Acta Radiologica

Kupffer cells (KC) have an important role in the host defense in obstructive cholangitis. Non-invasive monitoring of phagocytic function of KC is pivotal. Several studies showed the possibility of non-invasive monitoring of phagocytic function of KC using superparamagnetic iron oxide-enhanced magnetic resonance imaging (SPIO-MRI) or contrast-enhanced ultrasound (CEUS).

To investigate the serial change of KC function using SPIO-MRI and CEUS and whether the SPIO-MRI parameter correlates with the CEUS parameter in obstructive cholangitis rat models.

With our institutional Animal Care and Use Committee approval, 19 rats (common bile duct ligation [CBDL]: n = 9; control: n = 10) underwent SPIO-MRI and CEUS at baseline, two, and four weeks after CBDL. The relative signal loss (RSL) of T2* value on SPIO-MRI and Kupffer phase parenchymal echogenicity (KPE) on CEUS were measured. The correlation between SPIO-MRI and CEUS parameters were compared with KC count.

In CBDL group, RSL and KPE had significantly decreased (72.1% to 29.5%, 2.7 to 0.4) at four weeks compared with those in the control group (68.2% to 58.3%, 2.5 to 3.0, P < 0.05). During the follow-up period, RSL showed significantly positive correlations with KPE (P = 0.007). In addition, at four weeks, we found RSL was positively correlated with KPE (ρ = 0.750, P = 0.002). KC count was negatively correlated to RSL and KPE at four weeks (ρ = −0.771, P = 0.001 and ρ = −0.644, P = 0.013).

SPIO-MRI and CEUS may be equally useful for monitoring the serial changes of KC phagocytic function in vivo.

Traditional computed tomography (CT) can predict the lymph node metastasis of gastric cancers with moderate accuracy; however, investigation of spectral CT imaging in this field is still limited.

To explore the application of spectral CT imaging in evaluating lymph node metastasis in patients with gastric cancers.

Twenty-four patients with gastric cancers prospectively underwent spectral CT imaging in the arterial phase. The short and long diameters, material concentrations, and CT values were measured and compared between lymph nodes with and without metastasis. The diagnostic performance of the CT index in identifying metastatic lymph nodes was analyzed with receiver operating characteristic (ROC) analysis.

A total of 102 lymph nodes (77 metastatic, 25 non-metastatic) were detected on spectral CT imaging with the reference of postoperative pathologic exanimation. The short and long diameters, water/fat concentrations, CT value, and ratio between lymph nodes vs. tumors of metastatic lymph nodes were significantly higher than those of non-metastatic ones (all P < 0.05). With a cut-off of 0.785, the CT ratio of lymph node/tumor on 70-keV monochromatic images yielded an accuracy of 81.4% in differentiating lymph nodes with and without metastasis.

Spectral CT imaging detects lymph nodes more clearly, and the CT ratio of lymph node/tumor on 70-keV monochromatic images holds great potential in differentiating lymph nodes with and without metastasis, which is more accurate than size measurement.

Virtual monochromatic images (VMI) generated using spectral computed tomography (CT) are promising recently available tools to improve diagnostic performance in oncologic patients.

To investigate if virtual monochromatic datasets are suitable for clinical routine use in patients with hypervascularized abdominal tumors.

A total of 41 patients with hypervascularized hepatocellular carcinoma (HCC), renal cell carcinoma (RCC), or neuroendocrine tumors (NET) were enrolled in the study; 451 CT series were analyzed. In an intra-individual study design, virtual monochromatic datasets of the arterial phase of each scan were computed. Image quality was assessed objectively by determining signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR) and subjectively by using five-point Likert-scales. The volume CT dose index (CTDI_vol) was taken from each radiation dose report. The increase in reading time was estimated from the increase in the number of images.

