Figure 10.

A 58-year-old man with large gastrointestinal stromal tumor (GIST). Staging PET/CT study demonstrated an extensive primary tumor displaying a peripheral rim of intense metabolic activity (top row) [arrows] surrounding a central photopenic core consistent with massive central tumor necrosis. The patient was treated with Gleevec (bottom row) [arrows] with excellent therapeutic response, as documented by follow-up PET/CT at 2 weeks, showing resolution of the metabolic activity in the tumor with only mild activity.