CT enterography in evaluating postoperative recurrence of Crohn's disease after ileocolic resection: complementary role to endoscopy

Outcomes and Endpoints of Postoperative Recurrence in Crohn's Disease: Systematic Review and Consensus Conference

BACKGROUND

Outcomes after ileocolonic resection in Crohn's disease [CD] are heterogeneous, and a clear definition of postoperative recurrence remains to be determined. Our Endpoints Working Group of the International Organization for the study of Inflammatory Bowel Disease [IOIBD] aimed to standardise postoperative outcomes, to discuss which endpoints should be used for postoperative clinical trials, and to define those which could be used in trials or registries.

METHODS

Based on a systematic review of the literature, recommendations and statements were drafted and sent to all IOIBD members for a first round of voting. Recommendations and statements were revised based on the voters' comments during a consensus hybrid conference open to all IOIBD members. If no agreement was reached after two rounds of voting, the statement was excluded.

RESULTS

In the systematic review, 3071 manuscripts were screened of which 434 were included. Sixteen recommendations were identified, of which 11 were endorsed. Recommendations and statements include that endoscopy remains the gold standard and should be used as a short-term primary endpoint in both observational cohorts and randomised controlled trials. Clinical symptoms classically used in clinical trials for luminal CD are not reliable in this specific situation. For that reason, longer-term endpoints should be based on the evidence of macroscopic inflammation assessed by imaging techniques, endoscopy, or as reflected by the presence of complications.

CONCLUSIONS

Agencies recommend the use of clinical evaluations, as in the case of luminal CD, and do not recognise primary endpoints based solely on endoscopy. This consensus has led to agreement on the need to define postoperative endoscopy-based and/or imaging-based endpoints.

Diagnostic value of MR and CT enterography in post-operative recurrence of Crohn's disease: a systematic review and meta-analysis

Post-operative recurrence is a critical issue in the surveillance of Crohn's disease after ileocecal resection. This meta-analysis aims to assess the diagnostic yield of enterography techniques in post-operative recurrence of Crohn's disease. A systematic electronic bibliographic databases search was conducted. The inclusion criteria of original articles were: Utilized MR enterography or CT enterography after ileocolonic resection; Documented recurrence by ileo-colonoscopy (Rutgeerts' score ≥ i2); Provided crude data of diagnostic performance. A random-effect method was used for analysis. Relative risk and diagnostic value of each imaging feature were calculated. Eleven studies (11 populations and 589 patients) were included (4 CTE and 7 MRE with 248 and 341 patients, respectively). The pooled sensitivity and specificity of the enterography were 91% (95% CI: 0.85-0.95) and 75% (95% CI: 0.56-0.87), respectively. The pooled sensitivity and specificity of CTE were 93% (95% CI: 0.87-0.96) and 67% (95% CI: 0.35-0.90), respectively. MRE revealed pooled sensitivity and specificity of 90% (95% CI: 0.78-0.96) and 78% (95% CI: 0.57-0.90), respectively. The inter-study heterogeneity was low for sensitivity (I2 = 29%, p-value = 0.17) and high for specificity (I2 = 85%, p-value < 0.01). Wall enhancement, anastomosis wall thickening, anastomosis stenosis, pre-anastomotic dilatation, penetrating lesion, comb sign, and perivisceral edema were significantly higher in POR patients. Wall thickening and penetrating lesion were the most sensitive (81%) and specific (97%) findings, respectively. MRE and CTE exhibit high sensitivity and acceptable specificity (especially MRE) for detection of recurrence in Crohn's disease which makes them an effective initial screening tool and reserves ileo-colonoscopy for those patients with inconclusive enterography results.

Postoperative small bowel Crohn's disease: how to diagnose, manage and treat

PURPOSE OF REVIEW

Crohn's disease is a relapsing inflammatory condition and disease recurrence after surgery is common. Significant variation in clinical practice remains despite progress in management of postoperative Crohn's disease. In this review, we summarise current management strategies and guidelines, unmet needs, and research progress in this field.

RECENT FINDINGS

There has been real progress in risk stratifying individuals' postsurgery and tailoring therapies based on their risk; this has been incorporated into current management guidelines in the USA, UK, and Europe. Furthermore, novel noninvasive monitoring tools such as intestinal ultrasound have shown high sensitivity and specificity at detecting disease recurrence and are an attractive point-of-care test. Recent studies are also investigating multiomic biomarkers to prognosticate postoperative Crohn's disease. However, given the heterogeneity within this condition, large multicentre clinical validation across all age groups is needed for clinical translation in the future.

SUMMARY

Ongoing progress in research and the development of novel prognostic and noninvasive disease monitoring tools offers hope for personalised therapy tailored to individual recurrence risk in postoperative Crohn's disease.

Clinical Update on the Prevention and Management of Postoperative Crohn's Disease Recurrence

PURPOSE OF REVIEW

Despite advances in therapeutics, a significant portion of patients with Crohn's disease still require surgical management. In this article, we present updates to the natural history, prognostication and postoperative monitoring, and novel therapeutics in the prevention and treatment of postoperative Crohn's disease recurrence.

RECENT FINDINGS

Clinical risk factors have been associated with higher rates of postoperative recurrence (POR), and in recent studies demonstrate an increased cumulative risk with presence of additional risk factors. Additional novel clinical, histologic, and "-omic" risk factors for recurrence have recently been elucidated, including the role of the mesentery on recurrence and perioperative intraabdominal septic complications. High-risk patients benefit most from medical prophylaxis, including anti-TNF with or without immunomodulator therapy to prevent recurrence. New biologics such as vedolizumab and ustekinumab have emerging evidence in the use of prophylaxis, especially with recent REPREVIO trial data. Non-invasive disease monitoring, such as cross-sectional enterography, intestinal ultrasound, and fecal calprotectin, have been validated against ileocolonoscopy. Recent advances in the prediction, prevention, and monitoring algorithms of postoperative Crohn's disease may be leading to a reduction in postoperative recurrence. Ongoing trials will help determine optimal monitoring and management strategies for this at-risk population.

