Soft-Tissue Tumor Reporting and Data System (St-Rads): Mri Reporting Guideline with Multi-Institutional Validation Study of Extremity Soft Tissue Tumors

Abstract BackgroundTo our knowledge, no current guideline exists in outlining follow-up or interventional strategies in musculoskeletal soft tissue tumor management. To develop and validate soft-tissue tumor reporting and data system (ST-RADS) with the hypothesis that the proposed guideline reliably and accurately assists in separating benign from malignant musculoskeletal soft tissue tumors.Methods This is a multi-institutional cross-sectional study of soft-tissue masses. An expert consensus agreement was reached for ST-RADS categories using the terminology from WHO classification. Adipocytic tumors, T2-hyperintense and T2-hypointense masses of extremities with a wide spectrum of histologies were assessed. MRI categories were: STRADS 0 - incomplete imaging, I – no lesion identified, II - definitely benign, III - probably benign, IV - indeterminate or suspicious for malignancy, V- highly suggestive of malignancy, and VI - known biopsy-proven malignancy or recurrence. Eight readers evaluated cases and ICC and AUC were calculated. Results 200 soft tissue masses were tested. There was good inter-reader agreement with ICC= 0.72 [95% CI=0.64-0.79] and 0.69 [95% CI=0.59-0.70] for adipocytic and T2-hyperintense, and fair, 0.48 [95% CI=0.35-0.62] for T2- hypointense masses. The sensitivity and specificity for detection of malignancy were 96% and 63%, 93% and 71%, 64% and 84% for adipocytic, T2-hyperintense, and T2-hypointense masses, respectively. The AUC was 0.79-0.89.Conclusion ST-RADS guideline using standardized terminology stratifies musculoskeletal tumors into benign and malignant categories and provides management strategy. This MRI-based guideline is meant to be a "dynamic" document that can be further refined and updated in response to future user feedback and as new scientific data becomes available.