Crohn's disease: CT enterography manifestations before and after treatment

Association Between Bowel Wall Thickening and Long-Term Outcomes in Decompensated Liver Cirrhosis

INTRODUCTION

Bowel wall thickening is commonly observed in liver cirrhosis, but few studies have explored its impact on the long-term outcomes of patients with cirrhosis.

METHODS

Overall, 118 patients with decompensated cirrhosis were retrospectively enrolled, in whom maximum wall thickness of small bowel, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum could be measured in computed tomography (CT) images. X-tile software was employed to determine the best cut-off values of each segment of bowel wall thickness for predicting the risk of further decompensation and death. Cumulative rates of further decompensation and death were calculated by Nelson-Aalen cumulative risk curve analyses. Predictors of further decompensation and death were evaluated by competing risk analyses. Sub-distribution hazard ratios (sHRs) were calculated.

RESULTS

Cumulative rates of further decompensation were significantly higher in patients with wall thickness of ascending colon ≥ 11.7 mm (P = 0.014), transverse colon ≥ 3.2 mm (P = 0.043), descending colon ≥ 9.8 mm (P = 0.035), and rectum ≥ 7.2 mm (P = 0.045), but not those with wall thickness of small bowel ≥ 8.5 mm (P = 0.312) or sigmoid colon ≥ 7.1 mm (P = 0.237). Wall thickness of ascending colon ≥ 11.7 mm (sHR = 1.70, P = 0.030), transverse colon ≥ 3.2 mm (sHR = 2.15, P = 0.038), and rectum ≥ 7.2 mm (sHR = 2.38, P = 0.045) were independent predictors of further decompensation, but not wall thickness of small bowel ≥ 8.5 mm (sHR = 1.19, P = 0.490), descending colon ≥ 9.8 mm (sHR = 1.53, P = 0.093) or sigmoid colon ≥ 7.1 mm (sHR = 0.63, P = 0.076). Small bowel, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum wall thickness were not significantly associated with death.

CONCLUSIONS

Colorectal wall thickening, but not small bowel wall, may be considered for the prediction of further decompensation in cirrhosis.

Evaluation of extensive inflammatory conditions of the bowel using three-dimensional CT cinematic rendering: focus on inflammatory bowel disease

Inflammatory conditions that affect long segments of bowel and/or the mesentery and mesenteric vasculature are a common cause of emergency department visits and evaluation by cross-sectional imaging. Inflammatory bowel disease, specifically Crohn disease and ulcerative colitis, can be unsuspected at presentation and may only be eventually diagnosed based on initial imaging findings. Traditional 2D axial reconstructions and multi-planar reformations can be limited in their ability to globally assess the extent of disease. 3D methods such as volume rendering (VR) are often used as adjunctive means of visualizing the pathology in such patients. Recently, a novel technique known as cinematic rendering (CR) has emerged, utilizing advanced lighting models and ray tracing to simulate photon interactions with tissues, resulting in realistic shadows and enhanced surface detail compared to VR. Generating CR images from select presets takes an experienced radiologist approximately 5 min, meaning that the technique can be incorporated into meaningful emergency department workflows. Given the apparent advantages of CR, we highlight its application in a series of cases in which patients had inflammatory conditions that affected long segments of bowel and/or involved the mesentery, particularly those patients with inflammatory bowel disease, but also including patients with mesenteric venous thrombosis and lymphedema. Those conditions included inflammatory bowel disease, mesenteric venous thrombosis, and bowel lymphedema. We present examples of those conditions in this pictorial essay and describe the potential of CR to visualize key findings. As CR exhibits possible advantages, further studies are warranted to support its broader clinical adoption and assess its efficacy in diagnosing and guiding managing of inflammatory conditions in emergency settings.

Recent advances in clinical practice: advances in cross-sectional imaging in inflammatory bowel disease

Endoscopy remains the reference standard for the diagnosis and assessment of patients with inflammatory bowel disease (IBD), but it has several important limitations. Cross-sectional imaging techniques such as magnetic resonance enterography (MRE) and intestinal ultrasound (IUS) are better tolerated and safer. Moreover, they can examine the entire bowel, even in patients with stenoses and/or severe inflammation. A variety of cross-sectional imaging activity scores strongly correlate with endoscopic measures of mucosal inflammation in the colon and terminal ileum. Unlike endoscopy, cross-sectional techniques allow complete visualisation of the small-bowel and assess for extraintestinal disease, which occurs in nearly half of patients with IBD. Extramural findings may predict outcomes better than endoscopic mucosal assessment, so cross-sectional techniques might help identify more relevant therapeutic targets. Coupled with their high sensitivity, these advantages have made MRE and IUS the primary non-invasive options for diagnosing and monitoring Crohn's disease; they are appropriate first-line investigations, and have become viable alternatives to colonoscopy. This review discusses cross-sectional imaging in IBD in current clinical practice as well as research lines that will define the future role of these techniques.

