Manifestations of the female reproductive organs on MR images: changes induced by various physiologic states

Unlike other reproductive organs, the uterus and ovaries are known to undergo dynamic morphologic changes according to various physiologic states. It is vitally important for radiologists when diagnosing gynecologic disorders to understand how normal female reproductive organs appear on magnetic resonance (MR) images for a given physiologic state. The authors focused on the effects of the menstrual cycle, pregnancy, and aging on MR images of normal female reproductive organs. During menstruation, the zonal architecture of the uterine corpus may be indistinct and the ovarian stroma may shrink and have lower signal intensity on both T2- and diffusion-weighted (DW) images. During periovulation, the ovarian stroma may be reach its maximum size and have high signal intensity on both T2- and DW images. Functional cysts may often be seen in ovaries of reproductive age and usually spontaneously shrink, whereas surface-epithelial inclusion cysts may be commonly seen in postmenopausal ovaries. Pregnancy-related changes, such as decidual changes in ectopic endometrial tissue and hyperreactio luteinalis in ovaries, may mimic gynecologic tumors and must be correctly diagnosed to avoid unnecessary and excessive surgical intervention. The authors offer some clues that may be helpful for making the differential diagnosis when evaluating MR images of female reproductive organs. Radiologists should, as much as practicably possible, check the physiologic states of patients before interpreting MR images.