- FDG-PET avid lesion with uptake above the background liver uptake as described below: i.e. with a marked accumulation of FDG, at least 1.5-fold greater than liver SUV mean + 2 SDs (in 3cm spherical ROI in normal right lobe of liver). If liver is abnormal, target lesion should have uptake > 2.0 x SUV mean of blood pool in 1cm diameter ROI in descending thoracic aorta)