Predictive Value of Pretreatment SUVmax on 18F-FDG PET Imaging for Survival Outcomes of Synovial Sarcoma in Pediatric Patients

Synovial sarcoma is the most common nonrhabdomyosarcoma soft tissue sarcoma in children and adolescents, typically associated with more favorable outcomes compared with adults. However, the role of 18 F-fluorodeoxyglucose ( 18 F-FDG) PET imaging in pediatric synovial sarcoma is underexplored. This study investigates the prognostic value of pretreatment maximum standardized uptake value (SUVmax) on 18 F-FDG PET imaging in 15 pediatric patients with synovial sarcoma who underwent PET/CT or PET/MRI and MRI. SUVmax of the primary tumors were analyzed for their association with overall survival (OS) and progression-free survival (PFS). The median SUVmax was 4.64 (range: 1.66 to 12.46). Although higher SUVmax tended to be associated with poorer OS and PFS, no statistically significant associations were found. MRI findings also showed no significant association with outcomes. Our result highlights that tumors with low SUVmax can still exhibit aggressive behavior. High-grade tumors and those larger than 5 cm were associated with higher SUVmax, and were more frequently located in axial regions. These findings suggest integrating SUVmax with tumor grade, tumor size and location may enhance risk stratification and support more individualized treatment strategies in pediatric synovial sarcoma.