Rates of Endoscopic Recurrence In Postoperative Crohn's Disease Based on Anastomotic Techniques: A Systematic Review And Meta-Analysis

BACKGROUND

Patients with Crohn's disease (CD) after ileocolic resection may develop an endoscopic postoperative recurrence (ePOR) that reaches 40% to 70% of incidence within 6 months. Recently, there has been growing interest in the potential effect of anastomotic configurations on ePOR. Kono-S anastomosis has been proposed for reducing the risk of clinical and ePOR. Most studies have assessed the association of ileocolonic anastomosis and ePOR individually, while there is currently limited data simultaneously comparing several types of anastomosis. Therefore, we performed a systematic review and meta-analysis to assess the impact of different ileocolonic anastomosis on ePOR in CD.

METHODS

We searched PubMed and Embase from inception to January 2023 for eligible studies reporting the types of anastomoses and, based on these, the rate of endoscopic recurrence at ≥6 months. Studies were grouped by conventional anastomosis, including side-to-side, end-to-end, and end-to-side vs Kono-S, and comparisons were made between these groups. Pooled incidence rates of ePOR were computed using random-effect modelling.

RESULTS

Seventeen studies, with 2087 patients who underwent ileocolic resection for CD were included. Among these patients, 369 (17,7%) Kono-S anastomoses were performed, while 1690 (81,0%) were conventional ileocolic anastomosis. Endoscopic postoperative recurrence at ≥6 months showed a pooled incidence of 37.2% (95% CI, 27.7-47.2) with significant heterogeneity among the studies (P < .0001). In detail, patients receiving a Kono-S anastomosis had a pooled incidence of ePOR of 24.7% (95% CI, 6.8%-49.4%), while patients receiving a conventional anastomosis had an ePOR of 42.6% (95% CI, 32.2%-53.4%).

CONCLUSIONS

Kono-S ileocolic anastomosis was more likely to decrease the risk of ePOR at ≥6 months compared with conventional anastomosis. Our findings highlight the need to implement the use of Kono-S anastomosis, particularly for difficult to treat patients. However, results from larger randomized controlled trials are needed to confirm these data.

Mesenteric creeping fat index defined by CT enterography is associated with early postoperative recurrence in patients with Crohn's disease

OBJECTIVES

To investigate the value of mesenteric creeping fat index (MCFI) defined by computed-tomography enterography (CTE) in patients with Crohn's Disease (CD) for predicting early postoperative recurrence.

METHODS

A total of 110 patients with CD who underwent CTE and I-stage intestinal resection surgery from December 2013 to December 2018 were enrolled. Two radiologists independently assessed CTE parameters, including MCFI, with scores ranging from 1 to 8; bowel-wall thickening, with a scale of 1 to 3; mural hyperenhancement, mural stratification, submucosal fat deposition, mesenteric fibrofatty proliferation, mesenteric hypervascularity, mesenteric fat stranding, with a scale of 0 to 2; abscess/fistula, enlarged mesenteric lymph node, abdominal and pelvic effusion, with a scale of 0 to 1. Imaging findings associated with early recurrence were assessed using logistic regression analysis.

RESULTS

Within one year follow-up, early postoperative recurrence occurred in 56.4 % (62/110) patients with CD. In univariate analysis, MCFI, bowel-wall thickening, mesenteric hypervascularity, mesenteric fat stranding, abscess/fistula and mesenteric lymphadenopathy were associated with early postoperative recurrence. Among all variables, MCFI (score ≥ 4) contributes the optimal AUC (0.838 [0.758-0.919]), specificity (89.6 %), positive predictive value (90.7 %), accuracy (83.6 %), and risk ratio (OR = 32.42 [10.69-98.33], p < 0.001). In multivariate analysis, only MCFI was an independent predictor of early postoperative recurrence (OR = 25.71 [7.65-86.35], p < 0.001).

CONCLUSION

CTE features are useful in predicting early postoperative recurrence in patients with CD, MCFI may be a valuable tool for clinical monitoring and follow-up.

Results of the Eighth Scientific Workshop of ECCO: Diagnosing Postoperative Recurrence of Crohn's Disease After an Ileocolonic Resection With Ileocolonic Anastomosis

Despite the introduction of potent biologic therapies, many patients with Crohn's disease [CD] still require an ileocolonic resection [ICR] during the course of their disease. Furthermore, the need of redo ICR has not decreased over the past few decades, highlighting the need for better strategies to prevent and treat postoperative recurrence [POR]. The first step to develop such a strategy would be to define and standardise the description of POR with adequate diagnostic instruments. In this article, we will describe the different methodologies used to report POR [endoscopic, histological, radiological, biochemical, clinical, and surgical], and review their potential benefits and limitations, as well as the optimal timing of evaluation.

New score models for assessing disease activity in Crohn's disease based on bowel ultrasound and biomarkers: Ideal surrogates for endoscopy or imaging

Disease activity evaluation is important in Crohn's disease (CD). We aimed to establish new disease activity indices for CD based on noninvasive parameters. The data of 110 patients with CD were retrospectively analyzed. Parameters from bowel ultrasound and biomarkers were measured to select the variables included in the models by univariate analysis. Logistic regression analysis was performed to predict mucosal and transmural activities defined by ileocolonoscopy or computed tomography enterography, respectively. The models' performance was measured by the area under the receiver operating characteristic (ROC) curve (AUC). Leave-one-out cross validation (LOOCV) was applied to adjust for overconfidence in the newly established score models. To predict mucosal activity, erythrocyte sedimentation rate (ESR) and (LimG × BWT)-SUM (the sum of the product of Limberg grade [LimG] and bowel wall thickness [BWT] of each bowel segment) were selected for model A, and the equation was A = 2 × ESR + 9.3 × (LimG × BWT)-SUM. The AUC of ROC, sensitivity, and specificity were 0.927%, 89.8%, and 86.4%, respectively. The AUC of the ROC curve verified by LOOCV was 0.913. To predict transmural activity, albumin (ALB) and LimG-SUM (the sum of the LimG of all the bowel segments) were selected for model B, which was established as B = -1.3 × ALB +1.7 × LimG-SUM. The AUC of ROC, sensitivity, and specificity were 0.851%, 78.0%, and 84.2%, respectively. The AUC of the ROC curve verified by LOOCV was 0.833. Nomograms were developed for two score models. New score models based on noninvasive parameters established in this study showed good abilities in detecting active disease and performed well in the validation phase.

