triangulation without instrument crossing or clashing. However, its ultimate application in LESS-Pp remains to be proven as our experience showed an increased procedure time. Also at present, the assistant port may be required to pass suture needles as these cannot be passed through the instrument ports. Nonetheless, LESS-Pp is a safe and feasible option using the SPIDER system.

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FIG. 1.

[Top Left] Extracorporeal view of SPIDER and assistant port. [Bottom Left] Skin Incision with blake drain. [Right] Intracorporeal view of SPIDER arm triangulation during suturing.

Introduction: Laparoscopic partial nephrectomy (LPN) is the traditional approach to minimally invasive nephron-sparing surgery; however, it can be challenging technically and relies on resection without visible landmarks in a limited field of view, especially when tumors are endophytic. Ultrasound elastography, relying on the elastic properties of tissues, can discriminate and classify lesions in a number of tumor models. In order to improve the safety, applicability and dissemination of LPN and related surgeries, a real-time, image-guided intervention system using 3D elastic imaging (EI) registered to preoperative CT was created.

Methods: The strain computation process of 3DEI is optimized using dynamic programming algorithms and electromagnetic tracking of the US probe to create a 3D volume reconstruction with few low-quality frames. EI stiffness values are registered to CT density information using Mattes Mutual Information (Equation 1) as the metric for registering two distinct modalities. Three landmarks are chosen in US and CT and registered via optimization algorithms. The tumor is outlined on 2D imaging by the user, then scaled and stored into 3D by the navigation part of the system. Using electromagnetic (EM) sensors in the tumor, US probe, laparoscope and instruments, a 3D “tumor” is overlaid into the live video stream. Porcine-based and synthetic kidney phantoms with tumors were used for all experiments. \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} \begin{align*} S(\mu)= -\sum_{\iota \in L_T} \sum_{\kappa \in L_R} p(\iota, \kappa; \mu){\rm log} \frac{p(\iota, \kappa;\mu)}{p_T(\iota; \mu)p_R(\kappa)} \end{align*} \end{document}

Equation 1. Similarity metric according to Mattes Mutual Information (MMI) comparing two images with histograms LT, LR, with one image experiencing displacement μ, and joint and marginal probability distributions p, pT, and pR.

Results: Registration of the volume of interest was complete in 5 to 10 seconds for three translational degrees of freedom. With high quality, robust strain imaging, kidney tumors were imaged reliably in an interventional setting. Using EM sensors, real-time motion tracking was achieved (Figure 1).

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FIG. 1.

Real-time “augmented reality” overlay of tracked target region onto intra-operative video stream from a tracked webcam. An EM sensor (left) was manually inserted under US guidance into the tumor ROI after 3D US acquisition, with its position projected back into camera coordinates (left center and right center). The same position can be used to overlay a 3D surface model of the segmented tumor region (right).

Conclusions: Through real-time elastrography, fast 3DEI/CT registration and intraoperative tracking, kidney tumors could be located and tracked in a phantom model for laparoscopic partial nephrectomy.

Acknowledgements: IGT-JHU Grant, Georg Sakas, Professors Russell Taylor and Elliot McVeigh.

Introduction: Laparoscopic partial nephrectomy (LPN) is the traditional approach to minimally invasive nephron sparing surgery; however, it can be challenging technically and relies on resection without visible landmarks in a limited field of view, especially when tumors are endophytic. Advances in intra-operative imaging, navigation and registration with preoperative imaging may improve the safety, applicability and dissemination of LPN and related surgeries. We describe the creation and use of renal phantoms for the use in the creation of image-guided LPN.

Methods: Ex vivo phantoms (animal tissue preparations exhibiting structures resembling actual in-vivo conditions) were based on porcine kidneys (extracted shortly after exitus) due to their similarity to the human organs. The kidneys were treated partially with arterially and per urethra applied CT contrast agent (5% suspension of TiO powder (5m) in agar solution), and embedded in a stabilizing porcine gelatin mold. Additional fiducials were inserted into the phantoms to facilitate later registration. Pseudotumors were created with radiofrequency ablation and alginate injection. Using a novel system based on 3D-US elasticity imaging (EI) registration with CT imaging, pseudo-tumor containing phantoms were tested for ability to identify, register and track tumors for intra-operative motion tracking.

