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

Automatic Segmentation and Radiomics for Identification and Activity Assessment of CTE Lesions in Crohn's Disease

BACKGROUND

The purpose of this article is to develop a deep learning automatic segmentation model for the segmentation of Crohn's disease (CD) lesions in computed tomography enterography (CTE) images. Additionally, the radiomics features extracted from the segmented CD lesions will be analyzed and multiple machine learning classifiers will be built to distinguish CD activity.

METHODS

This was a retrospective study with 2 sets of CTE image data. Segmentation datasets were used to establish nnU-Net neural network's automatic segmentation model. The classification dataset was processed using the automatic segmentation model to obtain segmentation results and extract radiomics features. The most optimal features were then selected to build 5 machine learning classifiers to distinguish CD activity. The performance of the automatic segmentation model was evaluated using the Dice similarity coefficient, while the performance of the machine learning classifier was evaluated using the area under the curve, sensitivity, specificity, and accuracy.

RESULTS

The segmentation dataset had 84 CTE examinations of CD patients (mean age 31 ± 13 years, 60 males), and the classification dataset had 193 (mean age 31 ± 12 years, 136 males). The deep learning segmentation model achieved a Dice similarity coefficient of 0.824 on the testing set. The logistic regression model showed the best performance among the 5 classifiers in the testing set, with an area under the curve, sensitivity, specificity, and accuracy of 0.862, 0.697, 0.840, and 0.759, respectively.

CONCLUSION

The automated segmentation model accurately segments CD lesions, and machine learning classifier distinguishes CD activity well. This method can assist radiologists in promptly and precisely evaluating CD activity.

Residual abnormalities on CTE predict adverse outcomes in Crohn's disease with endoscopic healing

BACKGROUND

Residual abnormalities on computed tomography enterography (CTE) in Crohn's disease (CD) with endoscopic healing (EH) may have prognostic implications and affect therapeutic strategy.

METHODS

CD patients with EH who underwent CTE between March 2015 and June 2022 were enrolled. CTE findings of the terminal ileum and the most severe segment of colon at the time of EH were assessed respectively for each patient. Cox regression analysis and Kaplan-Meier curves were used to evaluate the association between residual abnormalities and adverse outcomes.

RESULTS

A total of 140 patients (217 digestive segments) were included. Mesenteric edema (hazard ratio [HR] = 3.61, 95% CI = 1.81-7.20, P<0.001), fibrofatty proliferation (HR = 3.40, 95% CI = 1.97-5.85, P<0.001) and active small bowel inflammation (HR = 2.74, 95% CI = 1.59-4.71, P<0.001) were risk factors for clinical relapse. Furthermore, we built a scoring system using the three parameters. Radiologic score ≥ 1 was the best threshold to predict clinical relapse (HR = 4.56, 95% CI = 2.54-8.19, P<0.001) and it was validated in different outcomes.

CONCLUSION

The scoring system based on three residual abnormalities on CTE can predict adverse outcomes in CD patients with EH.

Mucosal healing assessment in Crohn's disease with normalized iodine concentration from dual-energy CT enterography: comparison with endoscopy

OBJECTIVES

Mucosal healing (MH) is an important goal in the treatment of patients with Crohn's disease (CD). Noninvasive assessment of MH with normalized iodine concentration (NIC) is unknown.

METHODS

In this retrospective study, 94 patients with diagnosed CD underwent endoscopy and dual-energy CT enterography (DECTE) at the post-infliximab treatment review. Two radiologists reviewed DECTE images by consensus for assessing diseased bowel segments of the colon or terminal ileum, and the NIC was measured. Patients were divided into transmural healing (TH), MH and non-MH groups. The diagnostic performance of the MH and non-MH groups with clinical factors and NIC was assessed utilizing receiver operating characteristic (ROC) curve analysis.

RESULTS

Of the 94 patients included in our study, 8 patients achieved TH, 34 patients achieved MH, and 52 patients did not achieve MH at the post-IFX treatment review. The area under the ROC curve (AUC), sensitivity, specificity, and accuracy values were 0.929 (95% confidence interval [CI] 0.883-0.967), 0.853, 0.827, and 0.837, respectively, for differentiating MHs from non-MHs, and the optimal NIC threshold was 0.448. The AUC of the combined model for distinguishing MHs from non-MHs in CD patients, which was based on the NIC and calprotectin, was 0.964 (95% CI 0.935-0.987).

CONCLUSIONS

The normalized iodine concentration measurement in DECTE has good performance in assessment MH in patients with CD. Iodine concentration from DECTE can be used as a radiologic marker for MH.

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.

