Circular smooth muscle contributes to esophageal shortening during peristalsis

A Study of Small and Large Bowel Wall Thickness Using Computed Tomography and Its Histopathological Correlation

BACKGROUND

Small bowel imaging presents significant challenges due to the bowel's length, narrow caliber, and complex looping. Accurate diagnosis of gastrointestinal disorders often requires detailed imaging to differentiate various pathologies, such as inflammatory bowel disease (IBD), infections, ischemic conditions, and neoplasms.

INTRODUCTION

The small bowel plays a crucial role in digestion and absorption and is susceptible to various pathologies. CT imaging is essential for diagnosing bowel wall thickening, which can indicate a range of conditions. Dual-energy CT (DECT) and CT enterography offer advanced imaging capabilities to address these diagnostic challenges. This study aims to evaluate the efficacy of CT in staging malignant lesions by correlating imaging findings with histopathology to enhance non-invasive diagnosis and treatment strategies.

METHODOLOGY

This cross-sectional study was conducted over two years at Era's Medical College and Hospital, Lucknow, India, with 60 subjects. Patients with abnormal bowel wall thickening (>5 mm) on ultrasound were included, while those with renal dysfunction or pregnancy were excluded. After informed consent, subjects consumed a mannitol solution before undergoing CT scans using a 384-slice Dual Energy CT scanner (Somatom Force, Siemens Healthcare, Erlangen, Germany). All images were post-processed on a workstation using Synovia software (Synovia Solution, Fort Worth, Texas), which allows for image analysis using three-material decomposition. Statistical analysis was performed using IBM SPSS Statistics for Windows, Version 26 (Released 2019; IBM Corp., Armonk, New York).

RESULTS

The majority of patients were young adults aged 20-39 years (63.33%), with a slight male predominance (53.33%). Abdominal pain was the most common complaint (35.00%). Mild wall thickening (<10 mm) was associated with IBD (48.28%), while marked thickening (>10 mm) was linked to neoplastic lesions (48.39%). Symmetrical thickening was common in infective and inflammatory conditions, whereas asymmetrical thickening was typical of neoplastic lesions. CT scans demonstrated high diagnostic accuracy, with 83.33% sensitivity, 95.24% specificity, 88.24% positive predictive value, and 93.02% negative predictive value, resulting in an overall accuracy of 91.67%.

CONCLUSION

The study highlights that neoplastic lesions are associated with marked bowel wall thickening, while inflammatory conditions present with mild thickening. CT scans proved highly effective in diagnosing gastrointestinal disorders, with significant accuracy in distinguishing between benign and malignant lesions. This underscores the importance of advanced imaging techniques in clinical practice for improved patient outcomes.

Volumetric Tissue Imaging of Surgical Tissue Specimens Using Micro-Computed Tomography: An Emerging Digital Pathology Modality for Nondestructive, Slide-Free Microscopy-Clinical Applications of Digital Pathology in 3 Dimensions

OBJECTIVES

Micro-computed tomography (micro-CT) is a novel, nondestructive, slide-free digital imaging modality that enables the acquisition of high-resolution, volumetric images of intact surgical tissue specimens. The aim of this systematic mapping review is to provide a comprehensive overview of the available literature on clinical applications of micro-CT tissue imaging and to assess its relevance and readiness for pathology practice.

METHODS

A computerized literature search was performed in the PubMed, Scopus, Web of Science, and CENTRAL databases. To gain insight into regulatory and financial considerations for performing and examining micro-CT imaging procedures in a clinical setting, additional searches were performed in medical device databases.

RESULTS

Our search identified 141 scientific articles published between 2000 and 2021 that described clinical applications of micro-CT tissue imaging. The number of relevant publications is progressively increasing, with the specialties of pulmonology, cardiology, otolaryngology, and oncology being most commonly concerned. The included studies were mostly performed in pathology departments. Current micro-CT devices have already been cleared for clinical use, and a Current Procedural Terminology (CPT) code exists for reimbursement of micro-CT imaging procedures.

CONCLUSIONS

Micro-CT tissue imaging enables accurate volumetric measurements and evaluations of entire surgical specimens at microscopic resolution across a wide range of clinical applications.