Results: Porcine phantoms were created by the above methods (Figure 1). Renal parenchyma, blood vessels, the collecting system, pseudo-tumors and fiducials (Figure 2) were visualized using CT and US. With high quality, robust strain imaging (through a combination of parallelized 2D-EI, optimal frame pair selection, and optimized palpation motions), kidney tumors that were previously unregistrable or sometimes even considered isoechoic with conventional B-mode ultrasound were imaged reliably.

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FIG. 1.

Porcine kidney phantom embedded in gelatin.

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FIG. 2.

US (left) and CT (right) images of the kidney phantom. The fiducials are visible in both images. The pseudotumor is visible in the CT image.

Conclusions: Porcine-based renal phantoms with tumor models are easily produced viewable in US and CT imaging. The transformation of planning CT data to the intra-operative setting with a markerless mutual-information-based registration and intraoperative tracking, using these phantoms is feasible.

Acknowledgements: IGT-JHU Grant, Georg Sakas, Professors Russell Taylor and Elliot McVeigh.

Introduction: Ureteral stents are one of the most commonly used implants in urology. Different designs and materials have been created to decrease the morbidity associated with an indwelling stent. We characterized the flow of a novel spiral cut flexible stent in a porcine model.

Methods: Flow characteristics of the novel stent were determined in an acute and chronic swine model and compared to a standard Percuflex stent. The flow characteristics in the model were determined after ligating the renal vessels and after establishing an nephrostomy tube delivering a standard rate of 0.9% saline at 35 cm H₂0. Flows in the unobstructed ureter, normal stent, intraluminally obstructed stent, extraintrinsically obstructed stent and both intraluminally and extrainsically obstructed stent were determined. In the chronic animals (animals with indwelling stent for 10 days), flow was determine in the normal stent and after stent removal.

Results: The novel stent performed as well as the standard Percuflex stent in all flow characteristics in the acute animals. Antegrade nephrostograms revealed that the novel stent appeared to conform subjectively better to the shape of the ureter. Flows were also similar in the chronic animals. Size and weight of the kidney, degree of hydronephrosis as determined on nephrostogram, and presence of urinary tract infection were also similar between stents in the chronic animals. The sectioned diameter of the mid ureter was slightly smaller in the novel stent compared to the standard stent (11.8±1.21 mm vs. 15.7±0.89 mm, p=0.032); however, other ureteral measurements did not differ significantly.

Conclusion: This novel stent with spiral cuts appears to perform as well as the standard Percuflex stent; however, the spiral cut shape of the stent seems to allow it to better conform to the ureter. Clinical trials will be necessary to determine if this characteristic will impact stent-related morbidity.

65. 5-Part Percutaneous Access Needle with Glidewire (5-PANG) Technique for Percutaneous Nephrolithotomy: Technique and Outcomes

Introduction: Initial tract creation and dilatation during percutaneous nephrolithotomy (PCNL) still remains a challenging step as the traditionally described techniques have their own shortcomings. We describe our 5-part Percutaneous Access Needle over Glidewire (5-PANG) technique in an attempt to make PCNL tract creation and dilatation a fast, safe, and less cumbersome procedure.

Methods: The 5-PANG needle was designed, fabricated, patented, and published by our institute. During PCNL the initial puncture and tract dilatation was done with the 5-PANG needle, followed by rigid telescopic metal dilatation. 364 renal units evaluated for PCNL from April 2005 to Oct 2010 were considered suitable candidates for the study. 5-PANG technique was performed at the hands of a single attending surgeon and the patients followed up to 5 years. The data were analyzed prospectively. The technique was evaluated with emphasis on the safety, efficacy, conversion rate, and associated complications. The video describes the procedure and results in detail.

Results: Average time calculated from successful puncture to rod placement was 51.32 seconds with an average radiation time of 3.31 seconds. No failure, limitations, early or late complications or sequelae related to the procedure were observed. Conversion to the conventional technique was not needed in any instance. Learning curve in different hands needs to be evaluated.

Conclusion: 5-PANG makes PCNL tract creation and dilatation, safe, fast, effective, and inexpensive. It is easy to learn and master.

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FIG. 1.

66. 5-Part Percutaneous Access Needle Over Glidewire - Suprapubic Access Technique (5-PANG-SAT): A Minimally Invasive Solution for Suprapubic Vesical Access: Our Initial Experience

Introduction: Describe and evaluate our 5-part Percutaneous Access Needle over Glidewire-suprapubic access technique (5-PANG-SAT) for easy suprapubic access of the bladder.