Intra-individual comparison of the spectral mode in the arterial phase with the portal venous phase revealed no significant increase in the applied dose. SNR, CNR_{tumor-to-liver} , and CNR_{tumor-to-muscle} were significantly increased by lowering virtual monochromatic energy. Subjective image quality scores revealed an increase of contrast in low energy datasets, resulting in significantly higher diagnostic confidence, but an increased image noise at low energies. While diagnostic confidence improved, taking all datasets into account resulted in a significantly longer estimated reading time.

In clinical practice, the use of low energy VMI improved diagnostic confidence without a significant increase in dose. The main disadvantage is a decrease in efficiency due to longer reading times.

Determining the growth rate of pancreatic cystic lesions on follow-up imaging is important in managing patients with these lesions. However, the growth rates of serous pancreatic neoplasms (SPNs) have been reported to vary among studies.

To determine the in vivo growth rate of SPNs.

This retrospective, single-institutional study included patients diagnosed with SPNs during 2006–2015. The diagnosis of SPNs was based on the results of surgery, endoscopic ultrasonography (EUS)-guided fine needle aspiration (FNA) or core needle biopsy (CNB), or typical radiologic features of SPN. A linear mixed-effects model was utilized to determine whether the diagnostic intervention was associated with tumor growth rate in all patients. The in vivo growth rate of SPNs was estimated from patients without or before diagnostic intervention. SPN growth rates were compared before and after diagnostic intervention.

SPN growth rates in the overall patient cohort (n = 304) differed significantly between patients who did and did not undergo diagnostic interventions. The in vivo SPN growth rate in 204 patients without or before diagnostic intervention was 1.9 mm/year (95% confidence interval [CI] = 1.6–2.2). In the 130 patients who underwent diagnostic intervention, the SPN growth rate was significantly greater before than after diagnostic intervention (1.8 vs. 0.2 mm/year).

In the absence of diagnostic intervention, the in vivo growth rate of SPNs was 1.9 mm/year (95% CI = 1.6–2.2). EUS-guided FNA or CNB may affect the growth rate of SPNs.

Liver magnetic resonance imaging (MRI) provides reliable diagnostic performance for detecting liver metastasis but is costly and time-consuming.

To compare the diagnostic performance of non-contrast liver MRI to whole MRI using gadoxetic acid for detecting liver metastasis in patients with colorectal cancer (CRC).

We included 175 patients with histologically confirmed 401 liver metastases and 73 benign liver lesions. A non-contrast MRI (T1-weighted, T2-weighted, and diffusion-weighted images) with or without multidetector computed tomography (MDCT) and a whole MRI (gadoxetic acid-enhanced and non-contrast MRI) were analyzed independently by two observers to detect liver metastasis using receiver operating characteristic analysis.

We found no significant differences in Az value (range = 0.914–0.997), sensitivity (range = 95.2–99.6%), specificity (range = 77.3–100%), or positive (range = 92.9–100%) or negative predictive value (range = 87.5–95.7%) between the non-contrast MRI with or without MDCT and the whole MRI for both observers for all lesions as well as lesions ≤1.0 cm and lesions >1.0 cm in size (P = 0.203–1.000). Combined MDCT and non-contrast MRI led to similar numbers of false-positive diagnosis to the whole MRI (eight for Observers 1 and 4 vs. 3 for Observer 2).

Non-contrast liver MRI may serve as an alternative to gadoxetic acid-enhanced MRI for detecting and characterizing liver metastasis from CRC, at least in patients with relatively high risk of liver metastasis who underwent MDCT. Non-contrast liver MRI could be beneficial especially for patients with lesions that are already documented as benign but require additional follow-up MRIs.

Predicting the exact extent of a breast tumor is of great importance for oncologic treatment strategies. Different types of elastography can be used as new tools for measuring lesion size.

To provide evidence regarding the accuracy of tumor size measurement of strain elastography (SE), two-dimensional (2D) and three-dimensional (3D) shear wave elastography (SWE), and conventional B-image ultrasound.

