MRI (Figure C) is highly accurate for making the diagnosis of adenomyosis. On MRI, many of the ndings reect smooth muscle proliferation in reaction to the heterotopic endometrial tissue. The junctional zone is thickened (Figure C), and a cut­off measurement of 12 mm is used to suggest the diagnosis. Small foci with high signal intensity are seen within the myo­metrium on T2-weighted sequences (Figure C) and sometimes on T1-weighted sequences. It is important to distinguish focal adenomyosis from a leiomyoma because the treatment differs for each entity. MRI is helpful in this role, particularly when subtle ultrasound ndings are present and additionally because the appearance of an adenomyoma as a calcied uterine mass, mimicking a myoma on ultrasound, has been reported in the literature. On MRI, the borders of an adenomyoma are irregu­lar, and the presence of the high signal foci in the myome­trium on T2-weighted sequences should aid in the distinction of these two entities. Adenomyosis can now be diagnosed and differentiated with a high degree of accuracy by both ultra­sound and MRI.