F-18FDG PET for assessing tyrosine kinase-related signal transduction inhibition in a GIST c-Kit-positive tumor patient by imatinib

Gastrointestinal stromal tumor (GIST) is a rare group of stromal or connective tissue tumors that arises from mesenchymal cells of the gastrointestinal tract characterized by positive expression of c-Kit. Accurate assessment of GIST tumor spread by anatomic imaging techniques can be difficult in poorly defined tumor lesions such as bowel, peritoneal, or bone metastases. Therefore, an under-estimation of tumor burden may result. In addition, such techniques cannot discriminate early tumor response to therapy. In this rare case, baseline F-18 FDG PET imaging proved to be more efficient than CT in delineating the true metastatic tumor burden and the early-on excellent response to medication targeting cellular tyrosine kinase. Copyright © 2005 by Lippincott Williams & Wilkins.