Defining the ultrasound longitudinal natural history of newly diagnosed pediatric small bowel Crohn disease treated with infliximab and infliximab-azathioprine combination therapy

Quantitative intestinal ultrasound color doppler vessel density in children and young adults with Crohn's disease: Correlation with modified Limberg score and contrast-enhanced ultrasound parameters

What is Known

What is New

Contrast-enhanced ultrasound of Crohn's disease in children and young adults: quantitative metric correlations and MRI disease severity associations

BACKGROUND

There is a paucity of data comparing contrast-enhanced ultrasound (CEUS) to MR enterography in children and young adults with Crohn's disease.

OBJECTIVE

To measure correlations across CEUS quantitative metrics in children and young adults with Crohn's disease, and to evaluate if these metrics are associated with MRI features of disease activity.

MATERIALS AND METHODS

Patients <21 years old with Crohn's disease affecting the terminal ileum who underwent clinically-indicated MR enterography were recruited between 2021 and 2024. Research CEUS of the terminal ileum was performed using sulfur hexafluoride lipid-type A microspheres, and images were analyzed using VueBox (Bracco Group). MRI exams were independently reviewed by three radiologists to document features of disease activity. Pearson's correlation (r) was used to measure associations across nine CEUS quantitative metrics and between CEUS metrics and mean or consensus MRI features.

RESULTS

Twenty-five participants, 13 (52%) male, with a mean age of 16.5 years (range, 13-20 years) were included. The mean terminal ileal maximum bowel wall thickness at MRI was 7.5 mm±1.8 mm. The mean sMaRIA score was 3.4±0.8, consistent with severely active disease. CEUS quantitative measurements were highly variable across participants. The mean rise time was 7.0±2.7 s, while the mean peak enhancement was 3,282±3,754 a.u. Twelve of 36 (36%) CEUS quantitative metric bivariate comparisons were highly collinear with r>0.8 (P<0.0001). There were significant positive correlations between CEUS rise time and MRI maximum bowel wall thickness (r=0.40; P=0.046), visual analog scale assessment of overall inflammation (r=0.43; P=0.032), and postcontrast enhancement ratio (r=0.47; P=0.018); there were no other significant correlations between CEUS metrics and MRI measures of inflammation.

CONCLUSION

CEUS quantitative measurements are highly variable across patients with Crohn's disease, with multiple metrics being highly correlated with one another. CEUS rise time correlates with MRI features of disease activity.

Early Intestinal Ultrasound Response to Biologic Therapy Predicts Endoscopic Remission in Children with Ileal Crohn's Disease: Results from the Prospective Super Sonic Study

BACKGROUND AND AIMS

STRIDE-II recommends early biomarker targets for treatment optimization to achieve treat-to-target [T2T] endoscopic remission [ER] in Crohn's disease [CD]. The predictive capabilities of intestinal ultrasound [IUS] for T2T ER remain unknown. We aimed to evaluate IUS response to predict ER in children with CD.

METHODS

This was a prospective longitudinal cohort study of children with ileal [TI] CD initiating biologic therapy undergoing IUS, clinical disease activity, and C-reactive protein [CRP] assessments at baseline, week 8, 6 months, and T2T within 1 year. The primary outcome was the accuracy of optimal cut-points to predict TI ER [SES-CD ≤ 2] for change in bowel wall thickness [BWT] on IUS from baseline to week 8, and BWT at week 8. Area under the receiver operating curve [AUROC] analysis was performed and univariate analysis tested associations.

RESULTS

In total, 44 children (median age 13 [IQR 12-17] years, 29 [66%] biologic naïve) were included, and 29 [66%] achieved ER. A ≥18% decrease in TI BWT at week 8 predicted ER with an AUROC of 0.99 [95% CI 0.98-1.00], 100% sensitivity, 93% specificity, 97% positive predictive value, and 100% negative predictive value, superior to a ≥46% decrease in PCDAI (AUROC 0.67 [95% CI 0.49-0.84]) and ≥84% decrease in CRP (AUROC 0.49 [95% CI 0.31-0.67]) at week 8.

CONCLUSIONS

Early change in TI BWT on IUS is highly predictive of ER in children with CD and superior to symptoms and CRP. Our findings suggest that IUS could be used for treatment optimization and tight control to guide T2T strategies.

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.