Methods: A 5-PANG access needle (Figure 1) designed, fabricated, and published by our institute was used for suprapubic access during suprapubic cystostomy (SPC) and percutaneous cystolithotomy (PCCL).

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FIG. 1.

Procedure: Supine position under local (for SPC) and regional/general anaesthesia (for PCCL).

Step 1: Ultrasound guided vesical puncture- with inner 3 parts of the needle. Part 1 and 2 are withdrawn. Urine flow out of part 3 confirms the puncture. A wire is parked into the bladder through part 3.

STEP 2: The 4th and 5th part are then telescoped over the part 3 till the markings. The 3^rd and 4^th parts are removed.

STEP 3: For SPC – An infant feeding tube is parked in the bladder through part 5 and part 5 removed.

For PCCL -Alkens rod is passed through part 5 and part 5 withdrawn. Alkens dilatation till desired size is followed with sheath placement.

Prospective collection of data from June 2009 to May 2011; was evaluated. Safety, potential strengths and weaknesses were assessed.

Results: All punctures were successful in the first attempt. Results not altered by the status of bladder fullness.

Advantages: Less exchange of dilators makes it a fast and painless procedure. Low chance of the wire slipping into the retropubic space. Easily done in partially full bladders. “Give away” sensation on entering bladder with USG guidance makes “controlled puncture” possible.

Eliminates posterior bladder wall injury. Drainage during SPC can be controlled allowing “slow decompression” if desired. Cheap alternative for the commercially available SPC sets.

Learning curve: easy

Conclusion: The 5-PANG-SAT allows “controlled vesical puncture” and “controlled slow decompression.” It is a safe, fast, inexpensive, and effective technique in an emergency as well as elective setup. It is easy to learn and master.

67. Ablation of Small Renal Masses: Practice Patterns at Academic Insitutions in the United States

Introduction: The purpose of our study was to determine the current practice patterns at academic institutions in the use of ablative technologies for the management of small renal masses.

Methods: Mail surveys were sent to 124 academic institutions in the United States. The survey consisted of 12 questions pertaining to the institutional use of ablation technology for treatment of small renal masses and the role of the urologist in evaluation and treatment.

Results: The overall response rate for the survey was 52% (64/124). Ablation was offered by all of the responding academic centers and included: percutaneous cryoablation (75%), percutaneous RFA (52%), laparoscopic cryoablation (83%), and laparoscopic RFA (19%). Eighty-eight percent of institutions performed 1 to 5 total ablation procedures each month. The procedure was performed primarily by radiologists alone (45%) or a combined approach with both urologist and radiologist present (42%). In combined procedures, the urologist was present at the time of ablation in 59% of institutions and placed the ablation probes in only 32% of institutions. Pre-ablative biopsy of the mass was performed at 89% of academic institutions, with 67% performing a core biopsy. Biopsy was performed prior to the day of the procedure so that the pathology was known prior to ablation in only 19% of responding institutions.

Conclusions: Ablative technologies are widely utilized for the treatment of small renal masses at current academic institutions with urologists participating in the ablation procedure in half of the institutions. While pre-ablation biopsy is common, pathology is known rarely prior to ablation.

69. Novel Robot for Trans-Perineal Prostate Needle Intervention: Phantom Study

Purpose: To evaluate in phantom prostates the accuracy of a novel robotic ultrasound-guided intervention device, which may be utilized for active surveillance and focal therapy of prostate cancer in the near future.

Materials and Methods: The BioXbot (Biobot Surgical, Singapore) is an automated robotic intervention delivery device that utilizes 2D ultrasound imaging to create 3D planning models for needle delivery. Once the targets are designated in the 3D model, the robotic positioning system serially positions the delivery arm for each target. Needle is delivered transperineally with conformation to a dual-cone template in which a maximum of two skin puncture sites are required to cover the entire prostate. We first targeted the center of pre-made hypoechoic lesions randomly distributed within three commercially available prostate phantoms (Model 053MM, CIRS, Norfolk, Virginia). As we retracted the needle from each target, we injected colored dye to mark the needle tracts. After targeting and delivering the needles to the center of the hypoechoic lesions once, we re-positioned the BioXBot device and re-captured the images of the phantom prostate to create a new planning model. Re-targeting of the hypoechoic lesion centers was then performed a second time, and the needle tracts were inked as described. Additionally, we also targeted and delivered needles to additional areas of the phantom prostate away from the pre-made hypoechoic lesions following a sextet template. The first and re-targeted sextet needle tracks were all inked. Finally, we acquired 1-mm step MR imaging of the phantom prostates and utilized the images to measure the spatial distance between tips of the needle tracts and their intended targets.

