Small intestine contrast ultrasonography vs computed tomography enteroclysis for assessing ileal Crohn's disease

Current Developments and Role of Intestinal Ultrasound including the Advent of AI

Intestinal ultrasound is a non-invasive, safe, and cost-effective technique to study the small and large intestines. In addition to conventional B-mode and color doppler imaging, new US tools have been developed in more recent years that provide auxiliary data on many GI conditions, improving the diagnosis and assessment of relevant outcomes. We have reviewed the more recent literature (from 2010 onwards) on auxiliary tools in bowel ultrasound such as elastography techniques, CEUS, SICUS, and the potential contribution by artificial intelligence (AI) to overcome current intestinal ultrasound limitations. For this scoping review, we performed an extensive literature search on PubMed and EMBASE to identify studies published until December 2023 and investigating the application of elastography techniques, CEUS, SICUS, and AI in the ultrasonographic assessment of the small and large intestines. Multiparametric intestinal ultrasound shows promising capabilities in Crohn's disease, while less is known about the role in ulcerative colitis. Despite some evidence, the CEUS role as a point-of-care examination tool for rare conditions such as intestinal GvHD and ischemic small bowel disease seems promising, possibly avoiding the need to perform further cross-sectional imaging. The use of AI in intestinal ultrasound is still anecdotical and limited to acute appendicitis.

Systematic review: Defining, diagnosing and monitoring small bowel strictures in Crohn's disease on intestinal ultrasound

BACKGROUND

Stricturing Crohn's disease (CD) occurs most commonly in the terminal ileum and poses a clinical problem. Cross-sectional imaging modalities such as intestinal ultrasound (IUS), computed tomography enterography (CTE), and magnetic resonance enterography (MRE) allow for assessment of the entire bowel wall and associated peri-enteric findings. Radiologic definitions of strictures have been developed for CTE and MRE; their reliability and responsiveness are being evaluated in index development programs. A comprehensive assessment strategy for strictures using IUS is needed.

AIMS

To provide a detailed summary of definitions, diagnosis and monitoring of strictures on IUS as well as technical aspects of image acquisition.

METHODS

We searched four databases up to 6 January 2024. Two-stage screening was done in duplicate. We assessed risk of bias using QUADAS-2.

RESULTS

There were 56 studies eligible for inclusion. Definitions for strictures on IUS are heterogeneous, but the overall accuracy for diagnosis of strictures is high. The capability of IUS for characterising inflammation versus fibrosis in strictures is not accurate enough to be used in clinical practice or trials. We summarise definitions for improvement of strictures on IUS, and discuss parameters for image acquisition and standardisation.

CONCLUSIONS

This systematic review is the first step for a structured program to develop a stricture IUS index for CD.

Small Intestinal Contrast Ultrasonography (SICUS) in Crohn's Disease: Systematic Review and Meta-Analysis

The diagnosis of Crohn's Disease (CD) is based on a combination of clinical symptoms, laboratory tests, endoscopy, and imaging data. In Small Intestine Contrast Ultrasonography (SICUS), the ingestion of a macrogol solution as an oral contrast medium may optimize image quality. We performed a meta-analysis to evaluate the diagnostic performance of SICUS for CD. A literature search was performed in August 2023. We selected only studies where SICUS was compared to a technique that allows the assessment of the whole gastrointestinal tract, such as an MRE, a CT scan, or a surgical evaluation. We estimated pooled weighted sensitivity, specificity, and likelihood ratio for positive and negative tests (PLR/NLR) of SICUS. Summary receiver operating characteristic curves (SROC) were drawn, and pooled areas under the curve (AUC) were calculated. Five studies with 325 CD patients were included. SICUS showed a pooled sensitivity for the diagnosis of 95% (95% confidence interval CI 89-99%), a specificity = 77% (95% CI 60-90%), and the AUC was 0.94. SICUS demonstrated a pooled sensitivity for strictures of 78% (95% CI 63-88%) and a specificity = 96% (95% CI 85-99%), with AUC = 0.93. For abscesses, SICUS demonstrated a pooled sensitivity of 100% (95% CI 59-100%) and a specificity of 90% (95% CI 74-98%). Fistulae were detected with a pooled sensitivity of 77% (95% CI 46-95%) and a specificity of 92% (95% CI 75-99%). SICUS demonstrated excellent diagnostic performance compared to the gold standard despite some clinical scenarios (stenosis/fistulae) showing suboptimal diagnostic effectiveness.

Crohn's disease related strictures in cross-sectional imaging: More than meets the eye?

