Improving the detecting efficiency of suspected gastrointestinal tumors with dual-time-point 18F-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 （ASUVma~） 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 %ASUVmax 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） （x2= 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 SUVaelay 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.