Ely Felker

Diagnosis of Liver Fibrosis and Cirrhosis With Diffusion-Weighted Imaging: Value of Normalized Apparent Diffusion Coefficient Using the Spleen as Reference Organ

OBJECTIVE The purpose of this study is to compare the diagnostic accuracy of liver apparent diffusion coefficient (ADC) versus normalized liver ADC using the spleen as a reference organ for the diagnosis of liver fibrosis and cirrhosis. MATERIALS AND METHODS Fifty-six patients, 34 with liver disease and 22 control subjects, were assessed with breath-hold single-shot echo-planar diffusion-weighted imaging using b values of 0, 50, and 500 s/mm(2). Liver ADC and normalized liver ADC (defined as the ratio of liver ADC to spleen ADC) were compared between patients stratified by fibrosis stage. Receiver operating characteristic (ROC) analysis was used to determine the performance of ADC and normalized liver ADC for prediction of liver fibrosis and cirrhosis. Reproducibility was assessed by measuring coefficient of variation (n = 7). RESULTS Liver ADC failed to distinguish individual stages of fibrosis, except between stages 0 and 4. There were significant differences in normalized liver ADC between control livers and intermediate stages of fibrosis (stages 2-3) and cirrhosis (stage 4) and between stages 1 and 4, and there was a trend toward significance between stages 0 and 1 (p = 0.051) and stages 1 and 3 (p = 0.06). ROC analysis showed that normalized liver ADC was superior to liver ADC for detection of stage > or = 2 (area under the ROC curve, 0.864 vs 0.655; p = 0.013) and stage > or =3 (0.805 vs 0.689; p = 0.015), without a difference for diagnosing cirrhosis (0.935 vs 0.720; p = 0.185). Normalized liver ADC had higher reproducibility than ADC (mean coefficient of variation, 3.5% vs 12.6%). CONCLUSION Our results suggest that normalizing liver ADC with spleen ADC improves diagnostic accuracy for detection of liver fibrosis and cirrhosis when using breath-hold diffusion-weighted imaging, with better reproducibility.

Qualitative and Quantitative MDCT Features for Differentiating Clear Cell Renal Cell Carcinoma From Other Solid Renal Cortical Masses

OBJECTIVE The purpose of this study was to differentiate clear cell renal cell carcinoma (RCC) from other solid renal masses on four-phase MDCT. MATERIALS AND METHODS Our study cohort included all pathologically proven solid renal masses that underwent pretreatment four-phase MDCT at our institution from 2001 to 2012. Both retrospective qualitative analysis (blinded dual-radiologist evaluation of morphologic features: enhancement pattern, lesion contour, neovascularity, and calcification) and quantitative analysis (mean absolute and relative attenuation and changes in attenuation across phases) were performed. ANOVA with post-hoc analysis, Pearson chi-square tests, and ROC analysis were used. RESULTS One hundred fifty-six consecutive patients (99 men, 57 women) with a mean age of 62.7 years (range, 26-91 years) had 165 solid renal masses (median size, 3.0 cm): 86 clear cell RCCs, 36 papillary RCCs, 10 chromophobe RCCs, 23 oncocytomas, and 10 lipid-poor angiomyolipomas. Kappa for interradiologist agreement regarding morphologic features was 0.33-0.76. There were significant associations between histologic subtype and enhancement pattern (p < 0.001), lesion contour (p < 0.014), and neovascularity (p < 0.001). Clear cell RCC had the highest mean relative corticomedullary attenuation (p < 0.02). Clear cell RCC had greater deenhancement than oncocytoma (p < 0.001); deenhancement less than 50 HU or relative corticomedullary attenuation greater than 0% differentiated clear cell RCC from oncocytoma with a positive predictive value of 90%. Lipid-poor angiomyolipoma had the highest mean absolute unenhanced attenuation (p < 0.01); absolute unenhanced attenuation greater than 45 HU and relative corticomedullary attenuation less than 10% differentiated lipid-poor angiomyolipoma from clear cell RCC with a negative predictive value of 97%. CONCLUSION Four-phase MDCT renal attenuation profiles enable differentiation of clear cell RCC from other solid renal cortical masses, most notably papillary RCC and lipid-poor angiomyolipoma.

Prostate cancer risk stratification with magnetic resonance imaging.