CT enterography for evaluation of disease activity in patients with ileocolonic Crohn's disease

BACKGROUND

CT enterography (CTE) is used routinely for assessment of activity and severity in Crohn's disease (CD), but there are few CTE scoring systems. The aim of this study was to develop a quantitative CTE scoring system for ileocolonic Crohn's disease activity.

METHODS

Forty-nine CD patients with ileocolonic involvement were retrospectively included between March 2015 and May 2018. All patients underwent CTE and ileocolonoscopy. Mural hyperenhancement and mural thickening at CTE were scored quantitatively, while mural stratification, submucosal fat deposition, comb sign, perienteric fat hypertrophy and mesenteric fibrofatty proliferation were qualitative variables. A Tobit regression model was applied for assessing the association between Crohn's disease endoscopic index of severity (CDEIS) and CTE variables.

RESULTS

A total of 280 intestinal segments were evaluated. Independent predictors for CDEIS were mural thickness (p < 0.001), mural stratification (p < 0.001) and comb sign (p = 0.002). In order to quantify disease activity based on CTE findings in each segment, a simplified CT enterography index of activity (CTEIA) was derived from logistic regression analysis. The formula was as follows: CTEIA (segment) = 2.1 mural thickness(mm) + 9.7 mural stratification + 5.2 comb sign. There was a high and significant correlation coefficient between CDEIS and CTEIA (r = 0.779, p < 0.001) for per-segment analysis. The model for the detection of ulcerative lesions in the colon and terminal ileum achieved an area under the receiver-operating curve of 0.901 using a cut-off point of 6.25.

CONCLUSIONS

CTEIA is a new qualitative tool for evaluation of ileocolonic Crohn's disease, which need to be validated in further studies.

Is the Mixed Use of Magnetic Resonance Enterography and Computed Tomography Enterography Adequate for Routine Periodic Follow-Up of Bowel Inflammation in Patients with Crohn's Disease?

OBJECTIVE

Computed tomography enterography (CTE) and magnetic resonance enterography (MRE) are considered substitutes for each other for evaluating Crohn's disease (CD). However, the adequacy of mixing them for routine periodic follow-up for CD has not been established. This study aimed to compare MRE alone with the mixed use of CTE and MRE for the periodic follow-up of small bowel inflammation in patients with CD.

MATERIALS AND METHODS

We retrospectively compared two non-randomized groups, each comprising 96 patients with CD. One group underwent CTE and MRE (MRE followed by CTE or vice versa) for the follow-up of CD (interval, 13-27 months [median, 22 months]), and the other group underwent MRE alone (interval, 15-26 months [median, 21 months]). However, these two groups were similar in clinical characteristics. Three independent readers from three different institutions determined whether inflammation had decreased, remained unchanged, or increased within the entire small bowel and the terminal ileum based on sequential enterography of the patients after appropriate blinding. We compared the two groups for inter-reader agreement and accuracy (terminal ileum only) using endoscopy as the reference standard for enterographic interpretation.

RESULTS

The inter-reader agreement was greater in the MRE alone group for the entire small bowel (intraclass correlation coefficient [ICC]: 0.683 vs. 0.473; p = 0.005) and the terminal ileum (ICC: 0.656 vs. 0.490; p = 0.030). The interpretation accuracy was higher in the MRE alone group without statistical significance (70.9%-74.5% vs. 57.9%-64.9% in individual readers; adjusted odds ratio = 3.21; p = 0.077).

CONCLUSION

The mixed use of CTE and MRE was inferior to MRE alone in terms of inter-reader reliability and could probably be less accurate than MRE alone for routine monitoring of small bowel inflammation in patients with CD. Therefore, the consistent use of MRE is favored for this purpose.

Efficiency of dual-energy computed tomography enterography in the diagnosis of Crohn's disease

Background

This retrospective study aimed to investigate the usefulness of the optimized kiloelectron volt (keV) for virtual monoenergetic imaging (VMI) combined with iodine map in dual-energy computed tomography enterography (DECTE) in the diagnosis of Crohn’s disease (CD).

