Ultrasound in Crohn's disease of the small bowel

Small bowel imaging in Crohn’s disease with a special focus on obesity, pregnancy and postsurgical assessment

Crohn’s disease (CD) is an immune-mediated, multisystem inflammatory disorder characterised by discontinuous transmural, sometimes granulomatous, inflammation of the gastrointestinal tract. Although it can occur anywhere in the gastrointestinal tract, it has a 70% predilection for the terminal ileum. Ileocolonoscopy with biopsy remains the gold standard for initial diagnosis and assessment of CD activity but has several limitations, including invasiveness, risk of complications and cost. With a shifting focus towards treatment targets including transmural healing, non-invasive imaging modalities are being used increasingly to assess the small bowel, particularly the terminal ileum. CT enterography, magnetic resonance enterography and gastrointestinal ultrasound are widely used for small bowel imaging in clinical practice and have relatively good sensitivity and specificity. Obesity is a growing problem for patients with CD and is associated with limitations in medical imaging. Equally, cross-sectional imaging in pregnant and postsurgical patients with CD has its own challenges. In this article, we review small bowel imaging in CD with a special focus on obesity, pregnancy and postsurgical assessment.

Diagnostic Accuracy of Intestinal Ultrasound in the Detection of Intra-Abdominal Complications in Crohn's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Crohn's disease [CD] is frequently associated with the development of strictures and penetrating complications. Intestinal ultrasound [IUS] is a non-invasive imaging modality ideal for point-of-care assessment. In this systematic review and meta-analysis we provide a current overview on the diagnostic accuracy of IUS and its advanced modalities in the detection of intra-abdominal complications in CD compared to endoscopy, cross-sectional imaging, surgery, and pathology.

METHOD

We conducted a literature search for studies describing the diagnostic accuracy of IUS in adult patients with CD-related intra-abdominal complications. Quality of the included studies was assessed with the QUADAS-2 tool. Meta-analysis was performed for both conventional IUS [B-mode] and oral contrast IUS [SICUS].

RESULTS

Of the 1498 studies we identified, 68 were included in this review and 23 studies [3863 patients] were used for the meta-analysis. Pooled sensitivities and specificities for strictures, inflammatory masses, and fistulas by B-mode IUS were 0.81 and 0.90, 0.87 [sensitivities] and 0.95, and 0.67 and 0.97 [specificities], respectively. Pooled overall log diagnostic odds ratios were 3.56, 3.97 and 3.84, respectively. Pooled sensitivity and specificity of SICUS were 0.94 and 0.95, 0.91 and 0.97 [sensitivities], and 0.90 and 0.94 [specificities], respectively. The pooled overall log diagnostic odds ratios of SICUS were 4.51, 5.46, and 4.80, respectively.

CONCLUSION

IUS is accurate for the diagnosis of intra-abdominal complications in CD. As a non-invasive, point-of-care modality, IUS is recommended as the first-line imaging tool if there is a suspicion of CD-related intra-abdominal complications.

Intestinal ultrasonography in pediatric population

Bowel ultrasound (US) is a low-cost, non-invasive, bed side practice and a reproducible procedure that represents a high yield tool in clinical practice and in the diagnostic workup of a consistent group of acute and chronic gastrointestinal (GI) tract disease. Moreover, in case of GI diseases of neonatal and pediatric age, it allows an easier evaluation due to the small body size and scarce presence of fat tissue in the abdominal wall and peritoneal cavity and gas content. No particular preparation of the patient is needed, nevertheless a 3- to 5-hour fasting state improves the quality of the examination. The exam focuses on wall thickness and stratification, lumen content, distensibility and compressibility, presence of peristalsis of explorable segment of the GI tract and includes the investigation of mesentery, perivisceral tissues and nodes features. Color doppler flowmetry admits a qualitative evaluation of GI wall and mesentery vascularization. Healthy GI wall appears at a US evaluation as a multilayered structure in which hyperechoic and hypoechoic layers alternate sequentially. In this article we provide a quickly available overview on findings, signs and applications of US in major GI pediatric diseases.

Altered Bioavailability and Pharmacokinetics in Crohn's Disease: Capturing Systems Parameters for PBPK to Assist with Predicting the Fate of Orally Administered Drugs

Backgrond and Objective

Crohn’s disease (CD) is a chronic inflammatory bowel disease that affects a wide age range. Hence, CD patients receive a variety of drugs over their life beyond those used for CD itself. The changes to the integrity of the intestine and its drug metabolising enzymes and transporters (DMETs) can alter the oral bioavailability of drugs. However, there are other changes in systems parameters determining the fate of drugs in CD, and understanding these is essential for dose adjustment in patients with CD.

Methods

The current analysis gathered all the available clinical data on the kinetics of drugs in CD (by March 2021), focusing on orally administered small molecule drugs. A meta-analysis of the systems parameters affecting oral drug pharmacokinetics was conducted. The systems information gathered on intestine, liver and blood proteins and other physiological parameters was incorporated into a physiologically based pharmacokinetic (PBPK) platform to create a virtual population of CD patients, with a view for guiding dose adjustment in the absence of clinical data in CD.

Results

There were no uniform trends in the reported changes in reported oral bioavailability. The nature of the drug as well as the formulation affected the direction and magnitude of variation in kinetics in CD patients relative to healthy volunteers. Even for the same drug, the reported changes in exposure varied, possibly due to a lack of distinction between the activity states of CD. The highest alteration was seen with S-verapamil and midazolam, 8.7- and 5.3-fold greater exposure, respectively, in active CD patients relative to healthy volunteers. Only one report was available on liver DMETs in CD, and indicated reduced CYP3A4 activity. In a number of reports, mRNA expression of DMETs in the ileum and colon of CD patients was measured, focussing on P-glycoprotein (p-gp) transporter and CYP3A4 enzyme, and showed contradictory results. No data were available on protein expression in duodenum and jejunum despite their dominant role in oral drug absorption.

Conclusion

There are currently inadequate dedicated clinical or quantitative proteomic studies in CD to enable predictive PBPK models with high confidence and adequate verification. The PBPK models for CD with the available systems parameters were able to capture the major physiological influencers and the gaps to be filled by future research. Quantification of DMETs in the intestine and the liver in CD is warranted, alongside well-defined clinical drug disposition studies with a number of index drugs as biomarkers of changes in DMETs in these patients, to avoid large-scale dedicated studies for every drug to determine the effects of disease on the drug’s metabolism and disposition and the consequential safety and therapeutic concerns.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-022-01169-4.

