Mural attenuation in normal small bowel and active inflammatory Crohn’s disease on CT enterography: location, absolute attenuation, relative attenuation, and the effect of wall thickness. AJR Am J Roentgenol. 2009;192:417-423. [PMID: 19155404 DOI: 10.2214/AJR.08.1267]

Computed Tomography and Magnetic Resonance Enterography: From Protocols to Diagnosis

Both Magnetic Resonance Enterography (MRE) and Computed Tomography Enterography (CTE) are crucial imaging modalities in the diagnosis and treatment of inflammatory bowel disease (IBD). CTE is often used in acute scenarios, such as when complications (such as abscesses, perforations, or bowel obstructions) are suspected. It can also help determine the degree and extent of pathological processes. Although CTE is rapid, generally accessible, and offers precise images that are useful in emergencies, it does expose patients to ionizing radiation. Nevertheless, MRE is very useful in assessing perianal illness and the small intestine, and it is frequently used in patients who need repeated follow-ups or are pregnant to minimize radiation exposure. Moreover, MRE can demonstrate oedema, fistulas, abscesses, and the thickening of the bowel wall. In addition, MRE offers superior soft tissue contrast resolution without ionizing radiation, which helps identify complications such as fistulas and abscesses. With their respective advantages and disadvantages, both approaches play essential roles in assessing IBD. The primary goal of this review is to provide an overview of the technical specifications, benefits, drawbacks, and imaging findings of CTE and MRE.

Dual-energy CT late arterial phase iodine maps for the diagnosis of acute non-occlusive mesenteric ischemia

PURPOSE

To evaluate the diagnostic accuracy of dual-energy CT (DECT) iodine maps in comparison to conventional CT series for the assessment of non-occlusive mesenteric ischemia (NOMI).

MATERIAL AND METHODS

We evaluated data from 142 patients (72 men; 50.7%) who underwent DECT between 2018 and 2022, with surgically confirmed diagnosis of NOMI. One board-certified radiologist performed region of interest (ROI) measurements in bowel segments on late arterial (LA) and portal venous (PV) phase DECT iodine maps as well as LA conventional series, in both ischemic and non-ischemic bowel loops, using surgical reports as reference standard, and in a control group of 97 patients. Intra- and inter-reader agreement with a second board-certified radiologist was also evaluated. Receiver operating characteristic (ROC) curve analysis was performed to calculate the optimal threshold for discriminating ischemic from non-ischemic bowel segments. Subjective image rating of LA and PV iodine maps was performed.

RESULTS

DECT-based iodine concentration (IC) measurements showed significant differences in LA phase iodine maps between ischemic (median:0.72; IQR 0.52-0.91 mg/mL) and non-ischemic bowel loops (5.16; IQR 3.45-6.31 mg/ml) (P <.0001). IC quantification on LA phase revealed an AUC of 0.966 for the assessment of acute bowel ischemia, significantly higher compared to both IC quantification based on PV phase (0.951) and attenuation values evaluated on LA conventional CT series (0.828). Excellent intra-observer and strong inter-observer agreements were observed for the quantification of iodine concentration. Conversely, weak inter-observer agreement was noted for conventional HU assessments. The optimal LA phase-based IC threshold for assessing bowel ischemia was 1.34 mg/mL, yielding a sensitivity of 100% and specificity of 96.48%.

CONCLUSION

Iodine maps based on LA phase significantly improve the diagnostic accuracy for the assessment of NOMI compared to conventional CT series and PV phase iodine maps.

Reliability of CT Enterography for Describing Fibrostenosing Crohn Disease

Background Standardized methods to measure and describe Crohn disease strictures at CT enterography are needed to guide clinical decision making and for use in therapeutic studies. Purpose To assess the reliability of CT enterography features to describe Crohn disease strictures and their correlation with stricture severity. Materials and Methods A retrospective study was conducted in 43 adult patients with symptomatic terminal ileal Crohn disease strictures who underwent standard-of-care CT enterography at a tertiary care center at the Cleveland Clinic between January 2008 and August 2016. After training on standardized definitions, four abdominal radiologists blinded to all patient information assessed imaging features (seven continuous measurements and nine observations) of the most distal ileal stricture in two separate sessions (separated by ≥2 weeks) in random order. Features with an interrater intraclass correlation coefficient (ICC) of 0.41 or greater (ie, moderate reliability or better) were considered reliable. Univariable and multivariable linear regression analysis identified reliable features associated with a visual analog scale of overall stricture severity. Significant reliable features were assessed as components of a CT enterography-based model to quantitate stricture severity. Results Examinations in 43 patients (mean age, 52 years ± 16 [SD]; 23 female) were evaluated. Five continuous measurements and six observations demonstrated at least moderate interrater reliability (interrater ICC range, 0.42 [95% CI: 0.25, 0.57] to 0.80 [95% CI: 0.67, 0.88]). Of these, 10 were univariably associated with stricture severity, and three continuous measurements-stricture length (interrater ICC, 0.64 [95% CI: 0.42, 0.81]), maximal associated small bowel dilation (interrater ICC, 0.80 [95% CI: 0.67, 0.88]), and maximal stricture wall thickness (interrater ICC, 0.50 [95% CI: 0.34, 0.62])-were independently associated (P value range, <.001 to .003) with stricture severity in a multivariable model. These three measurements were used to derive a well-calibrated (optimism-adjusted calibration slope = 1.00) quantitative model of stricture severity. Conclusion Standardized CT enterography measurements and observations can reliably describe terminal ileal Crohn disease strictures. Stricture length, maximal associated small bowel dilation, and maximal stricture wall thickness are correlated with stricture severity. © RSNA, 2024 Supplemental material is available for this article. See also the article by Rieder et al in this issue. See also the editorial by Galgano and Summerlin in this issue.