Methods

Seventy-two patients (mean age: 41.89 ± 17.28 years) with negative computed tomography enterography (CTE) were enrolled for investigating the optimized VMI keV in DECTE by comparing subjective and objective parameters of VMIs that were reconstructed from 40 to 90 keV. Moreover, 68 patients (38.27 ± 15.10 years; 35 normal and 33 CD) were included for evaluating the diagnostic efficacy of DECTE iodine map at the optimized VMI energy level and routine CTE for CD and active CD. Statistical analysis for all data was conducted.

Results

Objective and subjective imaging evaluations showed the best results at 60 keV for VMIs. The CT values of the normal group, active subgroup, and CD group during the small intestinal phase at routine 120 kVp or 60 keV VMI had significant differences. The diagnostic efficacy of an iodine map was the best when NIC = 4% or fat value = 45.8% for CD, whereas NIC < 0.35 or the fat value < 0.38 for active CD. The combined routine CTE and optimized VMI improved the diagnostic efficacy (P < 0.001).

Conclusions

VMI at 60 keV provided the best imaging quality on DECTE. NIC and fat value provided important basis for active CD evaluation. Routine CTE combined with VMI at 60 keV improved the diagnostic efficiency for CD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12880-021-00716-y.

COMPARATIVE ANALYSIS OF TWO ORAL CONTRAST AGENT VOLUMES FOR COMPUTED TOMOGRAPHY ENTEROGRAPHY IN CROHN'S DISEASE PATIENTS

BACKGROUND

Crohn's disease (CD) is an inflammatory bowel disease characterized by a chronic and recurrent inflammation of the gastrointestinal tract caused by an interaction of genetic and environmental factors.

OBJECTIVE

To compare the quality and acceptance of two different oral contrast volumes for computed tomography enterography in Crohn's disease patients.

METHODS

A cross-sectional study was conducted in 58 consecutive Crohn's disease patients who randomly received an oral contrast agent composed of 78.75 g polyethylene glycol diluted in either 1,000 mL or 2,000 mL of water. An examination was performed to evaluate the presence of inflammation or complications in the small bowel. The variables included the quality of intestinal segment filling and luminal distension, and oral contrast agent acceptance and tolerance in the patients. Statistical analysis included descriptive statistics and association tests.

RESULTS

A total of 58 patients were assessed, in which 58.6% were female, 34.5% exhibited clinically-active disease, and 63.8% were receiving biologic therapy. As for comparative analysis between the two different volumes of oral contrast, no statistically significant difference was found regarding bowel loop filling (P=0.58) and adequate luminal distension (P=0.45). Patients who received a larger volume (2,000 mL) exhibited side-effects more frequently (51.7% vs 31.0%; P=0.06) and had greater difficulty ingesting the agent (65.5% vs 37.9%; P=0.07) compared with a volume of 1,000 mL.

CONCLUSION

The quality of computed tomography enterography was not influenced by the contrast volume. However, acceptance and tolerance were better in the 1,000 mL group.

Crohn's disease activity before and after medical therapy evaluated by MaRIA score and others parameters in MR Enterography

AIM

Aim of this retrospective study is to evaluate the response to therapy in Crohn's disease (CD) patients studied by MR Enterography (MRE) in comparison with Harvey Bradshaw Index (HBI).

METHODS

One hundred and sixty patients with histological proved CD have undergone MRE in the last years. Forty-six patients who repeated MRE after medical therapy within six months were selected for the study. Magnetic Resonance Index of Activity (MaRIA) was evaluated for each patient and used to define the MR judgment. In MRE we also evaluated wall thickening, longitudinal extension of wall thickening, presence of stratified mural hyperenhancement and extraintestinal signs. The clinical response to therapy was judged based on HBI and classified as improved, worsened or stable disease. Clinical judgment was correlated with MRE findings and the agreement was analysed using the Cohen Kappa test.

RESULTS

Among 46 enrolled patients, 18 (39%) improved clinically, 4 (10%) worsened, 24 (51%) remained stable. MR judgment was in agreement with clinical assessment in 33 patients (72%), showing moderate significant concordance (Kappa = 0.49; p < 0.01). No agreement was observed in 13 (28%) patients. Moreover, clinical improvement was significantly correlated to reduction of wall thickening, reduction of longitudinal extension of the disease and reduction of engorged vasa recta (p < 0.05). Worsening conditions were significantly correlated to increased wall thickening (p = 0.05).

