Diagnostic Performance of Magnetic Resonance Imaging in Discriminating Benign and Malignant Soft Tissue Tumors.

Objective: The study aimed to evaluate the role of magnetic resonance imaging (MRI) in differentiating between primary benign and malignant soft tissue tumors (STTs). Patients and Methods: The study was carried out on 110 patients with histopathological diagnoses of STTs. All patients underwent routine MRI before surgery/biopsy at Viet Duc University Hospital or Vietnam National Cancer Hospital, Hanoi, Vietnam, from January 2020 to October 2022. Data on preoperative MRI as well as the clinical features and pathological results of the patients were collected retrospectively. Univariate and multivariate linear regression were used to analyze the relationship between imaging, clinical parameters, and the ability to differentiate malignant from benign STTs. Results: Among 110 patients (59 men and 51 women), 66 had benign tumors and 44 had malignant tumors. The qualitative values that were significant in distinguishing between benign and malignant STTs were hypointensity on T1-weighted images (T1W; p<0.001), hypointensity on T2-weighted images (T2W; p=0.003), cysts (p=0.003)), necrosis (p<0.001), fibrosis (p=0.023), hemorrhage (p<0.001), lobulated margin (p<0.001), ill-defined border (p<0.001), peritumoral edema (p<0.001), vascular involvement (p<0.001), and heterogeneous enhancement (p<0.001). Regarding quantitative values, age (p=0.009), size (p<0.001), T1W signal quantification value (p=0.002), and T2W signal quantification value (p=0.007) showed statistically significant differences between benign and malignant tumors. Multivariate linear regression analysis showed that the combination of peritumoral edema and heterogeneous enhancement was the most valuable in the differential diagnosis of malignant tumors from benign tumors. Conclusion: MRI is valuable in discriminating between malignant and benign STTs. The presence of cysts, necrosis, hemorrhage, lobulated margin, ill-defined border, peritumoral edema, heterogeneous enhancement, vascular involvement, and T2W hypointensity is suggestive of malignant lesions, especially signs of peritumoral edema and heterogeneous enhancement. Advanced age and large tumor size are also suggestive of soft tissue sarcomas.