Faculty Bibliography

OBJECTIVE: The purpose of this study was to compare, with histopathologic examination of the liver explant as the reference standard, diffusion-weighted MRI with contrast-enhanced subtraction MRI in the assessment of necrosis of hepatocellular carcinoma (HCC) after trans arterial chemoembolization (TACE). MATERIALS AND METHODS: The cases of 21 patients with HCC who underwent MRI after TACE were evaluated. Two independent observers calculated the apparent diffusion coefficient (ADC) of HCC and measured percentage tumor necrosis on subtraction images. The ADCs of necrotic and viable tumor tissues were compared. ADC and percentage necrosis on subtraction images were correlated with percentage necrosis found at pathologic examination. Receiver operating characteristics analysis was performed on the diagnosis of complete tumor necrosis. RESULTS: Twenty-eight HCCs (mean diameter, 2.3 cm) were evaluated. There were significant differences between the ADC of viable tissue and that of necrotic tumor tissue (1.33 +/- 0.41 vs 2.04 +/- 0.38 x 10(-3) mm(2)/s, p < 0.0001). There was significant moderate correlation between ADC and the pathologic finding of percentage necrosis (r = 0.64, p < 0.001) and significant strong correlation between subtraction image and pathologic percentage necrosis (r = 0.89-0.91, depending on the phase; p < 0.001). In the diagnosis of complete tumor necrosis, ADC had an area under the curve, sensitivity, and specificity of 0.85, 75%, and 87.5% compared with 0.82-0.89, 100%, and 58.3-79.1% for subtraction imaging (p > 0.5 between ADC and subtraction imaging). CONCLUSION: Compared with diffusion-weighted imaging, contrast-enhanced MRI with subtraction technique had more significant correlation with the histopathologic findings in the evaluation of necrosis of HCC after TACE. There was no difference, however, between the two methods in diagnosis of complete tumor necrosis

PURPOSE: To retrospectively evaluate the sensitivity and specificity of several morphologic findings that may be seen with cystic pancreatic lesions, in the diagnosis of pseudocyst at magnetic resonance (MR) imaging. MATERIALS AND METHODS: This study was institutional review board approved and HIPAA compliant. From January 1, 2005, to December 31, 2007, electronic radiology and pathology databases were searched to identify patients with pancreatic cystic neoplasms or pseudocysts who underwent pancreatic MR imaging. Twenty-two patients with cystic pancreatic neoplasms that were confirmed at surgical resection (n = 12) or endoscopic ultrasonography (US) with cystic fluid analysis (n = 10) were identified. Of 20 patients with pancreatic pseudocysts, seven had pseudocysts that were identified at pathologic resection and 13 had a clinical history of pancreatitis, with initial computed tomography (CT) revealing no pancreatic cyst and subsequent follow-up MR imaging depicting cystic lesions. Two abdominal radiologists independently and randomly evaluated each case for presence or absence of septa and internal dependent debris and for external cyst morphology on axial and coronal T2-weighted images and three-dimensional gradient-echo T1-weighted images obtained before and after intravenous contrast agent administration. Logistic regression for correlated data was used to assess the usefulness of internal debris, external morphology, and septa for differentiating cystic neoplasms from pseudocysts. RESULTS: The readers' assessments of the presence or absence of cystic debris were concordant for 40 (95%) of the 42 patients, with a kappa coefficient of 0.889, which indicated nearly perfect agreement. Thirteen (93%) of 14 lesions found to have debris by either or both readers were pseudocysts, and only one (4%) of the 22 cystic neoplasms had debris. Both readers were more likely to identify septa within cystic neoplasms than within pseudocysts; however, the difference was not significant for either reader. The readers were more likely to observe microlobulated morphology in cystic neoplasms than in pseudocysts, with the difference between these lesion types, in terms of prevalence of microlobulated morphology, exhibiting a trend toward-but not reaching-statistical significance (P = .0627). CONCLUSION: Presence of internal dependent debris appears to be a highly specific MR finding for the diagnosis of pancreatic pseudocyst

