A noble objective method for discriminating pathological and physiological colorectal uptake in the lower abdominal region using whole-body dynamic 18F-FDG-PET

Abstract

Objectives To investigate whether the center-of-mass shift distance (CMSD) analysis on whole-body dynamic positron emission tomography (WBD-PET) with continuous bed motion was an objective index for discriminating pathological and physiological colorectal uptake in the lower abdominal region. Methods We retrospectively analyzed the CMSD in 39 patients who underwent delayed imaging to detect focal uptake that were difficult to determine as pathological and physiological on an conventional early PET (early) image reconstructed by five-phase WBD-PET images. The CMSD between each phase of WBD-PET images and between early to delayed (early–delayed) images were classified into pathological and physiological uptake groups based on endoscopic histology or other imaging diagnostics. The diagnostic performance of CMSD analysis on WBD-PET images was evaluated by receiver operator characteristic (ROC) analysis and compared to that of early–delayed images. Results A total of 66 focal uptake detected early image were classified into 17 and 49 pathological and physiological uptake groups, respectively. The CMSD on WBD-PET and early–delayed images in the pathological uptake group was significantly lower than that in the physiological uptake group (p < 0.01), respectively. The sensitivity, specificity, and accuracy in CMSD analysis on WBD-PET images at the optimal cutoff of 5.2 mm estimated by the Youden index were 94.7%, 89.4%, and 89.4%, respectively, which were not significantly different (p = 0.74) from those of early–delayed images. Conclusions The CMSD analysis on WBD-PET was useful in discriminating pathological and physiologicalcolorectal uptake in the lower abdominal region, and its diagnostic performance is comparable to that of early–delayed images. We suggested that CMSD analysis on WBD-PET images would be a new objective method to omit unnecessary additional delay imaging.