Intravoxel incoherent motion diffusion-weighted imaging in quantitative evaluation of Ileal Crohn's disease - A comparison with dynamic contrast-enhanced magnetic resonance imaging and ileocolonoscopy

OBJECTIVES

To investigate the prospective role of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in evaluating terminal ileal Crohn's disease (CD) inflammation quantitatively, compared with quantitative dynamic contrastenhanced magnetic resonance imaging (DCE-MRI) and ileocolonoscopic segmental score.

METHODS

Fifty CD patients underwent magnetic resonance enterography (MRE) including IVIM-DWI and quantitative DCE-MRI from Jan. 2017 to Nov. 2019. ADC, D, D* and f value of IVIM-DWI and Ktrans, Kep, and Ve value of DCE-MRI in normal (n = 50) and inflamed bowel segments (n = 50), defined during the clinical MRI analysis, were calculated and compared using Wilcoxon signed-rank tests respectively. Receiver operating characteristic (ROC) analysis was performed. Correlations between IVIM-DWI and DCE-MRI parameters in comparison with ileocolonoscopic segmental score were assessed using Spearman's rank correlation analysis.

RESULTS

For IVIM-DWI, ADC, D, D* and f value showed significant differences respectively between normal and inflamed bowel segments (p < 0.05). ADC value presented the highest diagnostic accuracy (AUC = 0.813) and sensitivity (92%), and D value presented the highest specificity (84%) for the evaluation of inflamed bowel segments. For DCE-MRI, Ktrans value presented the highest diagnostic accuracy (AUC = 0.835), the highest sensitivity for Kep value (88%) and the highest specificity for Ve value (96%). ADC, f and Ktrans value had high correlations with ileocolonoscopic score respectively (r = -0.739-0.876, p < 0.01). The logarithm of normalized signal intensity/b-values for IVIM-DWI could also indicate directly the evident difference between the normal and inflamed bowel segments of terminal ileal CD.

CONCLUSION

IVIM-DWI will be another promising noninvasive tool to provide precise quantitative-indicators in evaluating inflamed bowel segments of terminal ileal CD with little contrast-agent damage worries.

Related Factors for Unfavorable Disease Course in Patients with Crohn's Disease: An Observational Retrospective Study

Background: Crohn’s disease (CD) manifests a heterogeneous clinical spectrum and disease course, and it is challenging to predict the disease outcome based on initial presentation. Objective: To analyze the long-term disease course and factors leading to poor prognosis of CD. Methods: In total, 112 patients with CD who were initially diagnosed and treated at our institution from January 2009 to August 2020 were included. We analyzed their clinical data, disease characteristics according to the Montreal classification, and the endoscopic and computed tomography (CT) examinations at the initial visit and at 2-year, 5-year, and last follow ups. We categorized the disease course into the following four categories: remission, stable, chronic refractory, and chronic relapsing. Significant factors associated with a poorer prognosis were analyzed. Results: The median follow-up period was 107 (range, 61−139) months. Complicated disease behavior increased slightly over the follow-up period (20.5% to 26.2%). An unfavorable disease course was defined as chronic refractory (19.6%) and relapsing (16.1%) courses. The 2-year disease characteristics were significant factors for unfavorable disease course, and the combination of 2-year perianal disease and 2-year moderate-to-severe CT activity could predict unfavorable disease course with the highest accuracy (0.722; area under the curve: 0.768; p < 0.0001). Conclusions: One-third of the patients with CD showed an unfavorable disease course (35.7%), and 2-year disease characteristics were significant factors for an unfavorable disease course.

Post-operative prevention and monitoring of Crohn's disease recurrence

Crohn's disease (CD) and ulcerative colitis (UC) are relapsing and remitting chronic inflammatory diseases of the gastrointestinal tract. Although surgery for UC can provide a cure, surgery for CD is rarely curative. In the past few decades, research has identified risk factors for postsurgical CD recurrence, enabling patient risk stratification to guide monitoring and prophylactic treatment to prevent CD recurrence. A MEDLINE literature review identified articles regarding post-operative monitoring of CD recurrence after resection surgery. In this review, we discuss the evidence on risk factors for post-operative CD recurrence as well as suggestions on post-operative management.

Contemporary Management of Postoperative Crohn's Disease after Ileocolonic Resection

Surgery remains an important treatment modality in the multidisciplinary management of patients with Crohn's disease (CD). To illustrate the recent advances in the management of postoperative CD we outline the contemporary approach to treatment: diagnosing disease recurrence using endoscopy or noninvasive methods and risk stratification underlying decisions to institute treatment. Endoscopic scoring indices are being refined to guide treatment decisions by accurately estimating the risk of recurrence based on endoscopic appearance. The original Rutgeerts score has been modified to separate anastomotic lesions from lesions in the neoterminal ileum. Two further indices, the REMIND score and the POCER index, were recently developed with the same intention. Noninvasive monitoring for recurrence using a method with high negative predictive value has the potential to simplify management algorithms and only perform ileocolonoscopy in a subset of patients. Fecal calprotectin, intestinal ultrasound, and magnetic resonance enterography are all being evaluated for this purpose. The use of infliximab for the prevention of postoperative recurrence is well supported by data, but management decisions are fraught with uncertainty for patients with previous exposure to biologics. Data on the use of ustekinumab and vedolizumab for postoperative CD are emerging, but controlled studies are lacking.

Test Characteristics of Cross-sectional Imaging and Concordance With Endoscopy in Postoperative Crohn's Disease

BACKGROUND & AIMS

Postoperative Crohn's disease (CD) surveillance relies on endoscopic monitoring. The role of cross-sectional imaging is less clear. We evaluated the concordance of cross-sectional enterography with endoscopic recurrence and the predictive ability of radiography for future CD postoperative recurrence.

