Dynamic Contrast-Enhanced Magnetic Resonance Enterography and Dynamic Contrast-Enhanced Ultrasonography in Crohn's Disease: An Observational Comparison Study

Quantitative Magnetic Resonance Imaging (qMRI) of the Small Bowel in Crohn's Disease: State-of-the-Art and Future Directions

Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal tract in which repeated episodes of acute inflammation may lead to long-term bowel damage. Cross-sectional imaging is used in conjunction with endoscopy to diagnose and monitor disease and detect complications. Magnetic resonance imaging (MRI) has demonstrable utility in evaluating inflammatory activity. However, subjective interpretation of conventional MR sequences is limited in its ability to fully phenotype the underlying histopathological processes in chronic disease. In particular, conventional MRI can be confounded by the presence of mural fibrosis and muscle hypertrophy, which can mask or sometimes mimic inflammation. Quantitative MRI (qMRI) methods provide a means to better differentiate mural inflammation from fibrosis and improve quantification of these processes. qMRI may also provide more objective measures of disease activity and enable better tailoring of treatment. Here, we review quantitative MRI methods for imaging the small bowel in CD and consider the path to their clinical translation. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Novelties and Perspectives of Intestinal Ultrasound in the Personalised Management of Patients with Inflammatory Bowel Diseases-A Systematic Review

Inflammatory bowel diseases (IBDs) affect over 4.9 million individuals worldwide. Colonoscopy (CS) is the gold-standard technique for diagnosis. The remissive-recurrent pattern of evolution raises the need for non-invasive techniques to monitor disease activity. This review aims to present the advantages of intestinal ultrasound (IUS) in managing IBDs. Our search was conducted on the PubMed, Embase, and Cochrane (CENTRAL) databases, selecting original studies comparing IUS with other imaging and invasive monitoring methods. Our search yielded 8654 results, of which 107 met the inclusion criteria. Increased bowel wall thickness (BWT) and colour Doppler signal (CDS) are discriminative for disease activity. IUS can predict disease outcomes and detect response to treatment or postoperative recurrence. Contrast-enhanced ultrasound (CEUS) and elastography help differentiate fibrotic from inflammatory stenoses. The difficult rectal assessment limits the use of IUS in ulcerative colitis (UC). Transmural healing may develop as a therapeutic target as it is associated with better outcomes. Patients are compliant with this technique, and its results correlate well with CS and other imaging methods. In conclusion, IUS proves to be essential in assessing IBD activity and treatment response, predicting outcomes and detecting complications. CEUS and elastography are researched to improve the diagnostic values of IUS.

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.

EFSUMB Technical Review - Update 2023: Dynamic Contrast-Enhanced Ultrasound (DCE-CEUS) for the Quantification of Tumor Perfusion

Dynamic contrast-enhanced ultrasound (DCE-US) is a technique to quantify tissue perfusion based on phase-specific enhancement after the injection of microbubble contrast agents for diagnostic ultrasound. The guidelines of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) published in 2004 and updated in 2008, 2011, and 2020 focused on the use of contrast-enhanced ultrasound (CEUS), including essential technical requirements, training, investigational procedures and steps, guidance regarding image interpretation, established and recommended clinical indications, and safety considerations. However, the quantification of phase-specific enhancement patterns acquired with ultrasound contrast agents (UCAs) is not discussed here. The purpose of this EFSUMB Technical Review is to further establish a basis for the standardization of DCE-US focusing on treatment monitoring in oncology. It provides some recommendations and descriptions as to how to quantify dynamic ultrasound contrast enhancement, and technical explanations for the analysis of time-intensity curves (TICs). This update of the 2012 EFSUMB introduction to DCE-US includes clinical aspects for data collection, analysis, and interpretation that have emerged from recent studies. The current study not only aims to support future work in this research field but also to facilitate a transition to clinical routine use of DCE-US.

Comment on "Ultrasonographic scores for ileal Crohn's disease assessment: better, worse or the same as contrast‑enhanced ultrasound?"

