Acta Radiologica

Purpose: Treatment of residual or recurrent aneurysms after surgical clipping is a challenge and most surgeons prefer to avoid a second surgical attempt. We present treatment of 4 residual or recurrent aneurysms after surgical clipping with electrolytically detachable coils.

Material and Methods: In 3 of 4 patients, recurrent aneurysms were diagnosed with angiography 2 months, 5 years and 14 years after surgery, although the domes of the aneurysms were opened following clipping during the surgery. In the 4th patient, an early postoperative angiogram revealed filling of a residual aneurysm secondary to the incomplete neck clipping. Guglielmi detachable coils were used to occlude the residual or recurrent aneurysm.

Results: The endovascular approach was successful in all patients and the control angiograms showed complete obliteration of the aneurysms with no recanalization.

Conclusion: The endovascular approach is a good treatment option for patients in whom complete obliteration of the aneurysm cannot be achieved by surgical clipping. Opening of the aneurysm sac after clipping does not necessarily preclude aneurysm regrowth from a neck remnant proximal to the clip.

Purpose: To test the effect of digital compression of CT images on the detection of small linear or spotted high attenuation lesions such as coronary artery calcification (CAC).

Material and Methods: Fifty cases with and 50 without CAC were randomly selected from a population that had undergone spiral CT of the thorax for screening lung cancer. CT image data were compressed using JPEG (Joint Photographic Experts Group) or wavelet algorithms at ratios of 10:1, 20:1 or 40:1. Five radiologists reviewed the uncompressed and compressed images on a cathode-ray-tube. Observer performance was evaluated with receiver operating characteristic analysis.

Results: CT images compressed at a ratio as high as 20:1 were acceptable for primary diagnosis of CAC. There was no significant difference in the detection accuracy for CAC between JPEG and wavelet algorithms at the compression ratios up to 20:1. CT images were more vulnerable to image blurring on the wavelet compression at relatively lower ratios, and "blocking" artifacts occurred on the JPEG compression at relatively higher ratios.

Conclusion: JPEG and wavelet algorithms allow compression of CT images without compromising their diagnostic value at ratios up to 20:1 in detecting small linear or spotted high attenuation lesions such as CAC, and there was no difference between the two algorithms in diagnostic accuracy.

Purpose: To determine if ultrasound angioplasty in a percutaneous approach was capable of recanalizing occluded arteries in acute and subacute peripheral arterial occlusions.

Material and Methods: We applied an ultrasound angioplasty device in a percutaneous approach in 9 patients with peripheral arterial occlusions. All patients suffered from severe leg ischemia due to subacute thrombotic occlusions.

Results: The ultrasound transmitter easily created a channel within the occlusive material. To further reduce the mass of the occlusive material, an aspiration thrombectomy was performed in all cases, leading to a complete recanalization in 7 cases. In 2 cases, a remaining stenosis was successfully dilated.

Conclusion: Intravascular ultrasonic devices can be useful for recanalization of occluded peripheral arteries. In particular, if thrombolytic therapy of longer peripheral arterial occlusions fails or is contraindicated, ultrasound angioplasty may be a new approach for recanalization.

Purpose: To evaluate and compare the diagnostic accuracy of duplex ultrasound (US) and MR angiography (MRA) at 1.0 T in aortoiliac arterial disease using digital subtraction angiography (DSA) as the reference standard. In addition, a comparison of the 2D time-of flight (TOF) and 3D contrast-enhanced MRA (CE MRA) techniques was performed.

Material and Methods: Prospectively, 39 patients with symptoms of lower-extremity arterial occlusive disease were examined using US, TOF MRA, CE MRA and DSA. Significant lesions (stenosis ≥50%) and occlusions were evaluated blindly for each method.

Results: For all segments, the sensitivity for US, TOF MRA and CE MRA with regard to significant lesions was 0.72, 0.81 and 0.81, respectively, and the specificity for each was 0.97, 0.91 and 0.92, respectively. For significant lesions above the inguinal ligament the corresponding sensitivity was 0.84, 0.89 and 0.94 and the specificity 0.93, 0.82 and 0.73, respectively. The specificity was higher when the two MRA methods were combined. TOF MRA overgraded 7 segments as occluded. In most cases, the length of the occlusions was correctly determined on CE MRA, overestimated on TOF MRA and uncertain on US.