METHODS

We performed a multi-institution retrospective cohort study of postoperative adult patients with CD who underwent ileocolonoscopy and cross-sectional enterography within 90 days of each other following ileocecal resection. Imaging studies were interpreted by blinded, expert CD radiologists. Patients were categorized by presence of endoscopic postoperative recurrence (E+) (modified Rutgeerts' score ≥i2b) or radiographic disease activity (R+) and grouped by concordance status.

RESULTS

A total of 216 patients with CD with paired ileocolonoscopy and imaging were included. A majority (54.2%) exhibited concordance (34.7% E+/R+; 19.4% E-/R-) between studies. The plurality (41.7%; n = 90) were E-/R+ discordant. Imaging was highly sensitive (89.3%), with low specificity (31.8%), in detecting endoscopic postoperative recurrence. Intestinal wall thickening, luminal narrowing, mural hyper-enhancement, and length of disease on imaging were associated with endoscopic recurrence (all P < .01). Radiographic disease severity was associated with increasing Rutgeerts' score (P < .001). E-/R+ patients experienced more rapid subsequent endoscopic recurrence (hazard ratio, 4.16; P = .033) and increased rates of subsequent endoscopic (43.8% vs 22.7%) and surgical recurrence (20% vs 9.5%) than E-/R- patients (median follow-up, 4.5 years).

CONCLUSIONS

Cross-sectional imaging is highly sensitive, but poorly specific, in detecting endoscopic disease activity and postoperative recurrence. Advanced radiographic disease correlates with endoscopic severity. Patients with radiographic activity in the absence of endoscopic recurrence may be at increased risk for future recurrence, and closer monitoring should be considered.

Visceral adipose volume is correlated with surgical tissue fibrosis in Crohn's disease of the small bowel

Background

This study explored the diagnostic performance of visceral adiposity to predict the degree of intestinal inflammation and fibrosis.

Methods

The patients with Crohn’s disease (CD) who underwent surgical small bowel resection at the First Affiliated Hospital of Sun Yat-sen University (Guangzhou, China) between January 2007 and December 2017 were enrolled. We evaluated the intestinal imaging features of computed tomography enterography (CTE), including mesenteric inflammatory fat stranding, the target sign, mesenteric hypervascularity, bowel wall thickening, lymphadenopathy, stricture diameter, and maximal upstream diameter. We used A.K. software (Artificial Intelligence Kit, version 1.1) to calculate the visceral fat (VF) and subcutaneous fat (SF) volumes at the third lumbar vertebra level. Pathological tissue information was recorded. Diagnostic models were established based on the multivariate regression analysis results, and their effectiveness was evaluated by area under the curve (AUC) and decision curve analyses.

Results

Overall, 48 patients with CD were included in this study. The abdominal VF/SF volume ratio (odds ratio, 1.20; 95% confidence interval, 1.05–1.38; P = 0.009) and the stenosis diameter/upstream intestinal dilatation diameter (ND) ratio (odds ratio, 0.90; 95% confidence interval, 0.82–0.99; P = 0.034) were independent risk factors for the severe fibrosis of the small intestine. The AUC values of the VF/SF ratio, the ND ratio, and their combination were 0.760, 0.673, and 0.804, respectively. The combination of the VS/SF volume ratio and ND ratio achieved the highest net benefit on the decision curve.

Conclusion

The VF volume on CTE can reflect intestinal fibrosis. The combination of the VF/SF volume ratio and ND ratio of CD patients assessed using CTE can help predict severe fibrosis stenosis of the small intestine.

Clinical implication of radiologic complete remission on Crohn's Disease: Compared with endoscopic remission

OBJECTIVES

To determine the clinical implications of radiologic complete remission (CR) in Crohn's disease (CD) evaluated by computed tomography (CT) or magnetic resonance enterography (MRE) in comparison with endoscopic CR.

METHODS

Twenty-five CD patients who achieved endoscopic CR after medical treatment were retrospectively enrolled in this study. All patients underwent ileocolonoscopy, CT, or MRE at baseline, at the time of endoscopic CR, and during follow-up. Two radiologists assessed the mural and perienteric abnormalities on pre- and post-treatment CT or MRE in consensus. Patients were divided into radiologic CR and non-CR groups at the time of endoscopic CR. CD recurrence during subsequent follow-up periods was evaluated using clinical, laboratory, and CT/MRI findings. Statistical analysis was performed to assess whether there were significant differences in patient outcomes between the groups.

RESULTS

At the time of endoscopic CR, nine patients (mean age, 36.6 years) showed normalization of all radiologic features and were designated as the radiologic CR group. However, 16 patients (mean age: 32.9 years) showed residual CT/MRE abnormalities, suggesting persistent active inflammation, and were designated as the radiologic non-CR group. During follow-up, there was a significant difference between the groups regarding clinical outcomes (deep CR, 8/9 vs 5/16, P = 0.011; CD recurrence, 1/9 vs 14/16, P < 0.001). The mean fecal calprotectin level was significantly lower in the radiologic CR group (287.5 ug/g) than in the non-CR group (652.4 ug/g) (P = 0.023).

CONCLUSIONS

Radiologic CR can represent a better therapeutic endpoint in CD, showing superiority over endoscopic CR in predicting both clinical and biochemical outcomes.

What's New in the Postoperative Management of Crohn's Disease?

Patients with Crohn's disease (CD) often require surgical resection due to complications, such as strictures and abscesses, or disease refractory to medical therapy. To understand the evolving management of patients with CD after surgery, we outline the risk factors for postoperative recurrence, advances in postoperative endoscopic evaluation and characterization of recurrence, noninvasive methods of assessing postoperative recurrence, use of postoperative prophylactic medical therapy including newer biologics, and novel surgical methods to reduce postoperative recurrence. The Rutgeerts score (RS) was developed to predict progression of disease based on endoscopic appearance postoperatively and to guide medical therapy. However, this scoring system groups ileal and anastomotic lesions into the same category. A modified RS was developed to separate lesions isolated to the anastomosis and those in the neo-terminal ileum to further understand the role of anastomotic lesions in CD progression. Additional scoring systems have also been evaluated to better understand these differences. In addition, noninvasive diagnostic methods, such as small bowel ultrasound, have high sensitivity and specificity for the detection of postoperative recurrence and are being evaluated as independent methods of assessment. Studies have also shown a reduction in endoscopic recurrence with postoperative anti-TNFα therapy. However, preoperative exposure to anti-TNFα therapy may impact postoperative response to these medications, and therefore, determining optimal postoperative prophylaxis strategy for biologic-experienced patients requires further exploration. Lastly, new surgical modalities to reduce postoperative recurrence are currently being investigated with preliminary data suggesting that an antimesenteric functional end-to-end anastomosis (Kono-S) may decrease postoperative recurrence.