Nonspecific ileitis: Impact of histopathology and gastrointestinal ultrasound in achieving the diagnosis of Crohn's disease

Background and Aim

Nonspecific ileitis is inflammation of the ileum without specific diagnostic features. A minority may go on to develop Crohn's disease, but optimal pathways of further investigation have not been established. This study aimed to identify a cohort of patients with nonspecific ileitis and to determine the value of ileal histology and gastrointestinal ultrasound in identifying/excluding Crohn's disease.

Patients and Methods

In a retrospective analysis, all patients having nonspecific ileitis at colonoscopy from January 2010 to August 2021 were identified. Clinical associations with those subsequently diagnosed with Crohn's disease were examined with specific reference to ileal histology and gastrointestinal ultrasound.

Results

Of 29 638 procedures, 147 patients (0.5%) had nonspecific ileitis. Crohn's disease was subsequently diagnosed in 8 patients (5.4%) at a median of 148 (range 27–603) days after colonoscopy. The presence of chronic inflammation on ileal biopsies was more common in those subsequently diagnosed with Crohn's disease (63% vs 20%; P = 0.0145). On gastrointestinal ultrasound, none of the 26 patients with normal bowel wall thickness (<3 mm) were subsequently diagnosed with Crohn's disease, and repeat ultrasound in 15 patients 1 year later showed no change. Of the nine patients with abnormal sonographic findings, three were diagnostic for Crohn's disease. Repeat ultrasound revealed Crohn's disease in two, while four had resolution of the abnormal findings.

Conclusion

Although ileal histology was of limited value in identifying patients with nonspecific ileitis who were subsequently diagnosed with Crohn's disease, gastrointestinal ultrasound was highly informative. Prospective studies are needed to confirm the value of gastrointestinal ultrasound as a diagnostic and monitoring tool in this setting.

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.

Impact of intestinal ultrasound on the management of patients with inflammatory bowel disease: how to apply scientific evidence to clinical practice

Technological improvements and growing sonographers' expertise boost the role of intestinal ultrasound (IUS) in assessing patients with inflammatory bowel diseases (IBD). Non-invasiveness, low cost and good reproducibility make IUS attractive. Leveraging on the Authors' long-term field experience, this review focuses on the IUS role in IBD patients' clinical management. For detecting IBD, particularly Crohn's disease, the IUS parameters - above all the evidence of a thickened bowel wall (BWT) - show very good diagnostic accuracy similar to that of MRI or CT scan. The standard IUS parameters are not accurate enough to detect inflammatory activity, but intravenous contrast-enhanced US (CEUS) is highly accurate in ruling active inflammation out. However, its routinely use remains limited in clinical practice and its parameters need standardization. IUS is accurate in detecting IBD main complications: in particular, fistulae and abscesses. As to stenosis the recent introduction of IUS-based elastographic techniques allows to differentiate prevalently inflammatory from highly fibrotic strictures. IUS proves valid also for monitoring IBD patients. In particular, the evidence of transmural healing, defined as BWT normalization, has got an important prognostic meaning, as associated with better long-term clinical outcomes. Post-surgery CD recurrence can be suggested by early IUS assessment.

Characterizing intestinal strictures of Crohn's disease in vivo by endoscopic photoacoustic imaging

Crohn's disease (CD) is one type of inflammatory bowel disease where both inflammation and fibrosis cause the thickening of the bowel wall and development of the strictures. Accurate assessment of the strictures is critical for the management of CD because the fibrotic strictures must be removed surgically. In this study, a prototype capsule-shaped acoustic resolution photoacoustic (PA) endoscope, which can perform mulitwavelength side-view scanning, was developed to characterize the intestinal strictures of CD. The imaging performance of the probe was tested in phantom experiments and a rabbit trinitrobenzene sulfonic acid (TNBS) model with acute (inflammatory only) or chronic (mixed fibrotic and inflammatory) colitis in vivo. The motion artifacts due to intestinal peristalsis and the respiratory motion of the animals were compensated to improve image qualities. Quantitative molecular component images derived from multi-wavelength PA measurements of normal, acute and chronic intestinal strictures demonstrated statistically significant differences among the three groups that were confirmed by histopathology. A longitudinal study demonstrated the capability of the system in monitoring the development of fibrosis. The results suggest that the proposed novel, capsule-shaped acoustic resolution PA endoscope can be used to characterize fibrostenotic disease in vivo.

Identifying intestinal fibrosis and inflammation by spectroscopic photoacoustic imaging: an animal study in vivo

Crohn's disease (CD) is a chronic autoimmune disease characterized by obstructing intestinal strictures. Conventional imaging modalities can identify the strictures but cannot characterize whether a stricture is predominantly inflammatory or fibrotic. The purpose of this study is to examine the capability of photoacoustic (PA) imaging to characterize intestinal fibrosis and inflammation in vivo. Intestinal strictures in a rat model of CD were imaged with a PA-ultrasound parallel imaging system. Internal and external illuminations were attempted, both with transcutaneous PA signal reception. The PA signal magnitudes acquired at wavelengths targeting individual molecular components and the derived functional information showed significant differences between the inflammatory and fibrotic strictures, consistent with histological inflammation and fibrosis.

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

BACKGROUND

Little is known about changes in the imaging appearances of the bowel and mesentery over time in either pediatric or adult patients with newly diagnosed small bowel Crohn disease treated with anti-tumor necrosis factor-alpha (anti-TNF-α) therapy.

OBJECTIVE

To define how bowel ultrasound findings change over time and correlate with laboratory inflammatory markers in children who have been newly diagnosed with pediatric small bowel Crohn disease and treated with infliximab.

MATERIALS AND METHODS

We included 28 pediatric patients treated with infliximab for newly diagnosed ileal Crohn disease who underwent bowel sonography prior to medical therapy and at approximately 2 weeks, 1 month, 3 months and 6 months after treatment initiation; these patients also had laboratory testing at baseline, 1 month and 6 months. We used linear mixed models to compare mean results between visits and evaluate whether ultrasound measurements changed over time. We used Spearman rank correlation to assess bivariate relationships.

RESULTS

Mean subject age was 15.3±2.2 years; 11 subjects were girls (39%). We observed decreases in mean length of disease involvement (12.0±5.4 vs. 9.1±5.3 cm, P=0.02), maximum bowel wall thickness (5.6±1.8 vs. 4.7±1.7 mm, P=0.02), bowel wall color Doppler signal (1.7±0.9 vs. 1.2±0.8, P=0.002) and mesenteric color Doppler signal (1.1±0.9 vs. 0.6±0.6, P=0.005) at approximately 2 weeks following the initiation of infliximab compared to baseline. All laboratory inflammatory markers decreased at 1 month (P-values<0.0001). There was strong correlation between bowel wall color Doppler signal and fecal calprotectin (ρ=0.710; P<0.0001). Linear mixed models confirmed that maximum bowel wall thickness (P=0.04), length of disease involvement (P=0.0002) and bowel wall color Doppler signal (P<0.0001) change over time in response to infliximab, when adjusted for age, sex, azathioprine therapy, scanning radiologist and baseline short pediatric Crohn's disease activity index score.

