Changes in myometrial and junctional zone thickness and signal intensity: demonstration with kinematic T2-weighted MR imaging

PURPOSE: To demonstrate uterine contractions by evaluating changes during t ime in the thickness of the myometrium and junctional zone and in signal in tensity of the uterus with T2-weighted fast magnetic resonance (MR) images in a kinematic fashion. MATERIALS AND METHODS: Sagittal MR imaging was performed with T2-weighted f ast spin-echo (FSE) and multiphase-multisection single-shot FSE (SSFSE) in 60 premenopausal patients during free breathing. SSFSE MR images were evalu ated with cine display. The pattern of uterine contractions and changes in signal intensities of the uterine structures were evaluated. Thickness of b oth myometrium and junctional zone, and their signal intensities, were meas ured during 15 phases of SSFSE and FSE MR imaging. RESULTS: Slow-massive (mean, 55%), middle-cycle (mean, 80%), and fine (mean , 93%) contractions were observed. Shape of junctional zones dynamically ch anged during time, showing focal (mean, 58%) and diffuse (mean, 82%) thicke ning and wavelike motions (mean, 88%). Ratio of thickness of the myometrium to junctional zone with FSE MR imaging was not significantly different fro m the mean ratio during 15 phases of SSFSE MR imaging, although maximum per centage of change of the ratio during 15 phases was 42.5%-56.8%. The signal intensities of the myometrium (97%) and junctional zone (75%) changed duri ng time. CONCLUSION: Kinematic T2-weighted SSFSE MR images demonstrate uterine contr actions related to dynamic changes in thickness and signal intensities of t he myometrium and junctional zone, and these findings might affect the diag nosis of uterine disease.