Crohn's disease

Crohn's disease is a chronic inflammatory disease of the gastrointestinal tract that might lead to progressive bowel damage and disability. The exact cause of Crohn's disease is unknown, but evidence points towards multifactorial events causing dysregulation of the innate immune system in genetically susceptible people. Commonly affecting the terminal ileum and proximal colon, Crohn's disease inflammation is often discontinuous and patchy, segmental, and transmural. Identification of characteristic findings on ileocolonoscopy and histology remains the diagnostic gold standard, but complete assessment involves laboratory abnormalities, including micronutrient deficiencies, cross-sectional imaging to identify transmural disease extent, severity and complications, and a psychosocial assessment. Treatment strategies for patients with Crohn's disease now go beyond achieving clinical remission to include deeper targets of endoscopic healing and consideration of adjunctive histological and transmural targets to alter disease progression potentially further. The use of early effective advanced therapies and development of therapies targeting alternative novel pathways with improved safety profiles have resulted in a new era of healing in Crohn's disease management. Future combination of advanced therapies with diet or other biological drugs and small molecules, together with improvements in tight control monitoring tools and predictive biomarkers might continue to improve outcomes for patients with Crohn's disease.

Intestinal ultrasound score predicts therapeutic outcomes of infliximab in pediatric patients with Crohn's disease

BACKGROUND AND AIMS

Objective evaluation of treatment response is critical in the management of Crohn's disease (CD). Compared with endoscopy, intestinal ultrasound (IUS) is non-invasive and well-tolerated. This study is aimed to assess the predictive value of IUS score for treatment response in pediatric CD patients.

METHODS

We conducted a retrospective study in pediatric CD patients who underwent endoscopy and IUS at start of infliximab treatment [T0] and after 22-38 weeks [T1] between February 2021 and January 2023. Pediatric Crohn's Disease Activity Index (PCDAI), biochemical parameters, the Simple Endoscopic Score for Crohn's disease (SES-CD) and IUS parameters were collected at two timepoints. IUS scores were assessed by International Bowel Ultrasound Segment Activity Score (IBUS-SAS).

RESULTS

Thirty patients were included, with 53.3% reaching endoscopic response and 43.3% endoscopic remission. After infliximab treatment, IBUS-SAS (58.5 ± 24.2 vs 34.4 ± 21.6, p = .0001) was significantly decreased. At T1, change in IBUS-SAS (-38.2 ± 22.0 vs -7.9 ± 24.1, p = .0015) were pronounced in patients with endoscopic response compared with endoscopic non-response. Significant correlation were observed between IBUS-SAS and SES-CD, PCDAI, C-reaction protein, erythrocyte sedimentation rate, hemoglobin, albumin. The most accurate cutoff values for predicting endoscopic response were 57.4% decrease of IBUS-SAS (AUROC: 0.862, p < .001). The optimal cut-off of IBUS-SAS to correlate endoscopic remission was 26.0 (AUROC: 0.686, p = .017).

CONCLUSIONS

The validated ultrasound-base score, IBUS-SAS is an effective index for monitoring endoscopic response to infliximab therapy in CD. IUS evaluation could guide treatment decision for pediatric CD.

Point-of-Care Intestinal Ultrasound in Pediatric Inflammatory Bowel Disease

PURPOSE OF REVIEW

Intestinal ultrasound (IUS) is an emerging non-invasive point-of-care tool utilized by pediatric gastroenterologists for accurately detecting and monitoring inflammatory bowel disease (IBD) activity. In this article, we reviewed the evidence supporting and technique to perform IUS for children with IBD.

RECENT FINDINGS

IUS technique can visualize the colon from the distal sigmoid until the cecum and the terminal ileum without the need for bowel preparation, fasting, or sedation in children with IBD. IUS has been shown to be accurate to endoscopy in children with ulcerative colitis and Crohn's disease. IUS may be the most accurate biomarker to follow as a marker of treatment response that is predictive of endoscopic outcomes in children with IBD. Multiple studies have demonstrated that IUS can be performed at the point-of-care for IBD activity assessment in children. Recent studies have demonstrated the accuracy of IUS to endoscopy and magnetic resonance enterography with an ability to be repeated as a monitor of treatment response for tight control monitoring.

The Role of Noninvasive Surrogates of Inflammation in Monitoring Pediatric Inflammatory Bowel Diseases: The Old and the New

Effectiveness of limited available therapies for pediatric inflammatory bowel disease has reached stagnation. Previous non-invasive monitoring strategies have relied upon cumbersome tools to evaluate clinical symptoms and biochemical markers that do not reflect endoscopic activity or respond quickly to treatments. Novel, patient-centric, and highly accurate, monitoring strategies with a focus on intestinal ultrasound for a direct, precise monitoring of activity to achieve disease modification are now possible. Ultimately, research on the optimal tight control monitoring strategies, individualized to each pediatric inflammatory bowel disease patient, are in development and offer a hope to potential therapeutic ceiling breakthrough on the horizon.