CONCLUSION

The ultrasound appearance of the bowel changes as early as 2 weeks after the initiation of infliximab therapy. There is strong correlation between bowel wall color Doppler signal and fecal calprotectin.

Role of Bowel Ultrasound in the Diagnosis and Follow-up of Patients with Crohn's Disease

Crohn's disease (CD) is an inflammatory chronic bowel disorder; it can involve the whole gastrointestinal tract, but its localization in the ileum or colon is most common. The reference standard for the diagnosis of CD is ileocolonoscopy with histologic assessment. The reference standard for the detection of any complications is surgery. However, imaging techniques have an important role both in the detection/localization of CD and in the follow-up of CD patients. In the last few years, the technical development of ultrasound equipment, the advent of new technologies such as elastography and mostly the increased expertise of sonographers have boosted the role of bowel ultrasound in assessment of the gastrointestinal tract. In fact, bowel ultrasound is particularly attractive thanks to its widespread availability, non-invasiveness, low cost and good reproducibility, as it can be easily repeated during follow-up. The aim of this article is to provide an extensive overview of the actual role of bowel ultrasound in the detection and follow-up of patients with CD.

TNFΔARE Mice Display Abnormal Lymphatics and Develop Tertiary Lymphoid Organs in the Mesentery

Chronic inflammatory diseases are associated with a persistent and enhanced response to environmental antigens. As an adaptive response to this exaggerated immune state, affected tissue typically develops tertiary lymphoid organs. Studies of Crohn disease (CD), a chronic inflammatory disease of the intestinal tract, report tertiary lymphoid organs present within the mucosal wall, along with other lymphatic diseases, such as lymphangiogenesis and obstructed lymphatic vessels. These observations suggest that downstream mesenteric lymphatic vessels and lymph drainage into mesenteric lymph nodes may be compromised. However, information is lacking on the morphologic features and functional status of mesenteric lymphatics in CD. Using confocal imaging, PCR, flow cytometry, and functional strategies, we addressed these questions in the established TNFΔARE mouse model of CD and found that this mouse model had many lymphatic abnormalities reminiscent of human CD. These abnormalities include intestinal lymphangiectasia, mesenteric lymph node lymphadenopathy, and lymphangiogenesis in both the mesentery and mucosa. Critically, TNFΔARE mice also present mesenteric tertiary lymphoid organs and have altered lymphatic transport of dendritic cells to mesenteric lymph nodes, two features likely to actively modulate immunity. Our findings provide key insights into lymphatic remodeling in the TNFΔARE mouse model. They shed light on the involvement of these lymphatic changes in immune dysfunctions observed in CD and suggest the lymphatic system as new target for therapeutic options.

Characterizing intestinal inflammation and fibrosis in Crohn's disease by photoacoustic imaging: feasibility study

The pathology of Crohn's disease (CD) is characterized by obstructing intestinal strictures because of inflammation (with high levels of hemoglobin), fibrosis (high levels of collagen), or a combination of both. The accurate characterization of the strictures is critical for the management of CD. This study examines the feasibility of characterizing intestinal strictures by Photoacoustic imaging (PAI) without extrapolation from superficial biopsies. Ex vivo normal rat colon tissue, inflammatory and fibrotic intestinal strictures in rat trinitrobenzene sulfonic acid (TNBS) model were first differentiated by a PA-US parallel imaging system. Surgically removed human intestinal stricture specimens were afterwards imaged by a multiwavelength acoustic resolution PA microscope (ARPAM). The experiment results suggest that PAI is a potential tool for the diagnosis of the diseased conditions in intestinal strictures.

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.

Prospective cohort study of ultrasound-ultrasound and ultrasound-MR enterography agreement in the evaluation of pediatric small bowel Crohn disease

BACKGROUND

There is a paucity of published literature describing ultrasound (US)-US and US-MR enterography (MRE) inter-radiologist agreement in pediatric small bowel Crohn disease.

OBJECTIVE

To prospectively assess US-US and US-MRE inter-radiologist agreement in pediatric small bowel Crohn disease.

MATERIALS AND METHODS

Institutional Review Board approval and informed consent/assent were obtained for this HIPAA-compliant prospective cohort study of children with newly diagnosed distal small bowel Crohn disease (July 2012 to December 2014). Enrolled subjects (n = 29) underwent two small bowel US examinations performed by blinded independent radiologists both before and at multiple time points after initiation of medical therapy (231 unique US examinations, in total); 134 US examinations were associated with concurrent MRE. The MRE examination was interpreted by a third blinded radiologist. The following was documented on each examination: involved length of ileum (cm); maximum bowel wall thickness (mm); amount of bowel wall and mesenteric Doppler signal, and presence of stricture, penetrating disease and/or abscess. Inter-radiologist agreement was assessed with single-measure, three-way, mixed-model intra-class correlation coefficients (ICC) and prevalence-adjusted, bias-adjusted kappa statistics (κ). Numbers in brackets are 95% confidence intervals.

RESULTS

Ultrasound-US agreement was moderate for involved length (ICC: 0.41 [0.35-0.49]); substantial for maximum bowel wall thickness (ICC: 0.67 [0.64-0.70]); moderate for bowel wall Doppler signal (ICC: 0.53 [0.48-0.59]); slight for mesenteric Doppler signal (ICC: 0.25 [0.18-0.42]), and moderate to almost perfect for stricture (κ: 0.54), penetrating disease (κ: 0.80), and abscess (κ: 0.96). US-MRE agreement was moderate for involved length (ICC: 0.42 [0.37-0.49]); substantial for maximum bowel wall thickness (ICC: 0.66 [0.65-0.69]), and substantial to almost perfect for stricture (κ: 0.61), penetrating disease (κ: 0.72) and abscess (κ: 0.88).

CONCLUSION

Ultrasound-US agreement was similar to US-MRE agreement for assessing pediatric small bowel Crohn disease. Discrepancies in US-US and US-MRE reporting question the utility of US as an accurate, reproducible radiologic biomarker for assessing response to medical therapy and disease-related complications.