Strictures in Crohn's disease (CD) are a hallmark of long-standing intestinal damage, brought about by inflammatory and non-inflammatory pathways. Understanding the complex pathophysiology related to inflammatory infiltrates, extracellular matrix deposition, as well as muscular hyperplasia is crucial to produce high-quality scoring indices for assessing CD strictures. In addition, cross-sectional imaging modalities are the primary tool for diagnosis and follow-up of strictures, especially with the initiation of anti-fibrotic therapy clinical trials. This in turn requires such modalities to both diagnose strictures with high accuracy, as well as be able to delineate the impact of each histomorphologic component on the individual stricture. We discuss the current knowledge on cross-sectional imaging modalities used for stricturing CD, with an emphasis on histomorphologic correlates, novel imaging parameters which may improve segregation between inflammatory, muscular, and fibrotic stricture components, as well as a future outlook on the role of artificial intelligence in this field of gastroenterology.

Extracellular Matrix Components as Diagnostic Tools in Inflammatory Bowel Disease

Simple Summary

For decades, the extracellular matrix (ECM) has been defined as a structure component playing a rather neglected role in the human body. In recent years, research has shed light on the role of ECM within cellular processes, including proliferation, migration and differentiation, as well as in inflammation. In inflammation, ECM composition is constantly being remodeled and undergoes dynamic and rapid changes. Tracking these changes could serve as a novel diagnostic tool. Inflammatory bowel disease is accompanied by complications such as fibrosis, stenosis and fistulas. All of these structural complications involve excessive synthesis or degradation of ECM. With this review, we explored whether the analysis of ECM composition can be of support in diagnosing inflammatory bowel disease and whether changes within ECM can help to predict a complicated disease course early on.

Abstract

Work from the last years indicates that the extracellular matrix (ECM) plays a direct role in various cellular processes, including proliferation, migration and differentiation. Besides homeostatic processes, its regulatory function in inflammation becomes more and more evident. In inflammation, such as inflammatory bowel disease, the ECM composition is constantly remodeled, and this can result in a structuring of fistulizing disease course. Thus, tracking early ECM changes might bear the potential to predict the disease course. In this review, we provide an overview of relevant diagnostic methods, focusing on ECM changes.

Comparative study between bowel ultrasound and magnetic resonance enterography among Egyptian inflammatory bowel disease patients

BACKGROUND

Bowel ultrasound and magnetic resonance enterography (MRE) are decisive medical imaging modalities for diagnosing and locating bowel lesions with its extramural extent and complications. They assess the degree of activity, help clinicians to identify patients in need of surgery, and can be used for patient follow-up.

AIM

To compare the role of MRE and bowel ultrasound in diagnosis and follow-up of inflammatory bowel disease (IBD) patients in Egypt.

METHODS

The study was conducted on 40 patients with IBD. All patients were subjected to clinical assessment, laboratory investigations, bowel ultrasound, MRE, and colonoscopy up to the terminal ileum with biopsies for histopathological examination.

RESULTS

This study was conducted on 14 patients (35%) with ulcerative colitis and 26 patients (65%) with Crohn's disease; 34 (85%) of these patients had active disease. Bowel ultrasound detected different bowel lesions with the following accuracies: ileum (85%), large bowel (70%), fistula (95%), stricture and proximal dilatation (95%) and abscesses (100%). Also, it showed that statistically significance of bowel ultrasound in differentiation between remission and activity of IBD in comparison to MRE and colonoscopy.

CONCLUSION

In comparison to MRE, bowel ultrasound is a useful, non-invasive, and feasible bedside imaging tool for the detection of inflammation, detection of complications, and follow-up of IBD patients when performed by the attending physician.

Ultrasound vs Endoscopy, Surgery, or Pathology for the Diagnosis of Small Bowel Crohn's Disease and its Complications

BACKGROUND

In patients with inflammatory bowel disease, we strive to achieve mucosal healing, as this has been shown to decrease the risk of disease flares, hospitalization, and surgery. For this reason, we must use objective measures of mucosal healing to inform our clinical decision-making and can no longer rely on patient symptoms alone. Assessment of small bowel Crohn's disease (SBCD) is particularly challenging given its lack of accessibility via standard endoscopic techniques. Ultrasound (US) represents a readily available, cost-effective, minimally invasive, radiation-free alternative for the assessment of small bowel disease. In this study, we performed a systematic review to determine the accuracy of ultrasound in diagnosing SBCD and its complications as compared with endoscopic visualization, surgery, and/or pathology.

METHODS

We searched MEDLINE, EMBASE, and CENTRAL. Prospective cohort studies published up to March 2017 were reviewed. References meeting all eligibility criteria were assessed at the full-text level by 2 independent reviewers. Sensitivity and specificity were collected where available.

