Usefulness of dual-phase 18F-FDG PET/CT for diagnosing small pancreatic tumors.

OBJECTIVES:The usefulness of dual-phase F-fluorodeoxyglucose (F-FDG) positron emission tomography/computed tomography (PET/CT) for pancreatic tumors was investigated including numerous small tumors. METHODS:Consecutive 116 patients with solid pancreatic tumors were subjected. Maximum standard uptake values (SUVmax) at 1 and 2 hours after FDG injection were defined as early and delayed SUVmax, respectively. Receiver operating characteristic curve was used to determine the optimal cutoff value of early SUVmax. Diagnostic accuracy of dual-phase FDG PET/CT was compared with that of single phase. RESULTS:The mean ± SD tumor size was 25 ±12 mm in diameter. The level of early SUVmax and proportion of elevated SUVmax in delayed phase were significantly higher in malignancy than those in benignancy for less than 25 mm tumors (4.1 ± 2.6 vs 1.9 ± 0.5, P < 0.001; 89% vs 17%, P < 0.0001) although they did not reach statistical significance for greater than or equal to 25 mm tumors. When diagnostic criteria of dual-phase FDG PET/CT for less than 25 mm tumors were determined as (1) early SUVmax greater than or equal to 2.1 and/or (2) delayed SUVmax greater than early SUVmax, sensitivity, specificity, and over all accuracy of dual-phase FDG PET/CT were better than that of single phase for less than 25 mm tumor (93%, 83%, and 91% vs 79%, 83%, and 80%, respectively). CONCLUSIONS:Dual-phase FDG PET/CT might be useful for diagnosing small pancreatic tumors.