Role of 18F-FDG PET/CT in restaging and follow-up of patients with GIST.

Abstract

Gastrointestinal stromal tumor (GIST) is a rare tumor with high risk of recurrence and poor prognosis in case of advanced GIST. The aim of this study was to evaluate the possible role of 18F-FDG PET/CT in restaging GIST. Fifty-four patients (30 male) with histological proven GIST underwent 100 18F-FDG PET/CT for restaging in suspected recurrence or during follow-up. Histopathology results and/or clinical/imaging follow-up for at least 12months were considered as reference standard. Moreover, the diagnostic accuracy and clinical impact of 18F-FDG PET/CT were calculated. Twenty-seven (27%) 18F-FDG PET/CT were positive, while the remaining 73 (73%) were negative. Sensitivity, specificity, PPV, NPV, and accuracy of PET/CT were 89% (95% CI 72-98%), 97% (95% CI 90-100%), 93% (95% CI 76-98%), 96% (95% CI 89-98%), and 95% (95% CI 89-98%). 18F-FDG PET/CT had a positive clinical impact in 18/100 studies changing the management, in 8 cases switching from local therapy to systemic therapy due to the detection of disseminate disease at PET/CT, in three cases recognizing relapse not detected by conventional imaging, and in 7 cases demonstrating to be true negative and avoiding unnecessary therapies. 18F-FDG PET/CT seems to be an accurate method for detection and localization of local and distant recurrence in GIST with good sensitivity and specificity and significant impact on clinical decision-making.