In recent years, multiparametric magnetic resonance imaging (mpMRI) has shown promise for prostate cancer (PCa) risk stratification. mpMRI, often followed by targeted biopsy, can be used to confirm low-grade disease before enrollment in active surveillance. In patients with intermediate or high-risk PCa, mpMRI can be used to inform surgical management. mpMRI has sensitivity of 44% to 87% for detection of clinically significant PCa and negative predictive value of 63% to 98% for exclusion of significant disease. In addition to tumor identification, mpMRI has also been shown to contribute significant incremental value to currently used clinical nomograms for predicting extraprostatic extension. In combination with conventional clinical criteria, accuracy of mpMRI for prediction of extraprostatic extension ranges from 92% to 94%, significantly higher than that achieved with clinical criteria alone. Supplemental sequences, such as diffusion-weighted imaging and dynamic contrast-enhanced imaging, allow quantitative evaluation of cancer-suspicious regions. Apparent diffusion coefficient appears to be an independent predictor of PCa aggressiveness. Addition of apparent diffusion coefficient to Epstein criteria may improve sensitivity for detection of significant PCa by as much as 16%. Limitations of mpMRI include variability in reporting, underestimation of PCa volume and failure to detect clinically significant disease in a small but significant number of cases.

Use of MDCT to Differentiate Autoimmune Pancreatitis From Ductal Adenocarcinoma and Interstitial Pancreatitis.

OBJECTIVE The purposes of this study were to identify the most common imaging features of autoimmune pancreatitis and to evaluate the utility of MDCT for differentiating autoimmune pancreatitis from two more frequently encountered differential diagnoses--pancreatic ductal adenocarcinoma and acute interstitial pancreatitis. MATERIALS AND METHODS Dual-phase contrast-enhanced MDCT images of 91 patients (39 with autoimmune pancreatitis, 25 with pancreatic ductal adenocarcinoma, 27 with acute interstitial pancreatitis) were evaluated by two radiologists in consensus for distribution of pancreatic abnormality, sausage shape, low-attenuation halo, pancreatic duct dilatation, peripancreatic stranding, lymphadenopathy, biliary abnormality, vascular involvement, and renal lesions. Chi-square tests, multiple logistic regression analysis, and ROC analysis were performed. RESULTS The most common imaging features of autoimmune pancreatitis were sausage shape (25/39 [64%]) and low-attenuation halo (23/39 [59%]). Pancreatic duct dilatation (20/25 [80%]) and biliary dilatation (11/25 [44%]) were most frequent in pancreatic ductal adenocarcinoma. Peripancreatic stranding (22/27 [81%]) was most frequent in acute interstitial pancreatitis. Sausage shape, low-attenuation halo, and absence of a pancreatic duct or biliary dilatation differentiated autoimmune pancreatitis from pancreatic ductal adenocarcinoma with an accuracy of 0.88. Sausage shape and absence of peripancreatic stranding differentiated autoimmune pancreatitis from acute interstitial pancreatitis with an accuracy of 0.82. There was no significant difference in the frequency of vascular involvement or of lymphadenopathy among these diagnoses. CONCLUSION Typical cases of autoimmune pancreatitis can be accurately differentiated from pancreatic ductal adenocarcinoma and acute interstitial pancreatitis on the basis of characteristic MDCT features. However, autoimmune pancreatitis should be considered in the presence of atypical features.

Risk Stratification Among Men With Prostate Imaging Reporting and Data System version 2 Category 3 Transition Zone Lesions: Is Biopsy Always Necessary?

OBJECTIVE The objective of our study was to determine the clinical and MRI characteristics of clinically significant prostate cancer (PCA) (Gleason score ≥ 3 + 4) in men with Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) category 3 transition zone (TZ) lesions. MATERIALS AND METHODS From 2014 to 2016, 865 men underwent prostate MRI and MRI/ultrasound (US) fusion biopsy (FB). A subset of 90 FB-naïve men with 96 PI-RADSv2 category 3 TZ lesions was identified. Patients were imaged at 3 T using a body coil. Images were assigned a PI-RADSv2 category by an experienced radiologist. Using clinical data and imaging features, we performed univariate and multivariate analyses to identify predictors of clinically significant PCA. RESULTS The mean patient age was 66 years, and the mean prostate-specific antigen density (PSAD) was 0.13 ng/mL2. PCA was detected in 34 of 96 (35%) lesions, 14 of which (15%) harbored clinically significant PCA. In univariate analysis, DWI score, prostate volume, and PSAD were significant predictors (p < 0.05) of clinically significant PCA with a suggested significance for apparent diffusion coefficient (ADC) and prostate-specific antigen value (p < 0.10). On multivariate analysis, PSAD and lesion ADC were the most important covariates. The combination of both PSAD of 0.15 ng/mL2 or greater and an ADC value of less than 1000 mm2/s yielded an AUC of 0.91 for clinically significant PCA (p < 0.001). If FB had been restricted to these criteria, only 10 of 90 men would have undergone biopsy, resulting in diagnosis of clinically significant PCA in 60% with eight men (9%) misdiagnosed (false-negative). CONCLUSION The yield of FB in men with PI-RADSv2 category 3 TZ lesions for clinically significant PCA is 15% but significantly improves to 60% (AUC > 0.9) among men with PSAD of 0.15 ng/mL2 or greater and lesion ADC value of less than 1000 mm2/s.

