Tracy A. Jaffe (tracy.jaffe@duke.edu)

· MR is a widely accepted modality for imaging the uterus because of its superior soft tissue contrast · Routine imaging of the benign uterus includes evaluation of zonal anatomy with multiplanar high resolution T2-weighted images

· Uterine anomalies, uterine enlargement and dysfunctional uterine bleeding (DUB) are common benign diagnoses identified on MRI.

Radiologists and MR technologists interested in reviewing MR imaging of the female pelvis. Attendees will learn review uterine anatomy on MRI, learn the Müllerian duct anomaly (MDA) classification system and the MR appearance of MDAs, and the MR appearance of common benign causes of uterine enlargement and dysfunctional uterine bleeding (DUB) including leiomyomas and adenomyosis.MRI is been widely accepted as an essential modality in imaging of the female pelvis given its superior soft tissue contrast when compared to ultrasound and CT. MRI has become the imaging modality of choice for problem solving in the uterus as it readily depicts congenital uterine anomalies as well as distinguishes between the routine causes of uterine enlargement and bleeding. Routine MRI of the female pelvis should include axial, coronal and sagittal T2W sequences as well as axial and sagittal T1W sequences pre and post gadolinium administration.The uterus arises from the Müllerian ducts which fuse by week 12 in embryologic development to form the uterus and upper 2/3 of the vagina. The uterus is comprised of three zones: the endometrium, junctional zone and myometrium. The endometrium, a T2W bright structure, is the inner lining of the uterine cavity which contains glandular tissue and thickens during the menstrual cycle. The endometrium will decrease in the post-menopausal patient. The junctional zone, made of muscular tissue with high nuclear-to-cytoplasmic ratio, is dark on T2W images and measures less than 11 mm in thickness. The remaining uterine myometrium is intermediate on T2W images but darkens in postmenopausal patients. The normal uterus enhances homogenously on post contrast T1W imaging.Identification of Müllerian duct anomalies is important as this patient population is at high risk for infertility and treatment varies based on anomaly subtype. MDAs are characterized by the Buttram and Gibbons Classification System which include agenesis/hypoplasia, unicornuate, didelphys, bicornuate, septate, arcuate, and DES uterus. MRI is the preferred imaging modality for characterizing MDA as it allows for visualization of both the external contour of the uterus as well as internal cavity. Care should be taken to identify renal anomalies as they coexist in 29% of MDA cases. The most common benign uterine masses that are associated with uterine enlargement and/or DUB include leiomyomas and adenomyosis. Leiomyomas are the most common tumor of the female GU tract, occurring in 25% of women over the age of 35. They are well circumscribed masses and are isointense on T1W, dark on T2W, and enhance uniformly post contrast unless they have undergone necrosis. Degeneration of fibroids can be seen as increase signal on T1 and T2 which does not enhance. Adenomyosis, the ectopic location of endometrial glands and stroma in the myometrium, is commonly encountered in hysterectomy specimens and often presents symptomatically as pain, uterine enlargement, and DUB. MRI is an exceptionally good imaging modality to diagnose adenomyosis as it clearly depicts the typical changes in zonal anatomy seen on T2W sequences which include thickening of the junctional zone >11mm and punctate T2 foci within the thickened junctional zone. Focal, rounded thickening of the junctional zone may be seen and is referred to as an adenomyoma. Adenomyosis enhances uniformly post contrast administration. Other causes of DUB seen on MRI include endometrial hyperplasia and endometrial polyps.