Apparent diffusion coefficient values of the normal uterus: Interindividual variations during menstrual cycle

To assess the apparent diffusion coefficient (ADC) changes of the normal uterine zones among reproductive women during the menstrual cycle.

The study included 101 women of reproductive age, each with regular cycle and normal endometrium/myometrium, as proved on histopathology or MR imaging examination. Diffusion-weighted (DW) imaging was performed along the axial plane, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 800s/mm(2). The mean and standard deviation of the ADC values of normal endometrium/myometrium were calculated for menstrual, proliferative and secretory phase. Analysis of variance followed by the least significant difference test was used for statistical analysis.

The ADC values of the endometrium were different in the three phases of the menstrual cycle (menstrual phase: 1.25±0.27; proliferative phase: 1.39±0.20; secretory phase: 1.50±0.18) (F: 9.64, p: 0.00). Statistical significant difference was observed among all groups (p<0.05). The ADC values of the normal myometrium were different in the three phases of the menstrual cycle (menstrual phase: 1.91±0.35; proliferative phase: 1.72±0.27; secretory phase: 1.87±0.28) (F: 3.60, p: 0.03). Statistical significant difference was observed between menstrual and proliferative phase and between proliferative and secretory phase (p<0.05). No significant difference was noted between menstrual and secretory phase (p>0.05).

A wide variation of ADC values of normal endometrium and myometrium is observed during different phases of the menstrual cycle.