Connectivity of the Superficial Muscles of the Human Perineum: A Diffusion Tensor Imaging-Based Global Tractography Study.

Despite the importance of pelvic floor muscles, significant controversy still exists about the true structural details of these muscles. We provide an objective analysis of the architecture and orientation of the superficial muscles of the perineum using a novel approach. Magnetic Resonance Diffusion Tensor Images (MR-DTI) were acquired in 10 healthy asymptomatic nulliparous women, and 4 healthy males. Global tractography was then used to generate the architecture of the muscles. Micro-CT imaging of a male cadaver was performed for validation of the fiber tracking results. Results show that muscles fibers of the external anal sphincter, from the right and left side, cross midline in the region of the perineal body to continue as transverse perinea and bulbospongiosus muscles of the opposite side. The morphology of the external anal sphincter resembles that of the number '8' or a "purse string". The crossing of muscle fascicles in the perineal body was supported by micro-CT imaging in the male subject. The superficial muscles of the perineum, and external anal sphincter are frequently damaged during child birth related injuries to the pelvic floor; we propose the use of MR-DTI based global tractography as a non-invasive imaging technique to assess damage to these muscles

Esophageal Biomechanics: Work, Power, and Modulus using Impedance-Manometry

The esophagus is a vital gastrointestinal organ that transports food and liquid from the mouth to the stomach. When its function is disrupted, swallowing issues can result, which can lead to serious degradation in quality of life, malnutrition, and starvation if not properly treated. The aim of this work was to examine the mechanical function of the esophagus during swallowing in patients with clinically relevant dysphagia.Two steps were taken to achieve this: In Chapter 2, a new test was developed based on standard clinical High Resolution Impedance Manometry (HRIM). A new swallow testing material is introduced which allows for the electrical impedance signals to be used to estimate the cross-sectional area (CSA) of the esophagus while material is traveling through it. Then in Chapter 3, both the pressure and CSA information from the new HRIM test is used to calculate the work, power, and elastic modulus of the esophagus during a swallow. This investigation was performed on patients with dysphagia and two groups without dysphagia (controls). In summary, it was found that the esophagi of the patients with dysphagia generated a lower amount of work and power than the controls. There also were differences in the elastic modulus, which were distinct per disease groups. These results are reflective of the decreased esophageal motor function seen in patients with dysphagia. This work adds to our understanding of esophageal physiology and pathophysiology by developing a mechanical model of the esophagus during primary peristalsis. Here the esophagus is assessed as a cylinder using standard engineering metrics of Work (in units of Joules) and Power (in units of Watts) during a swallow cycle. These advancements could lead to sophisticated and complex models of the esophagus which could play an important part in esophageal diagnostics and targeted therapeutics

A Predictive Model to Identify Patients With Fecal Incontinence Based on High-Definition Anorectal Manometry

Background & aimsThree-dimensional high-definition anorectal manometry (3D-HDAM) is used to assess anal sphincter function; it determines profiles of regional pressure distribution along the length and circumference of the anal canal. There is no consensus, however, on the best way to analyze data from 3D-HDAM to distinguish healthy individuals from persons with sphincter dysfunction. We developed a computer analysis system to analyze 3D-HDAM data and to aid in the diagnosis and assessment of patients with fecal incontinence (FI).MethodsIn a prospective study, we performed 3D-HDAM analysis of 24 asymptomatic healthy subjects (control subjects; all women; mean age, 39 ± 10 years) and 24 patients with symptoms of FI (all women; mean age, 58 ± 13 years). Patients completed a standardized questionnaire (FI severity index) to score the severity of FI symptoms. We developed and evaluated a robust prediction model to distinguish patients with FI from control subjects using linear discriminant, quadratic discriminant, and logistic regression analyses. In addition to collecting pressure information from the HDAM data, we assessed regional features based on shape characteristics and the anal sphincter pressure symmetry index.ResultsThe combination of pressure values, anal sphincter area, and reflective symmetry values was identified in patients with FI versus control subjects with an area under the curve value of 1.0. In logistic regression analyses using different predictors, the model identified patients with FI with an area under the curve value of 0.96 (interquartile range, 0.22). In discriminant analysis, results were classified with a minimum error of 0.02, calculated using 10-fold cross-validation; different combinations of predictors produced median classification errors of 0.16 in linear discriminant analysis (interquartile range, 0.25) and 0.08 in quadratic discriminant analysis (interquartile range, 0.25).ConclusionsWe developed and validated a novel prediction model to analyze 3D-HDAM data. This system can accurately distinguish patients with FI from control subjects

High‐frequency ultrasound imaging of the anal sphincter muscles in normal subjects and patients with fecal incontinence

IntroductionThe 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.AimsThe 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.MethodsStudies 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.ResultsThe 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.ConclusionHigh-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