RESULTS

A total of 2817 unique references were identified. Twenty-two studies were included. All studies were at low-moderate risk of bias based on the Quality Assessment of Diagnostic Accuracy Studies criteria. Transabdominal US (TAUS) yielded moderately high sensitivity and specificity for the diagnosis of SBCD and its postoperative recurrence. Detection was more accurate for severe postoperative recurrence. The diagnostic accuracy of US in stricture and abscess detection was high. Contrast enhancement improved the detection of abscess. Diagnostic detection of fistulas was of moderate accuracy. Entero-enteric fistulization and entero-mesenteric fistulization were most clearly identified.

CONCLUSIONS

Ultrasound can be used to diagnose SBCD in those with known or suspected Crohn's disease. It can be used to detect postoperative recurrence and can accurately identify abscesses and fistulas, especially with the aid of contrast enhancement.

Assessment of Crohn's disease-associated small bowel strictures and fibrosis on cross-sectional imaging: a systematic review

Patients with Crohn's disease commonly develop ileal and less commonly colonic strictures, containing various degrees of inflammation and fibrosis. While predominantly inflammatory strictures may benefit from a medical anti-inflammatory treatment, predominantly fibrotic strictures currently require endoscopic balloon dilation or surgery. Therefore, differentiation of the main components of a stricturing lesion is key for defining the therapeutic management. The role of endoscopy to diagnose the nature of strictures is limited by the superficial inspection of the intestinal mucosa, the lack of depth of mucosal biopsies and by the risk of sampling error due to a heterogeneous distribution of inflammation and fibrosis within a stricturing lesion. These limitations may be in part overcome by cross-sectional imaging techniques such as ultrasound, CT and MRI, allowing for a full thickness evaluation of the bowel wall and associated abnormalities. This systematic literature review provides a comprehensive summary of currently used radiologic definitions of strictures. It discusses, by assessing only manuscripts with histopathology as a gold standard, the accuracy for diagnosis of the respective modalities as well as their capability to characterise strictures in terms of inflammation and fibrosis. Definitions for strictures on cross-sectional imaging are heterogeneous; however, accuracy for stricture diagnosis is very high. Although conventional cross-sectional imaging techniques have been reported to distinguish inflammation from fibrosis and grade their severity, they are not sufficiently accurate for use in routine clinical practice. Finally, we present recent consensus recommendations and highlight experimental techniques that may overcome the limitations of current technologies.

Advanced imaging techniques for small bowel Crohn's disease: what does the future hold?

Treatment of Crohn's disease (CD) is intrinsically reliant on imaging techniques, due to the preponderance of small bowel disease and its transmural pattern of inflammation. Ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) are the most widely employed imaging methods and have excellent diagnostic accuracy in most instances. Some limitations persist, perhaps the most clinically relevant being the distinction between inflammatory and fibrotic strictures. In this regard, several methodologies have recently been tested in animal models and human patients, namely US strain elastography, shear wave elastography, contrast-enhanced US, magnetization transfer MRI and contrast dynamics in standard MRI. Technical advances in each of the imaging methods may expand their indications. The addition of oral contrast to abdominal US appears to substantially improve its diagnostic capabilities compared to standard US. Ionizing dose-reduction methods in CT can decrease concern about cumulative radiation exposure in CD patients and diffusion-weighted MRI may reduce the need for gadolinium contrast. Clinical indexes of disease activity and severity are also increasingly relying on imaging scores, such as the recently developed Lémann Index. In this review we summarize some of the recent advances in small bowel CD imaging and how they might affect clinical practice in the near future.

Capsule Endoscopy, Magnetic Resonance Enterography, and Small Bowel Ultrasound for Evaluation of Postoperative Recurrence in Crohn's Disease: Systematic Review and Meta-Analysis

BACKGROUND

Anastomotic recurrence is frequent in patients with Crohn's disease (CD) following ileocecal resection. The degree of endoscopic recurrence, quantified by the Rutgeerts score (RS), is correlated with the risk of clinical and surgical recurrence. Noninvasive modalities such as capsule endoscopy (CE), magnetic resonance enterography (MRE), and intestinal ultrasound (US) may yield similar information without the need for ileocolonoscopy (IC). The aim of our meta-analysis was to evaluate the accuracy of those modalities for detection of endoscopic recurrence in postoperative CD patients.

METHODS

We performed a systematic literature search for studies comparing the accuracy of CE, MRE, and US with IC for detection of postoperative recurrence in CD. We calculated pooled diagnostic sensitivity, specificity, diagnostic odds ratio (DOR), and area under the curve (AUC) for each comparison.