Monitoring disease activity and progression in Crohn's disease. A Swiss perspective on the IBD ahead 'optimised monitoring' recommendations

BACKGROUND AND AIMS

The structured IBD Ahead 'Optimised Monitoring' programme was designed to obtain the opinion, insight and advice of gastroenterologists on optimising the monitoring of Crohn's disease activity in four settings: (1) assessment at diagnosis, (2) monitoring in symptomatic patients, (3) monitoring in asymptomatic patients, and (4) the postoperative follow-up. For each of these settings, four monitoring methods were discussed: (a) symptom assessment, (b) endoscopy, (c) laboratory markers, and (d) imaging. Based on literature search and expert opinion compiled during an international consensus meeting, recommendations were given to answer the question 'which diagnostic method, when, and how often'. The International IBD Ahead Expert Panel advised to tailor this guidance to the healthcare system and the special prerequisites of each country. The IBD Ahead Swiss National Steering Committee proposes best-practice recommendations adapted for Switzerland.

METHODS

The IBD Ahead Steering Committee identified key questions and provided the Swiss Expert Panel with a structured literature research. The expert panel agreed on a set of statements. During an international expert meeting the consolidated outcome of the national meetings was merged into final statements agreed by the participating International and National Steering Committee members - the IBD Ahead 'Optimized Monitoring' Consensus.

RESULTS

A systematic assessment of symptoms, endoscopy findings, and laboratory markers with special emphasis on faecal calprotectin is deemed necessary even in symptom-free patients. The choice of recommended imaging methods is adapted to the specific situation in Switzerland and highlights the importance of ultrasonography and magnetic resonance imaging besides endoscopy.

CONCLUSION

The recommendations stress the importance of monitoring disease activity on a regular basis and by objective parameters, such as faecal calprotectin and endoscopy with detailed documentation of findings. Physicians should not rely on symptoms only and adapt the monitoring schedule and choice of options to individual situations.

Gastrointestinal ultrasound in neonates, infants and children

Today US plays an important and increasing role in the assessment of many, partially age-specific conditions in the GI tract in neonates, infants and children. Knowledge of the potential capabilities of US and its restrictions together with a skillful performance of GI US examination can provide essential anatomic and functional diagnostic information in many pediatric GI disorders. The aim of this review is to highlight the potential of ultrasound (US) in the evaluation of the gastrointestinal (GI) tract in neonates, infants and children. Basic and potential applications of modern US tools in pediatric GI tract are addressed, the GI US examination technique is discussed - including some common and/or typical clinical applications of and indications for US.

Cross-sectional imaging modalities in Crohn's disease

The standard tools assessing the activity of Crohn's disease (CD) measure the severity of symptoms (the Crohn's Disease Activity Index) or the degree of endoscopic lesions (the Crohn's Disease Endoscopic Index of Severity, the Simplified Endoscopy Score), not the global bowel damage. It is necessary to find new instruments able to assess the structural and functional damage to the intestine and the progression over time. We reviewed recent publications on the accuracy of abdominal ultrasound (US), computed tomography enterography (CTE), and magnetic resonance imaging enterography (MRE) for the assessment of CD. US, CTE and MRE have been shown to have a high and comparable diagnostic accuracy for both the diagnosis and complications of CD, but US and MRE have the major advantage of not imparting ionizing radiation. In summary, findings from these imaging modalities with endoscopic lesions and surgical history incorporating into the Lémann score will allow measuring the global bowel damage at specific time and the progression of disease over time and assessing the impact of different strategies.

Ultrasound as a diagnostic tool in detecting active Crohn's disease: a meta-analysis of prospective studies

OBJECTIVES

To evaluate the diagnostic accuracy of ultrasound in assessing active Crohn's disease (CD) in adults.

METHODS

We systematically searched PubMed, EMBASE, Web of Science and the Cochrane Library for prospective studies in which ultrasound was performed to evaluate active CD in adults from January 1993 to April 2013. Pooled sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR-) and diagnostic odds ratios (DORs) in a per-patient-based analysis were estimated. Additionally, the area under the receiver-operating characteristic (ROC) curve was calculated to measure the diagnostic accuracy of ultrasound in patients with known or suspected CD.

RESULTS

Fifteen studies involving 1,558 patients were included in this meta-analysis. Overall, the pooled sensitivity (0.88) and LR- (0.14) were not heterogeneous, whereas the pooled specificity (0.97, I(2) = 72.9 %) and LR + (15.10, I(2) = 71.8 %) were. The DOR of ultrasound for assessing active CD was 121.70, with significant heterogeneity (I(2) = 63.3 %). A symmetrical summary ROC curve was plotted showing that the area under the curve was 0.94, indicating good diagnostic accuracy. Meta-regression and subgroup analysis showed that the disease location may be a major cause of heterogeneity.

CONCLUSIONS

This meta-analysis suggests that ultrasound has high diagnostic accuracy in detecting active CD in adults, especially for small bowel CD.

KEY POINTS

• Ultrasound can detect active Crohn's disease (CD). • A meta-analysis of ultrasound for detecting active CD was carried out. • This revealed that ultrasound has high diagnostic accuracy for detecting CD.

Transcutaneous bowel sonography for inflammatory bowel disease is sensitive and specific when performed in a nonexpert low-volume North American center

OBJECTIVES

Transcutaneous bowel sonography is a nonionizing imaging modality used in inflammatory bowel disease. Although available in Europe, its uptake in North America has been limited. Since the accuracy of bowel sonography is highly operator dependent, low-volume centers in North America may not achieve the same diagnostic accuracy reported in the European literature. Our objective was to determine the diagnostic accuracy of bowel sonography in a nonexpert low-volume center.

METHODS

All cases of bowel sonography at a single tertiary care center during an 18-month period were reviewed. Bowel sonography was compared with reference standards, including small-bowel follow-through, computed tomography, magnetic resonance imaging, colonoscopy, and surgical findings.

RESULTS

A total of 103 cases were included for analysis during the study period. The final diagnoses included Crohn disease (72), ulcerative colitis (8), hemolytic uremic syndrome (1), and normal (22). The sensitivity and specificity of bowel sonography for intestinal wall inflammation were 87.8% and 92.6%, respectively. In the subset of patients who had complications of Crohn disease, the sensitivity and specificity were 50% and 100% for fistulas and 14% and 100% for strictures. One patient had an abscess, which was detected by bowel sonography. Abnormal bowel sonographic findings contributed to the escalation of treatment in 55% of cases.

CONCLUSIONS

Bowel sonography for inflammatory bowel disease can be performed in low-volume centers and provides diagnostic accuracy for luminal disease comparable with published data, although it is less sensitive for complications of Crohn disease.