Avoiding contrast-enhanced sequences does not compromise the precision of the simplified MaRIA for the assessment of non-penetrating Crohn's disease activity

OBJECTIVES

Patients with Crohn's disease (CD) require multiple assessments with magnetic resonance enterography (MRE) from a young age. Standard MRE protocols for CD include contrast-enhanced sequences. Gadolinium deposits in brain tissue suggest avoiding gadolinium could benefit patients with CD. This study aimed to compare the accuracy of the simplified Magnetic Resonance Index of Activity (sMaRIA) calculated with and without contrast-enhanced sequences in determining the response to biologic drugs in patients with CD.

METHODS

This post hoc analysis of a prospective study included patients with CD with endoscopic ulceration in ≥ 1 intestinal segment starting biologic drug therapy. Two blinded radiologists used the sMaRIA to score images obtained at baseline and week 46 of treatment first using only unenhanced sequences (T2-sMaRIA) and 1 month later using both unenhanced and enhanced images (CE-sMaRIA). We calculated the rates of agreement between T2-sMaRIA, CE-sMaRIA, and ileocolonoscopy for different conceptualizations of therapeutic response.

RESULTS

A total of 46 patients (median age, 36 years [IQR: 28-47]) were included. Agreement with ileocolonoscopy was similar for CE-sMaRIA and T2-sMaRIA in identifying ulcer healing (kappa = 0.74 [0.55-0.93] and 0.70 [0.5-0.9], respectively), treatment response (kappa = 0.53 [0.28-0.79] and 0.44 [0.17 - 0.71]), and remission (kappa = 0.48 [0.22-0.73] and 0.43 [0.17-0.69]). The standardized effect size was moderate for both CE-sMaRIA = 0.63 [0.41-0.85] p < 0.001 and T2-sMaRIA = 0.58 [0.36-0.80] p < 0.001.

CONCLUSIONS

sMaRIA with and without contrast-enhanced images accurately classified the response according to different therapeutic endpoints determined by ileocolonoscopy.

KEY POINTS

• The simplified Magnetic Resonance Index of Activity is accurate for the assessment of Crohn's disease activity, severity, and therapeutic response, using four dichotomic components that can be evaluated without the need of using contrast-enhanced sequences, representing a practical and safety advantage, but concerns have been expressed as to whether the lack of contrast sequences may compromise precision. • The simplified Magnetic Resonance Index of Activity can assess the response to biologic therapy in patients with Crohn's disease without the need for intravenous contrast agents obtaining comparable results without and with contrast-enhanced sequences. • Avoiding intravenous contrast agents could reduce the duration of the MRE examination and its cost and would increase the acceptance and safety of MRE in clinical research in patients with Crohn's disease.

Magnetic resonance enterography in Crohn's disease patients: current state of the art and future perspectives

INTRODUCTION

Crohn's disease (CD) is a major concern due to relatively high incidence and major complications like stricture or fistulas, often requiring surgical treatment. In recent years, magnetic resonance enterography (MRE) became a popular method of diagnosis and disease surveillance. The purpose of this review is to summarize and discuss the major and most recent advances in various aspects of MRE usage in diagnosong Crohn's disease, and to discuss advances in technique, disease activity monitoring and response to treatment.

METHODS

A literature search was performed and relevant publications were included, with emphasis on articles from the past decade.

AREAS COVERED

In this review we have presented articles with major advances in the field of MRE of CD patients such as proper sequence selection, recent advances in scoring of disease activity, differentiation between inflammation and fibrosis, response to treatment and technological advances such as the use of AI.

EXPERT OPINION

The main goal in improving MRE performance will be sequence selection aimed at differenting between inflammation and stricture while shortening the study length adjusted to patient compliance, and developing a standardized scoring system for MRE reporting assisted by artificial intelligence.

Validation of the Simplified Magnetic Resonance Index of Activity [sMARIA] Without Gadolinium-enhanced Sequences for Crohn's Disease

BACKGROUND

Gadolinium-enhanced sequences are not included in the simplified Magnetic Resonance Index of Activity [sMARIA], but in the derivation of this index readers had access to these sequences. The current study aimed to validate the sMARIA without gadolinium-enhanced sequences for assessing disease activity, severity, and response to treatment in patients with Crohn's disease.

METHODS

We prospectively included patients with active Crohn's disease and at least one segment with severe inflammation [ulcers] at ileocolonoscopy, who required treatment with biologic drugs. Patients were evaluated by both magnetic resonance enterography [MRE] and ileocolonoscopy at baseline and 46 weeks after initiation of medical treatment. We compared the quantification of disease activity and response to treatment with sMARIA versus with ileocolonoscopy Crohn's Disease Index of Severity [CDEIS], considered the gold standard.

