Fat-saturation magnetic resonance (MR) imaging for detection and chara
cterization 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 hyp
erintense on T1- and T2-weighted images. Small endometrioma was diagno
sed when a well-demarcated hyperintense lesion less than 1 cm in diame
ter was seen on T1-weighted or fat-saturated T1-weighted images. Surge
ry 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 acc
urately 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 addi
tion of fat-saturated images, so their use together with conventional
images is recommended in assessment of endometriosis.