Evaluation of pancreatic carcinoma with FDG PET

Background: To assess the diagnostic usefulness and clinical impact of posi tron emission tomography with [F-18]fluorodeoxyglucose (FDG PET) on the man agement of patients with known or suspected pancreatic carcinoma. Methods: Attenuation-corrected FDG PET was performed in 20 patients (12 mal e, eight female) with pancreatic carcinoma at the time of initial diagnosis (n = 7), for tumor surveillance after Whipple surgery (n = 11), and for re evaluation after chemoradiation therapy (n = 2). Visual analysis of PET ima ges were correlated with the results of abdominal computed tomography (CT) and carbohydrate antigen (CA) 19-9 serum tumor marker level that were obtai ned within 1 month of the PET study. Diagnostic validation was by histology in nine patients and by clinical or radiologic follow-up (5-48 months) in 11 patients. Changes in therapeutic management that were prompted by PET we re tabulated. Results: PET was concordant with the findings of abdominal CT in 14 patient s (13 true positive, 1 true negative). PET detected clinically unsuspected lung lesions, confirmed subsequently by a chest CT, in one of these 14 pati ents. PET was discordant with CT in six patients. PET detected tumor recurr ence in three patients in this group (15% of total) with nondiagnostic CT f indings and elevated CA 19-9 serology. In two of these three patients, chem otherapy with gemcitabine was initiated based on PET localization of diseas e. Tumor was confirmed in the remaining one of the three patients at autops y shortly after the PET study. FDG localization in a displaced loop of bowe l resulted in an apparent false-positive hepatic lesion in one of six patie nts in the discordant group. PET underestimated the extent of metastatic di sease in the remaining two of six patients due to hyperglycemia, Conclusion: In patients with suspected pancreatic carcinoma at the time of initial presentation, PET is complementary to abdominal CT and allows detec tion of unsuspected distant metastases. In patients with suspected recurren t pancreatic carcinoma, based on elevated or rising CA 19-9 serology, PET c an localize the disease when abdominal CT is nondiagnostic as a result of p osttherapy anatomic alteration. Imaging evaluation with PET may impact the clinical management of patients with pancreatic carcinoma.