Analysis of the effect of phloroglucinol on pregnancy outcomes involving frozen embryo transfers in patients with endometriosis: A retrospective case-control study

Objective

Abnormal contraction of uterus and vascular smooth muscle lead to the formation of hypoxia environment in uterus. Abnormal contraction may be the basis of dysmenorrhea, endometriosis, infertility and other diseases. Phloroglucinol is a non-atropine and non-papaverine smooth muscle spasmolytic agent, which can reduce the abnormal contraction of uterine smooth muscle. This study investigated the effect of phloroglucinol on frozen embryo transfer in patients with endometriosis.

Methods

The data of patients with endometriosis who underwent a frozen embryo transfer in Shanghai Changzheng Hospital from August 2018 to August 2021, comprising a total of 453 cycles, were retrospectively analyzed. The patients for whom phloroglucinol was included over 217 cycles were administered intramuscully 40 mg phloroglucinol starting on the day of progesterone administration, then once daily up to day 7 after the embryo transfer. Those for whom phloroglucinol was not administered over 236 cycles were used as the control group. The age of 35 years was used as a boundary in this study to observe the pregnancy outcomes of patients in the two different age groups.

Results

The biochemical pregnancy rate (63.13% vs. 51.27%), embryo implantation rate (44.64% vs. 33.60%), clinical pregnancy rate (59.64% vs. 48.30%), and live birth rate (52.99% vs. 36.86%) after the administration of phloroglucinol were higher than for patients in the control group, and the early abortion rate (7.75% vs. 20.18%) was also lower. The differences were statistically significant (P < 0.05). In particular, in the age group <35 years old, the embryo implantation rate (51.81% vs. 39.38%), clinical pregnancy rate (69.34% vs. 57.55%), and the live birth rate (63.50% vs. 44.60%) after phloroglucinol intervention rose significantly, and the abortion rate dropped (6.32% vs. 17.5%), indicating a statistically significant difference (P < 0.05). However, pregnancy outcomes showed no difference in the age group ≥35 years old (P > 0.05).

Conclusion

Continuous low-dose phloroglucinol pretreatment before and after frozen embryo transfer can improve both the clinical pregnancy and live birth rates and reduce the risk of abortion in younger infertile patients with endometriosis.

Microscopic dual-energy CT (microDECT): a flexible tool for multichannel ex vivo 3D imaging of biological specimens

Dual-energy computed tomography (DECT) uses two different x-ray energy spectra in order to differentiate between tissues, materials or elements in a single sample or patient. DECT is becoming increasingly popular in clinical imaging and preclinical in vivo imaging of small animal models, but there have been only very few reports on ex vivo DECT of biological samples at microscopic resolutions. The present study has three main aims. First, we explore the potential of microscopic DECT (microDECT) for delivering isotropic multichannel 3D images of fixed biological samples with standard commercial laboratory-based microCT setups at spatial resolutions reaching below 10 μm. Second, we aim for retaining the maximum image resolution and quality during the material decomposition. Third, we want to test the suitability for microDECT imaging of different contrast agents currently used for ex vivo staining of biological samples. To address these aims, we used microCT scans of four different samples stained with x-ray dense contrast agents. MicroDECT scans were acquired with five different commercial microCT scanners from four companies. We present a detailed description of the microDECT workflow, including sample preparation, image acquisition, image processing and postreconstruction material decomposition, which may serve as practical guide for applying microDECT. The MATLAB script (The Mathworks Inc., Natick, MA, USA) used for material decomposition (including a graphical user interface) is provided as a supplement to this paper (https://github.com/microDECT/DECTDec). In general, the presented microDECT workflow yielded satisfactory results for all tested specimens. Original scan resolutions have been mostly retained in the separate material fractions after basis material decomposition. In addition to decomposition of mineralized tissues (inherent sample contrast) and stained soft tissues, we present a case of double labelling of different soft tissues with subsequent material decomposition. We conclude that, in contrast to in vivo DECT examinations, small ex vivo specimens offer some clear advantages regarding technical parameters of the microCT setup and the use of contrast agents. These include a higher flexibility in source peak voltages and x-ray filters, a lower degree of beam hardening due to small sample size, the lack of restriction to nontoxic contrast agents and the lack of a limit in exposure time and radiation dose. We argue that microDECT, because of its flexibility combined with already established contrast agents and the vast number of currently unexploited stains, will in future represent an important technique for various applications in biological research.

