Diagnostic Performance of Diffusion-Weighted MRI and ADC Values in Differentiating Atypical Leiomyomas from Uterine Sarcomas

Abstract

Background: Leiomyomas are the most common benign uterine tumors, whereas uterine sarcomas are rare malignant neoplasms associated with high morbidity and mortality. Differentiation using imaging remains challenging because of overlapping radiologic features. Purpose: To evaluate magnetic resonance imaging (MRI) characteristics of atypical leiomyomas and uterine sarcomas, with emphasis on diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) values. Materials and Methods: In this retrospective study, 22 patients with histopathologically confirmed uterine leiomyoma or sarcoma underwent MRI for atypical or suspicious uterine lesions. MRI assessment included T2-weighted imaging, DWI with ADC maps, and fat-suppressed T1-weighted sequences before and after gadolinium administration. Results: Thirteen atypical leiomyomas (59%) and nine sarcomas (41%) were analyzed. Mean patient age was similar between groups. Abnormal vaginal bleeding was more frequent in sarcomas (89% vs. 38%). Sarcomas more commonly showed irregular margins (89% vs. 69%) and T2 hyperintensity (89% vs. 15%). Heterogeneous enhancement and cystic or hemorrhagic changes occurred in both tumor types, while extrauterine disease was observed only in sarcomas. All sarcomas demonstrated high DWI signal intensity exceeding that of the endometrium, whereas most leiomyomas showed intermediate signal intensity. Mean ADC values were significantly lower in sarcomas (0.813 × 10⁻³mm²/s) than in leiomyomas (1.050 × 10⁻³ mm²/s), with an optimal cutoff of 0.892 × 10⁻³mm²/s. Conclusion: MRI, particularly DWI and ADC analysis, provides valuable differentiation between atypical leiomyomas and uterine sarcomas, with sarcomas demonstrating higher DWI signal intensity and significantly lower ADC values.