Objective:

To evaluate the abilities of conventional MRI and IVIM in differentiating benign, intermediate, and malignant fibrous soft-tissue tumors.

Approach:

• Study Design: Prospective study involving 55 patients with fibrous STTs, categorized into benign, intermediate, and malignant.
• MRI Examination: Patients underwent MRI including IVIM, with analysis of conventional MRI signs and diffusion parameters.
• Statistical Analysis: Utilized Kruskal–Wallis H test, Chi-square test, post hoc test with Bonferroni correction, ROC curves, and DeLong test.

Key Findings:

• Malignant tumors exhibited higher heterogeneity on T2WI (p = 0.020 and 0.009) and contrast enhancement T1WI (p = 0.013 and 0.029) compared to benign and intermediate tumors.
• Malignant tumors were more prone to necrosis (p < 0.001 and p = 0.001) than benign and intermediate tumors.
• Tail-like patterns (p = 0.034 and 0.009) and invasiveness (p = 0.018 and 0.033) were more frequently observed in intermediate and malignant tumors than in benign tumors.
• Standard-ADCmean showed the highest AUC (0.894) for differentiating intermediate from benign STTs.
• Dmean demonstrated the highest AUC (0.961 and 0.905) for differentiating malignancies from benign and intermediate STTs, respectively.
• The combination of conventional MRI signs and IVIM parameters yielded the highest AUC of 0.971 for distinguishing benign from non-benign STTs.

Interpretation:

IVIM diffusion parameters differentiated benign, intermediate, and malignant fibrous STTs and can complement conventional MRI signs.

Limitations:

• Study limited to patients with pathologically proven fibrous tumors.
• Exclusion of tumors with myxoid components and those with poor image quality.

Conclusion:

IVIM diffusion parameters can enhance the differentiation of fibrous STTs when used alongside conventional MRI.