In this prospective study, the diameter of 105 malignant breast lesions was measured by SE, 2D and 3D SWE, and B-mode ultrasound. The histopathological lesion size was compared to all imaging-based measuring methods.

The mean lesion size of all breast carcinomas was 1.54 cm. B-mode ultrasound underestimates breast cancer size in 65.7 % of all cases in this study (P < 0.0001). Mean lesion size was more accurately determined by SE, 2D and 3D SWE compared to B-mode ultrasound. Absolute differences between measured and actual lesion are smaller for B-mode ultrasound (0.26 cm) than for SE (0.41 cm) and 2D and 3D SWE (0.41 cm and 0.44 cm, respectively).

B-mode ultrasound allows more accurate lesion size measurement than SE and 2D or 3D SWE but has a significantly higher risk of underestimating tumor size which could lead to incomplete margins during surgery. 3D SWE was not superior to 2D SWE or SE but by trend more precise in predicting the size of invasive lobular carcinoma.

Regional fat density assessed by computed tomography (CT) has been suggested as a marker of perivascular adipose tissue inflammation. Dual energy CT (DECT) allows improved tissue characterization compared to conventional CT.

To explore whether DECT might aid regional fat density discrimination.

We included patients who had completed a non-enhanced cardiac CT scan, CT coronary angiography (CTCA), and a delayed enhancement CT. Attenuation levels (Hounsfield units [HU]) were assessed at the epicardial, paracardial, visceral, and subcutaneous fat. The number of coronary segments with disease (SIS) was calculated.

A total of 36 patients were included in the analysis. Twenty-six (72%) patients had evidence of obstructive disease at CCTA and 25 (69%) patients had evidence of previous myocardial infarction. At non-contrast CT, we did not identify significant attenuation differences between epicardial, paracardial, subcutaneous, and visceral fat depots (−110.8 ± 9 HU, vs. −113.7 ± 9 HU, vs. −114.7 ± 8 HU, vs. −113.8 ± 11 HU, P = 0.36). Significant attenuation differences were detected between fat depots at mid and low energy levels, both at CTCA and delayed-enhancement scans (P < 0.05 for all). Epicardial fat showed the least negative attenuation, irrespective of the acquisition mode; epicardial fat evaluated at 40 keV was related to the SIS (r = 0.37, P = 0.03).

In this study, regional fat depots amenable to examination during thoracic CT scans have distinctive regional attenuation values. Furthermore, such differences were better displayed using contrast-enhanced monochromatic imaging at low energy levels.

Aortic valve calcification quantification using cardiac computed tomography (CCT) is a reliable marker for aortic stenosis (AS) in patients with bicuspid aortic valve (BAV) disease.

To determine the association of Agatston aortic valve calcium score (AVCS) with morphological and hemodynamic characteristics of BAV and define cut-off AVCS for optimizing the grade of AS in patients with bicuspid AS.

This study included 161 BAV patients with AS regardless of aortic regurgitation who underwent transthoracic echocardiography and CCT. BAVs were classified according to orientation of cusps and presence of raphe. Associations of AVCS with characteristics of BAV morphology and functional variables were determined by linear regression analysis. Area under the receiver operating characteristic curve (AUC) was used to determine the cut-off AVCS greater than which the diagnosis of severe AS was optimized.

AVCS was significantly different according to sex (P < 0.001), AS severity (P < 0.001), type of valvular dysfunction (P = 0.011), and orientation of cusps (P = 0.028). Multiple linear regression showed that AVCS was significantly associated with sex (estimate = −0.583, P < 0.001) and AS severity (estimate = 0.817, P < 0.001). AVCS was a predictor for severe AS with AUC of 0.80 in both women (P = 0.002) and men (P < 0.001). Its cut-off value was 1423 Agatston unit (AU) in women and 2573 AU in men.

In patients with bicuspid AS, AVCS was significantly higher in men and those with severe AS. However, AVCS was not significantly associated with morphological characteristics of BAV or the type of valvular dysfunction.

