The value of 1.5-T magnetic resonance (MR) imaging in diagnosing endometrial cysts and differentiating them from other gynecologic masses was prospectively evaluated in 374 female patients with clinically suspected adnexal masses. A suggestive diagnosis of endometrial cyst was made when a cyst that was hyperintense on T1-weighted images exhibited homogeneous hyperintensity on T2-weighted images. A definitive diagnosis was made when a cyst that was hyperintense on T1-weighted images exhibited hypointense signal on T2-weighted images (shading) or when the lesion consisted of multiple hyperintense cysts on T1-weighted images (multiplicity) regardless of the signal intensity on T2-weighted images. Surgery was performed in 293 patients, and confirmation was obtained in 354 lesions. MR imaging enabled accurate diagnosis of 77 of 86 endometrial cysts and exclusion of the diagnosis of endometrial cyst in 263 of 268 other gynecologic masses with or without internal hemorrhage. The overall diagnostic sensitivity, specificity, and accuracy were 90%, 98%, 96%, respectively. MR imaging seems to be an acceptable diagnostic test on which clinical decisions can be based in selecting treatment.

Three findings (a, b, and d) seem to be diagnostic of the twisted adnexal tumor and may facilitate prompt surgical intervention at examination with MR imaging or CT.

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Fifteen pregnant women were studied with magnetic resonance (MR) imaging. In 14 women, the myometrium exhibited distinct hypointense bulging on T2-weighted images that distorted the gestational sac and decidua but not the outer uterine coutour. In 12 women, an obvious discrepancy was observed between the inner myometrial configuration on T1-weighted images and that on intermediate and T2-weighted images. In three women who underwent serial T2-weighted studies separated by about 30 minutes during one MR examination, hypointense myometrial bulging was observed at a different site on each study. In two women who underwent follow-up MR study within a week after dilation and curettage, the previously distinct hypointense bulging completely disappeared. These findings confirm the transient and mobile nature of this myometrial bulging. This phenomenon can be attributed to sustained uterine contractions, which partially force the blood out of the uterus. The decrease in blood volume results in a decrease in water content, which accounts for the decrease in myometrial signal intensity on T2-weighted images.

A total of 206 nongravid patients with various gynecologic problems underwent pelvic magnetic resonance (MR) examinations that included both sagittal T2-weighted and contrast agent-enhanced T1-weighted images. MR images were retrospectively reviewed to identify changes in endometrial configuration on serial images obtained during the same MR examination. In 20 MR examinations (all in women of reproductive age), endometrial distortion due to myometrial bulging was noted on T2-weighted or contrast-enhanced T1-weighted images. It was absent on other MR images obtained at different times. Myometrial bulging exhibited low signal intensity in 18 examinations. The finding resembled adenomyosis or leiomyoma on T2-weighted or contrast-enhanced T1-weighted images. These results evidence the presence of transient myometrial bulging and transient low-intensity myometrium in the nongravid uterus. This phenomenon is thought to represent uterine contraction. Clinicians should be aware of the potential presence of transient low-signal-intensity myometrial bulging that could present diagnostic problems in the normal uterus.