Magnetic resonance imaging (MRI) of the myometrium – benign and malignant disease

Abstract

Myometrial lesions are a common indication for pelvic imaging, with accurate characterisation crucial for guiding management. While ultrasonography remains the first-line modality, magnetic resonance imaging (MRI) offers superior tissue contrast, multiplanar capability, and functional assessment, offering the highest accuracy for characterising uterine masses. This review highlights the pivotal role of MRI in differentiating benign from malignant myometrial lesions. We summarise characteristic imaging features of adenomyosis and the spectrum of leiomyomas, including atypical and degenerated leiomyomas, with reference to the Federation of Gynaecology and Obstetrics (FIGO) classification system. Emphasis is placed on MRI findings that help differentiate leiomyosarcoma (LMS) from atypical leiomyoma, a persistent diagnostic challenge due to their overlapping imaging appearances. Emerging approaches, including radiomics and machine learning, show promise in improving imaging-based differentiation of both entities. Rare myometrial lesions such as cysts and uterine arteriovenous malformations are also briefly reviewed. MRI remains the modality of choice for comprehensive evaluation and management planning of myometrial masses, supporting accurate diagnosis and effective multidisciplinary decision-making.