We read with interest the study by Freitas et al. comparing contrast-enhanced ultrasound (CEUS) and parameters from a time-intensity curve (TIC) with the SUS-CD score and IBUS-SAS score in patients with Crohn's disease (CD) undergoing gastrointestinal ultrasound (GIUS) and ileocolonoscopy. The aim was to compare the accuracy of CEUS and aforementioned scores in predicting terminal ileal inflammatory activity in patients with CD. In this retrospective study of 50 patients, inflammatory activity was defined as a segmental score of SES-CD ≥ 7 in the terminal ileum. The study found 30 patients with active endoscopic disease demonstrating no significant difference between the "inactive" and "active" SUS CD and IBUS-SAS scores. However, the CEUS peak enhancement derived from the TIC was shown to be significantly different. The authors conclude CEUS was superior for detecting inflammation in the terminal ileum, as opposed to ultrasound scores relying on bowel wall thickness and color Doppler.

Biomechanical Properties of Strictures in Crohn’s Disease: Can Dynamic Contrast-Enhanced Ultrasonography and Magnetic Resonance Enterography Predict Stiffness?

Strictures and abdominal pain often complicate Crohn’s disease (CD). The primary aim was to explore whether parameters obtained by preoperative contrast-enhanced (CE) ultrasonography (US) and dynamic CE MR Enterography (DCE-MRE) of strictures associates with biomechanical properties. CD patients undergoing elective small intestinal surgery were preoperatively examined with DCE-MRE and CEUS. The excised intestine was distended utilizing a pressure bag. Luminal and outer bowel wall cross-sectional areas were measured with US. The circumferential stricture stiffness (Young’s modulus E) was computed. Stiffness was associated with the initial slope of enhancement on DCE-MRE (ρ = 0.63, p = 0.007), reflecting active disease, but lacked association with CEUS parameters. For structural imaging parameters, inflammation and stricture stiffness were associated with prestenotic dilatation on US (τ_b = 0.43, p = 0.02) but not with MRE (τ_b = 0.01, p = 1.0). Strictures identified by US were stiffer, 16.8 (14.0–20.1) kPa, than those graded as no or uncertain strictures, 12.6 (10.5–15.1) kPa, p = 0.02. MRE global score (activity) was associated with E (ρ = 0.55, p = 0.018). Elastography did not correlate with circumferential stiffness. We conclude that increasing activity defined by the initial slope of enhancement on DCE-MRE and MRE global score were associated with stricture stiffness. Prestenotic dilatation on US could be a potential biomarker of CD small intestinal stricture stiffness.

Intestinal Conventional Ultrasonography, Contrast-Enhanced Ultrasonography and Magnetic Resonance Enterography in Assessment of Crohn's Disease Activity: A Comparison with Surgical Histopathology Analysis

BACKGROUND AND AIMS

Contrast-enhanced ultrasonography (CEUS) is a potential interesting method for assessing accurately Crohn's disease (CD) activity. We compared the value of intestinal ultrasonography (US) coupled with contrast agent injection with that of magnetic resonance enterography (MRE) in the assessment of small bowel CD activity using surgical histopathology analysis as reference.

METHODS

Seventeen clinically active CD patients (14 women, mean age 33 years) requiring an ileal or ileocolonic resection were prospectively enrolled. All performed a MRE and a US coupled with contrast agent injection (CEUS) less than 8 weeks prior to surgery. Various imaging qualitative and quantitative parameters were recorded and their respective performance to detect disease activity, disease extension and presence of complications was compared to surgical histopathological analysis.

RESULTS

The median wall thickness measured by US differed significantly between patients with non-severely active CD (n = 5) and those with severely active CD (n = 12) [7.0 mm, IQR (6.5-9.5) vs 10.0 mm, IQR (8.0-12.0), respectively; p = 0.03]. A non-significant trend was found with MRE with a median wall thickness in severe active CD of 10.0 mm, IQR (8.0-13.7) compared with 8.0 mm, IQR (7.5-10.5) in non-severely active CD (p = 0.07). The area under the ROC curve (AUROC) of the wall thickness assessed by US and MRE to identify patients with or without severely active CD on surgical specimens were 0.85, 95% CI (0.64-1.04), p = 0.03 and 0.80, 95% CI (0.56-1.01), p = 0.07, respectively. Among the parameters derived from the time-intensity curve during CEUS, time to peak and rise time were the two most accurate markers [AUROC = 0.88, 95% CI (0.70-1.04), p = 0.02 and 0.86, 95% CI (0.68-1.04), p = 0.03] to detect patients with severely active CD assessed on surgical specimens.