Small Bowel Imaging: Clinical Applications of the Different Imaging Modalities—A Comprehensive Review

In the last years, MR and CT techniques have been optimized for small bowel imaging and are playing an increasing role in the evaluation of small bowel disorders. In comparison to traditional barium fluoroscopic examinations, spatial and temporal resolution is now much more improved partially thanks to modern bowel distending agents. However, there is a global interest in implementing techniques that either reduce or eliminate radiation exposure. This is especially important in patients with chronic diseases such as inflammatory bowel disease who may require multiple studies over a lifetime. Owing to the excellent soft tissue contrast, direct multiplanar imaging capabilities, new ultrafast breath-holding pulse sequences, lack of ionizing radiation, and availability of a variety of oral contrast agents, MR is well suited to play a critical role in the imaging of small bowel disorders.

Resistance index in mural arteries of thickened bowel wall: predictive value for Crohn disease activity assessment in pediatric patients

OBJECTIVE

To define reliable Doppler parameters in mural arteries of affected bowel loops for quantitative assessment of Crohn disease (CD) activity in pediatric population and compare Doppler parameters with Pediatric Crohn Disease Activity Index (PCDAI).

PATIENTS AND METHODS

Thirty-four pediatric patients (7 with inactive, 27 with active disease of different severity; 13 male and 21 female; mean age 13; range 7-18) with CD were prospectively evaluated by Doppler ultrasound (DUS) of affected bowel segments. Using semiquantitative color and power Doppler assessment of vascularization of thickened bowel wall and mesentery, patients were divided in four grades. Spectral measurements (peak systolic velocity (PSV), end diastolic velocity (EDV), resistance index (RI)) of mural arteries were compared with PCDAI.

RESULTS

There was a significant difference in distribution of semiquantitative color values between inactive and active group. PSV and EDV values showed no significant difference between inactive and active group, while mean RI was significantly higher in the inactive group. RI was also significantly negatively correlated with PCDAI.

CONCLUSION

Intensity of color and power Doppler signals and RI measurement of mural arteries in thickened bowel wall is linked to CD activity and therefore might be of use in pediatric patients.

Imaging for luminal disease and complications: CT enterography, MR enterography, small-bowel follow-through, and ultrasound

The advent of cross-sectional enterography has revolutionized small-bowel imaging, providing comprehensive, reproducible evaluation of CD and its complications. Continued collaboration between radiologists and gastroenterologists is critical to ensure further progress toward the common goals of classifying disease activity, predicting response to treatment, and appropriate triage to medical versus surgical therapy.

A new nonlinear parameter in the developed strain-to-applied strain of the soft tissues and its application in ultrasound elasticity imaging

Strain developed under quasi-static deformation has been mostly used in ultrasound elasticity imaging (UEI) to determine the stiffness change of tissues. However, the strain measure in UEI is often less sensitive to a subtle change of stiffness. This is particularly true for Crohn's disease where we have applied strain imaging to the differentiation of acutely inflamed bowel from chronically fibrotic bowel. In this study, a new nonlinear elastic parameter of the soft tissues is proposed to overcome this limit. The purpose of this study is to evaluate the newly proposed method and demonstrate its feasibility in the UEI. A nonlinear characteristic of soft tissues over a relatively large dynamic range of strain was investigated. A simplified tissue model based on a finite element (FE) analysis was integrated with a laboratory developed ultrasound radio-frequency (RF) signal synthesis program. Two-dimensional speckle tracking was applied to this model to simulate the nonlinear behavior of the strain developed in a target inclusion over the applied average strain to the surrounding tissues. A nonlinear empirical equation was formulated and optimized to best match the developed strain-to-applied strain relation obtained from the FE simulation. The proposed nonlinear equation was applied to in vivo measurements and nonlinear parameters were further empirically optimized. For an animal model, acute and chronic inflammatory bowel disease was induced in Lewis rats with trinitrobenzene sulfonic acid (TNBS)-ethanol treatments. After UEI, histopathology and direct mechanical measurements were performed on the excised tissues. The extracted nonlinear parameter from the developed strain-to-applied strain relation differentiated the three different tissue types with 1.96 ± 0.12 for normal, 1.50 ± 0.09 for the acutely inflamed and 1.03 ± 0.08 for the chronically fibrotic tissue. T-tests determined that the nonlinear parameters between normal, acutely inflamed and fibrotic tissue types were statistically significantly different (normal/ fibrotic [p = 0.0000185], normal/acutely inflamed [p = 0.0013] and fibrotic/acutely inflamed [p = 0.0029]). This technique may provide a sensitive and robust tool to assess subtle stiffness changes in tissues such as in acutely inflamed bowel wall.

Contrast-enhanced ultrasonography (CEUS) vs. MRI of the small bowel in the evaluation of Crohn's disease activity

PURPOSE

The presence of disease activity in Crohn's disease (CD) is one of the main parameters used to establish whether optimal therapy should be drug therapy or surgery. However, a major problem in monitoring CD is the common mismatch between the patient's symptoms and imaging objective signs of disease activity. Bowel ultrasonography (US) has emerged as a low-cost, noninvasive technique in the diagnosis and follow-up of patients with CD. Accordingly, the use of contrast-enhanced US (CEUS) has made possible an evaluation of the vascular enhancement pattern, similar to the use of magnetic resonance imaging (MRI). The aim of our study was to evaluate the role of CEUS in comparison with small-bowel MRI for assessing Crohn's disease activity.

MATERIALS AND METHODS

We prospectively enrolled 30 consecutive patients with known CD. Clinical and laboratory data were compared with imaging findings obtained from MRI and CEUS of the small bowel. MRI was performed with a 1.5-T system using phased-array coils and biphasic orally administered contrast agent prior to and after gadolinium chelate administration. We performed US with a 7.5-MHz linear-array probe and a second-generation contrast agent. The parameters analysed in both techniques were the following: lesion length, wall thickness, layered wall appearance, comb sign, fibroadipose proliferation, presence of enlarged lymph nodes and stenosis. We classified parietal enhancement curves into two types in relation to the contrast pattern obtained with the time-intensity curves at MRI and CEUS: (1) quick washin, quick washout, (2) slow washin, plateau with a slow washout.

RESULTS

Comparison between Crohn's disease activity index (CDAI) and MRI showed a low correlation, with an rho=0.398; correlation between CDAI-laboratory data and CEUS activity was low, with rho=0.354; correlation between MRI activity and CEUS activity was good, with rho = 0.791; high correlation was found between CEUS and MRI of the small bowel when assessing wall-thickness, lymph nodes and comb sign; good correlation was fund when assessing layered wall appearance, disease extension and fibroadipose proliferation. At MRI, time-intensity curves for 12/30 patients were active, compared with for 14/30 patients at CEUS; therefore there was a poor correlation between curve on CEUS and curve on MRI (r=0.167; p=0.36).