Conclusion: Neither US nor MRA were sufficiently accurate to fully replace angiography. MRA was preferable to US as a non-invasive test when vascular intervention was contemplated. Although CE MRA was superior to TOF MRA, the most accurate results were achieved when the two methods were combined.

Objective: To determine the clinical feasibility of contrast-enhanced three-dimensional (3D) MR angiography (MRA) with fat suppression spectral inversion at lipids and to compare subtracted and nonsubtracted images.

Material and Methods: In 13 patients suspected of having lower extremity ischemia, 3D dynamic contrast-enhanced MRA of the iliac and femoral arteries was performed using the fat suppression technique. The validity of the MRA interpretations of the degree of stenoses was evaluated by comparing with conventional angiography as the gold standard. The contrast-to-noise (C/N) ratios of both subtracted and nonsubtracted maximum-intensity-projection (MIP) images were calculated.

Results: In the arteries with stenosis of 50% or greater, the sensitivity and specificity of the subtracted MR angiograms were 100% and 96.5%, respectively, not significantly different from the correponding values in nonsubtracted MRAs (100% and 94.1%, respectively). The C/N ratios of the subtracted images were significantly higher than those of the nonsubtracted images (p<0.001).

Conclusion: With this technique, fat suppression can be performed with only a slight increase in the examination time. A lower dose of contrast material can be used in MRA with fat suppression than without it. Subtracted MRA improves the ease of interpretation compared to nonsubtracted MRA.

Phase contrast MR angiography (PC-MRA) depends on phase shifts caused by blood flow. Generally, PC sequences employ one VENC (velocity-encoding) value for each encoded spatial direction to optimize the signal in major vessels during peak systolic flow. We compared a mono- (30) with a multi- (20/30/45) VENC-PC-MRA technique in 10 patients with peripheral arterial occlusive disease. In all patients, the multi-VENC-PC sequence enhanced the vascular signal in vessels with very different flow velocities in one measurement. Large fields-of-view can be measured in a relatively short examination time to obtain an overview of the peripheral arterial system of the patient when contrast-enhanced MRA is not possible.

Purpose: To prospectively register fluoroscopic and cine times in a random fashion, and to measure patient radiation exposure from routine coronary angiography and coronary balloon angioplasty. We also evaluated an optional dose reduction system used during interventions.

Material and Methods: The incident radiation to the patient was measured as kerma area product (KAP) in Gycm², obtained from an ionisation chamber mounted on the undercouch tube during 65 coronary angiography procedures and another 53 percutaneous transluminal coronary angioplasties (including 29 stent procedures), mostly directly following complete coronary angiography.

Results and Conclusion: The values from coronary angiography were comparable to other reports with a mean fluoroscopic time of 4.4 min and a mean KAP value of 62.6 Gycm². The corresponding figures from coronary balloon angioplasty without stenting were lower than otherwise reported, with 8.2 min and 47.9 Gycm², respectively. The use of coronary stents did prolong the mean fluoroscopic time (10.5 min) but did not significantly enhance the patient mean radiation dose (51.4 Gycm²). The dose reduction technique resulted in a significant KAP value reduction of 57%. In conclusion, with regard to radiation exposure, coronary angiography and balloon angioplasty are considered safe procedures.

Purpose: To evaluate the significance of bread and barium studies as a diagnostic tool as well as a supplement to manometric investigation of the esophagus in patients with suspected esophageal motility disorders.

Material and Methods: Eighty-nine patients suspected for primary esophageal motility disorders were examined. All patients were interviewed before the investigation to determine the prevalence of symptoms like heartburn, chest pain, and dysphagia. The patients underwent simultaneous roentgenologic and manometric investigations in the supine position during wet and solid barium swallow, and during continuous drinking, followed by investigation for gastroesophageal reflux (GER). The manometric examination was performed with triple-lumen catheters connected to a hydraulic capillary infusion system and external transducers.

Results: All patients with normal esophageal clearing (n=31) had normal manometry. Patients with delayed esophageal clearing (n=58) required manometry for identifying concommittant motility disorders; achalasia and diffuse esophageal spasms were found only in patients with delayed liquid and solid emptying. GER and/or esophageal rings was demonstrated in 31 patients.

Conclusion: We suggest bread and barium as the first diagnostic step in patients with clinical suspicion of primary esophageal motility disorders.

Purpose: In an experimental study in rats a correlation between nutritional status and hepatic attenuation in CT and signal intensities in MR imaging was shown. Is physiological nutritional status of importance in clinical CT and MR imaging?

