deSouza N M, Puni R, Zbar A, Gilderdale D J, Coutts G A, Krausz T
Robert Steiner Magnetic Resonance Unit, Hammersmith Hospital, London, England.
AJR Am J Roentgenol. 1996 Dec;167(6):1465-71. doi: 10.2214/ajr.167.6.8956578.
The aim of this study was to correlate the components of the normal female anal sphincter seen on high-resolution MR images with the in vitro anatomy and to describe the change in appearances of these components in multiparous women with fecal incontinence.
Ten asymptomatic female volunteers (32-72 years old; mean, 54 years old) and 22 women with fecal incontinence were studied. In six patients (26-68 years old; mean, 49 years old) fecal incontinence began immediately after childbirth; in the remaining 16 patients (45-77 years old; mean, 58 years old) fecal incontinence developed 15- 30 years after childbirth. In the latter group of patients, terminal motor latencies of the pudendal nerve were measured. Imaging was done on a 0.5-T Picker Asset unit and on a 1.0-T Picker HPQ unit. A saddle geometry endoanal receiver coil was used for all imaging. T1-weighted spin-echo (720-820/20 [range of TR/TE]), T2-weighted spin-echo (2500/80 [TR/TE]), fast spin-echo (4500/96 [TR/ effective TE]), and short inversion time inversion recovery (2500/80 [TR/TE]; inversion time, 107 msec) MR images were obtained in transverse, coronal oblique, and sagittal planes. Images were assessed for integrity of the sphincter components. A nonpaired separate-variance t test was used to compare thickness of individual muscle components between patients with delayed-onset fecal incontinence and asymptomatic age-matched volunteers. Degree of muscle atrophy was correlated with degree of delay in the terminal motor latency of the pudendal nerve.
The high resolution obtained with an endoanal coil allowed differentiation of the various muscle components of the anal sphincter complex. The internal sphincter was seen as a ring of homogeneously high signal intensity with a low-signal-intensity rim that was rich in collagen and contained neurovascular bundles. The external anal sphincter, which had low signal intensity on T1- and T2-weighted images, was shown as three components: subcutaneous, superficial, and deep. In six patients who had fecal incontinence that began immediately after childbirth, endoanal MR imaging revealed the site and extent of a tear. All tears were confirmed at surgery. In the 16 patients who had fecal incontinence that began several years after childbirth, atrophy of the external sphincter was revealed in all cases in the superficial and deep components. The internal sphincter remained normal. However, we found that the degree of atrophy of individual components of the external sphincter did not correlate with the degree of delay in pudendal nerve conduction.
MR imaging with an endoanal coil reveals the integrity and bulk of individual muscle components of the anal sphincter in multiparous women with fecal incontinence.
本研究旨在将高分辨率磁共振成像（MR）上所见正常女性肛门括约肌的各组成部分与体外解剖结构相关联，并描述这些组成部分在有大便失禁的经产妇中的外观变化。
研究了10名无症状女性志愿者（年龄32 - 72岁，平均54岁）和22名大便失禁女性。6例患者（年龄26 - 68岁，平均49岁）在产后立即出现大便失禁；其余16例患者（年龄45 - 77岁，平均58岁）在产后15 - 30年出现大便失禁。对后一组患者测量了阴部神经的终末运动潜伏期。成像在0.5T的Picker Asset设备和1.0T的Picker HPQ设备上进行。所有成像均使用鞍形腔内肛门接收线圈。在横断、冠状斜位和矢状位平面上获取了T1加权自旋回波（720 - 820/20 [TR/TE范围]）、T2加权自旋回波（2500/80 [TR/TE]）、快速自旋回波（4500/96 [TR/有效TE]）和短反转时间反转恢复序列（2500/80 [TR/TE]；反转时间，107毫秒）的MR图像。评估图像中括约肌各组成部分的完整性。采用非配对独立方差t检验比较延迟性大便失禁患者与年龄匹配的无症状志愿者之间各肌肉组成部分的厚度。肌肉萎缩程度与阴部神经终末运动潜伏期的延迟程度相关。
腔内肛门线圈获得的高分辨率使得能够区分肛门括约肌复合体的各种肌肉组成部分。内括约肌表现为均匀高信号强度的环，其边缘为低信号强度，富含胶原蛋白并包含神经血管束。在T1加权和T2加权图像上呈低信号强度的外括约肌显示为三个组成部分：皮下、浅部和深部。在6例产后立即出现大便失禁的患者中，腔内肛门MR成像显示了撕裂的部位和范围。所有撕裂在手术中均得到证实。在16例产后数年出现大便失禁的患者中，所有病例均显示外括约肌浅部和深部组成部分萎缩。内括约肌保持正常。然而，我们发现外括约肌各组成部分的萎缩程度与阴部神经传导延迟程度无关。
腔内肛门线圈MR成像可显示有大便失禁的经产妇肛门括约肌各肌肉组成部分的完整性和大小。