Development and stem cells of the esophagus

The esophagus is derived from the anterior portion of the developmental intermediate foregut, a structure that also gives rise to other organs including the trachea, lung, and stomach. Genetic studies have shown that multiple signaling pathways (e.g. Bmp) and transcription factors (e.g. SOX2) are required for the separation of the esophagus from the neighboring respiratory system. Notably, some of these signaling pathways and transcription factors continue to play essential roles in the subsequent morphogenesis of the esophageal epithelium which undergoes a simple columnar-to-stratified squamous conversion. Reactivation of the relevant signaling pathways has also been associated with pathogenesis of esophageal diseases that affect the epithelium and its stem cells in adults. In this review we will summarize these findings. We will also discuss new data regarding the cell-of-origin for the striated and smooth muscles surrounding the esophagus and how they are differentiated from the mesenchyme during development.

Regulation and dysregulation of esophageal peristalsis by the integrated function of circular and longitudinal muscle layers in health and disease

Muscularis propria throughout the entire gastrointestinal tract including the esophagus is comprised of circular and longitudinal muscle layers. Based on the studies conducted in the colon and the small intestine, for more than a century, it has been debated whether the two muscle layers contract synchronously or reciprocally during the ascending contraction and descending relaxation of the peristaltic reflex. Recent studies in the esophagus and colon prove that the two muscle layers indeed contract and relax together in almost perfect synchrony during ascending contraction and descending relaxation of the peristaltic reflex, respectively. Studies in patients with various types of esophageal motor disorders reveal temporal disassociation between the circular and longitudinal muscle layers. We suggest that the discoordination between the two muscle layers plays a role in the genesis of esophageal symptoms, i.e., dysphagia and esophageal pain. Certain pathologies may selectively target one and not the other muscle layer, e.g., in eosinophilic esophagitis there is a selective dysfunction of the longitudinal muscle layer. In achalasia esophagus, swallows are accompanied by the strong contraction of the longitudinal muscle without circular muscle contraction. The possibility that the discoordination between two muscle layers plays a role in the genesis of esophageal symptoms, i.e., dysphagia and esophageal pain are discussed. The purpose of this review is to summarize the regulation and dysregulation of peristalsis by the coordinated and discoordinated function of circular and longitudinal muscle layers in health and diseased states.

Circular and longitudinal muscles shortening indicates sliding patterns during peristalsis and transient lower esophageal sphincter relaxation

Esophageal axial shortening is caused by longitudinal muscle (LM) contraction, but circular muscle (CM) may also contribute to axial shortening because of its spiral morphology. The goal of our study was to show patterns of contraction of CM and LM layers during peristalsis and transient lower esophageal sphincter (LES) relaxation (TLESR). In rats, esophageal and LES morphology was assessed by histology and immunohistochemistry, and function with the use of piezo-electric crystals and manometry. Electrical stimulation of the vagus nerve was used to induce esophageal contractions. In 18 healthy subjects, manometry and high frequency intraluminal ultrasound imaging during swallow-induced esophageal contractions and TLESR were evaluated. CM and LM thicknesses were measured (40 swallows and 30 TLESRs) as markers of axial shortening, before and at peak contraction, as well as during TLESRs. Animal studies revealed muscular connections between the LM and CM layers of the LES but not in the esophagus. During vagal stimulated esophageal contraction there was relative movement between the LM and CM. Human studies show that LM-to-CM (LM/CM) thickness ratio at baseline was 1. At the peak of swallow-induced contraction LM/CM ratio decreased significantly (<1), whereas the reverse was the case during TLESR (>2). The pattern of contraction of CM and LM suggests sliding of the two muscles. Furthermore, the sliding patterns are in the opposite direction during peristalsis and TLESR.

