Focal colorectal uptake in 18FDG-PET/CT: maximum standard uptake value as a trigger in a semi-automated screening setting

Background Focal colorectal uptake in .sup.18FDG-PET/CT may be associated with a malignancy and can be quantified. This provides the basis for an automatic trigger threshold above which cases are flagged for colonoscopic evaluation and below which for individual assessment. Purpose To determine the lowest maximum standard uptake (SUV.sub.max) in colorectal cancer that could be used as a threshold to trigger endoscopic evaluation and to evaluate whether the SUV.sub.max needs to be further normalised to a priori known extrinsic factors. Methods The SUV.sub.max was measured in 54 colorectal carcinomas and correlated with gender, age, blood glucose level, injected activity, body mass index and time to scan using t test or correlation coefficients (Pearson or Spearman, according to distribution). Results There was no correlation between SUV.sub.max and any of the extrinsic factors mentioned above. The lowest SUV.sub.max value was 5 [mean [+ or -] SD (range): 11.1 [+ or -] 4.8 (5.0-24.6)]. Conclusion In contrast to most other screening techniques, semi-automation in colorectal screening seems possible with PET/CT. This opens the door for further study into the feasibility of automated screening. Independent from extrinsic factors, an SUV.sub.max [greater than or equai to]5.0 in a focal colorectal uptake in .sup.18FDG-PET/CT should automatically trigger for endoscopic evaluation, if not contraindicated. Cases with SUV.sub.max