Optimal interpretation of FDG PET in the diagnosis, staging and managementof pancreatic carcinoma

This study had two purposes: to optimize the semiquantitative interpretatio n of F-18-fluorodeoxyglucose (FDG) PET scans in the diagnosis of pancreatic carcinoma by analyzing different cutoff levels for the standardized uptake value (SUV), with and without correction for serum glucose level (SUVgluc) ; and to evaluate the usefulness of FDG PET when used in addition to CT for the staging and management of patients with pancreatic cancer. Methods: Si xty-five patients who presented with suspected pancreatic carcinoma underwe nt whole-body FDG PET in addition to CT imaging. The PET images were analyz ed visually and semiquantitatively using the SUV and SUVgluc, The final dia gnosis was obtained by pathologic (n = 56) or clinical and radiologic follo w-up (n = 9), The performance of CT and PET at different cutoff levels of S UV was determined, and the impact of FDG PET in addition to CT on patient m anagement was reviewed retrospectively. Results: Fifty-two patients had pro ven pancreatic carcinoma, whereas 13 had benign lesions, including chronic pancreatitis (n = 10), benign biliary stricture (n = 1), pancreatic complex cyst (n = 1) and no pancreatic pathology (n = 1). Areas under receiver ope rating characteristic curves were not significantly different for SUV and S UVgluc. Using a cutoff level of 3.0 for the SUV, FDG PET had higher sensiti vity and specificity than CT in correctly diagnosing pancreatic carcinoma ( 92% and 85% versus 65% and 61%), There were 2 false-positive PET (chronic p ancreatitis, also false-positive with CT) and 4 false-negative PET (all wit h true-positive CT, abnormal but nondiagnostic) examinations. There were 5 false-positive CT (4 chronic pancreatitis and 1 pancreatic cyst) and 18 fal se-negative CT (all with true-positive FDG PET scans) examinations. FDG PET clarified indeterminate hepatic lesions or identified additional distant m etastases (or both) in 7 patients compared with CT. Overall, FDG PET altere d the management of 28 of 65 patients (43%), Conclusion: FDG PET is more ac curate than CT in the detection of primary tumors and in the clarification and identification of hepatic and distant metastases. The optimal cutoff va lue of FDG uptake to differentiate benign from malignant pancreatic lesions was 2.0. Correction for serum glucose did not significantly improve the ac curacy of FDG PET, Although FDG PET cannot replace CT in defining local tum or extension, the application of FDG PET in addition to CT alters the manag ement in up to 43% of patients with suspected pancreatic cancer.