CONCLUSIONS

The use of CEUS can be recommended if there is a discrepancy between MRI and clinical/laboratory parameters. MRI of the small bowel remains the most accurate method for evaluating disease activity.

Crohn's disease imaging: a review

Crohn's disease is a chronic granulomatous inflammatory disease of the gastrointestinal tract, which can involve almost any segment from the mouth to the anus. Typically, Crohn's lesions attain segmental and asynchronous distribution with varying levels of seriousness, although the sites most frequently involved are the terminal ileum and the proximal colon. A single gold standard for the diagnosis of CD is not available and the diagnosis of CD is confirmed by clinical evaluation and a combination of endoscopic, histological, radiological, and/or biochemical investigations. In recent years, many studies have been performed to investigate the diagnostic potential of less invasive and more patient-friendly imaging modalities in the evaluation of Crohn's disease including conventional enteroclysis, ultrasonography, color-power Doppler, contrast-enhanced ultrasonography, multidetector CT enteroclysis, MRI enteroclysis, and 99mTc-HMPAO-labeled leukocyte scintigraphy. The potential diagnostic role of each imaging modality has to be considered in different clinical degrees of the disease, because there is no single imaging technique that allows a correct diagnosis and may be performed with similar results in every institution. The aim of this paper is to point out the advantages and limitations of the various imaging techniques in patients with suspected or proven Crohn's disease.

Development of the Crohn's disease digestive damage score, the Lémann score

Crohn's disease (CD) is a chronic progressive destructive disease. Currently available instruments measure disease activity at a specific point in time. An instrument to measure cumulative structural damage to the bowel, which may predict long-term disability, is needed. The aim of this article is to outline the methods to develop an instrument that can measure cumulative bowel damage. The project is being conducted by the International Program to develop New Indexes in Crohn's disease (IPNIC) group. This instrument, called the Crohn's Disease Digestive Damage Score (the Lémann score), should take into account damage location, severity, extent, progression, and reversibility, as measured by diagnostic imaging modalities and the history of surgical resection. It should not be "diagnostic modality driven": for each lesion and location, a modality appropriate for the anatomic site (for example: computed tomography or magnetic resonance imaging enterography, and colonoscopy) will be used. A total of 24 centers from 15 countries will be involved in a cross-sectional study, which will include up to 240 patients with stratification according to disease location and duration. At least 120 additional patients will be included in the study to validate the score. The Lémann score is expected to be able to portray a patient's disease course on a double-axis graph, with time as the x-axis, bowel damage severity as the y-axis, and the slope of the line connecting data points as a measure of disease progression. This instrument could be used to assess the effect of various medical therapies on the progression of bowel damage.

New concepts in intestinal imaging for inflammatory bowel diseases

In the last decade, multiple imaging technologies have been developed that improve visualization of the mucosal, mural, and perienteric inflammation associated with inflammatory bowel diseases. Whereas these technologies have traditionally been used to detect and stage suspected enteric inflammation, we review new, emerging roles in detecting clinically occult inflammation (in asymptomatic patients) and inflammatory complications, predicting response prior to therapy, assessing response after therapy, and enteric healing. We compare the relative performance of these technologies in detecting inflammation, focusing on their advantages and disadvantages and how they might complement each other. We also discuss their potential benefits for patients and clinical trials, reviewing technologic developments and areas of research that could provide important insights into the pathophysiology of inflammatory bowel diseases-related enteric inflammation.

99mTc-besilesomab (Scintimun) in peripheral osteomyelitis: comparison with 99mTc-labelled white blood cells

Purpose

The diagnosis of osteomyelitis is a challenge for diagnostic imaging. Nuclear medicine procedures including white blood cell imaging have been successfully used for the identification of bone infections. This multinational, phase III clinical study in 22 European centres was undertaken to compare anti-granulocyte imaging using the murine IgG antibody besilesomab (Scintimun®) with ^99mTc-labelled white blood cells in patients with peripheral osteomyelitis.

Methods

A total of 119 patients with suspected osteomyelitis of the peripheral skeleton received ^99mTc-besilesomab and ^99mTc-hexamethylpropyleneamine oxime (HMPAO)-labelled white blood cells (WBCs) in random order 2–4 days apart. Planar images were acquired at 4 and 24 h after injection. All scintigraphic images were interpreted in an off-site blinded read by three experienced physicians specialized in nuclear medicine, followed by a fourth blinded reader for adjudication. In addition, clinical follow-up information was collected and a final diagnosis was provided by the investigators and an independent truth panel. Safety data including levels of human anti-mouse antibodies (HAMA) and vital signs were recorded.

Results

The agreement in diagnosis across all three readers between Scintimun® and ^99mTc-HMPAO-labelled WBCs was 0.83 (lower limit of the 95% confidence interval 0.8). Using the final diagnosis of the local investigator as a reference, Scintimun® had higher sensitivity than ^99mTc-HMPAO-labelled WBCs (74.8 vs 59.0%) at slightly lower specificity (71.8 vs 79.5%, respectively). All parameters related to patient safety (laboratory data, vital signs) did not provide evidence of an elevated risk associated with the use of Scintimun® except for two cases of transient hypotension. HAMA were detected in 16 of 116 patients after scan (13.8%).

Conclusion

Scintimun® imaging is accurate, efficacious and safe in the diagnosis of peripheral bone infections and provides comparable information to ^99mTc-HMPAO-labelled WBCs.

Imaging techniques in inflammatory bowel disease: recent trends, questions and answers

Imaging techniques have undergone substantial progress in recent years and contribute significantly in the diagnosis of inflammatory bowel diseases in conjunction with patient history, clinical and laboratory examination. Modern cross-sectional imaging modalities such as computed tomography and magnetic resonance imaging allow an evaluation not only of the complete bowel wall of the small intestine, but also of extraluminal structures. They constitute a major diagnostic component in the initial workup, in stricturing or fistulizing disease and in suspected abscess. Transabdominal ultrasonography has been re-appreciated in these settings as an easy- and ready-to-use tool yielding real-time information. Positron emission tomography was found useful to add functional diagnosis of inflammation. Colonoscopy techniques still represent the gold standard for evaluation of inflammatory activity and for cancer surveillance. Here, chromoendoscopy has proven efficacy for enhanced detection of flat intraepithelial neoplasias in ulcerative colitis and has been incorporated into recent surveillance guidelines. Narrow band imaging may provide virtual chromoendoscopy in the future, but confirmatory studies are still on the way. Confocal endomicroscopy allows in vivo microscopy at high resolution and with excellent accuracy in first trials to predict histology of inflammatory and neoplastic lesions. The current data from endoscopic studies should result in an integrated approach to both identify and characterize a suspicious lesion during ongoing endoscopy for reliable, accurate diagnosis and targeted, immediate therapy.