Prognostic role of intestinal ultrasound in Crohn’s disease

The majority of patients affected by Crohn’s disease (CD) develop a chronic condition with persistent inflammation and relapses that may cause progressive and irreversible damage to the bowel, resulting in stricturing or penetrating complications in around 50% of patients during the natural history of the disease. Surgery is frequently needed to treat complicated disease when pharmacological therapy failes, with a high risk of repeated operations in time. Intestinal ultrasound (IUS), a non-invasive, cost-effective, radiation free and reproducible method for the diagnosis and follow-up of CD, in expert hands, allow a precise assessment of all the disease manifestations: Bowel characteristics, retrodilation, wrapping fat, fistulas and abscesses. Moreover, IUS is able to assess bowel wall thickness, bowel wall stratification (echo-pattern), vascularization and elasticity, as well as mesenteric hypertrophy, lymph-nodes and mesenteric blood flow. Its role in the disease evaluation and behaviour description is well assessed in literature, but less is known about the potential space of IUS as predictor of prognostic factors suggesting response to a medical treatment or postoperative recurrence. The availability of a low cost exam as IUS, able to recognize which patients are more likely to respond to a specific therapy and which patients are at high risk of surgery or complications, could be a very useful instrument in the hands of IBD physician. The aim of this review is to present current evidence about the prognostic role that IUS can show in predicting response to treatment, disease progression, risk of surgery and risk of post-surgical recurrence in CD.

Intestinal ultrasound as a non-invasive tool to monitor inflammatory bowel disease activity and guide clinical decision making

Intestinal ultrasound (IUS) is a non-invasive, real-time, cross-sectional imaging tool that can be used at the point-of-care to assess disease activity in patients with Crohn’s disease or ulcerative colitis. IUS promotes quick and impactful treatment decisions that can modify disease progression and enhance patient compliance. This review will summarize the technical aspects of IUS, the evidence to support the use of IUS in disease activity monitoring, the comparison of IUS to current standard of care monitoring modalities such as colonoscopy and calprotectin, and the optimal positioning of IUS in a tight-control monitoring strategy.

Intestinal Ultrasound for the Pediatric Gastroenterologist: A Guide for Inflammatory Bowel Disease Monitoring in Children: Expert Consensus on Behalf of the International Bowel Ultrasound Group (IBUS) Pediatric Committee

Crohn disease and ulcerative colitis are chronic inflammatory bowel diseases (IBD) often diagnosed in childhood. A strict monitoring strategy can potentially alter the disease course and facilitate early effective treatment before irreversible bowel damage occurs. Serial colonoscopy in children, the gold standard for monitoring, is impractical. Accurate, real-time, noninvasive markers of disease activity are needed. Intestinal ultrasound is an accurate, noninvasive, real-time, point-of-care, cross-sectional imaging tool used to monitor inflammation in pediatric IBD patients in Europe, Canada, and Australia. It is now emerging in a few expert centers in the United States as a safe, non-radiating, inexpensive, bedside tool used by the treating gastroenterologist for real-time decision-making. Unlike the standard biomarkers of pediatric IBD activity, C-reactive protein, and fecal calprotectin, intestinal ultrasound (IUS) facilitates disease localization, characterizes severity, extent, and accurately detects complications. Perhaps most importantly, IUS may enhance shared understanding and ease the burden of treatment decision-making for both the gastroenterologist and the patient. There is a lack of standardization for bedside IUS among pediatric gastroenterologists. The purpose is to outline a standardized approach to pediatric bedside IUS, including basic equipment requirements and technique, patient selection, preparation and positioning, technical considerations and limitations, documentation of mesenteric and luminal features of IBD, characterization of penetrating disease and strictures, and provide a proposed pediatric IUS monitoring algorithm to guide care.

