In vivo high-resolution magnetic resonance elastography of the uterine corpus and cervix.

Abstract

To apply 3D multifrequency MR elastography (3DMMRE) to the uterus and analyse the viscoelasticity of the uterine tissue in healthy volunteers considering individual variations and variations over the menstrual cycle. Sixteen healthy volunteers participated in the study, one of whom was examined 12 times over two menstrual cycles. Pelvic 3DMMRE was performed on a 1.5-T scanner with seven vibration frequencies (30-60 Hz) using a piezoelectric driver. Two mechanical parameter maps were obtained corresponding to the magnitude (|G (*) |) and the phase angle (φ) of the complex shear modulus. On average, the uterine corpus had higher elasticity, but similar viscosity compared with the cervix, reflected by |G (*) |uterine corpus = 2.58 ± 0.52 kPa vs. |G (*) |cervix = 2.00 ± 0.34 kPa (p < 0.0001) and φ uterine corpus = 0.54 ± 0.08, φ cervix = 0.57 ± 0.12 (p = 0.428). With 2.23 ± 0.26 kPa, |G (*) | of the myometrium was lower in the secretory phase (SP) compared with that of the proliferative phase (PP, |G (*) | = 3.01 ± 0.26 kPa). For the endometrium, the value of |G (*) | in SP was 68% lower than during PP (PP, |G (*) | = 3.34 ± 0.42 kPa; SP, |G (*) | = 1.97 ± 0.34 kPa; p = 0.0061). 3DMMRE produces high-resolution mechanical parameter maps of the uterus and cervix and shows sensitivity to structural and functional changes of the endometrium and myometrium during the menstrual cycle. MR elastography provided for the first time spatially resolved viscoelasticity maps of uterus. Uterine corpus had a higher elasticity, but similar viscosity compared with cervix. The stiffness of both endometrium and myometrium decreases during the menstrual cycle.