MR defecography: comparison of HMO system measurement between supine and lateral decubitus patient position

Pelvic floor dysfunction (PVD), a prevalent clinical issue impacting quality of life, can be effectively assessed using magnetic resonance defecography (MRD) with the patient either supine or in the lateral decubitus position.

To compare the measurement value and grading in dynamic MRD within the closed-magnet system of PFD patients performed in supine versus lateral decubitus position using the H line, M line, and organ prolapse (HMO) classification system.

During 2017-2019, 100 patients with PFD underwent MRD during defecation in both supine and lateral decubitus positions. MR images were measured and graded by two blinded radiologists. The mean value of each HMO parameter and grading severity were compared between supine and lateral positions. Image quality (IQ) between two positions was also evaluated. Paired t-test and Wilcoxon ranked test were performed for significant difference. P < 0.05 was considered statistically significant.

For HMO measurement, M-line, levator plate angle (LPA), urethral hypermobility (UH), uterine prolapse, and peritoneocele had significantly higher mean values when measured in the lateral decubitus position than in the supine position. For grading, M-line, uterine prolapse, and peritoneocele also had more grading severity in the lateral decubitus than supine position with statistical significance (P = 0.002, 0.004, and 0.001, respectively). Only anterior rectocele had a mean value and grading severity in the supine more than the lateral position (P = 0.003 and P = 0.005). IQ in the supine was better than in the lateral decubitus position (P < 0.001).

MRD in lateral decubitus showed a more severe degree of PFD in most parameters based on the HMO grading system irrespective of inferior imaging quality.