Gastrointestinal stromal tumors: a pictorial review.

We describe the pertinent organ-specific clinical manifestations of gastrointestinal stromal tumors (GISTs) as well as the radiological appearances that allow optimal depiction of pathology and diagnosis. Radiologic features of GISTs vary depending on tumor size and organ of origin. They most commonly have an exophytic growth pattern and manifest as dominant masses outside the organ of origin. Intramural and intraluminal masses are less common radiologic manifestations. GISTs may contain areas of hemorrhage, necrosis, or cyst formation that appear as focal areas of low attenuation on computed tomographic images. Most metastases of GISTs involve the liver and peritoneum by hematogenous spread and peritoneal seeding. CT and MRI are considered to be the imaging modality of choice for the detection, staging, surgical planning and follow-up of patients with GIST. A reduction in tumor size, extensive cystic changes, and calcification in primary and metastatic GISTs on CT and MRI indicate disease response to therapy. Radiologists and clinicians must recognize the imaging features of GISTs, detect, characterize the lesions and evaluate the tumor response during specific treatment.