Christopher Fung

Effect of Hepatic Steatosis on Liver FDG Uptake Measured in Mean Standard Uptake Values

PURPOSE To evaluate the association between diffuse fatty infiltration of the liver and average fluorine 18 fluorodeoxyglucose (FDG) uptake in the liver. MATERIALS AND METHODS Institutional review board approval was obtained for this study; the requirement for informed patient consent was waived. Consecutive nonenhanced whole-body hybrid FDG positron emission tomographic (PET)-computed tomographic (CT) scans obtained in 142 patients (mean age, 63.6 years; age range, 19-94 years) from October 1, 2008, to November 28, 2008, were retrospectively reviewed. Mean attenuation (in Hounsfield units) and standardized uptake value (SUV) measurements for the liver and spleen were obtained, with identical regions of interest used for the CT and PET examinations. The patients were assigned to three study groups: a control group-119 patients with a mean liver attenuation value greater than or equal to the mean spleen attenuation value, a diffuse fatty liver disease group-23 patients in whom the mean liver attenuation value was less than the mean spleen attenuation value, and a more strictly defined fatty liver disease group-a subset of 10 patients from the diffuse fatty liver disease group with a mean liver attenuation value minus mean spleen attenuation value difference of less than or equal to -10 HU. Mean SUV (SUV(m)) values were compared between the groups by using a two-sample t test for means. The association between mean liver attenuation and average FDG uptake was assessed with linear regression analysis. RESULTS The average SUV(m)for the control group was 2.18 (standard deviation [SD], 0.36; 95% confidence interval [CI]: 2.12, 2.24). No significant difference was identified when the average SUV(m)for the control group was compared with those for the fatty liver disease (SUV(m), 2.03; SD, 0.36; 95% CI: 1.90, 2.16) (P >.05) and more strictly defined fatty liver disease (SUV(m), 2.07; SD, 0.24; 95% CI: 1.92, 2.22) groups (P >.05). Linear regression analysis of liver SUV(m)as a function of mean liver attenuation revealed a mean slope of 0.005 (SD, 0.04; 95% CI: -0.005, 0.015) and a correlation coefficient of 0.02. CONCLUSION No association between liver attenuation and FDG uptake measured in terms of SUV(m)was observed. On the basis of these data, it is acceptable to use the liver as a comparator for extrahepatic foci of equivocal increased FDG activity in patients with fatty liver disease. (c) RSNA, 2010.

MR Imaging of Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is characterized by autoimmune inflammatory destruction of the pancreatic tissue. Imaging plays an essential role in the diagnosis. AIP type 1 is the pancreatic manifestation of immunoglobulin G4 (IgG4)-related disease and is associated with IgG4-positive plasma cell infiltration and fibrosis of multiple organ systems. Type 2 is a related disease with pancreatic inflammation with or without concurrent inflammatory bowel disease. The authors demonstrate the imaging findings that are associated with the pancreatic and extra-pancreatic manifestations of AIP. They emphasize the common MR imaging and magnetic resonance cholangiopancreatography findings to help make the diagnosis of AIP.

Case 43: Pancreatic Ductal Adenocarcinoma Arising After Intraductal Papillary Mucinous Neoplasm Resection

Fifty-one-year-old woman treated with IPMN with high-grade dysplasia previously treated with distal pancreatectomy presenting 4 years later with a pancreatic lesion.

Case 87: Intraductal Papillary Mucinous Neoplasm with Associated Colloid Cancer

76 year-old woman presented with 4-week history of jaundice, pruritus, and epigastric pain.

Case 74: VIPoma

70 year-old woman with a 1-year history of recurrent watery diarrhea, weight loss, and flushing.

Case 44: Main Duct Intraductal Oncocytic Papillary Neoplasm

65 year-old woman was found to have an incidental pancreatic cystic lesion on evaluation for bloating and nausea.

Case 76: Somatostatinoma

59-year-old woman with a history of diabetes mellitus presented with right upper quandrant pain and suspicious ampullary mass on subsequent endoscopy.

Case 77: Glucagonoma

56-year-old woman with a 2-year history of right upper quadrant pain. The patient also recently developed a trunk and inguinal rash.

Case 34: Mucinous Cystic Neoplasm with Intermediate-Grade Dysplasia

40-year-old woman presented with vomiting, anorexia, and weight loss. Abdominal imaging showed a cystic pancreatic mass.

Case 38: Mucinous Cystic Neoplasm in Pancreatic Head

40 year-old woman with nonspecific flank pain secondary to a urinary tract infection was found on CT to have an incidental pancreatic mass.