Spectrum of MR features in adenomyosis

Magnetic resonance (MR) imaging is a highly accurate non-invasive technique for the diagnosis of adenomyosis. Typical MR features include either diffuse or focal thickening of the junctional zone or an ill-defined area of low signal intensity in the myometrium on T2-weighted MR images. Occasionally, the islands of ectopic endometrial tissue can be identified as punctate foci of high signal intensity. Less commonly, adenomyosis can present as a well-circumscribed form known as adenomyoma, adenomyotic cyst characterized by the presence of haemorrhagic cyst, or adenomyomatous polyp protruding into the uterine cavity. The MR appearances of adenomyosis may occasionally fluctuate in response to hormonal stimulation and treatment. MR imaging is helpful not only in monitoring the treatment effect of hormonal therapy, but also in predicting therapeutic effect. In cases of endometrial cancer in the uterus with adenomyosis, evaluation of myometrial invasion may become difficult. Rarely, endometrial cancer may arise directly from adenomyosis resulting from malignant transformation of endometrial glands, creating diagnostic challenges. Differential diagnosis of adenomyosis on MR imaging include physiological myometrial contraction and almost all myometrial lesions, and they should be carefully differentiated from adenomyosis by identifying typical clinical and MR features in these lesions. Precise knowledge of the spectrum of MR features in adenomyosis greatly helps in determining an accurate diagnosis and appropriate management of the patients.