Results: Each hypoechoic lesion was targeted twice (six needle tracts per phantom x three phantoms=18 needle tracts) with the average distance from needle tip to lesion center being 3.81±1.25 mm. Of note, the needle tip was successfully placed within all nine pre-made lesions in both rounds. The tips of the sextet-based needle tracts (18 additional needle tracts) were each re-targeted by ultrasound imaging with the average distance between the first and second needle tips 4.68±1.18 mm (targeting hypoechoic lesions versus sextet biopsy tracts, p=0.06. Some difficulty was encountered in visualizing the tips of the first sextet needle tracts by ultrasound and likely contributed to an increased error in accuracy.

Conclusions: The BioXBot allows automated delivery of intervention needles, robotically targeting and re-targeting lesions within the prostate currently with reasonable accuracy. Although presently limited by its lack of real-time imaging during targeting to confirm actual needle location (versus planned target), this device has a promising future for the management of low-risk prostate cancer by active surveillance or focal therapy.

70. A Novel 3.0 Fr Ureteral Stent with Drainage Characteristics of a 4.7 Fr JJ Stent

Introduction: Double J (JJ) stents are used to manage ureteric obstruction from urolithiasis. Because the majority of flow past the obstruction is extra-luminal, a newly developed 3.0 Fr cannula with a film occlusion mechanism on the proximal end (MicroStent, PercSys) is hypothesized to provide similar drainage as a 4.7 Fr stent. Anchoring of the stent proximally to the stone within the ureter may have minimal effects on peristalsis and the smaller stent may improve patient comfort. We sought to determine whether the overall flow past the 3 Fr MicroStent is comparable to conventionally used 4.7 Fr JJ stents.

Methods: An in vitro silicone ureter model and ex vivo porcine kidney/ureter model were used to measure the overall flow through obstructed and unobstructed ureters in the presence or absence of a 3.0 Fr JJ stent (Cook), 3.0 Fr MicroStent (PercSys), or 4.7 Fr JJ stent (Cook). Six measurements in two stone positions were performed and mean flow rates were compared with descriptive statistics.

Results: Mean flow rates (mL/min) through the obstructed silicone ureter (12 mm stone) for the 3.0 Fr MicroStent, 3.0 Fr JJ Stent, and 4.7 Fr JJ Stent were 326.7±13.3, 283.3±19.2, and 356.7±14.1, respectively. Flow as a percentage of obstructed flow in the ex vivo porcine ureter model was 60%, 53%, and 50%, respectively. In both ureteric models, differences in flow rates were not significant statistically between the 3 Fr MicroStent and the 4.7 Fr JJ stent.

Conclusion: The 3.0 Fr MicroStent provides drainage equivalent to a 4.7 Fr JJ stent, in both the in vitro silicone and ex vivo porcine urinary models. We have demonstrated the crucial first step that this 3.0 Fr stent employing a novel anchoring device has similar if not improved drainage compared to its larger counterpart.

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FIG. 1.

3.0 Fr MicroStent (left), 3.0 Fr JJ stent (center), and 4.7 Fr JJ stent (right).

Introduction: Virtual reality (VR)-based simulation training tools are an attractive training solution that provides objective, performance-specific data to the user and the proctor. Validation studies of residents on the learning curve have been limited in urology due to low subject numbers at individual institutions. In order to address this issue, we designed a web-based learning management platform (LMP) that facilitates instantaneous, coordinated data acquisition, access, display, and analysis across institutions worldwide.

Methods: Requirements of the LMP include online access for demographic registration, account management for individual users vs. individual sites vs. a central-administrator level management of curricula and simulation settings, and instantaneous performance-metrics acquisition, analysis, and display for numerous real-time surgical simulators. Figure 1 demonstrates the LMP software framework with a client-server structure that collects data over the internet/intranet or locally. A client-side agent program connects and interfaces specific surgical training software, and communicates with a standardized data-server via network protocols. A front-end web application on a web-server interfaces user access to the LMP database.