CONCLUSIONS

MRE is useful in evaluating the response to therapy in CD patients.

Pursuing therapeutic success in Crohn’s disease: A matter of definition, tools and longterm outcomes

Management of Crohn’s disease (CD) based on symptom control is a tale of the past as new treatment strategies aim toward a “treat to target” concept and to a patient-tailored approach. Defining treatment goals and assessing therapeutic success have been in the center of IBD research in the past years. Clinical remission and mucosal healing are well-established treatment goals by current recommendations, although prospective data is required to determine whether achieving these targets is enough to alter disease natural course. Furthermore, there is no standard in assessing therapeutic success. Low relapse and hospitalization rates, as well as a low need of surgery are indicators of a successful treatment. Close monitoring is part of the new therapeutic strategy. Monitoring tools are numerous, comprising clinical, biological, endoscopic and imaging scores or parameters but are far from being perfect. The traditional strategy of managing CD patients based on clinical symptoms and response to treatment did not improve the long-term outcomes. Clinical activity scores are frequently used in clinical trials and daily practice, but their use alone is not an accurate measure of inflammation. Endoscopic remission is associated with a lower risk of complications and a better long-term prognostic. Several guidelines include recommendations regarding surveillance endoscopy, but there is an open debate regarding the follow-up intervals. Cross-sectional imaging techniques play a complementary role in assessing transmural inflammation and in identifying extra-intestinal complications of CD and should be used in conjunction with endoscopy. Therapeutic drug monitoring is essential in assessing loss of response and making therapeutic decisions, although firm recommendations are not implemented into daily practice. Extraintestinal manifestations are often disregarded when discussing monitoring protocols. There is no current guideline indication for extraintestinal manifestations monitoring during remission periods.

Differences in the imaging of Crohn's disease patients between North America and Europe: are we ready to bridge the divide?

The emphasis of treatment in Crohn's disease has evolved from a reactive model to "treat-to-target" approaches. Cross-sectional imaging has rapidly evolved in parallel, with a growing evidence base supporting its abilities for diagnosis, monitoring and prognostication. Whilst there are differences in emphasis between Europe and North America, particularly around the type of imaging modalities and patterns of multidisciplinary care, there is increasing convergence. This perspective piece provides an overview of the evolving role of cross-sectional imaging in Crohn's disease, discusses practice differences between North America and Europe and provides suggestions on areas for future collaboration and research priorities.

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.

Computed Tomography Enterography: Quantitative Evaluation on Crohn's Disease Activity

Objective

To explore the feasibility of computed tomography enterography (CTE) in the quantitative evaluation of the activity of Crohn's disease (CD).

Methods

There were 49 CD patients with whole clinical, enteroscopy, and CTE data to be analyzed retrospectively. The patients were graded as inactive (0–2), mild (3–6), and moderate-severe group (>6) based on simplified endoscopic activity score for Crohn's disease (SES-CD). The differences in bowel wall thickening, mural hyperenhancement in the portal vein period, and the ΔCT values were analyzed among groups using ANOVA (analysis of variance) and q test. Then, the parameters were correlated with SES-CD, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR).

Results

In the 49 patients, 13 ones were inactive, 19 ones were mild, and 17 ones were moderate-severe; the thickness of bowel wall, mural hyperenhancement in the portal vein period, and ΔCT value among groups were all significantly different (P < 0.001 in all). Correlative analysis showed that compared with the SES-CD, the bowel wall thickening (r = 0.564, P < 0.001), mural hyperenhancement in the portal vein period (r = 0.585, P < 0.001), and ΔCT value (r = 0.533, P < 0.001) were moderately correlated.

Conclusion

The mural hyperenhancement in the portal vein period, bowel wall thickening, and ΔCT value can accurately and quantitatively assess the activity of CD lesions and are potential visual biomarkers of CD lesions.

