Comparison of FDG-PET images with endoscopic and histopathologic findings in relation to clinical presentation and outcome in patients with suspected intestinal GVHD after allogeneic HSCT. A significant FDG uptake was detected in the colons of patients with clinical signs of GVHD and diagnostic or inconclusive histopathologic findings (B,C). The results are representative of 30 different patients with suspected gastrointestinal GVHD. Arrows indicate apoptotic mucosa cells, compared with physiological findings in a patient with no intestinal GVHD (A).