Velocity-Encoded Phase-Contrast MRI for Measuring Mesenteric Blood Flow in Patients With Newly Diagnosed Small-Bowel Crohn Disease

BACKGROUND. Intestinal inflammation is associated with radiologic and histologic hyperemia. A paucity of studies have used MRI to measure mesenteric blood flow in patients with Crohn disease. OBJECTIVE. The purpose of this study was to evaluate the application of velocity-encoded phase-contrast MRI for measuring mesenteric blood flow in patients with newly diagnosed small-bowel Crohn disease. METHODS. This prospective study included 20 patients with ileal Crohn disease newly diagnosed between December 2018 and October 2021 (eight female participants, 12 male participants; median age, 14.0 years), and 15 healthy control participants (eight female participants, seven male participants; median age, 17.0 years). Patients with Crohn disease underwent investigational MRI and laboratory assessments at diagnosis and at 6 weeks and 6 months after initiating anti-tumor necrosis factor-α medical therapy; control participants underwent a single investigational MRI examination. All MRI examinations included a velocity-encoded phase-contrast acquisition, which was used to measure blood flow in the abdominal aorta, superior mesenteric artery (SMA), and superior mesenteric vein (SMV). Mann-Whitney U test was used to compare blood flow measurements (ratios of SMA and SMV blood flow to aorta blood flow [hereafter, SMA-to-aorta and SMV-to-aorta blood flow, respectively]) between groups; Friedman test was used to evaluate temporal changes in blood flow. Spearman correlation was used to assess relationships between blood flow measurements and laboratory markers of intestinal inflammation. Diagnostic performance was assessed by ROC analysis. RESULTS. At baseline, SMA-to-aorta blood flow in patients versus control participants was 0.44 versus 0.30 (p = .003), and SMV-to-aorta blood flow was 0.36 versus 0.21 (p = .002). At 6 weeks and 6 months, SMA-to-aorta blood flow in patients decreased to 0.30 and 0.27 (p < .001), and SMV-to-aorta blood flow decreased to 0.27 and 0.21 (p = .02), respectively. SMA-to-aorta and SMV-to-aorta blood flow were positively correlated with C-reactive protein (rho, 0.34 [p = .01] and 0.35 [p = .008], respectively) and fecal calprotectin (rho, 0.34 [p = .01] vs 0.47 [p < .001]). AUCs for differentiating patients from controls were 0.79 for SMA-to-aorta (sensitivity, 60%; specificity, 100%) and 0.82 for SMV-to-aorta (sensitivity, 75%; specificity, 87%) blood flow. CONCLUSION. Mesenteric blood flow is quantifiable using velocity-encoded phase-contrast MRI. The measurements differ between patients with ileal Crohn disease and healthy control participants and change in response to medical therapy. CLINICAL IMPACT. MRI-based mesenteric blood flow measurements provide a potential novel marker of intestinal inflammation.

Longitudinal Bowel Behavior Assessed by Bowel Ultrasound to Predict Early Response to Anti-TNF Therapy in Patients With Crohn's Disease: A Pilot Study

BACKGROUND

Early changes in bowel behavior during anti-tumor necrosis factor (anti-TNF) induction therapy in Crohn's disease (CD) are relatively unknown. We determined (1) the onset of changes in bowel behavior in CD patients receiving anti-TNF therapy by ultrasound and (2) the feasibility of shear wave elastography (SWE) in predicting early response to anti-TNF therapy.

METHODS

Consecutive ileal or ileocolonic CD patients programmed to initiate anti-TNF therapy were enrolled. Bowel ultrasound was performed at baseline and at weeks 2, 6, and 14. Changes in bowel wall thickness, Doppler signals of the bowel wall (Limberg score), and SWE values were compared using a linear mixed model. Early response to anti-TNF therapy was based on a composite strategy of clinical and colonoscopy assessment at week 14.

RESULTS

Of the 30 patients enrolled in this study, 20 patients achieved a response to anti-TNF therapy at week 14. The bowel wall thickness and SWE value of the response group showed a significant downward trend compared with the nonresponse group (P = .003 and P = .011, respectively). Bowel wall thickness, the Limberg score, and SWE values were significantly reduced as early as week 2 compared with baseline (P < .001, P < .001, and P = .003, respectively) in the response group. Baseline SWE values (21.3 ± 8.7 kPa vs 15.3 ± 4.7 kPa; P = .022) and bowel wall thickness (8.5 ± 2.3 mm vs 6.9 ± 1.5 mm; P = .027) in the nonresponse group were significantly higher than in the response group.

CONCLUSIONS

This pilot study suggested that changes in bowel ultrasound behavior could be assessed as early as week 2 after starting anti-TNF therapy. Bowel ultrasound together with elasticity imaging could predict early response to anti-TNF therapy.

