Faculty Bibliography

OBJECTIVE: To determine whether suspicion for tumor on prostate MRI incorporating T2-weighted imaging (T2-WI) and diffusion-weighted imaging (DWI) predicts more adverse pathology on radical prostatectomy (RP). METHODS: From 2007 to 2009, 154 patients underwent 1.5 Tesla pelvic-phased-array magnetic resonance imaging (MRI) of the prostate that included T2-WI and DWI before RP. MRI examinations were retrospectively reviewed and grouped by degree of suspicion for tumor: no suspicion for tumor (NST, n = 15), equivocal suspicion for tumor (EST, n = 60), or strong suspicion for tumor (SST, n = 79). The NST/EST groups were combined and compared to the SST group. Preoperative variables were used to assemble a multivariate model. Outcomes reflective of adverse pathology included primary Gleason grade >/=4, pathologic stage >/=T3 (>/=pT3), and tumor upgrading. Subgroup analysis was performed for patients meeting eligibility criteria for active surveillance (n = 55). For this analysis, the NST group was compared to the EST/SST groups. RESULTS: SST status was associated with adverse preoperative risk factors for aggressive disease. Univariate analysis demonstrated significant association between SST and primary Gleason >/=4 pathology and stage >/=pT3 (P <.05). On multivariate analysis, SST was independently predictive of primary Gleason >/=4 pathology (odds ratio [OR] 6.14, 95% confidence interval [CI] 1.97-19.2) and Gleason upgrading (OR 2.47, 95% CI 1.01-6.02). Among patients eligible for active surveillance, those in the NST group had decreased likelihood of Gleason >/=7 disease or stage >/=pT3 compared to the EST/SST groups (7.7% vs 47.6%, P = .01). CONCLUSION: Increased tumor suspicion on T2-WI/DWI MRI is indicative of adverse pathology on RP. These findings suggest a role for MRI in pretreatment risk assessment.

We compared individual computed tomography (CT) and MRI findings in differentiating acute from chronic cholecystitis. Thirty-seven patients undergoing both studies before cholecystectomy were included. Two radiologists (R1/R2) independently assessed all cases. For detecting acute cholecystitis, MRI showed better sensitivity (R1) using gallbladder wall thickening, accuracy (R1) and sensitivity (R1) using gallstones, sensitivity (R1 and R2) and accuracy (R2) using gallbladder wall hyperemia, accuracy (R1 and R2) using gallbladder wall defect, and accuracy (R2) using adjacent liver hyperemia (P=.004-.063). MRI also showed better specificity (R2) using pericholecystic fat stranding (P=.016). Overall, several findings showed better sensitivity and/or accuracy for acute cholecystitis on MRI than CT.

AIM: To identify retrospectively potential associations between apparent diffusion coefficient (ADC) values of pancreatic adenocarcinoma and tumour grade as well as other pathological features, using histopathological assessment from the Whipple procedure as the reference standard. MATERIALS AND METHODS: Thirty patients with pancreatic adenocarcinoma underwent magnetic resonance imaging (MRI) including diffusion-weighted imaging with b-values of 0 and 500 s/mm before the Whipple procedure. Two radiologists independently recorded the ADC values of the tumour and benign pancreas for all cases. ADC values were compared with histopathological findings following the Whipple procedure. RESULTS: The intra-class correlation coefficient was 0.689 for benign pancreas and 0.695 for tumours, indicating good inter-reader agreement for ADC values. The mean ADC value was significantly lower in tumours than in benign pancreas for both readers (reader 1: 1.74 +/- 0.34 x 10 mm/s versus 2.08 +/- 0.48 x 10 mm/s, respectively, p = 0.006; reader 2: 1.69 +/- 0.41 x 10 mm/s versus 2.11 +/- 0.54 x 10 mm/s, respectively, p < 0.001). However, there was no significant difference in mean ADC between poorly and well/moderately differentiated tumours for either reader (reader 1: 1.69 +/- 0.36 x 10 mm/s versus 1.78 +/- 0.33 x 10 mm/s, respectively, p = 0.491; reader 2: 1.62 +/- 0.33 x 10 mm/s versus 1.75 +/- 0.49 x 10 mm/s, respectively, p = 0.405). The area under the curve (AUC) for differentiation of poorly and well/moderately differentiated tumours was 0.611 and 0.596 for readers 1 and 2, respectively, and was not significantly better than an AUC of 0.500 for either reader (p >/= 0.306). In addition, ADC was not significantly different for either reader between tumours with stage T3 versus stage T1/T2, between tumours with and without metastatic peri-pancreatic lymph nodes, or between tumours located in the pancreatic head versus other pancreatic regions (p >/= 0.413). CONCLUSION: No associations between ADC values of pancreatic adenocarcinoma and tumour grade or other adverse pathological features were observed.

PURPOSE: Past studies have identified a high frequency of recommendations for additional imaging (RAI) for computed tomography (CT) studies performed in an emergency department (ED), thereby potentially contributing to increased imaging utilization and costs. The purpose of this study was to compare rates of RAI within the ED setting between ED-based and organ-based subspecialty radiologists. METHODS: We identified 600 ED CT studies, comprising 200 head, chest, and abdominal CT studies, split equally between cases reviewed by ED-based and organ-based radiologists. Frequency of RAI for the three examinations was compared between these subspecialty groups. RESULTS: Frequencies of RAI were 21.5 %, 13.5 %, and 5.5 % for CT examinations of the chest, abdomen, and brain, respectively. There was a significantly higher frequency of RAI for chest CT studies interpreted by chest radiologists than by ED radiologists (28.0 % vs. 15.0 %, respectively, p = 0.036), largely due to a higher rate of RAI for incidentally detected lung nodules and masses as well as other pulmonary parenchymal abnormalities by chest radiologists. There was no significant difference in RAI on brain or abdominal CT studies between the two groups (p = 0.426-1.0). However, on abdominal studies, only ED-based radiologists provided RAI for abnormalities of the bowel or uterus, while only organ-based radiologists provided RAI for pancreatic abnormalities. Only 25.6 % of RAI were subsequently performed at our institution. CONCLUSION: For chest CT studies performed at the authors' institution, differences in management of incidental pulmonary nodules contributed to a significantly higher frequency of RAI by chest radiologists than by ED-based radiologists. Further investigation of the impact of these differences on cost and patient outcomes is warranted.