RESULTS

A total of 135 studies were retrieved; 14 studies were eligible for analysis. For CE, the pooled sensitivity was 100% (95% CI, 91%-100%), specificity was 69% (95% CI, 52%-83%), DOR was 30.8 (95% CI, 6.9-138), and AUC was 0.94. MRE had pooled sensitivity of 97% (95% CI, 89%-100%), specificity of 84% (95% CI, 62%-96%), DOR of 129.5 (95% CI, 16.4-1024.7), and AUC of 0.98. US had pooled sensitivity of 89% (95% CI, 85%-92%), specificity of 86% (95% CI, 78%-93%), DOR of 42.3 (95% CI, 18.6-96.0), and AUC 0.93.

CONCLUSIONS

CE, MRE, and US provide accurate assessment of postoperative endoscopic recurrence in CD. These modalities should gain wider use for detection of postoperative recurrence; the prognostic value of those diagnostic findings merits evaluation in further prospective studies.

SICUS and CEUS imaging in Crohn's disease: an update

Endoscopy remains the main technique in the diagnosis and treatment of Crohn's disease (CD); nevertheless, the recent development of innovative and non-invasive imaging techniques has led to a new tool in the exploration of small bowel in CD patients. This paper reviews the available data on ultrasound imaging used for the evaluation of CD, highlighting the role of small intestine contrast-enhanced ultrasonography with the use of oral and intravenous contrast agents.

Bowel Thickening in Crohn's Disease: Fibrosis or Inflammation? Diagnostic Ultrasound Imaging Tools

The high frequency of intestinal strictures in patients with Crohn's disease and the different treatment approaches specific for each type of stenosis make the differentiation between fibrotic and inflammatory strictures crucial in management of the disease. However, there is no standardized approach to evaluate and discriminate intestinal strictures, and until now, there was no established cross-sectional imaging modality to detect fibrosis. New techniques, such as contrast-enhanced ultrasound and sonoelastography allow the assessment of vascularization and mechanical properties of stenotic bowel tissue, respectively. These techniques have shown great potential to characterize strictures in Crohn's disease. The aim of this review is to sum up the current knowledge on bowel ultrasound tools to discriminate inflammatory from fibrotic stenosis in Crohn's disease considering the most recent published studies in the field.

Small intestine contrast ultrasonography for the detection and assessment of Crohn disease: A meta-analysis

BACKGROUND

Crohn disease (CD) is a chronic relapsing disease. Imaging modalities are essential for the diagnosis and assessment of CD. Small intestine contrast ultrasonography (SICUS) is a well-tolerated, noninvasive and radiation-free modality and has shown potential in CD assessment. We aimed at evaluating the diagnostic accuracy of SICUS in the detection and assessment of small-bowel lesions and complications in CD.

METHODS

We searched PubMed database for relevant studies published before April 24, 2016. We integrated the true positive, false positive, false negative, and true negative into the pooled estimates of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio. Forest plots were to represent the pooled results of all studies.

RESULTS

Thirteen articles were finally considered eligible. The pooled sensitivity and specificity of SICUS in detecting small-bowel lesions were 0.883 (95% confidence interval (CI) 0.847-0.913) and 0.861 (95% CI 0.828-0.890), respectively. The pooled diagnostic odds ratio was 39.123 (95% CI 20.014-76.476) and the area under the curve of summary receiver operating characteristic was 0.9273 (standard error: 0.0152). In subgroup analyses, SICUS represented fine sensitivity and specificity in proximal and distal small intestine lesion, as well as in CD-related complications such as stricture, dilation, abscess, and fistula.

CONCLUSION

SICUS is accurate enough to make a complete assessment about the location, extent, number, and almost all kinds of complications in CD small-bowel lesions.

Advanced multimodality imaging of inflammatory bowel disease in 2015: An update

The diagnosis and effective management of inflammatory bowel disease (IBD) requires a combination clinical, endoscopic, histological, biological, and imaging data. While endoscopy and biopsy remains the gold standard for diagnosis of IBD, imaging plays a central role in the assessment of extra mural disease, in disease surveillance and in the assessment of response to medical treatments, which are often expensive. Imaging is also vital in the detection and diagnosis of disease related complications, both acute and chronic. In this review, we will describe, with illustrative images, the imaging features of IBD in adults, with emphasis on up-to-date imaging techniques focusing predominantly on cross sectional imaging and new magnetic resonance imaging techniques.