Intestinal Ultrasound in Pediatric Inflammatory Bowel Disease: Promising, but Work in Progress

Intestinal ultrasound (IUS) is increasingly used and promulgated as a noninvasive monitoring tool for children with inflammatory bowel disease because other diagnostic modalities such as colonoscopy and magnetic resonance imaging cause significant stress in the pediatric population. The most important parameters of inflammation that can be assessed using IUS are bowel wall thickness and hyperemia of the bowel wall. Research has shown that IUS has the potential to be a valuable additional point-of-care tool to guide treatment choice and to monitor and predict treatment response, although evidence of its accuracy and value in clinical practice is still limited. This review gives an update and overview of the current evidence on the use and accuracy of IUS in children with inflammatory bowel disease.

Point-of-Care Testing and Home Testing: Pragmatic Considerations for Widespread Incorporation of Stool Tests, Serum Tests, and Intestinal Ultrasound

Breaking through the biologic therapy efficacy plateau for inflammatory bowel disease requires the strategic development of personalized biomarkers in the tight control model. After risk stratification early in the disease course, targeted serial monitoring consistently to assess clinical outcomes in response to therapy allows for quick therapeutic adjustments before bowel damage can occur. Point-of-care intestinal ultrasound performed by the treating gastroenterologist is an accurate cross- sectional biomarker that monitors intestinal inflammation in real-time, enhances patient care, and increases shared understanding to help achieve common treatment goals. Combining intestinal ultrasound during a clinic visit with existing serum and stool biomarkers in a home testing setup with electronic health monitoring allows for an optimized, patient-centered personalized treatment algorithm that may improve treatment outcomes. Here, we review the current state, pragmatic considerations, and future implications of point-of-care testing and home testing for noninvasive inflammatory bowel disease monitoring in the tight control model.

Intestinal ultrasonography and fecal calprotectin for monitoring inflammation of ileal Crohn's disease: two complementary tests

Background/Aims

Tight control of inflammation and adjustment of treatment if activity persists is the current strategy for the management of Crohn’s disease (CD). The usefulness of fecal calprotectin (FC) in isolated involvement of the small intestine in CD is controversial. To assess the usefulness of FC to determine the inflammatory activity detected by intestinal ultrasonography (IUS) in ileal CD.

Methods

Patients with exclusively ileal involvement CD who underwent IUS and an FC were prospectively included. Simple ultrasound index was used to determine inflammatory activity. The usual statistical tests for comparison of diagnostic techniques were used.

Results

One hundred and five patients were included, IUS showed inflammatory activity in 59% of patients and complications in 18.1%. FC showed a significant correlation with IUS in the weak range (Spearman coefficient r=0.502; P<0.001); the area under the receiver operating characteristic curve was 0.79 (95% confidence interval, 0.70–0.88; P<0.001). The FC value that best reflected the activity in IUS was 100 μg/g with sensitivity, specificity, and positive and negative predictive values of 73.0%, 71.4%, 79.3% and 63.8%, respectively. There were no differences in FC concentration between patients with or without transmural complications. The addition of serum C-reactive protein to FC did not improve the ability to assess IUS activity.

Conclusions

FC has a significant correlation with IUS to monitor ileal CD activity. This correlation is weak and it does not allow assessing the presence of CD complications. Both tests should be used in conjunction for tight control of ileal CD. More studies on noninvasive tests in this location are needed.

Defining Transabdominal Intestinal Ultrasound Treatment Response and Remission in Inflammatory Bowel Disease: Systematic Review and Expert Consensus Statement

BACKGROUND AND AIMS

No consensus exists on defining intestinal ultrasound response, transmural healing, or transmural remission in inflammatory bowel disease, nor clear guidance for optimal timing of assessment during treatment. This systematic review and expert consensus study aimed to define such recommendations, along with key parameters included in response reporting.

METHODS

Electronic databases were searched from inception to July 26, 2021, using pre-defined terms. Studies were eligible if at least two intestinal ultrasound [IUS] assessments at different time points during treatment were reported, along with an appropriate reference standard. The QUADAS-2 tool was used to examine study-level risk of bias. An international panel of experts [n = 18] rated an initial 196 statements [RAND/UCLA process, scale 1-9]. Two videoconferences were conducted, resulting in additional ratings of 149 and 13 statements, respectively.

RESULTS

Out of 5826 records, 31 full-text articles, 16 abstracts, and one research letter were included; 83% [40/48] of included studies showed a low concern of applicability, and 96% [46/48] had a high risk of bias. A consensus was reached on 41 statements, with clear definitions of IUS treatment response, transmural healing, transmural remission, timing of assessment, and general considerations when using intestinal ultrasound in inflammatory bowel disease.

