MRI Helpful for Deep Pelvic Endometriosis

Laurie Barclay, MD

July 27, 2004

July 27, 2004 — Magnetic resonance imaging (MRI) is highly accurate in predicting the locations of deep pelvic endometriosis, according to the results of a prospective study published in the August issue of Radiology.

"MRI is now commonly used for the diagnosis of endometriomas, but its value for diagnosis of endometriosis in the bladder, in superficial peritoneal lesions, and in ovarian foci is controversial," write Marc Bazot, MD, from Hôpital Tenon in Paris, France, and colleagues. "MRI was recently used for the diagnosis of endometriosis in the uterosacral ligaments (USL) but was found to lack sensitivity for diagnosis of the disease with rectal involvement."

At two institutions, 195 patients, mean age of 34.2 years (range, 20-71 years), with suspected pelvic endometriosis had MRIs evaluated independently by two experienced radiologists. Endometriosis was defined as implants or tissue masses appearing as hypointense areas and/or hyperintense foci on T1- or T2- weighted images.

Surgery and pathologic examination confirmed pelvic endometriosis in 163 (83.6%) of 195 patients, including endometriomas in 111 (68.1%), peritoneal lesions in 83 (50.9%), and deep pelvic endometriosis in 103 (63.2%). The most frequent sites of deep pelvic endometriosis were torus uterinus and USL.

For deep pelvic endometriosis, sensitivity of MRI was 90.3%, specificity was 91%, positive predictive value was 92.1%, negative predictive value was 89%, and accuracy was 90.8%. At specific sites, accuracy was 80.5% at the USL, 93.3% at the vagina, 96.9% at the rectovaginal septum, 94.9% at the rectosigmoid, and 97.9% at the bladder.

Study limitations include high prevalence of endometriosis and especially deep pelvic endometriosis introducing potential bias, possible artifacts affecting MRI interpretation, and readings by only two experienced radiologists.

"MR imaging has the advantages of aiding in the detection of all deep pelvic sites of endometriosis and of providing accurate depiction of extension of the disease for the surgeon," the authors write. "MRI, with its high contrast resolution and multiplanar imaging capacity, can help in the analysis of lesions that are difficult or impossible to explore during surgery."

Radiology. 2004;232:379-389

Reviewed by Gary D. Vogin, MD


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