Bowel Ultrasonography in the Management of Crohn's Disease. A Review with Recommendations of an International Panel of Experts

BACKGROUND

Bowel ultrasonography (US) is considered a useful technique for assessing mural inflammation and complications in Crohn's disease (CD). The aim of this review is to appraise the evidence on the accuracy of bowel US for CD. In addition, we aim to provide recommendations for its optimal use.

METHODS

Publications were identified by literature search from 1992 to 2014 and selected based on predefined criteria: 15 or more patients; bowel US for diagnosing CD, complications, postoperative recurrence, activity; adequate reference standards; prospective study design; data reported to allow calculation of sensitivity, specificity, agreement, or correlation values; articles published in English.

RESULTS

The search yielded 655 articles, of which 63 were found to be eligible and retrieved as full-text articles for analysis. Bowel US showed 79.7% sensitivity and 96.7% specificity for the diagnosis of suspected CD, and 89% sensitivity and 94.3% specificity for initial assessment in established patients with CD. Bowel US identified ileal CD with 92.7% sensitivity, 88.2% specificity, and colon CD with 81.8% sensitivity, 95.3% specificity, with lower accuracy for detecting proximal lesions. The oral contrast agent improves the sensitivity and specificity in determining CD lesions and in assessing sites and extent.

CONCLUSIONS

Bowel US is a tool for evaluation of CD lesions in terms of complications, postoperative recurrence, and monitoring response to medical therapy; it reliably detects postoperative recurrence and complications, as well as offers the possibility of monitoring disease progression.

Advances in the diagnosis and management of inflammatory bowel disease: challenges and uncertainties

Over the past two decades, several advances have been made in the management of patients with inflammatory bowel disease (IBD) from both evaluative and therapeutic perspectives. This review discusses the medical advancements that have recently been made as the standard of care for managing patients with ulcerative colitis (UC) and Crohn's Disease (CD) and to identify the challenges associated with implementing their use in clinical practice. A comprehensive literature search of the major databases (PubMed and Embase) was conducted for all recent scientific papers (1990-2013) giving the recent updates on the management of IBD and the data were extracted. The reported advancements in managing IBD range from diagnostic and evaluative tools, such as genetic tests, biochemical surrogate markers of activity, endoscopic techniques, and radiological modalities, to therapeutic advances, which encompass medical, endoscopic, and surgical interventions. There are limited studies addressing the cost-effectiveness and the impact that these advances have had on medical practice. The majority of the advances developed for managing IBD, while considered instrumental by some IBD experts in improving patient care, have questionable applications due to constraints of cost, lack of availability, and most importantly, insufficient evidence that supports their role in improving important long-term health-related outcomes.

Transabdominal ultrasound for diagnosis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disease, including Crohn's disease and ulcerative colitis. Patients with IBD need life-time treatment because the disease is characterized by alternating periods of remission and exacerbation. In recent years, the incidence of IBD has been increasing in China. Compared with magnetic resonance imaging (MRI) and computed tomography (CT), transabdominal ultrasound has many advantages such as real-time scanning, easy handling, no radiation, and low cost, representing the optimal modality for diagnosing IBD. A meta-analysis has showed that ultrasound is comparable to CT or MRI in evaluation of IBD. Contrast-enhanced ultrasound is capable of detecting microcirculation perfusion of the intestinal wall, and ultrasound elastography is able to assess the stiffness of the intestinal wall. Both of them have great potential in the diagnosis of IBD and will further improve diagnostic performance.

Diagnosis of bowel diseases: The role of imaging and ultrasonography

Examinations with a visualisation of the anatomy and pathology of the gastrointestinal (GI) tract are often necessary for the diagnosis of GI diseases. Traditional radiology played a crucial role for many years. Endoscopy, despite some limitations, remains the main technique in the differential diagnosis and treatment of GI diseases. In the last decades, the introduction of, and advances in, non-invasive cross-sectional imaging modalities, including ultrasound (US), computed tomography (CT), positron-emission tomography (PET), and magnetic resonance imaging, as well as improvements in the resolution of imaging data, the acquisition of 3D images, and the introduction of contrast-enhancement, have modified the approach to the examination of the GI tract. Moreover, additional co-registration techniques, such as PET-CT and PET-MRI, allow multimodal data acquisition with better sensitivity and specificity in the study of tissue pathology. US has had a growing role in the development and application of the techniques for diagnosis and management of GI diseases because it is inexpensive, non-invasive, and more comfortable for the patient, and it has sufficient diagnostic accuracy to provide the clinician with image data of high temporal and spatial resolution. Moreover, Doppler and contrast-enhanced ultrasound (CEUS) add important information about blood flow. This article provides a general review of the current literature regarding imaging modalities used for the evaluation of bowel diseases, highlighting the role of US and recent developments in CEUS.