CONCLUSIONS

Response criteria and time points of response assessment varied between studies, complicating direct comparison of parameter changes and their relation to treatment outcomes. To ensure a unified approach in routine care and clinical trials, we provide recommendations and definitions for key parameters for intestinal ultrasound response, to incorporate into future prospective studies.

Use of Small Bowel Ultrasound to Predict Response to Infliximab Induction in Pediatric Crohn's Disease

GOAL

The goal of this study was to explore the utility of small bowel ultrasound (SBUS) as a noninvasive tool to assess induction response to infliximab (IFX) in pediatric Crohn's disease (CD).

BACKGROUND

Inflammatory bowel disease management has shifted to a treat-to-target and tight control strategy utilizing noninvasive serum and fecal markers to monitor disease activity in response to therapy. Bowel wall changes as seen on cross-sectional imaging may be a more accurate marker of treatment success.

MATERIALS AND METHODS

Pediatric patients with CD with small bowel involvement initiating IFX were prospectively enrolled. Clinical activity, biomarkers, and SBUS findings were evaluated at baseline (T0) and postinduction at week 14 (T1). The primary outcome was to describe the changes in SBUS parameters pre and post IFX induction and how they associate with clinical and biomarker response. Descriptive statistics summarized the data and univariate analysis tested associations.

RESULTS

All 13 CD patients achieved steroid-free clinical remission (P<0.001) and a decrease in C-reactive protein (P=0.01) postinduction. Bowel wall hyperemia (BWH) (P=0.01) and bowel segment length involved (P=0.07) decreased postinduction. Decrease in fecal calprotectin at T1 moderately correlated with a decrease in bowel segment length (r=0.57; P=0.04). No correlation was seen with a change in bowel wall thickness or BWH postinduction.

CONCLUSIONS

Our pilot study suggests that SBUS is a feasible, noninvasive tool to measure early treatment response to IFX. BWH, not bowel wall thickness, is the first parameter to change. Larger longitudinal studies are warranted to validate the utility of SBUS as part of a disease monitoring strategy.

Relevance of monitoring transmural disease activity in patients with Crohn's disease: current status and future perspectives

Treatment targets of inflammatory bowel diseases (IBD), ulcerative colitis (UC) and Crohn's disease (CD) have evolved over the last decade. Goals of therapy consisting of symptom control and steroid sparing have shifted to control of disease activity with endoscopic remission being an important endpoint. Unfortunately, this requires ileocolonoscopy, an invasive procedure. Biomarkers [C-reactive protein (CRP) and fecal calprotectin (FCP)] have emerged as surrogates for endoscopic remission and disease activity, but also have limitations. Despite this evolution, we must not lose sight that CD involves transmural inflammation, not fully appreciated with ileocolonoscopy. Therefore, transmural assessment of disease activity by cross-sectional imaging, in particular with magnetic resonance enterography (MRE) and intestinal ultrasonography (IUS), is vital to fully understand disease control. Bowel-wall thickness (BWT) is the cornerstone in assessment of transmural inflammation and BWT normalization, with or without bloodflow normalization, the key element demonstrating resolution of transmural inflammation, namely transmural healing (TH) or transmural remission (TR). In small studies, achievement of TR has been associated with improved long-term clinical outcomes, including reduced hospitalization, surgery, escalation of treatment, and a decrease in clinical relapse over endoscopic remission alone. This review will focus on the existing literature investigating the concept of TR or residual transmural disease and its relation to other existing treatment targets. Current data suggest that TR may be the next logical step in the evolution of treatment targets.

Recommendations of the Spanish Working Group on Crohn's Disease and Ulcerative Colitis (GETECCU) on the use of abdominal ultrasound in inflammatory bowel disease

Ultrasound has an excellent diagnostic performance when Crohn's disease is suspected, when performing an activity assessment, or determining the extension and location of Crohn's disease, very similar to other examinations such as MRI or CT. It has a good correlation with endoscopic lesions and allows the detection of complications such as strictures, fistulas or abscesses. It complements colonoscopy in the diagnosis and, given its tolerance, cost and immediacy, it can be considered as a good tool for disease monitoring. In ulcerative colitis, its role is less relevant, being limited to assessing the extent and activity when it is not possible with other diagnostic techniques or if there are doubts with these. Despite its advantages, its use in inflammatory bowel disease (IBD) is not widespread in Spain. For this reason, this document reviews the advantages and disadvantages of the technique to promote knowledge about it and implementation of it in IBD Units.