CONCLUSION

The accuracy of intestinal CEUS is close to that of conventional US to detect disease activity. A thickened bowel and shortened time to peak and rise time were the most accurate to identify CD patients with severe histological disease activity.

Intestinal Ultrasound Early on in Treatment Follow-up Predicts Endoscopic Response to Anti-TNFα Treatment in Crohn's Disease

BACKGROUND

To assess treatment response, objective measures are superior to clinical improvement in Crohn's disease [CD]. Intestinal ultrasound [IUS] is an attractive, non-invasive alternative to endoscopy, demonstrating early transmural changes after treatment initiation. Therefore, we investigated IUS and contrast-enhanced ultrasound [CEUS] to predict [early] endoscopic treatment response.

METHODS

Consecutive patients with endoscopically active CD, starting anti-TNFα therapy, were included. Clinical, biochemical, IUS, and CEUS parameters at baseline [T0], after 4-8 weeks [T1] and 12-34 weeks [T2] were collected. The most severely inflamed segment at endoscopy (highest segmental Simplified Endoscopic Score for Crohn's Disease [SES-CD]) and IUS (highest segmental bowel wall thickness [BWT]) was identified. At T2, endoscopic response [decrease in SES-CD ≥ 50%] and remission [SES-CD = 0] were scored.

RESULTS

A total of 40 patients were included: 14 reached endoscopic remission and 17 endoscopic response. At T1 (3.1 mm [1.9-4.2] vs 5.3 mm [3.8-6.9], p = 0.005) and T2 (2.0 mm [1.8-3.1] vs 5.1 [3.0-6.3] mm, p = 0.002) BWT was lower in patients with endoscopic remission. At T1 and T2, 18% (area under the receiver operating curve [AUROC]: 0.77; odds ratio [OR]: 10.80, p = 0.012) and 29% [AUROC: 0.833; OR: 37.50, p = 0.006] BWT decrease predicted endoscopic response, respectively. To determine endoscopic remission, BWT 3.2 mm was most accurate [AUROC: 0.94; OR: 39.42, p < 0.0001] at T2. In addition, absence of colour Doppler signal [OR: 13.76, p = 0.03] and the CEUS parameter wash-out rate [OR: 0.76, p = 0.019] improved the prediction model.

CONCLUSIONS

Reduction in BWT, already after 4-8 weeks of follow-up, predicted endoscopic response and remission. CEUS parameters were of limited value. Furthermore, we have provided accurate cut-offs for BWT reflecting endoscopic response and remission at different time points.

Ultrasound imaging for assessing functions of the GI tract

OBJECTIVE

In the following review we outline how ultrasound can be used to measure physiological processes in the gastrointestinal tract.

APPROACH

We have investigated the potential of ultrasound in assessing gastrointestinal physiology including original research regarding both basic methodology and clinical applications.

MAIN RESULTS

Our main findings show the use of ultrasound to study esophageal motility, measure volume and contractility of the stomach, assess motility, wall thickness, and perfusion of the small bowel, and evaluate wall vascularization and diameters of the large bowel.

SIGNIFICANCE

Ultrasound is a widely accessible technology that can be used for both scientific and clinical purposes. Being radiation-free and user friendly, the examination can be frequently repeated enabling longitudinal studies. Furthermore, it does not influence normal GI physiology, thus being useful to estimate motility and subtle changes in physiology. Accordingly, ultrasound scanning and physiological measurements may make a big difference for the scientist and the doctor; and for the patients who receive an efficient work-up.

Contrast enhanced ultrasound: comparing a novel modality to MRI to assess for bowel disease in pediatric Crohn's patients

Background

To demonstrate the feasibility and reliability of a novel imaging modality, contrast enhanced ultrasound (CEUS), in evaluating for distal small bowel inflammation in pediatric Crohn's disease (CD), and compare this to concurrently obtained magnetic resonance imaging (MRI) findings.

