F-18 FDG PET imaging in gastrointestinal stromal tumor.

Gastrointestinal stromal tumor (GIST) is the most frequent mesenchymal malignancy of the gastrointestinal tract. Liver and peritoneum are the most frequent metastatic sites. Surgery is the mainstay of treatment in patients with localized disease. Imatinib mesylate (Gleevec; Novartis Pharmaceuticals, East Hanover, NJ), an inhibitor of tyrosine kinase activity of KIT receptor, has been shown to be an effective treatment in metastatic or unresectable disease. Follow-up of patients treated with Gleevec is controversial. The authors present a case of GIST that showed near-total response with Gleevec on fluorodeoxyglucose positron emission tomography. They suggest positron emission tomography as a useful imaging modality for the monitoring of therapy response in GIST tumors treated with Gleevec.