Use of small bowel imaging for the diagnosis and staging of Crohn's disease--a survey of current UK practice

OBJECTIVES

This study used a postal survey to assess the current use of small bowel imaging investigations for Crohn's disease within National Health Service (NHS) radiological practice and to gauge gastroenterological referral patterns.

METHODS

Similar questionnaires were posted to departments of radiology (n = 240) and gastroenterology (n = 254) identified, by the databases of the Royal College of Radiologists and British Society of Gastroenterologists. Questionnaires enquired about the use of small bowel imaging in the assessment of Crohn's disease. In particular, questionnaires described clinical scenarios including first diagnosis, disease staging and assessment of suspected extraluminal complications, obstruction and disease flare. The data were stratified according to patient age.

RESULTS

63 (27%) departments of radiology (20 in teaching hospitals and 43 in district general hospitals (DGHs)) and 73 (29%) departments of gastroenterology replied. These departments were in 119 institutions. Of the 63 departments of radiology, 55 (90%) routinely performed barium follow-though (BaFT), 50 (80%) CT, 29 (46%) small bowel ultrasound (SbUS) and 24 (38%) small bowel MRI. BaFT was the most commonly used investigation across all age groups and indications. SbUS was used mostly for patients younger than 40 years of age with low index of clinical suspicion for Crohn's disease (in 44% of radiology departments (28/63)). MRI was most frequently used in patients under 20 years of age for staging new disease (in 27% of radiology departments (17/63)) or in whom obstruction was suspected (in 29% of radiology departments (18/63)). CT was preferred for suspected extraluminal complications or obstruction (in 73% (46/63) and 46% (29/63) of radiology departments, respectively). Gastroenterological referrals largely concurred with the imaging modalities chosen by radiologists, although gastroenterologists were less likely to request SbUS and MRI.

CONCLUSION

BaFT remains the mainstay investigation for luminal small bowel Crohn's disease, with CT dominating for suspected extraluminal complications. There has been only moderate dissemination of the use of MRI and SbUS.

Ultrasound and inflammatory bowel disease

Transabdominal bowel sonography is a fast, efficient, and cheap way of examining the intestines. It is also virtually hazard-free and well accepted by patients. During the last 20 years, it has been established as a procedure for detecting bowel disease early in the diagnostic workup. Although rather unspecific, the method is sensitive for detection of bowel disease and can be applied to find the extent and location of inflammatory bowel disease. In patients with known ulcerative colitis and Crohn disease, it can also be used for follow-up because it is easily repeatable and radiation-free. Because it can be applied to find both intraluminal and peri-intestinal pathological features, it is a particularly valuable tool for the detection of complications of Crohn disease as stenosis, fistulas, and abscesses. Neither B-mode nor Doppler techniques have been proven obviously useful in categorizing disease activity, but new techniques using intravenous contrast might come closer to solving this question. Finally, recent longitudinal studies using transabdominal bowel sonography show that it can also give important prognostic information and be used for monitoring the effect of therapy.

Abdominal bowel ultrasound can predict the risk of surgery in Crohn's disease: proposal of an ultrasonographic score

OBJECTIVE

Abdominal bowel ultrasound (US) is widely used in the management of Crohn's disease (CD). The aim of this study was to evaluate the prognostic role of bowel-wall US morphology on the short-term risk of surgery.

MATERIAL AND METHODS

The 147 CD patients recruited in a case-control study comprised 49 cases operated on within 30 days after US examination and 98 matched non-operated controls. Clinical and US characteristics were analysed. Bowel-wall thickness was recorded, bowel-wall patterns were grouped into five types, but for final analysis they were grouped as "preserved" or "disrupted stratification".

RESULTS

Wall thickness and US patterns were significantly different between cases and controls (p<0.0001). A wall thickness >4.5 mm was observed in 45/49 cases and 47/98 controls (OR = 12.21), while "disrupted stratification" was observed in 34/49 cases and 12/98 controls (OR = 16.24). Among the clinical and US characteristics recorded, only 4 US variables were independently associated with surgery (pattern, thickness, presence of fistulae/abscesses and stenoses) and considered for the US score=(2.5*US pattern)+(1.5*Bowel thickness)+(3*Presence of fistulae/abscesses)+(1.5*Presence of stenoses). Based on this score, up to 84% of patients were correctly classified according to actual status (operated/non-operated).

CONCLUSIONS

Although it needs further prospective validation, the score we propose seems to be a reliable prognostic marker for the short-term risk of surgery in CD. In particular, the score points out those patients with an impending risk of surgery who need careful and frequent control in order to decide on the right time for surgery.

Enteroscopy and its relationship to radiological small bowel imaging

The field of radiological small bowel imaging is changing rapidly, as is small bowel enteroscopy. New techniques allow the depiction of intraluminal, mural, and extraintestinal features of various small bowel disorders, such as Crohn disease, small bowel polyposis syndromes, small intestinal malignancies, and celiac disease. For patients requiring repeated small bowel imaging, modalities that do not use ionizing radiation, such as ultrasound or magnetic resonance imaging, should be considered.

Sonography of the small intestine

In the last two decades, there has been substantial development in the diagnostic possibilities for examining the small intestine. Compared with computerized tomography, magnetic resonance imaging, capsule endoscopy and double-balloon endoscopy, ultrasonography has the advantage of being cheap, portable, flexible and user- and patient-friendly, while at the same time providing the clinician with image data of high temporal and spatial resolution. The method has limitations with penetration in obesity and with intestinal air impairing image quality. The flexibility ultrasonography offers the examiner also implies that a systematic approach during scanning is needed. This paper reviews the basic scanning techniques and new modalities such as contrast-enhanced ultrasound, elastography, strain rate imaging, hydrosonography, allergosonography, endoscopic sonography and nutritional imaging, and the literature on disease-specific findings in the small intestine. Some of these methods have shown clinical benefit, while others are under research and development to establish their role in the diagnostic repertoire. However, along with improved overall image quality of new ultrasound scanners, these methods have enabled more anatomical and physiological changes in the small intestine to be observed. Accordingly, ultrasound of the small intestine is an attractive clinical tool to study patients with a range of diseases.