The combination of a reduction in contrast agent dose with low tube voltage and an adaptive statistical iterative reconstruction algorithm in CT enterography: Effects on image quality and radiation dose

To investigate the subjective and quantitative image quality and radiation exposure of CT enterography (CTE) examination performed at low tube voltage and low concentration of contrast agent with adaptive statistical iterative reconstruction (ASIR) algorithm, compared with conventional CTE.One hundred thirty-seven patients with suspected or proved gastrointestinal diseases underwent contrast enhanced CTE in a multidetector computed tomography (MDCT) scanner. All cases were assigned to 2 groups. Group A (n = 79) underwent CT with low tube voltage based on patient body mass index (BMI) (BMI < 23 kg/m, 80 kVp; BMI ≥ 23 kg/m, 100 kVp) and low concentration of contrast agent (270 mg I/mL), the images were reconstructed with standard filtered back projection (FBP) algorithm and 50% ASIR algorithm. Group B (n = 58) underwent conventional CTE with 120 kVp and 350 mg I/mL contrast agent, the images were reconstructed with FBP algorithm. The computed tomography dose index volume (CTDIvol), dose length product (DLP), effective dose (ED), and total iodine dosage were calculated and compared. The CT values, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) of the normal bowel wall, gastrointestinal lesions, and mesenteric vessels were assessed and compared. The subjective image quality was assessed independently and blindly by 2 radiologists using a 5-point Likert scale.The differences of values for CTDIvol (8.64 ± 2.72 vs 11.55 ± 3.95, P < .001), ED (6.34 ± 2.24 vs 8.52 ± 3.02, P < .001), and DLP (422.6 ± 149.40 vs 568.30 ± 213.90, P < .001) were significant between group A and group B, with a reduction of 25.2%, 25.7%, and 25.7% in group A, respectively. The total iodine dosage in group A was reduced by 26.1%. The subjective image quality did not differ between the 2 groups (P > .05) and all image quality scores were greater than or equal to 3 (moderate). Fifty percent ASIR-A group images provided lower image noise, but similar or higher quantitative image quality in comparison with FBP-B group images.Compared with the conventional protocol, CTE performed at low tube voltage, low concentration of contrast agent with 50% ASIR algorithm produce a diagnostically acceptable image quality with a mean ED of 6.34 mSv and a total iodine dose reduction of 26.1%.

Ultrasound Shear Wave Elastography and Contrast Enhancement: Effective Biomarkers in Crohn's Disease Strictures

BACKGROUND

Inflammation, fibrosis, and muscular hypertrophy lead to thickened bowel in Crohn's disease forming strictures. Ultrasound shear wave elastography (SWE) measures bowel wall stiffness. Contrast-enhanced ultrasound (CEUS) uniquely detects bowel wall inflammation. We aim to correlate SWE of ileal Crohn's disease in vivo to CEUS peak enhancement and pathology grades of inflammation, fibrosis, and muscular hypertrophy.

METHODS

In a prospective institutional review board-approved study, 105 consecutive ileal patients with Crohn's disease received ultrasound. At maximal bowel wall thickness (>4 mm), SWE and CEUS were performed. Fifteen patients had ileal resection within a mean time interval of 71.0 ± 66.9 days. Pathology scores for inflammation, fibrosis, and muscular hypertrophy were compared with SWE and CEUS measurements.

RESULTS

Mean in vivo SWE velocity for patients with and without surgery was 2.8 ± 0.7 and 2.2 ± 0.8 m/s (P < 0.01), respectively. In all ileal specimens, chronic exceeded active inflammatory change (P < 0.001). There was an inverse relationship between CEUS peak enhancement and both fibrosis, r = -0.59, P = 0.02, and SWE velocity measurements, r = -0.61, P = 0.03. Strictured bowel specimens had more smooth muscle hypertrophy than fibrosis, P < 0.001. There was moderate correlation between SWE and muscular hypertrophy, r = 0.59, P = 0.02 and no significant relationship between SWE and fibrosis scores (P > 0.05).

CONCLUSIONS

Stiffer bowel from smooth muscle hypertrophy increases SWE measurements. We report a novel relation of high SWE with muscle hypertrophy, and inverse relationship with CEUS peak enhancement; providing differentiation between active and chronic bowel wall inflammation to improve selection between medical therapy and surgery.

Endoscopic Complete Remission of Crohn Disease After Anti-Tumor Necrosis Factor-α Therapy: CT Enterographic Findings and Their Clinical Implications

OBJECTIVE

The purpose of this study was to describe the CT enterographic (CTE) findings after endoscopic complete remission (CR) of Crohn disease in patients treated with anti-tumor necrosis factor-α (anti-TNF-α) and the clinical implications of these findings.

MATERIALS AND METHODS

The records of 27 patients with Crohn disease (14 men, 13 women; mean age, 28.4 ± 8.6 [SD] years) who achieved endoscopic (ileocolonoscopic) CR after anti-TNF-α therapy and underwent CTE both before therapy and at endoscopic CR were identified. Two readers independently assessed the frequencies and severities of mural and perienteric CTE abnormalities, generally regarded as active inflammatory findings, in the terminal ileum and colorectum in the endoscopic CR state and compared them with the corresponding findings before anti-TNF-α therapy. The association between the presence of CTE abnormalities in the face of endoscopic CR and patient outcome during subsequent follow-up was investigated.