A Novel Clinical Radiomics Nomogram to Identify Crohn's Disease from Intestinal Tuberculosis

Purpose

To establish a clinical radiomics nomogram to differentiate Crohn’s disease (CD) from intestinal tuberculosis (ITB).

Patients and Methods

Ninety-three patients with CD and 67 patients with ITB were recruited (111 in training cohort and 49 in test cohort). The region of interest (ROI) for the lesions in the ileocecal region was delineated on computed tomography enterography and radiomics features extracted. Radiomics features were filtered by the gradient boosting decision tree (GBDT), and a radiomics score was calculated by using the radiomics signature-based formula. We constructed a clinical radiomics model and nomogram combining clinical factors and radiomics score through multivariate logistic regression analysis, and the internal validation was undertaken by ten-fold cross validation. Analyses of receiver operating characteristic (ROC) curves and decision curve analysis (DCA) were used to evaluate the prediction performance. DeLong test was applied to evaluate the performance of the clinical, radiomics and combined model.

Results

The clinical radiomics nomogram, which was based on the 9 radiomics signature and two clinical factors, indicated that the clinical radiomics model had an area under the ROC curve (AUC) value of 0.96 (95% confidence interval [CI]: 0.93–0.99) in the training cohort and 0.93 (95% CI: 0.86–1.00) in validation cohort. The clinical radiomics model was superior to the clinical model and radiomics model, and the difference was significant (P = 0.006, 0.004) in the training cohort. DCA confirmed the clinical utility of clinical radiomics nomogram.

Conclusion

CTE-based radiomics model has a good performance in distinguishing CD from ITB. A nomogram constructed by combining radiomics and clinical factors can help clinicians accurately diagnose and select appropriate treatment strategies between CD and ITB.

Medical therapies for postoperative Crohn's disease

Postoperative recurrence of Crohn's disease is common and requires a multidisciplinary approach between surgeons and gastroenterologists in the perioperative and postoperative period to improve outcomes in this patient population. Endoscopic recurrence precedes clinical and surgical recurrence and endoscopic monitoring is crucial to guide postoperative management. Risk stratification of patients is recommended to guide early prophylactic management, and follow-up endoscopic monitoring can guide intensification of therapy. This review summarizes evidence behind postoperative recurrence rates, disease monitoring techniques, nonbiologic and biologic therapies available to prevent and treat postoperative recurrence, risk factors associated with recurrence, and postoperative management strategies guided by endoscopic monitoring.

Indian guidelines on imaging of the small intestine in Crohn's disease: A joint Indian Society of Gastroenterology and Indian Radiology and Imaging Association consensus statement

The Indian Society of Gastroenterology (ISG) Task Force on Inflammatory Bowel Disease and the Indian Radiological and Imaging Association (IRIA) developed combined ISG-IRIA evidence-based best-practice guidelines for imaging of the small intestine in patients suspected to have or having Crohn's disease. The 29 consensus statements, developed through a modified Delphi process, are intended to serve as reference for teaching, clinical practice, and research.

The Role of the Radiologist in Determining Disease Severity in Inflammatory Bowel Diseases

Crohn's disease and ulcerative colitis are chronic inflammatory diseases that lead to progressive bowel damage including the development of stricturing and penetrating complications. Increasingly, cross-sectional imaging with computed tomography or magnetic resonance scans have emerged as leading tools to: (1) assess disease activity; (2) monitor response to therapy or disease recurrence; and (3) identify disease-related complications. Several validated radiological scoring systems have been developed to quantify cross-sectional and longitudinal inflammatory burden in these diseases and to monitor response to treatment. Bowel ultrasound is also a simple and inexpensive tool but is operator dependent in its performance.

Intravenous Contrast-Enhanced Ultrasound for Assessing and Grading Postoperative Recurrence of Crohn's Disease

PURPOSE

The aim was to investigate the contribution of contrast-enhanced ultrasound (CEUS) to improve the results of US in the evaluation of recurrence in postsurgical Crohn's disease (CD) and establish its role in the assessment of the severity.

METHODS

Anastomotic site was assessed in 108 postsurgical CD patients with B-mode, color Doppler and CEUS. Bowel wall thickness (WT), transmural complications or stenosis, color Doppler grade, and bowel wall contrast enhancement (BWCE)-using time-intensity curves-were correlated with endoscopic Rutgeerts score. A receiver operating characteristic (ROC) curve was built to establish the best cutoff to predict recurrence and the severity. A US scoring system was elaborated in order to determine the grade of recurrence.

RESULTS

Ileocolonoscopy detected recurrence in 90 (83.3%) subjects and severe recurrence in 62. WT ≥ 3 mm had an accuracy of 90.7% in the detection of endoscopic recurrence. The combination of parameters-WT ≥ 3 mm and BWCE (≥ 46%)-demonstrated similar accuracy (90.7%). A WT ≥ 5 mm showed the best specificity (100%) for the diagnosis of recurrence and a WT ≥ 6 mm the best specificity (95.7%) for the detection of severe recurrence. The combination of sonographic parameters-WT ≥ 6 mm or WT between 5 and 6 mm with BWCE ≥ 70%, or complications-obtained the best results grading the recurrence (sensitivity, specificity, and accuracy of 90.3%, 87%, and 88.9%, respectively).

CONCLUSIONS

US shows high sensitivity and specificity for the diagnosis of postsurgical recurrence. When combined with CEUS, it can improve the detection of severe recurrence.

