Correlation of MRI Characteristics with the Histologic Grade of Soft Tissue Sarcoma of the Extremities and Trunk

Objective: The staging and treatment of soft tissue sarcoma depend on the histologic grades, which predicts overall survival. This study aimed to assess magnetic resonance imaging (MRI) characteristics to differentiate between low- and high-grade soft tissue sarcomas of the extremities and trunk.Material and Methods: This retrospective study included patients with soft tissue sarcomas who underwent preoperative MRI between October 2006 and December 2020. The data obtained included qualitative information (size, depth, MRI signal intensity, hemorrhage signal, margin, fascial tail sign, peritumoral edema/enhancement, and organ involvement) and quantitative information (apparent diffusion coefficient value). Logistic regression was performed to identify the MRI characteristics associated with histologic grades. Results: A total of 101 patients were included; 76 were diagnosed with histologically high-grade tumors. The final multivariate regression model showed a combination of 4 MRI characteristics: a large area of intratumoral heterogeneity on T2-weighted images (T2W), a large area of non-enhancing hyperintensity on T2W, a fascial tail sign, and peritumoral edema. These characteristics collectively predicted high-grade soft tissue sarcoma with 81% accuracy. The 2 strongest indicators were intratumoral heterogeneity on T2W (adjusted odds ratio (aOR) 3.96, 95% confidence interval (95% CI) 1.16-13.55, p-value=0.028) and a fascial tail sign (aOR 3.34, 95%CI 1.09-10.22, p-value=0.035). Conclusion: The 2 strongest MRI predictors of high-grade soft tissue sarcoma are marked intratumoral heterogeneity on T2W and a fascial tail sign. Furthermore, the combination of 4 MRI characteristics, including marked intratumoral heterogeneity on T2W, a fascial tail sign, non-enhancing hyperintensity on T2W, and peritumoral edema, can increase the accuracy of histologic grade prediction.