RESULTS

CTE abnormalities were present in the face of endoscopic CR in 11-18 (26-42%) of 43 bowel sections (18 terminal ileum, 25 colorectum), the most frequent being mural hyperenhancement (21-40%) followed by mural thickening (12-16%). Both findings were mild and unaccompanied by other findings. The frequency and severity of mural and perienteric CTE abnormalities were statistically significantly reduced at endoscopic CR compared with the pre-treatment state. Patients with (n = 10) and without (n = 17) CTE abnormalities at endoscopic CR did not significantly differ with respect to Crohn disease aggravation during subsequent follow-up periods averaging 27.4 and 28.5 months (0/10 versus 2/17, p = 0.516).

CONCLUSION

More than one-fourth of bowel sections in endoscopic CR after anti-TNF-α therapy had residual CTE abnormalities, predominantly mild mural thickening or hyperenhancement. These findings may not have any clinical significance.

Small bowel Crohn's disease: an emerging disease phenotype?

An increasing understanding of the pathogenesis of Crohn's disease (CD), coupled with improvements in therapeutic options, has promoted the concept of stratifying patients with CD into distinct disease phenotypes according to risk. Small bowel CD, due to the numerous non-specific potential symptoms and the anatomical location of the disease, is a particularly difficult phenotype to identify. The fact that the majority of de novo strictures occur in the ileum/ileo-colonic region ensures that recognition of small bowel involvement is essential. Certainly, it is becoming increasingly recognised due to improvements in imaging and endoscopic techniques. Both CT and MR enterography appear capable of accurately diagnosing small bowel CD. Furthermore, the development of capsule endoscopy and balloon-assisted enteroscopy allow direct visualisation of the small bowel. Limited data to date would suggest that small bowel CD is a difficult entity to treat even in the current era of the ever-expanding field of biological therapies. Further long-term follow-up studies are necessary using both small bowel capsule endoscopy and cross-sectional imaging to truly assess, firstly, whether small bowel CD is more resistant to treatment and, secondly, whether it has an effect over time in terms of complications. In the future, serological and genetic tests, coupled with the aforementioned investigations, will permit early diagnosis and early treatment of small bowel CD.

Comparison between clinical and radiological evaluation before and after medical therapy in patients with Crohn's disease: new prospective roles of CT enterography

PURPOSE

In recent years, CT enterography (CTE) has emerged as an important methodology to study patients with Crohn's disease (CD). The aim of this study was to evaluate the correlation between clinical response to therapy and CTE findings in CD patients.

MATERIALS AND METHODS

Forty-five patients with proven CD underwent CTE before and after medical therapy. In CTE we evaluated bowel thickness, longitudinal extension of parietal thickening, presence of target signs and extraintestinal signs. The clinical response to therapy was judged based on clinical global assessment and classified as improved, worsened or stable disease. Radiological judgement was compared to clinical judgement. The Cohen kappa test, t test or Anova analysis and χ (2) test were used for comparisons.

RESULTS

Among 45 enrolled patients, 21 (47 %) improved clinically, five (11 %) worsened, 19 (42 %) remained stable. Clinical improvement was significantly correlated to reduced intestinal thickness, reduced longitudinal extension of the disease, increased diameter of pathological bowel and reduced target signs (p < 0.05). Worsening conditions were significantly correlated to increased longitudinal extent, increased parietal thickness and reduced lumen diameter (p < 0.05). CT judgement was in agreement with physician's clinical assessment in 34 patients (76 %), showing improved disease in 16/21 patients (76 %), stable disease in 14/19 patients (74 %) and worsening in 4/5 patients (80 %). No agreement was observed in 11 (24 %) patients.

CONCLUSIONS

CT enterography provide specific and measurable parameters in evaluating the response to therapy in CD patients.

Imaging techniques in IBD and their role in follow-up and surveillance

The assessment of extent and severity of IBD is crucial for directing treatment decisions. Clinical symptoms alone are neither sensitive nor specific for the assessment of lesion severity in IBD. Cross-sectional imaging techniques, as well as small-bowel capsule endoscopy (SBCE) and device-assisted enteroscopy, have a high accuracy for assessing the extent of mucosal lesions, and are reliable alternatives to ileocolonoscopy. New endoscopic techniques and devices are emerging for improved follow-up and surveillance. In this Review, we discuss different imaging techniques that are used to assess IBD activity and to survey patients with IBD, and highlight the latest developments in each area. Moreover, technical improvements and new tools that aim to measure intestinal fibrosis, postoperative recurrence, activity indices and endoscopic features are analysed. All of these imaging techniques are aimed at changing the paradigm from symptom-driven to lesion-driven treatment of IBD.

