Type of study
This is a prospective case series study.
Duration of the study
The duration of this study is 36 months.
Inclusion criteria
Any patient with rectal outlet obstruction or obstructed defecation, recurrent pelvic organ prolapse, pelvic pain and sense of pelvic heaviness, urinary or fecal incontinence, and dyssynergic defecation (anismus).
Exclusion criteria
Patients with a cochlear implant, or with clips used for brain aneurysm, or with cardiac defibrillators and pacemakers, or metal coils placed within blood vessels, or patients suffered from claustrophobia and nulliparous women were excluded.
Consent
Every patient signed on informed written consent including the examination steps, sharing in the research protocol and the approval on publishing the results.
Ethical approval
The study received an ethical committee approval from our Institution’s Research Board. The reference number is MD/134.
Technique of MR
The study was conducted on 1.5 Tesla MRI (Philips MR Ingenia), every patient after signing down informed consent went for colonic preparation, and cleansing enema was done and asked not to void for 2 h before doing the study. Then, the study starts by introducing 120–150 ml of ultrasonographic gel into the rectum by using a 50-ml-wide nozzle syringe, no oral or IV contrast is needed, and the patient is instructed about the procedure and how and when to squeeze, strain, or defecate.
The patient’s position is to lie on a supine position with a phased array coil placed low around the pelvis. The patient can bend his knees to facilitate defecation after wearing a pad to avoid table contamination.
Imaging protocol
Static images of the pelvis are acquired in three planes using T2-weighted turbo spin-echo (TSE) sequences (TR/TE 5000/132; FOV 240-260 mm, slice thickness 5 mm, gap 0.7 mm, number of signals acquired 2, flip angle 90°, matrix 512 _ 512, and acquisition time 3.12 min for each sequence).
In patients reporting anal incontinence or obstructed defecation, the following sequences are added for assessment of the anal sphincter complex: T2-weighted BFFE images of the anal sphincter complex are obtained (9.0/4.0, FOV 220 mm, section thickness 3 mm, number of signals acquired 8, flip angle 45°, matrix 512 _ 512, acquisition time 2.12 min). In this sequence, section orientation is parallel (in the coronal plane) and perpendicular (in the axial plane) to the plane of the anal canal.
Acquisition of dynamic MRI sequences
Dynamic sequences are performed in the sagittal, axial, and coronal planes using a balanced fast-field echo (BFFE) sequence (TR/TE 850/120 ms, FOV 444 mm, slice thickness 6–7 mm, gap 0.7 mm).
In each plane, five slices during four phases are acquired; each phase takes 10 s, the following four phases are acquired:
- 1.
With the patient at rest.
- 2.
During contraction of the pelvic floor (the patient is instructed to squeeze her buttocks as if trying to prevent the escape of urine).
- 3.
During a repeated maximum straining sequence to ensure a maximal Valsalva maneuver (the patient is instructed to bear down as much as she can, as though she is constipated and trying to defecate).
- 4.
During defecation in the sagittal plane (the patient is asked to evacuate the injected intrarectal gel).
Dynamic magnetic resonance imaging
Diagnostic criteria
Dynamic MRI is best evaluated on midsagittal true fast imaging dynamic evacuation sequences and on sagittal, axial, and coronal images during maximum straining, when the pelvic organ descent should be greatest. The following are the criteria measured during maximum straining.
Sagittal plane
1. The pubococcygeus line (PCL) is used as the reference line. It extends from the inferior border of the symphysis pubis anteriorly to the last coccygeal joint posteriorly. The descent of pelvic organs is measured along a perpendicular line from the organ to the PCL, and this should be measured both at rest and during maximum straining.
Prolapse severity can be easily graded according to the “rule of three”:
Mild prolapse of an organ below the PCL by 3 cm
Moderate prolapse of 3–6 cm
Severe prolapse more than 6 cm
Other measurements in the sagittal plane during maximum straining include the following:
2. The H-line extends from the inferior aspect of the pubic symphysis to the anorectal junction. It represents the most caudal part of the levator ani group (puborectalis muscle) and allows the assessment levator hiatus in AP diameter during straining. A diameter greater than 6 cm is considered abnormal.
3. The M-line is dropped as a perpendicular line from the PCL to the posterior aspect of the H-line. It represents the measure of the muscular pelvic floor descent (pelvic floor relaxation). And the length that exceeds 2 cm is abnormal.
4. The levator plate angle is enclosed between the levator plate and the PCL, normally measured 11.7 ± 5.
The posterior compartment is assessed for anorectal descent and other pathologies as rectocele, peritoneocele, enterocele, intussusception, prolapse, anorectal angle, and anismus.
The MRI images were interpreted by 2 separate consultants who worked separately from each other, and some patients performed a conventional defecography to be used as a reference in case of image interpretation conflicts (Figs. 3, 4, 5, 6, 7, and 8).