Kinematics of the uterus: cine mode MR imaging

Cine mode magnetic resonance (MR) imaging has allowed evaluation of kinematics of the pelvis. Visualization of dynamic changes under strain facilitates evaluation of prolapses and adhesions between organs. The uterus, an organ of smooth muscle, has an inherent contractility that characterizes it as different from other visceral organs. This sustained contraction has occasionally been shown on static images as a finding masquerading as a leiomyoma or as adenomyosis. Cine mode MR imaging clearly shows the configuration of the myometrium during these dynamic changes, as well as its signal intensity during contractions. Uterine peristalsis, the subtle and rhythmic contractions of the inner myometrium, is also clearly identifiable on cine mode images as a wavy movement of the endometrium and/or inner myometrium. The direction and frequency of uterine peristalsis are different in each of the menstrual cycle phases and are thought to have important roles in uterine function, such as in fertility and menstrual blood discharge. Elucidation of these kinematics of the uterus will help in the evaluation of static MR images and study of the physiology of the uterus. Cine MR imaging is a novel technique for diagnosis and evaluation of the pelvic organs, especially the uterus.