Diffusion-weighted imaging in the evaluation of hormonal cyclic changes in abdominal wall endometriomas

To investigate the utility of diffusion-weighted (DW) magnetic resonance imaging (MRI) in the diagnosis of abdominal wall endometrioma (AWE) and to compare the ADC (apparent diffusion coefficient) values of AWE with those of the uterine endometrium during two different phases of the menstrual cycle.

A total of 22 women aged between 27 and 42 years (mean 32.8 years) and who had regular menstrual cycles were included in the study. These patients had a total of 25 AWE lesions. The mean and standard deviation of the ADC values of the normal endometrium/AWE were calculated for the menstrual and luteal phases. All examinations were performed using a 1.5 T magnet (b-values of 50, 400, and 800 mm/s(2)). The results were analysed using the Shapiro-Wilk test, the Pearson correlation test, the analysis of variance (ANOVA) test, and the paired sample t-test.

The ADC values of the endometrium were different in the two phases of the menstrual cycle (menstrual phase: 0.924 ± 0.171; luteal phase: 1.171 ± 0.135). Similarly, the ADC values of the AWE were different in these phases (menstrual phase: 0.937 ± 0.256, luteal phase: 1.256 ± 0.215). In both AWE and the uterine endometrium, the ADC measurements were significantly lower in the menstrual phase than during the luteal phase. This difference was statistically significant (p < 0.05). There was no significant difference in the ADC values between the endometrial layer and AWE during the same phase (p = 0.216 for menstrual phase, p = 0.104 for luteal phase, paired sample t-test).

The present study demonstrated that in all patients, the DWI features of AWEs were significantly similar to those of the uterine endometrial tissue. Additionally, the ADC measurements of the patients showed similar cyclical changes. These results suggest that the ADC values of a lesion close to the uterine endometrium may be used to differentiate AWE from the other disease entities of the abdominal wall.