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FIG. 1.

Client-Server framework for the Learning Management Platform.

Results: We have completed, integrated and tested the design of the LMP and implemented the first proof-of-concept example with the GreenLight SIM™ laser simulation curriculum to support multi-institutional studies.

Conclusion: This represents the first web-based LMP for a specific VR simulation platform in surgery. The LMP has demonstrated the aforementioned functionalities, and can be integrated as a common module with our existing and future simulation-development projects.

Sources of Funding: University of Minnesota Vincent Johnson Breakthrough Fund and sponsored research from American Medical Systems.

Introduction: Depending on size and density, Holmium:YAG laser disintegration of calculi can be a time consuming procedure. Therefore, strategies to improve stone disintegration are of major interest. We evaluated the effect of modifications in pulse sequence during Holmium:YAG laser lithotripsy in an in vitro model, using artificial calculi of varying densities.

Methods: Lithotripsy was conducted using 3 different types of artificial stones consisting of soft stone (plaster of Paris) and hard stone composition (Fujirock dental plaster grade 3 and 4). Ho:YAG laser stone fragmentation efficiency was evaluated in vitro at different pulse sequences at a standardized power output of 12 Watts (energy: 1.0 J, Pulse length 350 microsec.). Delivered energy was standardized to 750 Joule. Pulse sequence was modified. Therefore standard pulse sequence (A: 12 pulse/sec, pulse width 80 ms) was compared to modified sequences (B: 6 doublets/sec; C: 4 triplets/sec; D: 2×6 pulses/sec; E: 3×4 pulses/sec). All measurements were carried out 5 times. The volume was weighed by filling the resulting crater with fine granulated sand.

Results: With growing stone density, the volume of stone fragmentation decreased. The highest efficacy (ml/750 Joule) was achieved by standard pulse sequence (A) (see Table).

Conclusion: Modifications in pulse sequence do not lead to improved stone disintegration.

74. Jet Evacuation Technique (JET) for Calculi Extractionduring Ureteroscopy

Objectives: We describe an innovative “Jet Evacuation Technique (JET)” for easy and fast extraction of calculi during ureterorenoscopy.

Methods: Includes description of the JET and study of the advantages and pitfalls.

During ureteroscopy the “JET” is carried out as follows:

1. Place the ureteroscope in the bladder so that the orifice is seen in the centre of the field

Results: Ureteroscopy for large calculi is associated with a large ureteric stone fragment load. Stone fragment evacuation at times may be tedious. The JET facilitates fragment evacuation without increasing the risk of fragment migration. Forceful jet of saline through the ureteroscope abuts on the posterior wall of the ureter causing a whirlpool effect just outside the ureteric orifice. Some whirls enter the ureteric orifice causing eddies with exponentially decreasing diameters in the ureter proximal to the calculi. This combination of whirls and eddies help calculi evacuation and prevents proximal migration by virtue of their circular direction and decreasing magnitude in the proximal ureter. The whirlpool effect is augmented in cases of complete ureteric obstruction due to an impacted proximal calculus making the evacuation of distal calculi easier.

Conclusion: We find the JET technique fast, safe, effective, inexpensive, and easy to learn and master. This is a standard fragment evacuation technique at our institute.

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Introduction: Current diagnosis of bladder cancer is by white light cystoscopy, which has suboptimal specificity for differentiating non-papillary cancer from inflammation. Probe-based confocal laser endomicroscopy (CLE) provides dynamic in vivo imaging of the endoluminal tracts with micron-scale resolution. Real-time analysis of confocal images remains challenging with non-specific contrast agents such as intravesical fluorescein. Tumor imaging specificity may be enhanced by coupling CLE with fluorescently labeled tumor-specific antibodies or peptides. We report our preliminarily efforts of ex vivo bladder tumor imaging by CLE using an antibody against a known human tumor-specific surface biomarker and a peptide that binds human epidermal growth factor receptor (EGFR) as contrast. Studies have shown that both the antibody and peptide bind surface markers abundant in cancer but absent on the surface of normal urothelium.