Computed tomography pulmonary angiography (CTPA) is the standard imaging modality for detection or rule out of pulmonary embolism (PE); however, radiation exposure is a serious concern. With iterative reconstruction algorithms a distinct dose reduction could be achievable.

To evaluate a next generation iterative reconstruction algorithm for detection or rule-out of PE in simulated low-dose CTPA.

Low-dose CT datasets with 50%, 25%, and 12.5% of the original tube current were simulated based on CTPA examinations of 92 patients with suspected PE. All datasets were reconstructed with two reconstruction algorithms: standard filtered back-projection (FBP) and iterative model reconstruction (IMR). In total, 736 CTPA datasets were evaluated by three blinded radiologists regarding image quality, diagnostic confidence, and detectability of PE. Furthermore, contrast-to-noise ratio (CNR) was calculated.

Images reconstructed with IMR showed better detectability of PE than images reconstructed with FBP, especially at lower dose levels. With IMR, sensitivity was over 95% for central and segmental PE down to a dose level of 25%. Significantly higher subjective image quality was shown at lower dose levels (25% and 12.5%) for IMR images whereas it was higher for FBP images at higher dose levels. FBP was rated as showing less artificial image appearance. CNR was significantly higher with IMR at all dose levels.

By using IMR, a dose reduction of up to 50% while maintaining satisfactory image quality seems feasible in standard clinical situations, resulting in a mean effective dose of 1.38 mSv for CTPA.

Predicting postoperative lung function is critical in lung cancer patients. Perfusion scintigraphy has been used to estimate postoperative function after lung resection.

To evaluate the usefulness of the posterior oblique method in relation to other conventional processing methods for predicting postoperative lung function using lung perfusion scintigraphy.

Fifty-five patients with non-small-cell lung cancer who underwent lobectomy were enrolled. Forced expiratory volume in 1 s (FEV1) values were obtained from preoperative and postoperative pulmonary function tests. After performing lung perfusion scintigraphy, predicted FEV1 values were calculated using the segment, conventional, posterior, and posterior oblique methods. Postoperative FEV1 values were compared with predicted FEV1 values.

The mean value of the preoperative FEV1 was 2.29 L and that of the postoperative FEV1 was 1.89 L. The mean values of the predicted postoperative FEV1 values for the segment, conventional, posterior, and posterior oblique were 1.83 L, 1.94 L, 1.88 L, and 1.89 L, respectively. Between the observed and predicted FEV1 values, there was a strong correlation without significant difference except for conventional method. Bland–Altman analysis showed that segment and posterior methods underestimated the FEV1, whereas conventional and posterior oblique methods overestimated the FEV1.

Predictions with each processing method of lung perfusion scintigraphy showed nearly similar results to the actual postoperative lung function. The posterior oblique method of lung perfusion scintigraphy showed a very small difference to such an extent as to be equal to the observed FEV1, implying that this method may be applied for predicting postoperative lung function in lung cancer patients.

Non-traumatic avascular osteonecrosis of the femoral head (ONFH) is a severe disease causing destruction of the hip joint, often necessitating total hip arthroplasty (THA) even in young patients. Magnetic resonance imaging (MRI) is commonly used for diagnosis of ONFH, but provides limited insight into the subchondral bone microstructure.

To analyze routine MRI findings in comparison to high-resolution quantitative computed tomography (HR-QCT) with a special focus on the subchondral layer and to estimate the importance of differences determining the indication for THA.

Twelve patients with ONFH were included before THA. Preoperative MRI and HR-QCT of the retrieved femoral heads were aligned using a registration algorithm. Pathological findings and trabecular bone parameters in matched areas were analyzed by two readers. McNemar, marginal homogeneity test, and Pearson’s correlation coefficient were used for comparison.