Usefulness of intestinal ultrasound in inflammatory bowel disease

Imaging techniques play a fundamental role in the initial diagnosis and follow-up of inflammatory bowel disease. Intestinal ultrasound has high sensitivity and specificity in patients with suspected Crohn's disease and in the detection of inflammatory activity. This technique enables the early diagnosis of intra-abdominal complications such as stenosis, fistulas, and abscesses. It has also proven useful in monitoring the response to treatment and in detecting postsurgical recurrence. Technical improvements in ultrasound scanners, technological advances such as ultrasound contrast agents and elastography, and above all increased experience have increased the role of ultrasound in the evaluation of the gastrointestinal tract. The features that make ultrasound especially attractive include its wide availability, its noninvasiveness and lack of ionizing radiation, its low cost, and its good reproducibility, which is important because it is easy to repeat the study and the study is well tolerated during follow-up. This review summarizes the role of intestinal ultrasound in the detection and follow-up of inflammatory bowel disease.

Terminal Ileum Thickness During Maintenance Therapy Is a Predictive Marker of the Outcome of Infliximab Therapy in Crohn Disease

BACKGROUND

Mucosal healing has been associated with long-term response to therapy for Crohn disease (CD). However, little is known about the significance of terminal ileum (TI) transmural thickness in predicting clinical outcomes.

METHODS

In this retrospective observational cohort study, we examined the association of an index ultrasonographic assessment of TI thickness during the maintenance phase and the subsequent clinical outcome of CD in a cohort of patients treated with infliximab (IFX). Treatment failure was defined as treatment discontinuation because of lack of efficacy, a need for dose escalation, or surgery. Clinical response was defined as treatment continuation in the absence of any of the aforementioned failure criteria.

RESULTS

Sixty patients with CD receiving IFX therapy were included in the study. The patients were followed for a median of 16 months (5-24 months) after an index intestinal ultrasound. Thirty-eight patients (63.3%) maintained response to the therapy and 22 patients (36.6%) failed the treatment, with a mean follow up of 10.5 months (6.5-17 months) vs 9.25 months (1-10.25 months), respectively. On univariate analysis, the only variables differing between treatment response and failure were a TI thickness of 2.8 vs 5 mm (P < 0.0001) and an IFX trough level of 6.6 vs 3.9 µg/mL (P = 0.008).On multivariable analysis, only a small bowel thickness of ≥4 mm was associated with the risk of treatment failure (odds ratio, 2.9; 95% CI, 1.49-5.55; P = 0.002).

CONCLUSIONS

Our findings suggest that transmural thickness of ≥4 mm can predict subsequent treatment failure in patients with CD treated using IFX, indicating transmural thickness <4 mm as a potential novel valuable therapeutic target.

Intestinal ultrasound for monitoring therapeutic response in patients with ulcerative colitis: results from the TRUST&UC study

OBJECTIVE

Prospective evaluation of intestinal ultrasound (IUS) for disease monitoring of patients with ulcerative colitis (UC) in routine medical practice.

DESIGN

TRansabdominal Ultrasonography of the bowel in Subjects with IBD To monitor disease activity with UC (TRUST&UC) was a prospective, observational study at 42 German inflammatory bowel disease-specialised centres representing different care levels. Patients with a diagnosis of a proctosigmoiditis, left-sided colitis or pancolitis currently in clinical relapse (defined as Short Clinical Colitis Activity Index ≥5) were enrolled consecutively. Disease activity and vascularisation within the affected bowel wall areas were assessed by duplex/Colour Doppler ultrasonography.

RESULTS

At baseline, 88.5% (n=224) of the patients had an increased bowel wall thickness (BWT) in the descending or sigmoid colon. Even within the first 2 weeks of the study, the percentage of patients with an increased BWT in the sigmoid or descending colon decreased significantly (sigmoid colon 89.3%-38.6%; descending colon 83.0%-42.9%; p<0.001 each) and remained low at week 6 and 12 (sigmoid colon 35.4% and 32.0%; descending colon 43.4% and 37.6%; p<0.001 each). Normalisation of BWT and clinical response after 12 weeks of treatment showed a high correlation (90.5% of patients with normalised BWT had symptomatic response vs 9.5% without symptomatic response; p<0.001).

CONCLUSIONS

IUS may be preferred in general practice in a point-of-care setting for monitoring the disease course and for assessing short-term treatment response. Our findings give rise to the assumption that monitoring BWT alone has the potential to predict the therapeutic response, which has to be verified in future studies.

