Detection and grading of soft tissue sarcomas of the extremities with 18F-3′-fluoro-3′-deoxy-L-thymidine

Purpose: The aim of the study was to investigate the feasibility of F-18-3'-fluoro-3'-deoxy-L-thymidine positron emission tomography (FLT-PET) for the detection and grading of soft tissue sarcoma (STS). Experimental Design: Nineteen patients with 20 STSs of the extremities were scanned, using attenuation corrected whole-body FLT-PET. Standardized uptake values (SUVs) and tumor:nontumor ratios (TNTs) were compared with histopathological parameters using French and Japanese grading systems. Results: Mean SUV, maximal SUV, and TNT could differentiate between low- grade (grade 1; n = 6) STS and high-grade (grade 2 and 3; n = 14) STS according to the French grading system (P = 0.001). Mean SUV, maximal SUV, and TNT correlated with mitotic score, MIB-1 score, the French and Japanese grading system (e = 0.550-0.747). Conclusions: FLT-PET is able to visualize STS and differentiate between low-grade and high-grade STS. The uptake of FLT correlates with the proliferation of STS.