Imaging and Response Evaluation of Gastrointestinal Stromal Tumors
Authors: MD Sooyoung Shin, MD Haesun Choi
Publisher: Springer International Publishing
Imaging plays crucial roles in identifying lesions, staging workup, and more importantly, in assessing treatment response following molecular targeted therapy for gastrointestinal stromal tumor (GIST). Often, GIST is detected incidentally during endoscopic procedures for unrelated cause, and endoscopic ultrasound with or without fine-needle aspiration aids in the diagnosis. Computed tomography (CT) with and without iodinated intravenous contrast is currently the imaging modality of choice for detecting, characterizing, staging, and assessing treatment response in GISTs. Positron emission tomography (PET) is highly sensitive in detecting primary GISTs and metastasis throughout the body and highly specific in evaluating early treatment response. PET is indicated for imaging borderline resectable GISTs, for problem solving in response evaluation, and as a therapeutic monitoring modality on follow-ups. Magnetic resonance imaging (MRI) is preferred over CT in rectal GIST, particularly for presurgical planning, and is indicated when the use of iodine contrast is contraindicated. MRI can be a preferred modality for evaluating metastatic liver lesions; however, it is not used routinely owing to relatively low sensitivity for peritoneal disease.