Bowel ultrasound measurements in healthy children - systematic review and meta-analysis

BACKGROUND

Ultrasound (US) is a noninvasive method of assessing the bowel that can be used to screen for bowel pathology, such as Inflammatory Bowel Disease, in children. Knowledge about US findings of the bowel in healthy children is important for interpreting US results in cases where disease is suspected.

OBJECTIVE

To assess the bowel wall thickness in different bowel segments in healthy children and to assess differences in bowel wall thickness among pediatric age categories.

MATERIALS AND METHODS

We conducted a systematic search in the PubMed, Embase, Cochrane, and CINAHL databases for studies describing bowel wall thickness measured by transabdominal US in healthy children. We excluded studies using contrast agent. We calculated the pooled mean and standard deviation scores and assessed differences among age categories (0-4 years, 5-9 years, 10-14 years, 15-18 years), first with analysis of variance (ANOVA) and further with subsequent Student's t-tests for independent samples, corrected for multiple testing.

RESULTS

We identified 191 studies and included 7 of these studies in the systematic review. Reported bowel wall thickness values ranged from 0.8 mm to 1.9 mm in the small bowel and from 1.0 mm to 1.9 mm in the colon. The mean colonic bowel wall thickness is larger in children ages 15-19 years compared to 0-4 years (range in difference: 0.3-0.5 mm [corrected P<0.02]).

CONCLUSION

The reported upper limit of bowel wall thickness in healthy children is 1.9 mm in the small bowel and the colon, and mean thickness increases slightly with age in jejunum and colon. These values can be used as guidance when screening for bowel-related pathology in children.

Diagnostic Accuracy of Transabdominal Ultrasound in Detecting Intestinal Inflammation in Paediatric IBD Patients-a Systematic Review

BACKGROUND AND AIMS

Currently used non-invasive tools for monitoring children with inflammatory bowel disease [IBD], such as faecal calprotectin, do not accurately reflect the degree of intestinal inflammation and do not provide information on disease location. Ultrasound [US] might be of added value. This systematic review aimed to assess the diagnostic test accuracy of transabdominal US in detecting intestinal inflammation in children with IBD in both diagnostic and follow-up settings.

METHODS

We systematically searched PubMed, Embase [Ovid], Cochrane Library, and CINAHL [EBSCO] databases for studies assessing diagnostic accuracy of transabdominal US for detection of intestinal inflammation in patients diagnosed or suspected of IBD, aged 0-18 years, with ileo-colonoscopy and/or magnetic resonance enterography [MRE] as reference standards. Studies using US contrast were excluded. Risk of bias was assessed with QUADAS-2.

RESULTS

The search yielded 276 records of which 14 were included. No meta-analysis was performed, because of heterogeneity in study design and methodological quality. Only four studies gave a clear description of their definition for an abnormal US result. The sensitivity and specificity of US ranged from 39-93% and 90-100% for diagnosing de novo IBD, and 48-93% and 83-93% for detecting active disease during follow-up, respectively.

CONCLUSIONS

The diagnostic accuracy of US in detecting intestinal inflammation as seen on MRE and/or ileo-colonoscopy in paediatric IBD patients remains inconclusive, and there is currently no consensus on defining an US result as abnormal. Prospective studies with adequate sample size and methodology are needed before US can be used in the diagnostics and monitoring of paediatric IBD.

Treat-to-target in Crohn's disease: Will transmural healing become a therapeutic endpoint?

Crohn's disease (CD) represents a chronic transmural inflammatory condition of the gastrointestinal tract, which usually leads to structural damage and significant disability. Deep remission - defined by both clinical and endoscopic remission, signifying mucosal healing - represents the current endpoint in the treat-to-target strategy, significantly improving patients' long-term outcomes. Transmural healing (TH) could be a more effective target, but this possibility remains unclear. This narrative review aims to critically review and summarize the available literature relating TH to long-term outcomes, being the first of its kind and to the best of the author's knowledge. A systematic literature search (from inception to March 31 2018) was performed, using multiple databases, and identifying seven full-text manuscripts. In those studies, long-term favorable outcomes (≥ 52 wk) included sustained clinical remission, as well as fewer therapeutic changes, CD-related hospitalizations, and surgeries. Despite heterogeneous design and methodological limitations, six of the studies demonstrated that TH or intestinal healing (TH plus mucosal healing) were predictive for the aforementioned favorable outcomes. Therefore, TH may become a reasonable therapeutic target and be included in the concept of deep remission. Further prospective, well-designed, multicenter trials aiming to better define the role of TH in personalized therapy for CD and to determine the long-term influence of TH on bowel damage and disability are warranted.