• Ruixin Yan, Dapeng Hao, Jie Li, Jihua Liu, Feng Hou, Haisong Chen, Lisha Duan, Chencui Huang, Hexiang Wang, and Tengbo Yu.
• Department of Radiology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, 266003, China.
• J Magn Reson Imaging. 2021 Jun 1; 53 (6): 1683-1696.

BackgroundPreoperative prediction of soft tissue sarcoma (STS) grade is important for treatment decisions. Therefore, formulation an STS grade model is strongly needed.PurposeTo develop and test an magnetic resonance imaging (MRI)-based radiomics nomogram for predicting the grade of STS (low-grade vs. high grade).Study TypeRetrospective POPULATION: One hundred and eighty patients with STS confirmed by pathologic results at two independent institutions were enrolled (training set, N = 109; external validation set, N = 71).Field Strength/SequenceUnenhanced T1-weighted (T1WI) and fat-suppressed T2-weighted images (FS-T2WI) were acquired at 1.5 T and 3.0 T.AssessmentClinical-MRI characteristics included age, gender, tumor-node-metastasis (TNM) stage, American Joint Committee on Cancer (AJCC) stage, progression-free survival (PFS), and MRI morphological features (ie, margin). Radiomics feature extraction were performed on T1WI and FS-T2WI images by minimum redundancy maximum relevance (MRMR) method and least absolute shrinkage and selection operator (LASSO) algorithm. The selected features constructed three radiomics signatures models (RS-T1， RS-FST2, and RS-Combined). Univariate and multivariate logistic regression analysis were applied for screening significant risk factors. Radiomics nomogram was constructed by incorporating the radiomics signature and risk factors.Statistical TestsClinical-MRI characteristics were performed by a univariate analysis. Model performances (discrimination, calibration, and clinical usefulness) were validated in the external validation set. The RS-T1 model, RS-FST2 model, and RS-Combined model had an area under curves (AUCs) of 0.645, 0.641, and 0.829, respectively, in the external validation set. The radiomics nomogram, incorporating significant risk factors and the RS-Combined model had AUCs of 0.916 (95%CI, 0.866-0.966, training set) and 0.879 (95%CI, 0.791-0.967, external validation set), and demonstrated good calibration and good clinical utility.Data ConclusionThe proposed noninvasive MRI-based radiomics models showed good performance in differentiating low-grade from high-grade STSs.Level Of Evidence3 TECHNICAL EFFICACY STAGE: 2.© 2021 International Society for Magnetic Resonance in Medicine.

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