Dynamic whole-body ¹⁸F-FDG PET for differentiating abnormal lesions from physiological uptake.

Abstract

Serial assessment of visual change in ¹⁸F-FDG uptake on whole-body ¹⁸F-FDG PET imaging was performed to differentiate pathological uptake from physiological uptake in the urinary and gastrointestinal tracts. In 88 suspected cancer patients, serial 3-min dynamic whole-body PET imaging was performed four times, from 60 min after ¹⁸F-FDG administration. In dynamic image evaluation, high ¹⁸F-FDG uptake was evaluated by two nuclear medicine physicians and classified as "changed" or "unchanged" based on change in uptake shape over time. Detectability of pathological uptake based on these criteria was assessed and compared with conventional image evaluation. Dynamic whole-body PET imaging provided images of adequate quality for visual assessment. Dynamic image evaluation was "changed" in 118/154 regions of high physiological ¹⁸F-FDG uptake (77%): in 9/19 areas in the stomach (47%), in 32/39 in the small intestine (82%), in 17/33 in the colon (52%), and in 60/63 in the urinary tract (95%). In the 86 benign or malignant lesions, 84 lesions (98%) were "unchanged." A high ¹⁸F-FDG uptake area that shows no change over time using these criteria is highly likely to represent pathological uptake, with sensitivity of 97%, specificity of 76%, PPV of 70%, NPV of 98%, and accuracy of 84%. Dynamic whole-body ¹⁸F-FDG PET imaging enabled differentiation of pathological uptake from physiological uptake in the urinary and gastrointestinal tracts, based on visual change of uptake shape.