INTRODUCTION: 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. AIMS: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
INTRODUCTION: 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. AIMS: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
Authors: Sigrid Pillen; Ramon O Tak; Machiel J Zwarts; Martin M Y Lammens; Kiek N Verrijp; Ilse M P Arts; Jeroen A van der Laak; Peter M Hoogerbrugge; Baziel G M van Engelen; Aad Verrips Journal: Ultrasound Med Biol Date: 2008-12-10 Impact factor: 2.998
Authors: Milena M Weinstein; Dolores H Pretorius; Sung-Ai Jung; Charles W Nager; Ravinder K Mittal Journal: Clin Gastroenterol Hepatol Date: 2008-08-16 Impact factor: 11.382
Authors: P T Heitmann; P Rabbitt; A Schloithe; V Patton; P P Skuza; D A Wattchow; P G Dinning Journal: Int J Colorectal Dis Date: 2019-07-06 Impact factor: 2.571
Authors: Anna-Lena Stickelmann; Lieven Nils Kennes; Miriam Hölscher; Charlotte Graef; Tomas Kupec; Julia Wittenborn; Elmar Stickeler; Laila Najjari Journal: BMC Womens Health Date: 2022-08-10 Impact factor: 2.742