Clinical implications of determination of safe surgical margins by using a combination of CT and 18FDG-positron emission tomography in soft tissue sarcoma

The study involved 7 patients with sarcoma who underwent surgery in our department and in whom evaluation with FDG-PET/CT was possible. Sarcoma was histologically rated as MFH in 6 cases and leiomyosarcoma in 1 case. In all cases, sarcoma was superficial (T1a or T2a). The tumor border was defined by contrast-enhanced MRI, and SUVs were measured at intervals of 1 cm over a 5-cm long area from the tumor border. Mapping of viable tumor cells was carried out on whole-mount sections of resected tissue, and SUVs were compared with histopathological findings.Preoperative maximum SUVs (SUV-max) of the tumor averaged 11.7 (range: 3.8-22.1). Mean SUV-max was 2.2 (range: 0.3-3.8) at 1 cm from the tumor border, 1.1 (0.85-1.47) at 2 cm, 0.83 (0.65-1.15) at 3 cm, 0.7 (0.42-0.95) at 4 cm, and 0.64 (0.45-0.82) at 5 cm. When resected tissue was mapped, tumor cells were absent in the areas where SUV-max was below 1.0.Our findings suggest that a safe surgical margin free of viable tumor cells can be ensured if the SUV cut-off level is set at 1.0. FDG-PET/CT is promising as a diagnostic imaging technique for setting of safe minimal margins for surgical resection of soft tissue sarcoma.In surgical treatment of soft tissue sarcoma, it is as a rule necessary to remove the tumor in a reliable fashion with surgical margins at which recurrence is unlikely. With this principle, Enneking et al. [1] proposed extensive resection based on the "compartment" concept. Later, Kawaguchi et al. [2] proposed curative extensive resection, adopting the concept of "barrier on the basis of tumor-resistant tissue." Guidelines for treatment of varying stages of soft tissue sarcoma such as the National Comprehensive Cancer Network (NCCN) Guidelines are available, and techniques for soft tissue sarcoma resection have been relatively well established. In the past, contrast-enhanced MRI was often used as a primary technique for determining surgical margins for soft tissue sarcoma. It is essential to perform gener