Irreversible Electroporation: Defining the MRI Appearance of the Ablation Zone With Histopathologic Correlation in a Porcine Liver Model

OBJECTIVE The purpose of this study is to evaluate the MRI appearance of the irreversible electroporation zone in porcine liver, with histopathologic correlation. MATERIALS AND METHODS Nine irreversible electroporation ablations were percutaneously created in two Yorkshire pigs. Irreversible electroporation was performed with a bipolar 16-gauge electrode with 3-cm exposure tip and fixed 8-mm interpolar distance. Gadoxetate disodium-enhanced 3-T MRI was performed 50 hours after irreversible electroporation. Livers were harvested immediately after MRI for histopathologic analysis. Ablation zone size was measured on each pulse sequence and correlated with pathologic ablation zone size. Qualitative MRI features of the ablation zone were assessed, and contrast-to-noise ratios (CNRs) were calculated. Statistical analysis included Pearson correlation and t tests. RESULTS Histopathologically, three distinct layers were present in the irreversible electroporation ablation zone: an inner layer of coagulative necrosis (hyperintense at T1- and T2-weighted imaging and nonenhancing), a middle layer of congestion and hemorrhage (hypointense at T1-weighted imaging, hyperintense at T2-weighted imaging and DWI, and progressively enhancing but hypointense at the hepatobiliary phase), and a peripheral layer of inflammation (hyperintense at the arterial phase but isointense at all other sequences). The hepatobiliary phase ablation zone size showed the highest correlation with the pathologic ablation zone size (r = 0.973). This correlation was significant (p < 0.001). T2-weighted imaging had the highest lesion-to-normal tissue CNR. CONCLUSION The irreversible electroporation ablation zone contains three distinct histopathologic zones, each with unique MRI features. T2-weighted imaging had the highest CNR, and the hepatobiliary phase had the strongest correlation with ablation zone size.

Liver MR Elastography at 3 T: Agreement Across Pulse Sequences and Effect of Liver R2* on Image Quality

OBJECTIVE The objectives of our study were to compare MR elastography (MRE) based on gradient-recalled echo (GRE) imaging with spin-echo echo-planar imaging (SEEPI) and rapid fractional (RF)-GRE MRE sequences at 3 T in terms of liver stiffness (LS) and image quality and to evaluate the effect of liver R2* on image quality. MATERIALS AND METHODS Eighty-one patients underwent 3-T liver MRE with GRE, SE-EPI, and RF-GRE sequences performed in variable order in this study. LS and ROI areas on the LS 95% confidence maps were compared among the three sequences. The relationship between liver R2* and ROI area was investigated. RESULTS There was no significant difference in mean LS among the three sequences (p = 0.49). Mean ROI area was significantly larger for RF-GRE (18,213 ± 9292 [SD] mm2) than for GRE (13,196 ± 8149 mm2) and SE-EPI (12,896 ± 8656 mm2) (p < 0.0001). Liver R2* was significantly higher among patients with one or more failed sequences (mean ± SD, 116 ± 76 s-1) than for patients with no failed sequences (59 ± 26 s-1) (p = 0.001). Technical failure rates were 10% (8/81), 4% (3/81), and 2% (2/81) for GRE, SE-EPI, and RF-GRE, respectively. Among patients with iron overload (R2* ≥ 100 s-1), there was a trend toward larger ROI area for SE-EPI (p = 0.09). CONCLUSION SE-EPI-and RF-GRE-based MRE sequences provide equivalent measures of LS compared with GRE-based MRE, and both have lower technical failure rates. The RF-GRE sequence yielded the largest measurable area of LS. Among patients with iron overload, there was a trend toward larger measurable area of LS for the SE-EPI sequence.