RESULTS

Data from both MRE and ileocolonoscopy 46 weeks after treatment initiation were available for 39 of the 50 patients. As in the derivation study, the optimal cutoffs were sMARIA ≥1 for predicting active disease (area under the curve [AUC] 0.92) and sMARIA ≥2 for predicting the presence of ulcers at ileocolonoscopy [AUC 0.93]. In evaluating the response to treatment, the sMARIA detected endoscopic ulcer healing at the segment level [sMARIA <2] with 89.5% sensitivity and 87.5% specificity. The sMARIA decreased significantly [p <0.001] in segments achieving endoscopic ulcer healing, but did not change [p = 0.222] in segments with persistent ulceration.

CONCLUSIONS

The sMARIA is accurate and reliable in quantifying disease activity and response to treatment in luminal Crohn's disease, without the need for gadolinium-enhanced sequences.

Imaging Findings of Ileal Inflammation at Computed Tomography and Magnetic Resonance Enterography: What do They Mean When Ileoscopy and Biopsy are Negative?

BACKGROUND AND AIMS

Our goal was to determine the importance of ileal inflammation at computed tomography or magnetic resonance enterography in Crohn's disease patients with normal ileoscopy.

METHODS

Patients with negative ileoscopy and biopsy within 30 days of CT or MR enterography showing ileal inflammation were included. The severity [0-3 scale] and length of inflammation within the distal 20 cm of the terminal ileum were assessed on enterography. Subsequent medical records were reviewed for ensuing surgery, ulceration at ileoscopy, histological inflammation, or new or worsening ileal inflammation or stricture on enterography. Imaging findings were classified as: Confirmed Progression [subsequent surgery or radiological worsening, new ulcers at ileoscopy or positive histology]; Radiologic Response [decreased inflammation with medical therapy]; or Unlikely/Unconfirmed Inflammation.

RESULTS

Of 1471 patients undergoing enterography and ileoscopy, 112 [8%] had imaging findings of inflammation with negative ileoscopy, and 88 [6%] had negative ileoscopy and ileal biopsy. Half [50%; 44/88] with negative biopsy had moderate/severe inflammation at enterography, with 45%, 32% and 11% having proximal small bowel inflammation, stricture or fistulas, respectively. Two-thirds with negative biopsy [67%; 59/88] had Confirmed Progression, with 68%, 70% and 61% having subsequent surgical resection, radiological worsening or ulcers at subsequent ileoscopy, respectively. Mean length and severity of ileal inflammation in these patients was 10 cm and 1.6. Thirteen [15%] patients had Radiologic Response, and 16 [18%] had Unlikely/Unconfirmed Inflammation.

CONCLUSION

Crohn's disease patients with unequivocal imaging findings of ileal inflammation at enterography despite negative ileoscopy and biopsy are likely to have active inflammatory Crohn's disease. Disease detected by imaging may worsen over time or respond to medical therapy.

Association of TRAP1 with infliximab-induced mucosal healing in Crohn's disease

BACKGROUND AND AIM

Anti-tumor necrosis factor (TNF) agents, such as infliximab (IFX), have been increasingly used to induce and maintain disease remission in patients with Crohn's disease (CD). Despite a considerable non-response rate, little is known about the genetic predictors of response to anti-TNF therapy in CD. Our aim in this study was to investigate the genetic factors associated with response to anti-TNF therapy in patients with CD.

METHODS

We performed a two-stage genome-wide association study (GWAS) to identify loci influencing the response to IFX among Korean patients with CD, comprising 42 good responders with mucosal healing and 70 non-responders. The achievement of mucosal healing was assessed by endoscopy and imaging. The functional significance of TRAP1 (TNF receptor associated protein 1) was examined using dextran sodium sulfate-induced colitis model in TRAP1 transgenic mice.

RESULTS

The GWAS identified rs2158962, an intronic single nucleotide polymorphism (SNP) of TRAP1, significantly associated with mucosal healing (odds ratio = 4.94; P_combined  = 1.35 × 10^-7 ). In the dextran sodium sulfate-induced acute colitis, TRAP1 transgenic mice showed a better response to IFX than the wild-type mice.

CONCLUSIONS

The TRAP1 gene is associated with mucosal healing in CD patients following IFX therapy. Identifying the genetic predictors of mucosal healing to anti-TNF therapy can prevent patients from exposure to ineffective therapies.

Persistent damage on magnetic resonance enterography in patients with Crohn's disease in endoscopic remission

BACKGROUND

In Crohn's disease, it is essential to distinguish between persistent damage and abnormalities that can heal with anti-inflammatory therapy.

AIM

To assess magnetic resonance enterography (MRE) lesions that persist in patients in long-standing endoscopic remission, analyse their relationship with baseline characteristics, and determine their prognostic implications.

