Magnetic resonance imaging of pelvic endometriosis

Endometriosis is a multifocal disease involving multiple pelvic sites. Although laparoscopy is the elective exam in the study of patients with clinically suspected endometriosis, MR imaging represents a valid noninvasive procedure for the study of areas unapproachable with laparoscopy. On MR imaging, areas of endometriosis over 1 cm in size appear homogeneously hyperintense in T1-weighted images and hypointense in T2-weighted images, while areas of endometriosis less than 1 cm in size appear hyperintense in T1-weighted images and with variable signal in T2-weighted images. Endometriosis may also appear as small cystic lesions, hyperintense in T1-weighted images. While MR imaging has some limitations in the visualization of small endometriotic implants and adhesions, it has the ability to characterize the lesions, to study extraperitoneal locations and the contents of pelvic masses. The reliability of MR imaging findings of endometriosis and the assessment of pelvic organ involvement is important for guiding subsequent laparoscopy.