Methods

Pediatric patients diagnosed with or having suspicion of CD with small bowel involvement, whose disease merited imaging with an MRI, concurrently underwent imaging with CEUS. We assessed the ability of CEUS to demonstrate distal small bowel disease by evaluating wall thickness, enhancement pattern, mucosal disruption and pericolonic inflammation. Concordance between imaging modalities was then assessed.

Results

Twenty patients were recruited for the study, 16 with known CD, 3 with concern for CD, and one with known colitis, but unknown bowel disease status. Six patients (3 with prior diagnosis of CD, 3 without) had absence of bowel enhancement on both ultrasound and MRI. Eleven patients with findings of inflammation and enhancement on MRI also had concurrent evidence of enhancement on CEUS. Three patients who had no evidence of inflammation on MRI, with known CD, had prominent bowel enhancement on CEUS. One patient with known colitis, whom we enrolled to evaluate for small bowel disease, had no evidence on either MRI or CEUS, however CEUS showed significant fat stranding around the colon, supporting the diagnosis of CD.

Conclusions

The sensitivity of CEUS to detect bowel inflammation when seen on MRI was 100%. In addition, CEUS may also have the ability to detect bowel inflammation, even in the presence of a normal MRI.

Predicting Malignancy Risk in Gastrointestinal Subepithelial Tumors with Contrast-Enhanced Harmonic Endoscopic Ultrasonography Using Perfusion Analysis Software

Background/Aims

Contrast-enhanced harmonic endoscopic ultrasonography (CEH-EUS) is a promising imaging modality that can differentiate subepithelial tumors (SETs) by detecting the degree of enhancement. However, whether CEH-EUS alone can predict the malignancy risk of gastrointestinal stromal tumors (GISTs) remains unclear. This study aimed to evaluate the feasibility of CEH-EUS by using perfusion analysis software for distinguishing among SETs and predicting the malignancy risk of GISTs.

Methods

We retrospectively included patients with SETs who underwent preoperative CEH-EUS. In this study, 44 patients with histologically proven GISTs and benign SETs were enrolled. Perfusion analysis was performed using perfusion quantification software. Peak enhancement (PE), wash-in rate (WiR), wash-in perfusion index (WiPI), and wash-in and wash-out areas under the time-intensity curve (WiWoAUC) were calculated and compared between the GISTs and benign SETs.

Results

When we allocated the enrolled patients into the leiomyoma group and low- and high-grade malignancy GIST groups, significant statistical differences in PE (p<0.001), WiR (p=0.009), WiPI (p<0.001), and WiWoAUC (p<0.001) were identified in the high-grade malignancy group compared with the leiomyoma group.

Conclusions

CEH-EUS with perfusion analysis using perfusion analysis software could be a quantitative and independent method for predicting malignancy risk in gastrointestinal SETs.

Healing Response of a Structural Hamstring Injury: Perfusion Imaging 8-Week Follow-Up

CONTEXT

Hamstring injuries are frequently observed in various sports disciplines both in elite and recreational sport.

OBJECTIVE

To quantify intramuscular tissue perfusion via contrast-enhanced ultrasound in the acute phase and during the healing of a structural muscle injury confirmed by high-resolution magnetic resonance imaging.

DESIGN

Case study.

SETTING

Laboratory environment.

PATIENT

A 32-year-old wakeboarder (height = 176 cm, body weight = 76 kg, and body mass index = 24.5 kg/m2) with an acute indirect muscle injury of the semimembranosus muscle.

MAIN OUTCOME MEASURES

Average values of quantifiable contrast-enhanced ultrasound, represented as peak enhancement and wash-in area under the curve, as well as conventional ultrasound, 1.5T magnetic resonance imaging were assessed at 48-hour, 3-week, and 8-week postinjury.

RESULTS

Average values of the quantitative perfusion analysis at 48-hour and 8-week postinjury revealed an approximate 5-fold increase in peak enhancement, and the wash-in area under the curve increased more than 3-fold in the center of the lesion. Magnetic resonance imaging, performed 48 hours after the injury to gather reference data as gold standard, revealed a grade III structural muscle tear.