Quality, clinical influence and tolerance of computed tomography enteroclysis in patients with suspected small bowel disease

BACKGROUND

Computed tomography enteroclysis (CTE) may be superior to other small bowel imaging techniques, detecting subtle mucosal lesions and extraluminal pathology. This study aimed to define the technical success, clinical influence and tolerance of CTE in patients with suspected small bowel disease.

METHODS

CTE scans of 42 consecutive patients (aged 21-78 years, 12 men) were reviewed by a single radiologist for technical adequacy and diagnosis. A panel of gastroenterologists reviewed clinical information. At a telephone interview, tolerance of CTE was graded numerically from 1 (unbearable) to 10 (excellent) and descriptively as unbearable, fair, good or excellent.

RESULTS

Good or optimal distension of small bowel was achieved in 98%. The entire small bowel was imaged in 88%. Eighteen patients had a normal small bowel, whereas 12 (29%) had active small bowel Crohn disease, 4 intussusception, 3 small bowel diverticula and 7 having other diagnoses. Mesenteric lymphadenopathy was evident in 11 and fat stranding in 5. CTE resulted in a new or altered diagnosis in 13 (31%) patients and identified more extensive Crohn disease in a further 8 (19%). A change in management plan was instituted in 18 (43%) patients, with subsequent clinically significant improvement in 12. 33 (85%) described the procedure as 'fair' or 'unbearable' rather than 'good' or 'excellent'. The median tolerance score was 3 out of 10.

CONCLUSION

CTE provided high-quality images in nearly all patients and had an effect on diagnosis, management or outcome in most, but was not well tolerated.

Prevalence and clinical significance of sonographic evidence of mesenteric fat alterations in Crohn's disease

BACKGROUND

Mesenteric adipose tissue hypertrophy is a frequent sonographic finding in Crohn's disease (CD). This study assessed its sonographic prevalence, the correlation with the degree of clinical or biochemical activity of the disease, and its impact on disease outcome in CD patients.

METHODS

In all, 185 consecutive CD patients underwent bowel ultrasound to assess the presence of mesenteric fat tissue alteration as well as thickness and echopattern of the bowel wall, site and extent of CD, and presence of stenosis, fistulas, and abscesses. Clinical and biochemical parameters of disease activity were also assessed. Multiple logistic regression analysis was used to identify variables related to mesenteric adipose tissue alteration.

RESULTS

Mesenteric adipose tissue alteration, detected in 88 (47.6%) patients, showed a significant correlation both with clinical and biochemical CD activity and with internal fistulas, bowel wall thickness, and length of thickened bowel wall. Logistic regression analysis showed that internal fistulas (odds ratio [OR] = 13.5), thickened bowel wall (OR = 7.6), C-reactive protein (OR = 6.1), CD Activity Index (CDAI) (OR = 3.1), and length of diseased bowel walls (OR = 2.6) were significantly associated with mesenteric adipose tissue alteration. Of the 111 patients with quiescent CD, 22 showed mesenteric adipose tissue hypertrophy. These patients did not show increased risk of relapse compared with quiescent patients without mesenteric fat alteration.

CONCLUSIONS

Mesenteric adipose tissue alteration is correlated with biochemical and clinical activity of CD and with internal fistulas and increased bowel wall thickness. In quiescent CD, mesenteric hypertrophy does not appear to be a risk factor of relapse.

Reproducibility of bowel ultrasonography in the evaluation of Crohn's disease

BACKGROUND

Bowel ultrasonography is increasingly used in the detection and follow-up of patients with Crohn's disease, but a limitation to its further diffusion is the lack of standardisation of ultrasonography parameters.

AIMS

This study aimed to standardise the most common bowel ultrasonography parameters in order to develop an unequivocal imaging interpretation and to assess bowel ultrasonography reproducibility.

PATIENTS

Twenty patients with Crohn's disease were examined.

METHODS

Six ultrasonographers (mean bowel ultrasonography experience=16 years) performed the study. They chose and discussed a common assessment methodology concerning eight ultrasonography parameters: bowel wall thickness, bowel wall pattern, bowel wall blood flow, enlarged mesenteric lymph nodes, mesenteric hypertrophy, abdominal free fluid, and stenosis or fistulae at four preliminary meetings. The day of the study operators were randomised to two rooms where they independently and in turn performed ultrasonography scans. Interobserver agreement was scored by kappa statistics.

RESULTS

Excellent k values were observed for bowel wall thickness (0.72-1). k Values were poor for bowel wall pattern (-0.22-0.85) and good for bowel wall blood flow (0.53-0.89). The presence of lymph nodes was reproducible (0.56-0.90) except in one case (0.25). Concordance on free fluid was excellent (0.85-1), whereas that on mesenteric hypertrophy was generally poor (0.14-0.69). Agreement was excellent for stenosis (0.81-1) whereas that for fistula was fair in room abscesses (0.31-0.48) and very good in room B (0.87-1).

CONCLUSION

Bowel ultrasonography signs used in Crohn's disease can be standardised as most of them showed a fair to good reproducibility. In particular, bowel wall thickness, the most relevant parameter for Crohn's disease detection, showed an excellent reproducibility.

Crohn's disease and color Doppler sonography: response to treatment and its relationship with long-term prognosis

PURPOSE

To evaluate the ability of sonography to detect changes in patients undergoing treatment for Crohn's disease and whether these findings are related to the patient's long-term outcome.

METHODS

Twenty-eight patients with Crohn's disease were examined prospectively using gray-scale and color Doppler sonography before and during treatment. Three sonographic examinations were made: on the first day of treatment, between 3 and 8 days later, and approximately 4 weeks after starting the treatment. Sonographic examination included an evaluation of maximum bowel wall thickness and vascularity pattern. The sonographic data were compared with clinical and laboratory data, and possible relation with the patient's long-term outcome was considered.

RESULTS

Initial baseline sonograms revealed at least 1 thickened segment of the bowel wall in all of the patients. In this initial examination, 18 of 22 patients (81%) with clinically active disease had moderate or marked parietal vascularity. A statistically significant reduction in the vascularity of the affected bowel was observed on the third sonographic examination (p < 0.05). Seventeen patients who were in clinical remission had relapses and were treated with immunosuppressive therapy or surgery during the follow-up. Eighty-six percent of the patients with residual hyperemia on sonographic examination after treatment had an unfavorable clinical course compared with only 30% of the patients with no, or barely visible, residual hyperemia (p < 0.01).

CONCLUSION

Sonography can identify bowel inflammation and its changes during treatment. In patients with Crohn's disease, hyperemia on color Doppler sonography during clinical remission after treatment may reflect an increased risk of relapse.