Imaging of Gastrointestinal Stromal Tumors

Purpose of Review In this paper, we review gastrointestinal stromal tumors (GISTs), including their clinical presentation, pathology, staging and grading, imaging characteristics of primary and metastatic disease, treatment options, and typical imaging appearance of treatment response and recurrence. We discuss the use of contrast-enhanced CT, which remains the primary modality for diagnosis and surveillance, as well as MRI, FDG PET/CT, and rarely ultrasound. Recent Findings Recent metanalysis has established improved epidemiologic data regarding GISTs worldwide. Imaging factors influencing risk stratification, including the use of MRI and FDG PET/CT, has also been explored. Numerous smaller studies and case reports have explored atypical presentations of GISTs and extra-gastrointestinal stromal tumors (E-GISTs), including discussions of rare metastatic lesions. Additional discussion of the best practice for surveillance, in which CECT is the current modality of choice, has also been reviewed. Summary GISTs are a rare mesenchymal tumor with a predilection for the stomach and small bowel. Typical imaging characteristics allow the astute radiologist to suggest this diagnosis in the absence of a unifying or pathognomonic clinical symptomatology. Diagnosis of GIST is imperative as immunotherapeutic agents are highly effective, alone or in combination with surgery, significantly prolonging patient survival. The imaging characteristics of partial or complete treatment response and subsequent disease recurrence is predictable on CECT, the current workhorse modality for surveillance. The radiologist is therefore a vital member of the care team for staging the initial disease, evaluating for treatment response, and identifying disease recurrence.