Improving the detecting efficiency of suspected gastrointestinal tumors with dual-time-point 18 F-FDG PET/CT

We conducted a retrospective analysis of 221 subjects with 256 suspected gastrointestinal lesions from 2007 to 2015 to explore the detecting efficiency of dual-time-point fluorine-18 fludeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) and pathology examination. The abdominal delayed PET/CT was performed within 45 min of the conventional scan. The change in maximum standardized uptake value (ΔSUVmax) and morphological features of the suspected lesions between the conventional and dual-time-point PET/CT were compared. The sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of conventional PET/CT were 81.6% (84/103), 56.2% (86/153), 55.6% (84/151), and 81.9% (86/105), respectively. Those of dual-time-point PET/CT were 94.1% (97/103), 78.4% (120/153), 74.6% (97/130), and 95.2% (120/126), respectively. There was a significant difference between the conventional and dual-time-point PET/CT (P < 0.005). The SUVearly and the %ΔSUVmax could not present more information in differential diagnoses, but the rate of tumors with increased SUVdelay accounted for 79.6% (82/103) and more than that of nonneoplastic lesions (15.5%, 29/187) (x 2 = 115.5, P < 0.01). Therefore, the dual-time-point 18F-FDG PET/CT had a higher sensitivity and NPV than the conventional PET/CT to detect gastrointestinal tumors. The constant morphology and increased SUVdelay help to detect the tumors and adding delayed imaging on the locality will be an effective method when we accidentally find a suspected gastrointestinal tumor on the conventional PET/CT images.