False-negative fluorine-18-FDG PET in metastatic carcinoid.

Carcinoid tumors have high numbers of somatostatin receptors that allow scintigraphic imaging with the radiolabeled somatostatin analog octreotide. Experience, however, with PET using 2-[18F]fluoro-2-deoxy-D-glucose (18FDG) in carcinoid is very limited. In two prior studies which investigated the utility of 18FDG-PET in cancer detection, three patients with small, solitary, indolent carcinoid tumors had false-negative results. We report a case where 18FDG-PET imaging was false-negative in a patient with known metastatic carcinoid and a positive octreotide scan.