Subchondral delamination was found in nine cases on HR-QCT, but missed or underestimated in all but one case on MRI (P = 0.016). Chondral discontinuity was found in all cases on HR-QCT and in two cases on MRI (P = 0.016). Areas of complete bone resorption on HR-QCT were linked to high signal intensity on 3D gradient-echo MRI sequences with water-selective excitation, while there was no correlation between trabecular bone parameters and MRI signal intensities in other areas (P = 0.304).

Subchondral delamination, subchondral resorption, and chondral discontinuity are found frequently in advanced stages of ONFH. These lesions tend to be underestimated on conventional MRI. Our results support the importance of CT imaging in the evaluation of ONFH.

Sex-related differences of vertebral bone marrow fat in relation to varying bone densities have not yet been evaluated although some studies have reported an inverse association of bone marrow fat and bone mineral density (BMD).

To evaluate the relationship between bone marrow fat and BMD and to demonstrate the sex-related differences of the vertebral bone marrow fat in normal adults with varying bone densities.

A total of 123 normal adult volunteers were enrolled in this study. ¹H-MRS of the lumbar spine was performed. The fat fraction (FF) values of vertebral bone marrow were measured. Volumetric BMD measurement was performed by quantitative computed tomography (QCT). All participants were divided into three groups according to BMD (normal, osteopenia, osteoporosis). The differences in the FF and body mass index (BMI) values of the three groups were compared, and partial correlation analysis was used to evaluate the correlation between FF values and BMD/BMI.

The FF values increased with decreasing BMD in both male and female participants. There were significant sex differences for the FF values in the normal bone density group (P < 0.001). The FF values of the normal bone density group in male participants were significantly higher than those of the female participants (P < 0.001). The FF values were significantly negative correlated with BMD for all participants (r = −0.820, P < 0.001).

The FF values of vertebral bone marrow correlated inversely with BMD. Sex-related differences of FF values was related to BMD.

Residual tumor volume (RTV) and extent of resection (EOR) have previously been shown to affect survival in glioblastoma (GB) patients. Quantitative radiological assessment (QRA) of these factors could potentially affect clinical decision-making in the postoperative period.

The first aim was to evaluate the reproducibility of different volume estimation methods of RTV and EOR by comparing QRA with subjective visual estimation and with objective volume estimations. The second aim was to clarify whether QRA of RTV and EOR would provide accuracy in predicting progression-free survival (PFS) and overall survival (OS) in GB patients.

Seventy GB patients were studied retrospectively. Reproducibility of QRA was compared to conventional visual analysis. Intra-rater agreement between two repeated measurements of 25 patients was calculated. QRA for RTV and EOR was made for the entire study population. Survival analysis was performed by multivariate cox-regression analysis.

QRA of RTV and EOR gave superior intra-rater agreement compared to subjective evaluation. Multivariate survival analysis showed prognostic significance on 18 months PFS (hazard ratio [HR] = 0.44, P = 0.003) and OS (HR = 0.42, P = 0.012) at RTV < 1.6 mL and with EOR > 96% on PFS (HR = 2.152, P = 0.005) but not on OS (HR = 1.92, P = 0.053).

QRA of tumor volumes is more robust compared to standard evaluation methods. Since EOR and RTV are correlated to the prognosis in GB, quantitative analysis of tumor volumes could aid decision-making and patient management postoperatively.

Recently, histogram analysis based on voxel-wise apparent diffusion coefficient (ADC) value distribution has been increasingly performed. However, few studies have been reported regarding its repeatability.

To evaluate the repeatability of ADC histogram metrics of the uterus in clinical magnetic resonance imaging (MRI).

Thirty-three female patients who underwent pelvic MRI including diffusion-weighted imaging (DWI) were prospectively included after providing informed consent. Two sequential DWI acquisitions with identical parameters and position were obtained. Regions of interest (ROIs) for histologically confirmed uterine lesions (five cervical and three endometrial cancers, and one endometrial hyperplasia) and normal appearing tissues (21 endometrium and 33 myometrium) were assigned on the first DWI dataset and then pasted onto the second DWI dataset. ADC histogram metrics within the ROIs were calculated and repeatability was evaluated by calculating within-subject coefficient of variance (%) (wCV (%)) and Bland–Altman plot (%).

