Division of Gastroenterology, Department of Medicine and Department of Biomedical Engineering, University of California San Diego ACTRI, La Jolla, California.
Neurogastroenterol Motil. 2019 Apr;31(4):e13537. doi: 10.1111/nmo.13537. Epub 2019 Jan 24.
The current "gold standard" to diagnose anal sphincter morphology and disruptions utilizes low-frequency (3-9 MHz) ultrasound (US) imaging techniques that provide a general outline of the sphincter muscles, but not their microstructural details. High-frequency US transducers (7-15 MHz) have been used to study the muscle architecture (direction of muscle fascicles) in the limb muscle.
The goal of our study was to visualize the microstructural anatomy of the anal sphincters, specifically the external anal sphincter (EAS), using high-frequency US imaging.
Studies were conducted in asymptomatic female and male subjects and patients with fecal incontinence. US images were acquired using a low-frequency US (3-9 MHz) and high-frequency (7-15 MHz) US transducer. The latter was placed intra-anally to image the anal canal at 12, 9, 3, and 6 o'clock positions.
The low-frequency US images revealed the general outline of the anal sphincter muscles. On the other hand, high-frequency imaging visualized muscle fascicles and connective tissue inside the external anal sphincter (EAS). In FI patients, there was loss of muscle fascicles and alteration in the echo-intensity pattern in the region of damaged EAS suggestive of muscle fibrosis.
High-frequency ultrasound imaging is a powerful tool to visualize the microstructural details of the EAS. Our studies show that damage to the EAS muscle results in the alteration of its myoarchitecture, that is, loss of muscle fascicles and increase in the muscle connective tissue.
目前，用于诊断肛门括约肌形态和损伤的“金标准”是利用低频（3-9MHz）超声（US）成像技术，该技术可以提供括约肌的大致轮廓，但无法显示其微观结构细节。高频超声换能器（7-15MHz）已用于研究肢体肌肉的肌纤维结构（肌束方向）。
本研究旨在使用高频超声成像来可视化肛门括约肌的微观结构解剖，特别是外部肛门括约肌（EAS）。
该研究在无症状的女性和男性受试者以及大便失禁患者中进行。使用低频 US（3-9MHz）和高频（7-15MHz）US 换能器获取 US 图像。后者被置于肛门内，以在 12、9、3 和 6 点钟位置对肛门管进行成像。
低频 US 图像显示了肛门括约肌肌肉的大致轮廓。另一方面，高频成像可视化了外部肛门括约肌（EAS）内的肌束和结缔组织。在 FI 患者中，EAS 区域的肌束丢失和回声强度模式改变提示肌肉纤维化。
高频超声成像技术是可视化 EAS 微观结构细节的有力工具。我们的研究表明，EAS 肌肉损伤会导致其肌纤维结构发生改变，即肌束丢失和肌肉结缔组织增加。