MP38-11 PROSTATE CANCER VOLUME ON 3-TESLA MULTIPARAMETRIC DIFFERENT SEQUENCES: CORRELATED AND VERIFIED ON WHOLE MOUNT HISTOPATHOLOGY SECTIONED WITH 3D-PRINTED CUSTOM-DESIGNED MOLDS

INTRODUCTION AND OBJECTIVES: Transperineal template mapping MRI/TRUS fusion biopsy (TMBx) offers superior accuracy and allows optimal risk stratification for patients detected with prostate cancer. However, limited data is available regarding complications and morbidity following TMBx. The goal of this retrospective analysis was to obtain the complication rate follwing TMBx in a large series. METHODS: The records of 402 consecutive patients undergoing TMBx between June 2013 and August 2016 were reviewed. All patients received a single shot antibiotic prophylaxis with 80 mg gentamicin. All underwent transperineal fusion targeted biopsy of MRIsuspicious lesions (median 3 cores per lesion) and transperineal extended template biopsy (median 41 cores). The complications were reported according to the modified Clavien-Dindo classification system. RESULTS: Of the 421 biopsies, 371 (88.1%) had an uneventful biopsywithout complications. Twenty patients (4.8%) showedpost-biopsy complications requiring an outpatient consultation or hospital admission within 30 days of the procedure. According to the Clavien-Dindo classification there were 25 patients (5.9%) with grade I complications, 24 (5.7%) with grade II and one patient (0.2%) with a grade IIIb complication (TUR-P within 30 days as a patients desire). Eleven patients (2.6%) developed an urosepsis (fever >38.5 C), 38 (9%) had an urinary retention requiring urethral catheterization and two (0.5%) had an acute bacterial prostatitis. Of the eleven patients with urosepsis, seven carried Escherichia coli, the other four cases were ESBL, Enterococcus faecalis, Serratia marcenscens and Enterobacter cloacae complex with Staphyloccocus aureus. Those patients had to be hospitalised for 2.5 days on average (range 1-7 days). 37 patients (8.8%) mentioned haematospermia while 93 (22.1%) noticed haematuria within 30 days of the procedure. A binomial logistic regressionshowed that an increasedprostate volumewasassociatedwith an increased likelihood of exhibiting urinary retention (p 1⁄4 0.006). CONCLUSIONS: In this analysis we demonstrated a low morbidity following TMBx. The procedure is very well tolerated and safe for patients. Especially the rate of major infections and urosepsis are low. Haematuria and haematospermia were very common but selflimiting in most of the cases. However, urinary retention is a major complication with 9% of all cases and is associated with increased prostate volume. Therefore we now leave the catheter for two days in patients with larger prostate glands.

Tu1468 Evaluation of International Consensus Diagnostic Criteria in the Diagnosis of Autoimmune Pancreatitis: A Single Center North American Cohort Study

Context In 2011, an international symposium on Autoimmune Pancreatitis produced the International Consensus Diagnostic Criteria, which can be used to stratify patients with autoimmune pancreatitis as having type 1, type 2, or autoimmune pancreatitis – not otherwise specified. There are few studies examining the application of International Consensus Diagnostic Criteria to a cohort of North American patients with autoimmune pancreatitis. Objectives To apply International Consensus Diagnostic Criteria to a cohort of 51 patients with autoimmune pancreatitis followed at a North American medical center. To compare International Consensus Diagnostic Criteria with other guidelines with emphasis on patients who were unclassifiable using International Consensus Diagnostic Criteria. Design We applied International Consensus Diagnostic Criteria using clinical-radiological-pathological features. We reevaluated patients who were unclassifiable per ICDC with Japanese Pancreatic Society-2006, HISORt, Korean, Asian, and JPS-2011 guidelines. We statistically compared type 1, type 2, and unclassifiable patients based on demographic and clinical presentation. T-test and chi-square analysis was used for statistical analysis. Results 37 patients were categorized as definitive type 1 or type 2 autoimmune pancreatitis, 1 patient as probable type 1 autoimmune pancreatitis, and 13 were unclassifiable. Unclassifiable patients had indeterminate/atypical parenchymal imaging or none at all, and 6 patients had elevated serology. Diagnostic endoscopic retrograde cholangio-pancreatography was performed on 6 patients and 1 patient had persistent waxing and waning of clinical and radiologic features. 6 patients could be diagnosed with autoimmune pancreatitis using JPS-2006, Korean, or Asian Criteria, and 4 patients using either HISORt or JPS-2011. There was no statistically significant difference between classifiable and unclassifiable patients based on demographics or clinical presentation. Conclusions The ICDC’s dependence on histology, diagnostic endoscopic retrograde cholangio-pancreatography, and lack of acknowledgment of waxing-waning features limits applicability. Our cohort evolved during routine practice and we identify discrepancies amongst guidelines.