PELVIC ENDOMETRIOSIS - MR-IMAGING SPECTRUM WITH LAPAROSCOPIC CORRELATION AND DIAGNOSTIC PITFALLS

Endometriosis is a common multifocal disease involving a number of ana tomic sites in the pelvis, Although laparoscopy is the standard of ref erence for diagnosis, magnetic resonance (MR) imaging is a noninvasive method for evaluating areas inaccessible to laparoscopy. A large endo metrioma (greater than or equal to 1 cm in diameter) appears as a homo geneously hyperintense mass on T1-weighted MR images and as a low-sign al-intensity mass with areas of high signal intensity on T2-weighted i mages, A small endometrioma may be indicated when a pelvic mass less t han 1 cm in diameter is hyperintense on T1-weighted images irrespectiv e of its appearance on T2-weighted images, Endometriosis may also mani fest as multiple, homogeneously hyperintense cysts on T1-weighted imag es, Involvement of the alimentary tract or bladder can appear as areas of high signal intensity, Although MR imaging is limited in its abili ty to depict small endometrial implants and adhesions, the advantages of MR imaging over laparoscopy include the ability to characterize end ometriotic lesions and to evaluate extraperitoneal sites of involvemen t, contents of a pelvic mass, or lesions hidden by dense adhesions, Th e roles of the two modalities are therefore complementary. Knowledge o f the variety of MR imaging appearances of endometriosis and organ inv olvement within the pelvis is important for guiding a subsequent lapar oscopic examination.