Material and Methods: In a cross-over study including 12 healthy volunteers (6 women and 6 men, mean age 34 years), CT and MR imaging of the liver were performed with nutritional status at three different levels, i.e., normal, fasting and after glycogen-rich meals. CT and MR were performed on clinical imaging systems and hepatic attenuation and signal intensity, respectively, were assessed. In MR, T1-weighted, proton density-weighted and T2-weighted pulse-sequences were used.

Results: In CT there were significantly (p<0.01) higher liver attenuations in normal nutritional status and after glycogen rich-meals compared to the fasting condition. The difference between fasting and glycogen-rich meals were 10.5 HU for men, 7.4 for women and mean 8.8 HU for all 12 volunteers. In MR imaging the differences were small and non-significant. The results of this study are in accordance with an earlier experimental study in rats.

Conclusion: In CT it may be of importance not to have patients in a fasting condition as it lowers the attenuation in normal liver tissue. The findings are important for planning of clinical studies where hepatic attenuation will be assessed and may be of some importance in clinical CT. In MR imaging the results indicate that the nutritional status is of less importance.

Objective: To determine the frequency, character, methods of treatment, and outcome of ischemic complications after transcatheter hepatic artery chemoembolization (TACE).

Material and Methods: Between 1985 and 1998, 827 sessions of TACE with Doxorubicin mixed with iodized oil, and gelatin sponge particles were performed in 282 patients with primary and metastatic liver cancer. Post-TACE monitoring included clinical observation, US and CT.

Results: Ischemic complications appeared in 13 (4.6%) and included the following: hepatic (n=6) and splenic abscess (n=1), cholecystitis (n=3), and bile duct necrosis (n=3). The treatment was US-guided drainage in 12 cases and systemic antibacterial therapy in 1. No negative influence of these complications on survival of patients was detected.

Conclusion: Serious ischemic complications of TACE occur in about 5% of patients and can be successfully managed without open surgery. These complications do not worsen the survival of patients.

The case of a 3-month-old boy with a hepatic infantile hemangioendothelioma is reported. There was no previous history of disease and no symptoms, only an incidentally found abdominal mass. The case is presented as an example of establishing the diagnosis, deciding upon the treatment, and performing the follow-up using only non-invasive imaging techniques.

We describe the case of a 35-year-old man who had suffered a severe multitrauma with blunt thoracic injury, left scapula and humerus fractures 5 years earlier. At the time of the trauma, a diaphragmatic lesion went unnoticed. Five years later, the patient had a 24-h history of increasingly severe abdominal pain with repeated vomiting. Helical CT showed a portion of the left hemidiaphragm avulsed from its insertions on the ribs with large-bowel loop obstruction herniated in the left hemithorax. The preoperative CT diagnosis was confirmed by surgery: reduction of the hernia and reinsertion of the hemidiaphragm to the lumbocostal arch were performed.

Purpose: To analyse factors behind the variation of patient doses from barium enema (BE) examinations.

Material and Methods: The patients' (n=89) organ and effective doses (E) due to BE examinations were computed with the ODS-60 program. An average risk factor for BE examinations was derived using the BEIR V schema. The correlation of E with several independent variables was analysed.

Results: Median Es at five hospitals were 4.4, 6.1, 7.1, 13 and 16 mSv. The E of the female patients (median 9.2 mSv) was higher than that of the males (median 5.4 mSv) (p&lt;0.001) due to the higher female doses to the gonads, bladder and uterus, resulting from different body structure. An average fatal risk factor of 0.02% per one BE examination was derived. Factors controlled by the radiologist (screening time, number of exposures) explained 40% and patient-related factors explained 16% of the total variation of E. The equipment-related factors are included in the residual 44%.

Conclusion: Due to the large contribution of the radiologists' examination technique in the value of E, an optimal examination technique is essential in reducing doses and the stochastic risk to patients.

Purpose: To examine the value of superselective arterial stimulation venous sampling (ASVS) to localize insulinomas.

Material and Methods: Superselective ASVS (SS-ASVS) was performed in 9 patients with insulinoma. Injection of secretagogue (calcium gluconate: 0.01 mEq Ca⁺⁺/kg) was performed into the gastroduodenal, splenic (proximal and distal), and superior mesenteric arteries in 9 patients and additionally into the dorsal pancreatic artery in 6 patients. Sampling from the hepatic vein was performed to measure serum insulin concentrations at 30, 60 and 120 s after each injection of secretagogue into these arteries. SS-ASVS results were correlated with surgical findings, compared to those of conventional ASVS.