Methods: The tumor-specific antibody or the EGFR-binding 12-amino acid peptide was labeled with fluorescein isothiocyante (FITC) and instilled intravesically into a fresh cystectomy specimen (n=4 for antibody; n=1 for peptide). For a negative control, tumor-specific antibody was instilled into the renal pelvis of a radical nephrectomy specimen removed for RCC. After 15–30’ incubation at 37°C, the bladder was drained, opened, and imaged with a CLE system (Mauna Kea Technologies, Paris, France). Imaging was performed of normal-appearing, tumor, and suspicious areas, followed by excision of imaged tissues for histopathology with H&E. Tumor-specific staining with the antibody was further confirmed with immunofluorescence.

Results: All bladders had high-grade urothelial carcinoma on pathology. The tumor-specific antibody consistently showed greater fluorescent staining with CLE in areas of tumor, compared to normal urothelium in all 4 bladders (Figure 1). An erythematous area was not stained by the antibody and was confirmed to be inflammation by pathology. Immunofluorescence showed tumor-specific antibody on the most superficial layer of tumor but not on normal urothelium. Similarly, preferential staining of tumor compared to normal urothelium was observed when using the EGFR-binding peptide as a contrast agent. Imaging with tumor-specific antibody on normal urothelium from the renal pelvis of a nephrectomy specimen also did not show any fluorescent signal on CLE.

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FIG. 1.

CLE of normal and tumor areas after administration of tumor-specific antibody. Corresponding H&E confirmed pathology.

Conclusion: Both the known tumor-specific antibody and EGFR-specific peptide show specificity for bladder cancer by CLE, ex vivo. Our study shows the feasibility of optical imaging of bladder cancer with CLE and tumor-specific contrast agents and raise the possibility of using intravesical molecular contrast agents for in vivo endoscopic targeted imaging of bladder cancer.

Introduction: Dynamic force feedback is integral to traditional open surgical practice. Minimally invasive techniques reduce this sense of touch and in the case of robotic-assisted surgery, remove it altogether. We have developed a lightweight and potentially minimally invasive probe which provides haptic feedback. The probe has the potential to discriminate between malignant and benign prostatic tissues and has been validated in the ex vivo setting on the human prostate.

Methods: The rolling probe consists of a spherical metal roller and an ATI Nano 17 six-axis force/torque sensor (resolution 0.0003N). It is connected to a position-sensing device. This is currently a PHANTOM Omni (SensAble), which provides 6 degrees of freedom position sensing (Figure 1). Patients undergoing robotic-assisted radical prostatectomy were recruited with full ethical approval. Immediately following prostate removal, real time data were collected by the passage of the haptic probe over the excised specimen in a standardised manner covering all aspects of the perimeter (Figure 2). During the rolling indentation, the measured tissue reaction forces along the rolling paths are fused together to generate a map showing the stiffness distribution using Matlab software (Figure 3). The force feedback maps were correlated with pre-operative clinical examination, ultrasound guided prostate biopsies, staging MRI, and the final histopathology.

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FIG. 1.

Rolling probe and position sensing device set up for testing.

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FIG. 2.

Base of prostate prepared for rolling probe examination.

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FIG. 3.

Typical 2D map on excised human prostate identifying 2 apical index lesions.

Results: As generally tumors are stiffer than the surrounding tissue, the tumor areas were indicated as higher stiffness, red colored areas. There was good correlation with clinical data, in particular for index lesions.

Conclusion: This is a new method to augment haptic feedback during robotic-assisted radical prostatectomy. It seems able to discriminate pathological tissue variations and could be used in a variety of settings. This may eventually reduce positive margins and allow more accurate nerve sparing to be performed. In vivo laparoscopic testing is planned.

Introduction: Ablative treatments are playing an increasingly important role in the management of small renal masses. Percutaneous image-guided tumor ablation has demonstrated low morbidity with encouraging renal function and oncological outcomes. ROSA™ is a new robotic system, initially developed for neurosurgical treatments, which has shown precision in instrument guidance. The aim of this study was to evaluate the feasibility and accuracy of this platform for percutaneous renal focal therapy.

Methods: Incremental targets were placed inside a body model. Fiducial markers were subsequently placed at time of the 3D CT scan acquisition (Figure 1). DICOM data were transferred to the ROSA™ system. After synchronization, preplanification consisted of defining the entry point, trajectory and target point (Figure 2). The robotic arm steered into position allowing manually insertion of the probe into the target (Figure 3). Accuracy then was evaluated.