Myelomeningocele: How we can improve the assessment of the most severe form of spina bifida

Myelomeningocele (MMC) is a devastating spinal cord birth defect, which results in significant life-long disabilities, impaired quality of life, and difficult medical management. The pathological progression of MMC involves failure in neural tube and vertebral arch closure at early gestational ages, followed by subsequent impairment in spinal cord and vertebral growth during fetal development. MMC is irreversible at term. Thus, prenatal therapeutic strategies that interrupt progressive pathological processes offer an appealing approach for treatment of MMC. However, a thorough understanding of pathological progression of MMC is mandatory for appropriate treatment to be rendered. This article is part of a Special Issue entitled SI: Spinal cord injury.

Esophageal function testing: beyond manometry and impedance

Manometry and impedance provide only surrogate information regarding longitudinal wall function and are focused on contractile amplitude and lumen content. Ultrasound imaging provides a unique perspective of esophageal function by providing important information regarding longitudinal muscle contraction. Laser Doppler assessment of perfusion may be an important complementary tool to assess abnormal wall blood perfusion as a possible mechanism of pain.

Longitudinal muscle of the esophagus: its role in esophageal health and disease

PURPOSE OF REVIEW

The muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. The function of the longitudinal muscle and its role in bolus propulsion are not clear. The goal of this review is to summarize what is known of the role of the longitudinal muscle in health, as well as in sensory and motor disorders of the esophagus.

RECENT FINDINGS

Simultaneous manometry and ultrasound imaging reveal that, during peristalsis, the two muscle layers of the esophagus contract in perfect synchrony. On the contrary, during transient lower esophageal sphincter (LES) relaxation, longitudinal muscle contracts independent of the circular muscle. Recent studies have provided novel insights into the role of the longitudinal muscle in LES relaxation and descending relaxation of the esophagus. In certain diseases (e.g. some motility disorders of the esophagus), there is discoordination between the two muscle layers, which likely plays an important role in the genesis of dysphagia and delayed esophageal emptying. There is close temporal correlation between prolonged contractions of the longitudinal muscles of the esophagus and esophageal 'angina-like' pain. Novel techniques to record longitudinal muscle contraction are reviewed.

SUMMARY

Longitudinal muscles of the esophagus play a key role in the physiology and pathophysiology of esophageal sensory and motor function. Neuro-pharmacologic controls of circular and longitudinal muscle are different, which provides an opportunity for the development of novel pharmacological therapies in the treatment of esophageal sensory and motor disorders.

Longitudinal muscle dysfunction in achalasia esophagus and its relevance

Muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. Goal of this review is to summarize the role of longitudinal muscle in physiology and pathophysiology of esophageal sensory and motor function. Simultaneous manometry and ultrasound imaging that measure circular and longitudinal muscle contraction respectively reveal that during peristalsis 2 layers of the esophagus contract in perfect synchrony. On the other hand, during transient relaxation of the lower esophageal sphincter (LES), longitudinal muscle contracts independently of circular muscle. Recent studies provide novel insights, i.e., longitudinal muscle contraction of the esophagus induces LES relaxation and possibly descending relaxation of the esophagus. In achalasia esophagus and other motility disorders there is discoordination between the 2 muscle layers. Longitudinal muscle contraction patterns are different in the recently described three types of achalasia identified by high-resolution manometry. Robust contraction of the longitudinal muscle in type II achalasia causes pan-esophageal pressurization and is the mechanism of whatever little esophageal emptying that take place in the absence of peristalsis and impaired LES relaxation. It may be that preserved longitudinal muscle contraction is also the reason for superior outcome to medical/surgical therapy in type II achalasia esophagus. Prolonged contractions of longitudinal muscles of the esophagus is a possible mechanism of heartburn and "angina like" pain seen in esophageal motility disorders and possibly achalasia esophagus. Novel techniques to record longitudinal muscle contraction are on the horizon. Neuro-pharmacologic control of circular and longitudinal muscles is different, which provides an important opportunity for the development of novel pharmacological therapies to treat sensory and motor disorders of the esophagus.