CONCLUSIONS

The authors are able to demonstrate significant changes in intramuscular tissue perfusion in the center of the structural lesion as well as in the adjacent tissue. Quantifiable contrast-enhanced ultrasound seems to be able to gather relevant data for the assessment and monitoring of muscle injuries and could be established as a valuable tool for further studies focusing on healing processes or therapeutic interventions.

Persistent Enhancement on Contrast-Enhanced Ultrasound Studies of Severe Crohn's Disease: Stuck Bubbles?

A small population of patients with severe Crohn's disease (CD) exhibit atypical lack of intensity decline on intestinal contrast-enhanced ultrasound. From a retrospective CD cohort examined with contrast-enhanced ultrasound, 104 patients were identified. Twenty study patients with severe active disease exhibited high peak enhancement (>23 dB) and minimal decline. From the same cohort, 84 control patients also exhibited high peak enhancement >23dB, but with typical intensity decline. Patient outcomes were assessed. Time-intensity curve analysis revealed a significantly higher (p < 0.0001) area under the curve (44.7 ± 1.5 dB·s), washout time and intensities at 60s and 120s in the study population compared with controls (40.0 ± 1.1 dB·s). Study patients had a worse overall outcome with surgery in 30% versus 10% (p = 0.027) during follow-up. Heightened enhancement with lack of decline on contrast-enhanced ultrasound suggests microbubbles are stuck within the inflamed bowel wall for an extended period. This observation occurs in patients with severe disease and a bad outcome.

Validity of Contrast-enhanced Ultrasonography and Dynamic Contrast-enhanced MR Enterography in the Assessment of Transmural Activity and Fibrosis in Crohn's Disease

BACKGROUND AND AIMS

Increased small intestinal wall thickness correlates with both inflammatory activity and fibrosis in Crohn's disease [CD]. Assessment of perfusion holds promise as an objective marker distinguishing between the two conditions. Our primary aim was to determine if relative bowel wall perfusion measurements correlate with histopathological scores for inflammation or fibrosis in CD.

METHODS

A total of 25 patients were investigated before elective surgery for small intestinal CD. Unenhanced ultrasonography [US] and magnetic resonance enterography [MRE] were applied to describe bowel wall thickness. Perfusion was assessed with contrast-enhanced US [CEUS] and dynamic contrast-enhanced MRE [DCE-MRE]. Histopathology was used as gold standard.

RESULTS

Compared with histopathology, the mean wall thickness was 0.4 mm greater on US [range -0.3 to 1.0, p = 0.24] and 1.4 mm greater on MR [0.4 to 2.3, p = 0.006]. No correlation was found between the severity of inflammation or fibrosis on histopathology, and either DCE-MRE [r = -0.13, p = 0.54 for inflammation and r = 0.41, p = 0.05 for fibrosis] or CEUS [r = 0.16, p = 0.45 for inflammation and r = -0.28, p = 0.19 for fibrosis]. Wall thickness assessed with US was correlated with both histological inflammation [r = 0.611, p = 0.0012] and fibrosis [r = 0.399, p = 0.048]. The same was not true for MR [r = 0.41, p = 0.047 for inflammation and r = 0.29, p = 0.16 for fibrosis].

CONCLUSIONS

Bowel wall thickness assessed with US is a valid marker of inflammation in small intestinal CD. However, relative contrast enhancement of US or of MRE cannot distinguish between inflammatory activity and fibrosis.

Contrast-enhanced ultrasonography in clinical practice in Crohn's disease: feasibility of destruction/replenishment method and software analysis

The aim of this Pictorial Essay is to evaluate the feasibility in the clinical practice of CEUS destruction/replenishment method and time intensity curve (TIC) analysis using the available software in patients with Crohn's disease. The ultrasound (US) procedure using contrast agent is briefly described, elaboration and analysis of the US sequences are explained in detail, and some advantages and disadvantages of the method are highlighted. The Authors suggest that the destruction/replenishment method is useful and time-saving in Crohn's disease if multiple measurements are required on intestinal portions adjacent to each other or in different locations.