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Results: 10 targets were used. Average targets volume and size were 1.15±0.7 ml and 11.3±4.3 mm. Preplanification was successful in all cases. Synchronization was obtained with a registration error of 2.23 mm. Median trajectory length was 142 mm (range 115–201 mm). All probes successfully reached the planned target (Figure 4).

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Conclusion: Herein, we present the first urological application of the ROSA™ platform. Robotic assistance for percutaneous ablation of renal tumors is feasible and offers precise guidance for probe positioning in preclinical studies. Clinical evaluation is ongoing.

Objective: Primary objective was to determine the robustness of the Urostation (Koelis, France), which provides 3D mapping of transrectal prostate biopsies (Figure 2). Secondary objectives were to ensure that the device does not modify routine clinical practice and to determine the impact of performing additional biopsies in undersampled zones.

Design, Setting, and Participants: The method is based on 3D transrectal ultrasound (3D TRUS). We use a 3D TRUS probe on a Sonoace X8 scanner (Medison, Korea), linked to the computer with a network cable (Figure 1). The 3D cartography is based on an automatic registration method. The clinical workflow is unchanged, meaning that biopsies are performed under local anesthesia with the patient on the left side. An initial “reference” 3D image of the prostate is recorded before starting the biopsy sampling. After every biopsy gun shot, the needle is left in the prostate less than 3 seconds while a 3D TRUS image is transferred to the computer, and displayed in 3D on the reference prostate. The clinician may rotate, zoom or reslice the 3D prostate and biopsies using a trackball. Alternatively, a 3D TRUS image may be transferred before a biopsy shot in order to check the actual biopsy target, that can be reached afterwards providing the probe is unmoved. 222 patients requiring prostate biopsies either for the diagnosis of prostate cancer or to detect recurrence following external beam radiotherapy or HIFU were included. All biopsies were performed by a single operator. All patients were biopsied according to a protocol of 12 biopsies. Additional biopsies were performed when the operator considered that a zone was undersampled at the end of protocol. Robustness was defined as the number of correctly positioned biopsies divided by the total number of biopsies performed. The absence of modification of routine clinical practice was determined by the procedure time and the pain experienced by the patient scored on a visual analogue scale between 0 and 10.

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FIG. 1.

Left : Laptop, Middle : UltraSound, Right : Patient.

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FIG. 2.

Representation of the prostate showing 12 biopsies from a posterior view. Green biopsies are negative and red biopsies are positive.

Results and Limitations: A total of 3,246 biopsies were performed. Robustness was 96% and was not modified in patients previously treated by external beam radiotherapy or HIFU. The mean time required to perform a series of 12 biopsies was 13 minutes. Additional biopsies were performed in undersampled zones in 55 patients (25%) and were positive in 7 patients (13%). Two (29%) of these patients had negative standard biopsies.

Conclusions: The Urostation provides precise transrectal prostate biopsy mapping with no significant modification of routine clinical practice. The potential of this system is above all the possibility to create for each patient a precise map of sampled areas without significant change in routine clinical practice. Moreover, it can be used in the near future in order to merge repeated biopsy sessions or to plan an accurate focal therapy treatment.

Introduction: Bladder cancer, a significant cause of morbidity and mortality worldwide, presents a unique opportunity for aggressive treatment due to the ease of accessibility for visualization and resection. While the location affords advantages, transurethral resection of bladder tumors (TURBT) is limited by current instrumentation posing difficult challenges for surgeons. We are developing a rapidly deployable telerobotic slave to improve intravesicular visualization, dexterity and accuracy of resection with the aim of reducing complication rates for TURBT procedures.

Methods: A novel TURBT device must meet the clinical requirements of the current procedures while extending capabilities toward improving current techniques and providing instrumentation for novel procedures. The development has focused on combining new imaging capabilities and dexterity for en-bloc resection of bladder tumors. Kinematic analysis was performed in the Matlab computing environment to assess the workspace of the prototype design for resection throughout the bladder.

Results: The proposed telerobotic slave uses a snake-like continuum robot providing intravesicular dexterity and compatibility with a standard resectoscope (Figure 1 left). Instrument lumens provide working channels for light-based imaging, wire or laser resection instrumentation and novel imaging devices. Analysis shows the device is capable of visualizing and reaching throughout the bladder, including anterior aspects. A cross section of the reachable workspace is shown in Figure 1 (right).

