Diagnostic methods for initial evaluation of primary gastrointestinal stromal tumors.

Objective: To describe the imaging features of gastrointestinal stromal tumors (GISTs) at initial presentation with clinical, surgical, and pathologic correlation, and to evaluate values of various techniques in GISTs.

Methods: This retrospective study recruited 70 patients with histologically proved GISTs between December 2004, and May 2009 in the Department of General Surgery, Zhongshan Hospital, Fudan Univeristy, Shanghai, China. Each patient underwent CT scanning, 39 patients underwent simultaneous endoscopy, 12 patients underwent endoscopic ultrasound (EUS), and 36 patients underwent transabdominal ultrasonography (TAUS) simultaneously. Features of GISTs were assessed.

Results: Computerized tomography findings showed an eccentric mass in 44 patients, an intraluminal component in 24, and a transmural distribution in 2. Forty-two tumors were dumbbell-shaped, 2 were round, while 26 were irregular. Forty-three tumors presented with well-defined masses, while 27 with unclear borders. The arterial phase attenuation showed the continuous enhancement. The portal-venous phase attenuation was heterogeneous in 26 and homogeneous in the other 44. There was a significant correlation between certain CT features and tumor risk stratification. Gastrointestinal stromal tumors were characterized by a smooth shape and normal overlying mucosa in endoscopy, hypoechoic, and solid in TAUS.

Conclusion: Imaging examinations are pivotal in the management of GISTs. The CT scan is valuable in the diagnosis, staging, and treatment planning of GISTs. Endoscopy and EUS contribute to the detection of mucosal lesions. Other methods including TAUS, fluorodeoxyglucose positron emission tomography, CT gastrography, and MRI help in specific cases.