ADC 10%, 25%, median, 75%, 90%, maximum, mean, and entropy showed high repeatability (wCV (%) < 7, 95% limit of agreement in Bland–Altman plot (%) < ±20), followed by ADC minimum (wCV (%) = 8.12, 95% limit of agreement in Bland–Altman plot (%) < ±30). However, ADC skewness and kurtosis showed very low repeatability in all evaluations.

ADC histogram metrics like ADC 10%, 25%, median, 75%, 90%, maximum, mean, and entropy are robust biomarkers and could be applicable to clinical use. However, ADC skewness and kurtosis lack robustness. Radiologists should keep these characteristics and limitations in mind when interpreting quantitative DWI.

Ultrasound elastography is increasingly available in clinical practice. Recent studies showed higher velocity stiffness in testicular tumors compared to normal testicles.

To evaluate ultrasound elastography in combination with the apparent diffusion coefficient measurements in diffusion weighted (DW) magnetic resonance imaging (MRI) in testicles. DW can be a useful tool in evaluating testicular malignancies. However, the relationship between velocity stiffness and MRI diffusion is not well established.

We prospectively included 132 patients with testicular microlithiasis (n = 53), or normal testicular tissue (n = 53), or suspected for testicular cancer (n = 26). All 132 patients underwent ultrasonography including shear wave elastography and MRI diffusion coefficient examination of the scrotum.

No clinically relevant difference in velocity stiffness was found between normal and testicles with microlithiasis. There was a significant difference in stiffness between patients with testicular microlithiasis (0.78 m/s), normal testicular tissue (0.77 m/s), and patients with testicular cancer (1.95 m/s) (P ≤ 0.001). Similarly, there was a statistically significant difference in MRI diffusion values between patients with testicular microlithiasis (0.978 × 10⁻³mm²s⁻¹), normal testicular tissue (0.929 × 10⁻³mm²s⁻¹), and testicular cancers (0.743 × 10⁻³mm²s⁻¹) (P < 0.01).

Patients with testicular microlithiasis had no malignant characteristics measured with shear wave elastography or MRI diffusion. MRI diffusion and elastography may be useful to preoperatively differentiate benign from malignant testicular lesions.

Spontaneous superior mesenteric artery (SMA) dissection is rare cause of acute abdomen. Time-dependent change of SMA dissection has not been established.

To determine Sakamoto classification (SC) type of acute and chronic SMA dissection (aSMAD and cSMAD) to predict the treatment methods and outcome.

From April 2003 to March 2017, unenhanced and contrast-enhanced CT were used to diagnose acute symptomatic or chronic asymptomatic SMA dissection in 25 consecutive patients without aortic dissection. Correlations between SCs and treatment methods and outcomes were investigated.

All 13 patients with aSMAD initially received conservative treatment. Initial SCs in aSMAD were type I = 1, type III = 9, and type IV = 3. Three of nine initial type III and two of three initial type IV changed to type I at follow-up. One of nine type III changed to type II at follow-up. Ohers did not change. One with initial type III required vascular repair, so the final SC was not available. Three patients required bowel resection. In cSMAD of 12 patients, the initial/final SC were type I and IV in ten and two patients, respectively, without change during follow-up. cSMAD was significantly older than aSMAD. The initial length of dissection of aSMAD was longer than in the cSMAD group. In aSMAD, the final length of dissection was significantly shorter than in the initial computed tomography scan.

Initial SC differed significantly between aSMAD and cSMAD. Initial SC types in aSMAD were type III and IV mainly, and changed during the observation period. In cSMAD, SC types were I and IV without change.