MRI protocol of Pelvic Floor Dysfunction

Initially, axial, sagittal, and coronal T2-weighted turbo spin-echo (TSE) images were acquired at rest with imaging planes orthogonal to the orientation of the uterus. These images were acquired to evaluate for coexisting pelvic abnormalities and localize anatomic structures for optimal positioning during the dynamic sequences; however, these images were not evaluated as part of this study. Subsequently, based on the static T2-weighted TSE images, optimal midline sagittal or sagittal oblique planes were selected for the true FISP and HASTE sequences to include the pubic symphysis, urethra, vagina, rectum, and coccyx in the field of view accounting for anatomic asymmetry in individual patients. Patients underwent dynamic imaging for both sequences both at rest and at maximal strain.
The midline sagittal or sagittal oblique dynamic true FISP sequence was performed as a continuous acquisition with the patient alternating every 5 seconds between rest and maximal strain. The sequence parameters were a TR/TE of 3.9/1.9; refocusing flip angle, 70°; matrix, 256; rectangular field of view optimized to the patient's body habitus, 300–350 mm; slice thickness, 8 mm; bandwidth, 673 Hz per pixel; acquisition time per measure, 0.6 second; 90 consecutive measures; and acquisition time, 54 seconds.

The sagittal HASTE sequence was performed using five slice positions, one midline and four parasagittal, with seven measurements per slice position alternating between rest and maximal strain (total = 35 slices including 7 measurements at 5 slice positions). The following parameters were used: TR/TEeff, ∞/64; refocusing flip angle, 140°; matrix, 256; rectangular field of view, 300 mm; acquisition time, 2.5 seconds per slice; slice thickness, 5 mm; and bandwidth, 781 Hz per pixel.

 HASTE sequences were acquired before the true FISP sequences. This order was used to standardize the examination for technologists in terms of workflow so that the order of acquisitions was not randomized prospectively. However, in 10 cases due to technical inadequacy of the initial HASTE scans, the HASTE acquisition was repeated after the true FISP acquisition, and the HASTE images from the second acquisition were used in the analysis. A statistical analysis of the importance of sequence order was performed.