Computed Tomography and Magnetic Resonance Small Bowel Enterography: Current Status and Future Trends Focusing on Crohn's Disease

Computed tomography enterography (CTE) and magnetic resonance enterography (MRE) are presently state-of-the-art radiologic tests used to examine the small bowel for various indications. This article focuses on CTE and MRE for the evaluation of Crohn disease. The article describes recent efforts to achieve more standardized interpretation of CTE and MRE, summarizes recent research studies investigating the role and impact of CTE and MRE more directly for several different clinical and research issues beyond general diagnostic accuracy, and provides an update on progress in imaging techniques. Also addressed are areas that need further exploration in the future.

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%.

Imaging of the small intestine in Crohn's disease: Joint position statement of the Indian Society of Gastroenterology and Indian Radiological and Imaging Association

The Indian Society of Gastroenterology (ISG) Task Force on Inflammatory Bowel Disease and the Indian Radiological and Imaging Association (IRIA) developed combined ISG-IRIA evidence-based best-practice guidelines for imaging of the small intestine in patients with suspected or known Crohn's disease. These 29 position statements, developed through a modified Delphi process, are intended to serve as reference for teaching, clinical practice, and research.

NASPGHAN Clinical Report on Postoperative Recurrence in Pediatric Crohn Disease

Pediatric Crohn disease is characterized by clinical and endoscopic relapses. The inflammatory process is considered to be progressive and may lead to strictures, fistulas, and penetrating disease that may require surgery. In addition, medically refractory disease may be treated by surgical resection of inflamed bowel in an effort to reverse growth failure. The need for surgery in childhood suggests severe disease and these patients have an increased risk for recurrent disease and potentially more surgery. Data show that up to 55% of patients had clinical recurrence in the first 2 years after initial surgery. The current clinical report on postoperative recurrence in pediatric Crohn disease reviews the risk factors for early surgery and postoperative recurrence, operative risk factors for recurrence, and prevention and monitoring strategies for postoperative recurrence. We also propose an algorithm for postoperative management in pediatric Crohn disease.

CT Enterography for Surveillance of Anastomotic Recurrence within 12 Months of Bowel Resection in Patients with Crohn's Disease: An Observational Study Using an 8-Year Registry

OBJECTIVE

To investigate the diagnostic yield and accuracy of CT enterography (CTE) for early (< 12 postoperative months) surveillance of anastomotic recurrence after bowel resection for Crohn's disease (CD).

MATERIALS AND METHODS

We analyzed 88 adults (60 males and 28 females; mean age, 31.4 ± 9.6 years) who underwent bowel surgery for CD that created ileocolic anastomosis without enteric stoma, and underwent CTE for surveillance of CD recurrence/aggravation within 12 post-operative months. The CD activity index (CDAI) at the time of CTE was < 150 (i.e., clinically silent) in 51 patients, and ≥ 150 in 37 patients. Diagnostic yields of CTE regarding CD recurrence in the ileocolic anastomosis and extraluminal penetrating complications were determined. CTE-related step-up therapy was recorded. These outcomes were compared between the two CDAI groups after accounting for major risk factors for CD recurrence. In a subgroup of 31 patients who underwent both CTE and ileocolonoscopy within 1 month, CTE accuracy for anastomotic recurrence was assessed using the Rutgeerts scoring as the reference standard.

RESULTS

CTE diagnostic yield was 35.2% (31/88) for the anastomotic recurrence and 9.1% (8/88) for penetrating complications. 20.5% (18/88) of the patients underwent step-up therapy after CTE detection of anastomotic recurrence. These outcomes were not significantly different between CDAI < 150 and CDAI ≥ 150, except that CTE yield for extraluminal penetrating complications was significantly higher in CDAI ≥ 150 (16.2% [6/37] vs. 3.9% [2/51]; multivariable-adjusted p = 0.029). CTE showed 92.3% (12/13) sensitivity and 83.3% (15/18) specificity for anastomotic recurrence.

CONCLUSION

CTE may be a viable option for the early postsurgical surveillance of recurred disease in CD patients.

Identification of the distinguishing features of Crohn's disease and ischemic colitis using computed tomographic enterography

Background and aims: The differential diagnosis between Crohn’s disease (CD) and ischemic colitis (ISC) is important as their clinical management is different. ISC can easily be misdiagnosed as CD, especially in elderly populations. The distinctive radiographic features of the two disease entities have not been investigated. The aim of this study is to assess the utility of computed tomographic enterography (CTE) in the differential diagnosis between CD and ISC.

Methods: Patients with confirmed CD and ISC were identified through an electronic medical record search of the Cleveland Clinic Foundation. Patients who had undergone CTE, with or without concurrent colonoscopy and histopathological specimens, were included in this study. CTE images were blindly re-reviewed by an expert gastrointestinal radiologist. The sensitivities, specificities, accuracies and positive and negative predictive values for each of the CTE findings in differentiating CD from ISC were estimated. Kappa coefficients (κ) were calculated to measure diagnosis agreement between CTE and the reference standard.

Results: A total of 34 eligible patients were included in this study with 17 having CD and 17 having ISC. In differentiating CD from ISC, the presence of mucosal hyperenhancement and absence of the “target sign” on CTE showed a sensitivity of 100% each for CD, while the two radiographic features yielded a low specificity of 35.3% and 76.5%, respectively. The presence of stricture had a lower sensitivity of 64.7% for the detection of CD but had a high specificity of 100%. In distinguishing CD from ISC, the accuracy of presence of mucosal hyperenhancement, stricture and absence of target sign were 67.7%, 82.4% and 88.2%, respectively. The combination of the presence of mucosal hyperenhancement and the absence of the target sign achieved an accuracy of 100% for distinguishing CD from ISC. There was a good correlation between CTE and the reference standard for distinguishing CD from ISC (κ = 0.882).

Conclusions: CTE appeared to be clinically useful in distinguishing CD from ISC.

Management of post-operative Crohn's disease in 2017: where do we go from here?