Measuring disease activity in Crohn's disease: what is currently available to the clinician

Crohn’s disease (CD) is a chronic inflammatory bowel disease characterized by a relapsing-remitting clinical behavior and dominated by intestinal inflammation. Being a chronic disorder that with time develops into a disabling disease, it is important to monitor the severity of inflammation to assess the efficacy of medication, rule out complications, and prevent progression. This is particularly true now that the goals of treatment are mucosal healing and deep remission. Endoscopy has always been the gold standard for assessing mucosal activity in CD, but its use is limited by its invasiveness and its inability to examine the small intestine, proximal to the terminal ileum. Enteroscopy and the less invasive small bowel capsule endoscopy enable the small bowel to be thoroughly explored and scores are emerging for classifying small bowel disease activity. Cross-sectional imaging techniques (ultrasound, magnetic resonance, computed tomography) are emerging as valid tools for monitoring CD patients, assessing inflammatory activity in the mucosa and the transmucosal extent of the disease, and for excluding extra-intestinal complications. Neither endoscopy nor imaging are suitable for assessing patients frequently, however. Noninvasive markers such as C-reactive protein, and fecal biomarkers such as calprotectin and lactoferrin, are therefore useful to confirm the inflammatory burden of the disease and to identify patients requiring further investigations.

Magnetic resonance imaging for follow-up of Crohn's disease

AIM: To investigate the value of magnetic resonance imaging (MRI) in the follow-up of Crohn's disease.

METHODS: Thirty three patients (including 24 men and 9 women) with Crohn's disease diagnosed from June 2007 to August 2013 were analyzed retrospectively. According to the clinical data, the patients were divided into either an active phase group or a chronic phase group. All the patients underwent MRI, and the images were reviewed for the mural thickness, the degree of stenosis of diseased bowel segments, mesenteric lymph nodes, and complications (abscess, inflammatory mass, and fistula). Disease activity was assessed according to a multi-parameter score, and MR findings were compared with clinical data.

RESULTS: Of all patients, 24 were clinically identified to have active disease and 9 to have chronic disease, and MR-E identified active disease in 21 cases and chronic disease in the remaining 12. Using clinical diagnosis as the "gold standard", the sensitivity, specificity, positive predictive value and negative predictive value of MR for the depiction of disease activity of CD were 79.2%, 77.8%, 90.5% and 58.3%, respectively. The diagnostic performance of MRI was well matched with that of clinical diagnosis (Kappa = 0.857, P < 0.05). In all the patients, 26 had two or more than 2 segments of the small bowl involved, 29 had the ileocecal area involved, 8 had enlarged mesareic lymph nodes, 17 had "comb sign", and 12 had fistula. There were significant differences in mural thickness, the degree of stenosis of diseased bowel segments, lymph nodes, "comb sign" and fistula between the active disease group and chronic disease group (P < 0.05 for all).

CONCLUSION: The diagnostic performance of MRE is well matched with clinical diagnosis. MRI is more effective in differentiating fistula and abscess, and more suitable for long-term follow-up.

Accuracy of magnetic resonance enterography in assessing response to therapy and mucosal healing in patients with Crohn's disease

BACKGROUND & AIMS

We assessed the accuracy of magnetic resonance enterography (MRE) in monitoring response to therapy in patients with Crohn's disease (CD) using ileocolonoscopy as a reference standard.

METHODS

We performed a prospective multicenter study of 48 patients with active CD and ulcers in at least one ileocolonic segment. All patients underwent ileocolonoscopy and MRE at baseline and 12 weeks after completing treatment with corticosteroids (CS) or anti-tumor necrosis factor agents. Disease activity was quantified using Crohn's Disease Endoscopic Index of Severity (CDEIS) and Magnetic Resonance Index of Activity (MaRIA). The primary analysis was to determine the accuracy of MRE in identification of healing, defined as the disappearance of ulcers in endoscopy examination. Additional analyses established the accuracy of MRE in determining endoscopic remission (a CDEIS score <3.5) and change in severity based on consideration of all segments.