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FIG. 1.

Telerobotic slave for TURBT: Design and cross section of the reachable workspace.

Conclusion: A novel telerobotic slave is under development for precision resection during TURBT procedures. The platform provides capability of delivering simultaneous visualization and precision resection in a telerobotic slave system that can be rapidly deployed in transurethral urologic procedures. Computer assistance, augmented visualization and intravesicular dexterity will assist in improvement of TURBT procedures.

Introduction: We sought to evaluate the effectiveness of the da Vinci^® bowel clamp EndoWrist^® instrument compared to routinely used bulldog clamp for renal hilar control in an experimental setting.

Methods: The study was performed on the porcine animal model. The standard da Vinci system was used for the series of experiments. The robotic bowel clamp has a 4 cm long tip with coarsely ribbed and centrally fenestrated grip panel. Under general anesthesia and in flank position the kidney was exposed through a subcostal flank incision and renal hilum skeletonized. As the first experiment the renal artery was clamped directly with the robotic instrument, an upper pole partial nephrectomy performed and hemostasis assessed. As a subsequent experiment, the renal artery while clamped was directly transected and bleeding evaluated. To assess and compare potential direct mechanical tissue damage by the clamp to the vessel wall, in series of experiments renal artery and vein separately as well as en bloc were clamped for 20 and 40 minutes. Vessel segments then were harvested and examined histologically by a “blinded” pathologist. The contralateral kidney with the hilum being controlled by the bulldog clamp served as control in all experiments.

Results: Adequate hemostasis comparable to the bulldog clamp was achieved by the robotic instrument in all experiments. The robotic bowel clamp allowed also for a scaled vessel occlusion according to the degree of instrument closure. In the histologic examination assessing specifically direct tissue crushing effects, no differences between the specimens of different clamping techniques were observed. Accordingly, in tissue specimens clamped for increasing time intervals similar findings between the two groups were observed.

Conclusion: The robotic EndoWrist^® bowel clamp demonstrated effective renal vascular clamping properties in this study. Due to the significantly enhanced degrees of movement, the robotic instrument may allow for easier and faster clamp placement and removal facilitating more selective renal vascular occlusion compared to bulldog clamps.

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FIG. 1.

Comparison of the Bulldog clamp with the robotic EndoWrist^® bowel clamp. Harvested renal artery segments for histological assessment are demonstrated.

Introduction: A limitation of the DaVinci surgical system is a lack of direct sensory feedback to the operative surgeon. Experienced robotic surgeons use visual interpretation of tissue and suture deformation as a surrogate for tactile feedback. One of the difficulties encountered during robotic surgery is maintaining adequate suture tension while tying knots or following a running anastamotic suture. Measuring and displaying suture strain in real time has potential to decrease the learning curve and improve the performance and safety of robotic surgical procedures. Conventional strain measurement methods involve installation of complex sensors on the robotic instruments. This study presents a non- invasive image processing video-based method to determine strain in surgical sutures.

Methods: To measure suture strain, we employed a suture that was pre-marked with a set of dark markers at regular intervals. Shown in Figure 1 is a marked suture held between the two grippers of a surgical robot. The suture strain is measured by video detection of the displacement of these markers upon tension. The image processing algorithm is composed of image enhancement (color channel selection), edge detection, line detection (Hough transform), line profiling and marker detection, marker tracking (quadratic regression), and strain computation. The video analysis method was developed and validated using video of suture strain standards on an Instron 8500+servo-hydraulic testing system. Strain calculations were implemented in two ways: one point tracking and two point tracking.

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FIG. 1.

Marked 2.0 Dexon II suture held by the two robotic needle holders.

Results: These tests showed a minimum detectable strain of 0.2% for one marker tracking on stationary suture and 0.5% for the more clinically relevant two-marker tracking on moving suture. These minimum detectable strains are two orders of magnitude smaller than the known strain to failure of most suture materials (20+%), allowing a large margin of safety in the clinical setting.

Conclusion: This study presents a non-invasive method based on a video algorithm to calculate suture strain from the surgical video images, thus avoiding the complex installation of strain sensors.

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FIG. 2.

Snapshot of the video processing for strain measurement display.