Postoperative recurrence (POR) of Crohn's disease is common after surgical resection. How to best manage POR remains uncertain. Areas covered: In this review, we will first describe the natural course and the best modalities to diagnose this surgical sequela. We will then focus on the potential risk factors for relapse and highlight the main shortcomings in the current study designs and endoscopic and clinical scoring systems, which may partly explain the unexpected outcomes of recent clinical trials. Finally, we will propose a strategy to address the management of POR. Expert commentary: Anti-tumor necrosis factor (Anti-TNF) agents are the most effective therapy to prevent POR in Crohn's disease. Patient risk stratification and active monitoring with scheduled ileocolonoscopy are cornerstones of optimal POR management. Further studies are needed to address areas of uncertainty including timing and duration of therapy and the role of therapeutic drug monitoring in this setting.

Evolving roles of cross-sectional imaging in Crohn's disease

The implementation of cross-sectional imaging techniques for the clinical management of Crohn's disease patients has steadily grown over the recent years, thanks to a series of technological advances, including the evolution of contrast media for magnetic resonance, computed tomography and bowel ultrasound. This has resulted in a continuous improvement of diagnostic accuracy and capability to detect Crohn's disease-related complications. Additionally, a progressive widening of indications for cross-sectional imaging in Crohn's disease has been put forward, thus leading to hypothesize that in the near future imaging techniques can increasingly complement endoscopy in most clinical settings, including the grading of disease activity and the assessment of mucosal healing or Crohn's disease post-surgical recurrence.

Optimal delivery of follow-up care after surgery for Crohn's disease: current perspectives

Despite improvements in medical therapies for Crohn’s disease (CD), up to 70% of patients require surgery within 10 years of diagnosis. Surgery is not curative, and almost all patients will experience endoscopic recurrence, and many will go on to clinical recurrence. Identifying patients at high-risk of endoscopic recurrence and standardizing postoperative assessments are essential in preventing clinical recurrence of CD. In this review, we discuss the assessment, monitoring, and treatment of postoperative CD patients. We address the various individual risk factors as well as composite risk factors. Medications used for primary CD treatment can be used in the postoperative setting to prevent endoscopic or clinical recurrence with varying efficacy, although the cost-effectiveness of these approaches are not fully understood. Future directions for postoperative CD management include evaluation of newer biologic agents such as anti-integrin therapy and fecal microbiota transplant for prevention of recurrence. Development of a standard preoperative risk assessment tool to clearly stratify those at high-risk of recurrence is necessary to guide empiric therapy. Lastly, the incorporation of noninvasive testing into disease monitoring will likely lead to early detection of endoscopic recurrence that will allow for tailored treatment to prevent clinical recurrence.

Radiological Response Is Associated With Better Long-Term Outcomes and Is a Potential Treatment Target in Patients With Small Bowel Crohn's Disease

OBJECTIVES

Crohn's disease (CD) management targets mucosal healing on ileocolonoscopy as a treatment goal. We hypothesized that radiologic response is also associated with better long-term outcomes.

METHODS

Small bowel CD patients between 1 January 2002 and 31 October 2014 were identified. All patients had pre-therapy computed tomography enterography (CTE)/magnetic resonance enterography (MRE) with follow-up CTE or MRE after 6 months, or 2 CTE/MREs≥6 months apart while on maintenance therapy. Radiologists characterized inflammation in up to five small bowel lesions per patient. At second CTE/MRE, complete responders had all improved lesions, non-responders had worsening or new lesions, and partial responders had other scenarios. CD-related outcomes of corticosteroid usage, hospitalization, and surgery were assessed using Kaplan-Meier survival analysis and multivariable Cox models.

RESULTS

CD patients (n=150), with a median disease duration of 9 years, had 223 inflamed small bowel segments (76 with strictures and 62 with penetrating, non-perianal disease), 49% having ileal distribution. Fifty-five patients (37%) were complete radiologic responders, 39 partial (26%), and 56 non-responders (37%). In multivariable Cox models, complete and partial response decreased risk for steroid usage by over 50% (hazard ratio (HR)s: 0.37 (95% confidence interval (CI), 0.21-0.64); 0.45 (95% CI, 0.26-0.79)), and complete response decreased the risk of subsequent hospitalizations and surgery by over two-thirds (HRs: HR, 0.28 (95% CI, 0.15-0.50); HR, 0.34 (95% CI, 0.18-0.63)).

CONCLUSIONS

Radiological response to medical therapy is associated with significant reductions in long-term risk of hospitalization, surgery, or corticosteroid usage among small bowel CD patients. These findings suggest the significance of radiological response as a treatment target.

Medical Imaging in Small Bowel Crohn's Disease-Computer Tomography Enterography, Magnetic Resonance Enterography, and Ultrasound: "Which One Is the Best for What?"

BACKGROUND

Small bowel imaging in Crohn's disease (CD) is an important adjunct to endoscopy for the diagnosis, assessment of postoperative recurrence, and detection of complications. The best imaging modality for such indications though remains unclear. This systematic review aims to identify the imaging modality of choice considering the use of ultrasound (US), computed tomography enterography (CTE), and magnetic resonance enterography (MRE).

METHODS

Databases were systematically searched for studies pertaining to the performance of US, CTE, and MRE, as compared with a predefined reference standard in the assessment of small bowel CD.

RESULTS

Thirty-three studies, from a total of 1427 studies, were included in the final analysis. A comparable performance was demonstrated for MRE, CTE, and US for the diagnosis of small CD. Ultrasound was found to have the highest accuracy in the differentiation of inflammation and fibrosis. Postoperative recurrence detection was feasible with the use of MRE and US. All 3 modalities were shown to have a role in the detection of small bowel CD complications. The radiation exposure associated with CTE can be minimized by using lower radiation protocols.

CONCLUSIONS

Ultrasound, CTE, and MRE all play an important role in the diagnosis and management of small bowel CD, with preference for a particular modality being influenced by specific indication, institution resources, and patient preference.

Evaluation of intestinal tuberculosis by multi-slice computed tomography enterography

BACKGROUND

Multi-slice computed tomography enterography (MSCTE) is now widely used to diagnose and monitor intestinal disease. Preliminary studies suggest that MSCTE may be useful in detecting intestinal tuberculosis (ITB). We sought to assess the use of MSCTE for the diagnosis of ITB in our medical center.