Results: Insulinomas were correctly localized to the head, body or tail of the pancreas by SS-ASVS in 8 patients (89%). Conventional ASVS detected insulinomas in 7 patients (78%), although it could not distinguish whether the insulinoma was located in the pancreatic body or tail in 4 of the 7 patients. There were eight-fold or more increases in serum insulin levels in hepatic venous samples related to the artery supplying the tumor in 8 patients. Localization of the insulinomas was verified at surgery in all patients.

Conclusion: SS-ASVS is a useful method for detailed evaluation of overproduction of insulin from pancreatic insulinomas and their localization. When the pancreatic insulinoma is situated in the pancreatic body or tail, the localization is more accurately made by SS-ASVS than by conventional ASVS.

Purpose: According to the World Health Organization (WHO) criteria for response of bone metastases to therapy, new lesions indicate progressive disease. We intended to prove that a new sclerotic lesion on conventional radiography may also be a sign of a positive therapeutic response in a previously undetectable lytic metastasis.

Material and Methods: In a previous placebo-controlled clinical trial of clodronate (Ostac) therapy, 139 breast cancer patients with bone metastases underwent both conventional radiography and bone scan every 6 months for 2 years with ^99mTc before and during clodronate treatment. WHO criteria were applied for therapy response evaluation.

Results: In 24 patients, 52 new sclerotic lesions observed during therapy were selected for re-evaluation of conventional radiographs and bone scans. In 8 of the 24 patients, 17 of 52 new sclerotic lesions (33%) had showed positive uptake on previous bone scans. These lesions were possibly misinterpreted as new when applying WHO criteria.

Conclusion: For better assessment of new sclerotic lesions during treatment, more sensitive techniques, e.g. bone scan, are needed as a complement to conventional radiography.

Purpose: To evaluate a simple method for quantification of focal activity in bone scintigraphy (BS).

Material and Methods: The gamma camera was calibrated using a phantom. Quantitative bone scintigraphy (QBS) was performed on 11 men recently diagnosed with prostate cancer (PCa), for whom routine BS showed involvement of the skeleton. Following endocrine therapy for 4 to 8 months, a second QBS was performed. Changes in QBS values were then compared to changes in serum levels of prostate-specific antigen (PSA).

Results: PSA response indicating regression of PCa was accompanied by a decrease in the QBS value in 8 of the 11 patients. The overall mean error of the QBS values was 15%.

Conclusion: QBS according to this method is a relatively simple procedure that might contribute to objective evaluation of therapeutic effects in skeletal metastases, although its validity must be tested in a larger clinical material.

Purpose: To get an informative and detailed picture of the resource utilization in a radiology department in order to support its pricing and management.

Material and Methods: A system based mainly on the theoretical foundations of activity-based costing (ABC) was designed, tested and compared with conventional costing. The study was performed at the Pediatric Unit of the Department of Radiology, Oulu University Hospital. The material consisted of all the 7,452 radiological procedures done in the unit during the first half of 1994, when both methods of costing where in use. Detailed cost data were obtained from the hospital financial and personnel systems and then related to activity data captured in the radiology information system.

Results: The allocation of overhead costs was greatly reduced by the introduction of ABC compared to conventional costing. The overhead cost as a percentage of total costs dropped to one-fourth of total costs, from 57% to 16%. The change of unit costs of radiological procedures varied from −42% to +82%.

Conclusion: Costing is much more detailed and precise, and the percentage of unspecified allocated overhead costs diminishes drastically when ABC is used. The new information enhances effective departmental management, as the whole process of radiological procedures is identifiable by single activities, amenable to corrective actions and process improvement.

Purpose: We evaluated the usefulness of CT for assessing oxygen desaturation during walking in patients with emphysema.

Material and Methods: The study comprised 32 patients with emphysema (mean age 67±6 years). Serial CT images of 5 mm were obtained from the apex to the basal regions of the lung during deep inspiration. The severity of emphysema was scored by four physicians according to a visual method. A six-minute walking test and oxygen desaturation (pSO₂) measurements were performed.

Results and Conclusion: The mean CT score of the four observers was signfiicantly correlated with the nadir pSO₂ and ΔpSO₂, but did not correlate with the total distance walked. These results suggest that CT may be used for the assessment of oxygen desaturation during low-grade exercise in patients with emphysema.