OBJECTIVE: The purpose of our study was to determine whether gadolinium is necessary in the follow-up evaluation of pancreatic cystic lesions. MATERIALS AND METHODS: Fifty-six patients with pancreatic cystic lesions detected on initial MRI and who underwent follow-up MRI were identified. Mean cyst size was 1.9 cm, and mean follow-up was 9.1 months. MRI included multiacquisition T1- and T2-weighted sequences before contrast administration and 3D fat-suppressed T1-weighted images before and after gadolinium administration. Two radiologists independently reviewed the entire initial examination and follow-up MRI using only unenhanced T1- and T2-weighted sequences from the second examination. Each radiologist made one of three recommendations: 1, no follow-up necessary or follow-up imaging in 6-12 months; 2, cyst aspiration; or 3, cyst resection. Four weeks later, imaging studies were reevaluated with the contrast-enhanced images from the second examination. A second recommendation using the same outcomes was made. Interobserver and intraobserver variations for the same patient were summarized in terms of kappa coefficients and the percentage of times the decisions were concordant. A 95% CI for the percentage of times management decisions would change without and with gadolinium was calculated. RESULTS: Concordance between the two different readers for the interpretations (when using the same MRI interpretation technique for follow-up surveillance) was 87.5% with a kappa coefficient to assess interobserver variation of 0.075, suggesting only slight agreement between the two readers. However, treatment recommendations provided by a single reader with and without information from the contrast-enhanced images were discordant only 4.5% of the time. Recommendations were concordant without and with gadolinium 95.5% (107/112; kappa=0.67) of the time, suggesting substantial agreement. A retrospective consensus review of the five cases in which gadolinium effected a change in the observer's recommendation was performed. There was nothing on the gadolinium-enhanced sequences that would specifically alter a change in a management decision, and it is likely that the changes in management decisions in these five cases were simply related to expected variations in categorizing lesions rather than to the use of gadolinium. CONCLUSION: The use of gadolinium has minimal impact in the follow-up MR assessment of pancreatic cystic lesions

AIM: To determine whether epiploic appendagitis occurs in the caecum. METHODS: From 2000-2006, 58 cases with classic computed tomography (CT) features of acute epiploic appendagitis (focal round or oval fat density immediately adjacent to the colon with surrounding oedema and stranding, with or without a central area of high attenuation) were identified from a radiology information system and available for review on the picture archiving and communication system (PACS). Cases were assigned to one of six colonic segments: rectum, sigmoid, descending colon, transverse colon, ascending colon, and caecum. The Blyth-Still-Casella procedure was used to derive an exact upper bound on the likelihood of epiploic appendagitis occurring within the caecum. RESULTS: Twenty-eight cases occurred in the sigmoid colon, 16 in the descending colon, four in the transverse colon, and 10 in the ascending colon. No cases of acute epiploic appendagitis were identified in the caecum. Four cases of prospectively dictated caecal epiploic appendagitis were identified from the database. Retrospective review of these cases showed two cases to be epiploic appendagitis of the ascending colon. The third case demonstrated peritoneal thickening without evidence of an inflamed epiploic appendage. The fourth case was caecal diverticulitis. Based on these findings there is 95% confidence that no more than 4.6% of patients with epiploic appendagitis will show this condition within the caecum. CONCLUSION: In the authors' experience, epiploic appendagitis does not occur in the caecum. Therefore, it is an unlikely cause for an inflammatory process in this region and other conditions should be considered

Morphologic irregularities of the pancreatic duct are often noted on abdominal imaging studies obtained for unrelated symptoms or conditions. We report the case of a patient who was found to have an incidental, isolated pancreatic duct dilatation on multiple imaging studies and who was found to have a nonfunctioning pancreatic endocrine neoplasm at resection. His prognosis is excellent based on the histology of the lesion and a curative resection. This case highlights the importance of fully investigating incidental pancreatic duct abnormalities regardless of the setting in which they are found

A 59-year-old white man with atypical presentations of WD was initially diagnosed with HCC. Subsequent follow-up evaluations supported the diagnosis of WD with a strong family history, elevated serum ceruloplasmin levels, increased urinary copper, and significant copper deposition in the liver. The development of HCC in WD is most likely secondary to excessive copper deposition in the liver and concurrent cirrhosis

Cavernous transformation of the portal vein (portal cavernoma) consists of a periportal or/and intrahepatic venous collateral network, developed as a result of acute or long-standing portal vein thrombosis. Better control of hemorrhagic and thrombotic complications in the patients with portal cavernoma substantially improves their life span and the clinical outcome. However, biliary complications that occur in the late stages of this disease have been recently recognized as challenging management issues because they recur and are difficult to treat. Because of the relatively small number of the patients with cholangiopathy due to portal cavernoma, there is no current standardized treatment approach. We report the case of a predominantly intrahepatic portal cavernoma occurring in a patient with chronic idiopathic portal vein thrombosis, which led to severe cholangiopathy that mimicked primary sclerosing cholangitis and cholangiocarcinoma, was unresponsive to endoscopic stent placement, and finally required liver transplantation