GIST stage diagnosis, metastasis / recurrence diagnosis, and therapeutic effect judgment

We picked up the explanation of FDG-PET from various clinical practice guidelines, and explained the background of the current recommendation level and what kind of recommendation level may be changed in the future. Systemic ¹⁸F-FDG-PET has been reported to be excellent in detection of early primary GIST, is highly useful for diagnosing peritoneal disseminated lesions, and is characterized by nodular accumulation in the peritoneum and extra intestinal accumulation. Treatment with imatinib reduces viable tumor cells and reduces overall tumor metabolism, reducing their uptake. The criteria for determining efficacy are defined by EORTC and are based on standardized uptake value (SUV) changes compared to baseline. As an example, a man in his 60s who is thought to have relapsed rectal GIST after surgery and a man in his 70s who is thought to have recurrence of peritoneal dissemination and liver metastasis after gastric GIST are shown. (S.S.)