RESULTS

MRE determined ulcer healing with 90% accuracy and endoscopic remission with 83% accuracy. The mean CDEIS and MaRIA scores significantly changed at week 12 in segments with ulcer healing, based on endoscopic examination (CDEIS: 21.28 ± 9.10 at baseline vs 2.73 ± 4.12 at 12 weeks; P < .001 and MaRIA: 18.86 ± 9.50 at baseline vs 8.73 ± 5.88 at 12 weeks; P < .001). The MaRIA score accurately detected changes in lesion severity (Guyatt score: 1.2 and standardized effect size: 1.07). MRE was as reliable as endoscopy in assessing healing; no significant changes in CDEIS or MaRIA scores were observed in segments with persistent ulcers, based on endoscopic examination (CDEIS: 26.43 ± 9.06 at baseline vs 20.77 ± 9.13 at 12 weeks; P = .18 and MaRIA: 22.13 ± 8.42 at baseline vs 20.77 ± 9.17 at 12 weeks; P = .42). The magnitude of change in CDEIS scores correlated with those in MaRIA scores (r = 0.51; P < .001).

CONCLUSIONS

MRE evaluates ulcer healing with a high level of accuracy when ileocolonoscopy is used as the reference standard. The MaRIA is a valid, responsive, and reliable index assessing response to therapy in patients with CD.

Computed tomography enterography for evaluation of inflammatory bowel disease

Computed tomography enterography (CTE) has become a main modality for the evaluation of inflammatory bowel disease (IBD). It simultaneously offers visualization of the small bowel and extraintestinal status, which is helpful for diagnosing IBD. Crohn disease has long segmental enhancing wall thickening related with the eccentric longitudinal distribution. In addition, mural stratification, fibrofatty proliferation, positive comb sign by increased mesenteric vascularity and internal/perianal fistula are characteristics of Crohn disease and can be identified on CTE. Short segmental inflammatory wall thickening and the central low attenuated lymph nodes are favorable CT finding of intestinal tuberculosis. A geographic, relatively large, and deep penetrating ulcer with bowel wall thickening and mural hyperenhancement in ileocecal area are characteristics of intestinal Behcet disease. Each of CTE findings for the IBDs is helpful for differential diagnosis. The main disadvantage of this technique is the requisite radiation exposure of patients, particularly in young patients. However, recent development of advanced CT techniques is promising for radiation dose reduction without compromising diagnostic image quality.

Computed tomography of Crohn’s disease: The role of three dimensional technique

Crohn’s disease, a transmural inflammatory bowel disease, remains a difficult entity to diagnose clinically. Over the last decade, multidetector computed tomography (CT) has become the method of choice for non-invasive evaluation of the small bowel, and has proved to be of significant value in the diagnosis of Crohn’s disease. Advancements in CT enterography protocol design, three dimensional (3-D) post-processing software, and CT scanner technology have allowed increasing accuracy in diagnosis, and the acquisition of studies at a much lower radiation dose. The cases in this review will illustrate that the use of 3-D technique, proper enterography protocol design, and a detailed understanding of the different manifestations of Crohn’s disease are all critical in properly diagnosing the full range of possible complications in Crohn’s patients. In particular, CT enterography has proven to be effective in identifying involvement of the small and large bowel (including active inflammation, stigmata of chronic inflammation, and Crohn’s-related bowel neoplasia) by Crohn’s disease, as well as the extra-enteric manifestations of the disease, including fistulae, sinus tracts, abscesses, and urologic/hepatobiliary/osseous complications. Moreover, the proper use of 3-D technique (including volume rendering and maximum intensity projection) as a routine component of enterography interpretation can play a vital role in improving diagnostic accuracy.

Application of MSCT enterography in the evaluation of Crohn's disease

The assessment of small bowel abnormalities has always been a challenging task for radiologists and gastroenterologists. Conventional radiologic and endoscopic evaluations are often limited by the length and caliber of small bowel loops. CT enterography, a robust new method with high spatial and isotropic spatial resolution, is a variant of conventional CT technique optimized for the evaluation of the small bowel. Crohn's disease is an inflammatory disease which can involve different areas of the gastrointestinal tract, and it was characterized by segmental and transmural inflammation, with the terminal ileum being the most common site of involvement. CT enterography is well tolerated by these patients and enables accurate, efficient assessment of lesions arising from the small bowel wall or surrounding organs. In this article, we discuss the principle of CT enterography and its use in the evaluation of Crohn's disease.