Fluorodeoxyglucose PET imaging in the evaluation of gallbladder carcinoma and cholangiocarcinoma.

Our goal was to evaluate fluorodeoxyglucose (FDG) positron emission tomography (PET) in staging patients with biliary tract cancers. Fifty consecutive patients who underwent FDG-PET for suspected cholangiocarcinoma (n=36) or gallbladder carcinoma (n=14) were reviewed. Patients with cholangiocarcinoma were divided into two groups: group 1 had nodular type (mass=1 cm) (n=22) and group 2 had infiltrating type (n=14) cholangiocarcinoma. Thirty-one of 36 patients evaluated for cholangiocarcinoma had cholangiocarcinoma and five did not. Sensitivity was 85% for nodular morphology but only 18% for infiltrating morphology. Sensitivity for metastases was 65% but false negative for carcinomatosis in three of three patients. One false positive result occurred in a patient with primary sclerosing cholangitis who had acute cholangitis. Seven (58%) of 12 patients had FDG uptake along the tract of a biliary stent. FDG-PET led to a change in surgical management in 30% (11 of 36) of patients evaluated for cholangiocarcinoma because of detection of unsuspected metastases. Eleven of 14 patients with gallbladder carcinoma were newly diagnosed by cholecystectomy or another type of exploratory procedure, whereas three patients were undergoing follow-up. Nine had residual gallbladder carcinoma at the time of PET. Sensitivity for gallbladder carcinoma was 78%. Sensitivity for extrahepatic metastases was 50% in eight patients; six of them had carcinomatosis. These data suggest that PET is accurate in predicting the presence of nodular cholangiocarcinoma (mass>1cm) but was not helpful for the infiltrating type. PET was also helpful for detecting residual gallbladder carcinoma following cholecystectomy, but was not helpful in patients with carcinomatosis. Although FDG-PET led to a change in management in 30% of patients with cholangiocarcinoma, it must be interpreted with caution in patients with primary sclerosing cholangitis and with stents in place, as well as in those with known granulomatous disease.

2-Deoxy-2-[18F]fluoro-D-glucose positron emission tomography uptake in a giant adrenal myelolipoma.

Incidental adrenal lesions found on anatomic imaging are not uncommon. 2-Deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) imaging is highly accurate in the differentiation of benign from malignant adrenal lesions, both in patients with proven malignancy and with adrenal lesions detected incidentally. A 60-year-old white female with a history of lower mid-back pain underwent computerized tomography (CT) imaging that identified a 15-cm complex mass within the left adrenal gland with soft tissue, cystic, and adipose components. FDG-PET imaging showed significant hypermetabolic activity within portions of the mass with central photopenia suggesting a malignant lesion with central necrosis. Surgical excision and pathological examination, however, revealed a benign adrenal myelolipoma with extensive adenomatous and hematopoietic elements. Prior reports of adrenal myelolipoma evaluated with FDG-PET imaging have described no significant FDG uptake within these benign tumors. This case is an unusual example of histologically proven benign adrenal myelolipoma that was hypermetabolic on FDG-PET imaging. Correlation of pathologic and imaging findings demonstrated that the hypodense regions on CT were hypometabolic on FDG-PET and corresponded to cystic necrosis and adipose elements, whereas the adenomatous and hematopoietic elements were hypermetabolic.