Kato A, et al. - Researchers sought to investigate quantitative parameters in ¹⁸F-FDG PET/CT in terms of correlation with histologic grade and overall survival in patients with angiosarcoma. They retrospectively examined a total of 16 individuals with histologically confirmed angiosarcoma who had undergone pretreatment FDG PET/CT. They measured maximum standardized uptake value for the primary tumor (pSUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) for the whole body, tumor-to-blood ratio (TBR) for the primary tumor, and summed ratios of tumor-to-blood glycolytic activity for all lesions (whole-body TLG ratio). They categorized tumors into high grade and low grade, according to the pathologic results. They further evaluated the associations between these metabolic parameters and tumor grade. They found that high-grade tumors had significantly higher pSUVmax and primary TBR at FDG PET/CT in angiosarcoma. In this study, all evaluated quantitative parameters were found to be significant prognostic factors for overall survival.