METHODS

We systematically reviewed pre- and post-treatment MRE findings in patients with Crohn's disease and severe inflammation (segmental CDEIS ≥ 7 or ulcers in at least one segment) who achieved endoscopic remission (CDEIS < 2) after 1 year of treatment with TNF-inhibitors or autologous haematopoietic stem-cell transplantation. Logistic regression analysis was used to identify predictors of persistent abnormalities.

RESULTS

Endoscopic remission was achieved in 73 intestinal segments in 28 patients (69% females; 9.95 years disease duration, 67.9% inflammatory phenotype; 39.3% ileal location). Creeping fat and intestinal wall fat deposits were unchanged on pre- and post-treatment MRE despite the endoscopic remission. Luminal strictures persisted in 6 out of the 8 segments with baseline strictures, and wall thickening in 23 out of the 72 of segments with thickening at baseline. Predictors of persistent mural thickening were pre-treatment wall thickness > 5.9 mm (OR = 4.38, P = 0.027) and refractory disease prior to baseline (OR = 2.35, P = 0.001). Creeping fat was the only predictor for persistence of creeping fat (OR = 36.43, P < 0.001). Persistence of strictures at MRE is associated with earlier recurrence (P = 0.014).

CONCLUSIONS

Persistent MRE abnormalities are frequent in patients with Crohn's disease despite achieving endoscopic remission. Significant wall thickening, intestinal fat deposition, strictures, and creeping fat at baseline MRE are signs of established damage.

Diagnostic Value of Computed Tomography in Crohn's Disease Patients Presenting with Acute Severe Lower Gastrointestinal Bleeding

Objective

To investigate the diagnostic yield of contrast-enhanced computed tomography (CT) in Crohn's disease (CD) patients presenting with acute severe lower gastrointestinal bleeding (LGIB), and the role of CT in predicting the risk of rebleeding.

Materials and Methods

A consecutive series of 110 CD patients presenting with acute severe LGIB between 2005 and 2016 were analyzed. Among them, 86 patients who had undergone contrast-enhanced CT constituted the study cohort. The diagnostic yield of CT for detecting contrast extravasation was obtained for the entire cohort and compared between different CT techniques. In a subgroup of 62 patients who had undergone CT enterography (CTE) and showed a negative result for extravasation on CTE, the association between various clinical and CTE parameters and the risk of rebleeding during subsequent follow-up was investigated using Cox regression analysis.

Results

The diagnostic yield of CT was 10.5% (9 of 86 patients). The yield did not significantly differ between single-phase and multiphase examinations (p > 0.999), or between non-enterographic CT and CTE (p = 0.388). Extensive CD (adjusted hazard ratio [HR], 3.27; 95% confidence interval [CI], 1.09–9.80; p = 0.034) and bowel wall-to-artery enhancement ratio (adjusted HR, 2.81; 95% CI, 1.21–6.54; p = 0.016) were significantly independently associated with increased rebleeding risks, whereas anti-tumor necrosis factor-α therapy after the bleeding independently decreased the risk of rebleeding (adjusted HR, 0.26; 95% CI, 0.07–0.95; p = 0.041).

Conclusion

The diagnostic yield of contrast-enhanced CT was not high in CD patients presenting with acute severe LGIB. Nevertheless, even a negative CTE may be beneficial as it can help predict the risk of later rebleeding.

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.

Comparison of diagnostic performance between 1 millisievert CT enterography and half-standard dose CT enterography for evaluating active inflammation in patients with Crohn's disease

PURPOSE

To compare the diagnostic performance of CT enterography (CTE) images obtained at 1 millisievert (mSv) and reconstructed with filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR) with those of half-dose CTE images for the evaluation of active inflammation in patients with Crohn's disease.

METHODS

Forty-six consecutive patients (mean age 29 years; range 15-59 years) with Crohn's disease underwent CTE which comprised a standard-dose scan at the enteric phase (45 s), a half-dose scan with ASIR at the portal venous phase (70 s), and 1 mSv scans with FBP and ASIR at the delayed phase (90 s) under a fixed 120 kVp and variable mAs. Two blinded readers independently recorded confidence scores for active inflammation in the ileum and terminal ileum, respectively. The diagnostic performance of each image set was compared by pairwise comparison of receiver operating characteristic curves. The established image findings on standard-dose scan and ileocolonoscopy served as the reference standard.

RESULTS

A total of 92 bowel segments were analyzed. For reader 1, the diagnostic performance was increased from 1 mSv CT with FBP and 1 mSv CT with ASIR to half-dose scan with ASIR (AUC, 0.759, 0.794, and 0.845; P = 0.1429, P = 0.0107, respectively). For reader 2, there was no significant difference among the three image sets (AUC, 0.848, 0.865, and 0.845; P > 0.05, respectively).

CONCLUSIONS

The diagnostic performance of 1 mSv CTE may be comparable to that of half-dose CTE.