Procedure

No preparation is necessary. After adding about 150mL of ultrasound (US) gel to the rectum, anorectal and pelvic floor motion are visualized in real time while patients squeeze (i.e., contract) the pelvic floor muscles and expel rectal contents. Using a modified T2-weighted single-shot fast spin echo (SSFSE) imaging sequence or T2-weighted fast imaging with steady-state precession (FISP) MRI sequence, pelvic floor motion can be imaged at 1.2- to 2-second intervals.11 Images can be reconstructed in real time, or shortly after acquisition, so that patients can be instructed or encouraged during maneuvers. After the evacuation sequence, patients are removed from the magnet and asked to empty the bladder and remaining rectal contents. Patients are then repositioned within the magnet to obtain additional dynamic sagittal images during the Valsalva maneuver, in order to maximize the detection of cystoceles and ente-roceles.12 Finally, contiguous coronal images are acquired at rest and during the Valsalva maneuver.10

Rapid image acquisition is necessary to visualize pelvic floor motion in real time because patients can maintain maximum rectal excursion during evacuation or puborectalis contraction when they squeeze for 15 to 30 seconds at most (Figs. 12.4 and 12.5). In contrast to scintig-raphy or fluoroscopy, conventional, closed-configuration MR systems permit imaging in the supine position only. However, there is little difference in the detection of clinically relevant findings between supine MR and seated MR using open-configuration magnets. The exception is in detecting rectal intussusceptions for which seated MRI was superior.13

Similar to barium evacuation proctography, anorectal motion is quantified by measuring anorectal angles and anorectal junction during evacuation and squeeze maneuvers. Because the bony landmarks (e.g., pubis, sacrococcygeal junction) necessary to measure anorectal descent are more distinctly visualized during MRI, it is easier to make these measurements from MR compared to routine fluoroscopic images. A rectocoele is defined as an anterior bulge beyond the expected and extrapolated line

Figure 12.4. Magnetic resonance fluoroscopic images of the pelvis at rest (a), during squeeze (b), and simulated defecation (c) in a 52-year-old asymptomatic patient after filling the rectum with ultrasound gel.At rest,the pelvic floor was well supported; the anorectal angle was relatively obtuse (126 degrees). Pelvic floor contraction during the squeeze maneuver was accompanied by normal upward and anterior motion of the anorectal junction; the angle declined to 95 degrees. During rectal evacuation,the bladder base dropped by 2.5 cm below the pubococcygeal line; the 2.8-cm anterior rectocoele emptied completely and was probably not clinically significant; perineal descent (5 cm) was outside the normal range for evacuation proctography.

Figure 12.4. Magnetic resonance fluoroscopic images of the pelvis at rest (a), during squeeze (b), and simulated defecation (c) in a 52-year-old asymptomatic patient after filling the rectum with ultrasound gel.At rest,the pelvic floor was well supported; the anorectal angle was relatively obtuse (126 degrees). Pelvic floor contraction during the squeeze maneuver was accompanied by normal upward and anterior motion of the anorectal junction; the angle declined to 95 degrees. During rectal evacuation,the bladder base dropped by 2.5 cm below the pubococcygeal line; the 2.8-cm anterior rectocoele emptied completely and was probably not clinically significant; perineal descent (5 cm) was outside the normal range for evacuation proctography.

of the anterior rectal wall or a posterior bulge beyond the posterior wall.14 A peritoneocele is characterized by protrusion of the peritoneal fat or fluid crossing the junction of the upper third and distal two thirds of the vagina, with separation of the rectovaginal septum. When this pouch contains small intestinal loops, it is described as an enterocoele (Fig. 12.6). Descent of the bladder base and either the cervix (when the uterus is present) or vaginal apex (for women who had a previous hysterectomy) are recorded relative to the pubococcygeal line.14,15

Utility

In asymptomatic women without a history of, or risk factors for, pelvic floor injury, anorectal motion parameters were comparable to previous studies using barium defecography (Table 12.1).16 These normal values are derived from a group of women (mean age, 43; range 23-69 years) who did not have risk factors for anorec-tal trauma or bowel symptoms by detailed questionnaire. Observe that the normal range for anorectal angle change during evacuation was wide, perhaps because some asymptomatic subjects may have pelvic floor dysfunction. Normal values for anorectal motion may be technique dependent.15 The utility of dynamic MRI for diagnosing functional disorders of defecation has not been thoroughly studied. An early study suggested that MR revealed disordered anorec-tal motion in 13 patients with symptoms of disordered defecation and normal routine anorectal physiologic tests.17 More detailed studies suggest that dynamic MRI may have a

Figure 12.5. Pelvic magnetic resonance fluoroscopic images at rest (a) and squeeze (b) in a 57-year-old woman who has fecal incontinence. During squeeze, the puborectalis indentation on the posterior rectal wall was exaggerated compared to rest, and the anorectal angle declined from 143 degrees at rest to 90 degrees during squeeze; however, the anal canal remained patulous.

Figure 12.5. Pelvic magnetic resonance fluoroscopic images at rest (a) and squeeze (b) in a 57-year-old woman who has fecal incontinence. During squeeze, the puborectalis indentation on the posterior rectal wall was exaggerated compared to rest, and the anorectal angle declined from 143 degrees at rest to 90 degrees during squeeze; however, the anal canal remained patulous.

Figure 12.6. Endoanal T2-weighted fast spin echo imaging of the anal sphincters demonstrates marked diffuse thinning of the internal anal sphincter (arrowheads, a), along with correlative endoanal ultrasound (arrowheads, b). Dynamic MR proctography images at rest (c) demonstrates a patulous anal canal at rest (arrow). Dynamic MR proctography images during defecation (d) show a large enterocele (arrowheads), with mesenteric fat and small bowel.

Figure 12.6. Endoanal T2-weighted fast spin echo imaging of the anal sphincters demonstrates marked diffuse thinning of the internal anal sphincter (arrowheads, a), along with correlative endoanal ultrasound (arrowheads, b). Dynamic MR proctography images at rest (c) demonstrates a patulous anal canal at rest (arrow). Dynamic MR proctography images during defecation (d) show a large enterocele (arrowheads), with mesenteric fat and small bowel.

role when the diagnosis of an evacuation disorder cannot be confirmed by routine methods, for example, in patients with normal or increased perineal descent during a clinical examination, and a normal balloon expulsion test.18 In addition to characterizing disordered squeeze or evacuation, dynamic MRI can also characterize pelvic organ prolapse, including rectocoele size, which is associated with increased perineal descent.19 Lastly, patients find it useful to review images of evacuation for understanding the nature of their disorder, and the need for pelvic floor retraining.

Studies utilizing a relatively slow image acquisition sequence (i.e., every 4 to 31 seconds), found a poor correlation between MRI and barium proctography.20,21 In contrast, when the acquisition time is 1.2 to 2.0 seconds, the correlation between dynamic MRI and colposysto-proctography for all three pelvic floor compartments (anterior, middle, and posterior) was excellent.22

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Constipation Prescription

Constipation Prescription

Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.

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