Pelvic endometriosis: detection and diagnosis with chemical shift MR imaging.

Fat-saturation magnetic resonance (MR) imaging for detection and characterization of pelvic endometriosis was prospectively investigated in 35 women with a clinical diagnosis of the disease. Large endometrioma was diagnosed when the lesion was larger than 1 cm in diameter and hyperintense on T1- and T2-weighted images. Small endometrioma was diagnosed when a well-demarcated hyperintense lesion less than 1 cm in diameter was seen on T1-weighted or fat-saturated T1-weighted images. Surgery performed after MR imaging revealed a normal pelvis in six patients, endometriosis in 26 (33 large and 19 small endometriomas), and other cystic lesions in three. Conventional T1- and T2-weighted imaging accurately demonstrated 27 of 33 large endometriomas and two of 19 small endometriomas. Fat-saturation T1-weighted imaging in combination with conventional technique accurately demonstrated 30 of 33 large and nine of 19 small endometriomas. Diagnostic accuracy was improved with addition of fat-saturated images, so their use together with conventional images is recommended in assessment of endometriosis.