METHODS

In this retrospective study, 15 patients (11 males and 4 females, 6 to 65 years old) were enrolled and diagnosed with ITB by MSCTE. Diagnosis were confirmed by pathology or clinical criteria. Two experienced abdominal radiologists evaluated the images and defined the location, number, shape, edge, surrounding tissue alterations of ITB and other associated changes in the peritoneum, mesentery and solid abdominal organs.

RESULTS

The interval between the onset of symptoms and diagnosis varied from 20 days to 10 years. The most common symptom was abdominal pain (80 %). The ileocecum was the most common site affected by ITB (87 %). Morphological MSCTE findings were variable and included multi-segmental symmetric intestinal mural thickening found in 6 patients (40 %), solid masses found in 9 patients (60 %), and enlarged lymph nodes (LNs) found in 13 (87 %) patients. Non-enhancing central necrosis and rim enhancement were noted in 10 patients (67 %).

CONCLUSIONS

Characteristic MSCTE findings of ITB include solid mass or multi-segmental symmetric mural thickening involving the ileocecal area and rim enhanced LNs. Knowledge of these features in combination with a high index of suspicion can be useful in early diagnosis of ITB.

Grading of Crohn's disease activity using CT, MRI, US and scintigraphy: a meta-analysis

PURPOSE

To assess the grading of Crohn's disease activity using CT, MRI, US and scintigraphy.

MATERIALS AND METHODS

MEDLINE, EMBASE and Cochrane databases were searched (January 1983-March 2014) for studies evaluating CT, MRI, US and scintigraphy in grading Crohn's disease activity compared to endoscopy, biopsies or intraoperative findings. Two independent reviewers assessed the data. Three-by-three tables (none, mild, frank disease) were constructed for all studies, and estimates of accurate, over- and under-grading were calculated/summarized by fixed or random effects models.

RESULTS

Our search yielded 9356 articles, 19 of which were included. Per-patient data showed accurate grading values for CT, MRI, US and scintigraphy of 86% (95% CI: 75-93%), 84% (95% CI: 67-93%), 44% (95% CI: 28-61%) and 40% (95% CI: 16-70%), respectively. In the per-patient analysis, CT and MRI showed similar accurate grading estimates (P = 0.8). Per-segment data showed accurate grading values for CT and scintigraphy of 87% (95% CI: 77-93%) and 86% (95% CI: 80-91%), respectively. MRI and US showed grading accuracies of 67-82% and 56-75%, respectively.

CONCLUSIONS

CT and MRI showed comparable high accurate grading estimates in the per-patient analysis. Results for US and scintigraphy were inconsistent, and limited data were available.

KEY POINTS

• CT and MRI have comparable high accuracy in grading Crohn's disease. • Data on US and scintigraphy is inconsistent and limited. • MRI is preferable over CT as it lacks ionizing radiation exposure.

Systematic Review with Meta-analysis of Prospective Studies: Anti-tumour Necrosis Factor for Prevention of Postoperative Crohn's Disease Recurrence

BACKGROUND AND AIM

Although promising, the evidence supporting the use of anti-tumour necrosis factor agents [anti-TNFs] in postoperative Crohn's disease [CD] is still based on limited experience. We aimed to conduct a meta-analysis of prospective studies evaluating the efficacy and safety of anti-TNFs for prevention of postoperative recurrence [POR] in CD.

METHODS

MEDLINE, EMBASE, Web of Science, the Cochrane database and conference proceeding abstracts were searched. The primary outcome measure was the number of patients who developed POR as defined by the primary studies.

RESULTS

Six prospective studies were included. The rate of endoscopic recurrence [ER] was significantly lower using anti-TNFs [9.2%, 7/76] compared with the non-biologicals group [61.5%, 83/135] (odds ratio [OR] 0.05, 95% confidence interval [CI] 0.02-0.13; p < 0.001]. The rate of severe ER was also lower in the anti-TNFs group [1.6%, 1/64] than that in the non-biologicals group [32.7%, 18/55, OR 0.10; p = 0.04]. A significantly lower proportion of patients in the anti-TNFs group developed clinical recurrence [3.4%, 2/59] compared with the non-biologicals arm [41.1%, 49/119, OR 0.1; p < 0.001]. More anti-TNFs-treated patients [86.5%, 45/52] were maintained in clinical remission compared with the non-biologicals group [58.1%, 43/74, OR 4.05, 95% CI 1.60-10.29; p < 0.01]. The adverse events were similar between the two groups [anti-TNFs 44.9% [22/49] vs control 52.5% [42/80]; p = 0.69].

CONCLUSIONS

Anti-TNFs are superior to non-biological agents in preventing endoscopic and clinical recurrence of CD without causing more adverse events.

Diagnosis and monitoring of postoperative recurrence in Crohn's disease

Despite advances in medical management, many patients with Crohn's disease (CD) require intestinal surgery throughout their lives. Surgery is not a cure, and postoperative recurrence is common in patients with CD. Ileocolonoscopy has been considered to be the gold standard in the diagnosis and monitoring of postoperative recurrence. However, the optimal monitoring strategy for postoperative recurrence has yet to be established. Capsule endoscopy and cross-sectional imaging techniques, including ultrasonography, computed tomography and MRI, have been used in the postoperative setting, and their usefulness in the monitoring of disease activity has been evaluated in recent clinical trials. The value of fecal markers, such as calprotectin and lactoferrin, has been also assessed in several studies. This review was to identify optimized methods for the diagnosis and monitoring of postoperative recurrence in CD.

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.

Management of postoperative Crohn's disease

Surgical treatment does not cure Crohn's disease, and postoperative recurrence is a feature of the clinical course of the disease. Ileocolonoscopy remains the gold standard for the surveillance of recurrent Crohn's disease and should be performed 6-12 months after an operation. Many other non-invasive techniques are also useful and complement endoscopy for the early diagnosis of postoperative recurrence. Anti-TNF agents show great efficacy for the prevention of postoperative recurrence, and long-term use can maintain remission. It remains undetermined whether early treatment after postoperative endoscopic recurrence is ultimately as efficacious as prophylactic therapy.