Evaluation of Mucosal Healing in Crohn's Disease: Radiomics Models of Intestinal Wall and Mesenteric Fat Based on Dual-Energy CT

This study aims to assess the effectiveness of radiomics signatures obtained from dual-energy computed tomography enterography (DECTE) in the evaluation of mucosal healing (MH) in patients diagnosed with Crohn's disease (CD). In this study, 106 CD patients with a total of 221 diseased intestinal segments (79 with MH and 142 non-MH) from two medical centers were included and randomly divided into training and testing cohorts at a ratio of 7:3. Radiomics features were extracted from the enteric phase iodine maps and 40-kev and 70-kev virtual monoenergetic images (VMIs) of the diseased intestinal segments, as well as from mesenteric fat. Feature selection was performed using the least absolute shrinkage and selection operator (LASSO) logistic regression. Radiomics models were subsequently established, and the accuracy of these models in identifying MH in CD was assessed by calculating the area under the receiver operating characteristic curve (AUC). The combined-iodine model formulated by integrating the intestinal and mesenteric fat radiomics features of iodine maps exhibited the most favorable performance in evaluating MH, with AUCs of 0.989 (95% confidence interval (CI) 0.977-1.000) in the training cohort and 0.947 (95% CI 0.884-1.000) in the testing cohort. Patients categorized as high risk by the combined-iodine model displayed a greater probability of experiencing disease progression when contrasted with low-risk patients. The combined-iodine radiomics model, which is built upon iodine maps of diseased intestinal segments and mesenteric fat, has demonstrated promising performance in evaluating MH in CD patients.

Intestinal MRI in Inflammatory Bowel Disease - Literature and Survey-Based Recommendations regarding Reporting by the German Radiological Society (DRG) and the German Competence Network for Inflammatory Bowel Diseases

BACKGROUND

MR-enterography/enteroclysis (MRE) is increasingly used for primary diagnosis, detection of complications, and monitoring of patients with inflammatory bowel disease (IBD). Standardization of reporting is relevant to ensure quality of the methodology and to improve communication between different faculties. The current manuscript describes the features that are required for optimized reporting of MRE in IBD.

METHODS

An expert consensus panel of radiologists and gastroenterologists conducted a systematic search of the literature. In a Delphi process, members of the German Radiological Society (DRG) and members of the Competence Network for Inflammatory Bowel Diseases voted on relevant criteria for the reporting of findings in MRE. Based on the voting results, statements were developed by the expert consensus panel.

RESULTS

Clinically relevant aspects of MRE findings have been defined to optimize reporting and to standardize terminology. Minimal requirements for standardized reporting are suggested. The statements focus on the description of disease activity as well as on complications of IBD. Attributes of intestinal inflammation are described and illustrated by exemplary images.

CONCLUSION

The current manuscript provides standardized parameters and gives practical recommendations on how to report and how to characterize MRE findings in patients with IBD.

KEY POINTS

· Systematic overview provides practice-oriented recommendations and names and evaluates the decisive criteria for reporting and interpretation of MRI in inflammatory bowel disease.. · Standardized terminology and reporting criteria for MRI in IBD improves interdisciplinary communication.. · Standardized collection and documentation of MRI findings in IBD helps to further establish the method and to improve care for IBD patients..

CITATION FORMAT

· Wessling J, Kucharzik T, Bettenworth D et al. Intestinal MRI in Inflammatory Bowel Disease - Literature and Survey-Based Recommendations regarding Reporting by the German Radiological Society (DRG) and the German Competence Network for Inflammatory Bowel Diseases. Fortschr Röntgenstr 2023; 195: 675 - 690.

Dual-Energy CT for Accurate Discrimination of Intraperitoneal Hematoma and Intestinal Structures

The purpose of this study was to evaluate the potential of dual-energy CT (DECT) with virtual unenhanced imaging (VNC) and iodine maps (IM) to differentiate between intraperitoneal hematomas (IH) and bowel structures (BS) compared to linearly blended DECT (DE-LB) images (equivalent to single-energy CT). This retrospective study included the DECT of 30 patients (mean age: 64.5 ± 15.1 years, 19 men) with intraperitoneal hematomas and 30 negative controls. VNC, IM, and DE-LB were calculated. Imaging follow-up and surgical reports were used as references. Three readers assessed diagnostic performance and confidence in distinguishing IH and BS for DE-LB, VNC, and IM. Diagnostic confidence was assessed on a five-point Likert scale. The mean values of VNC, IM, and DE-LB were compared with nonparametric tests. Diagnostic accuracy was assessed by calculating receiver operating characteristics (ROC). The results are reported as medians with interquartile ranges. Subjective image analysis showed higher diagnostic performance (sensitivity: 96.7−100% vs. 88.2−96.7%; specificity: 100% vs. 96.7−100%; p < 0.0001; ICC: 0.96−0.99) and confidence (Likert: 5; IRQ [5−5] vs. 4, IRQ [3−4; 4−5]; p < 0.0001; ICC: 0.80−0.96) for DECT compared to DE-LB. On objective image analysis, IM values for DECT showed significant differences between IH (3.9 HU; IQR [1.6, 8.0]) and BS (39.5 HU; IQR [29.2, 43.3]; p ≤ 0.0001). VNC analysis revealed a significantly higher attenuation of hematomas (50.5 HU; IQR [44.4, 59.4]) than BS (26.6 HU; IQR [22.8, 32.4]; p ≤ 0.0001). DE-LB revealed no significant differences between hematomas (60.5 HU, IQR [52.7, 63.9]) and BS (63.9 HU, IQR [58.0, 68.8]; p > 0.05). ROC analysis revealed the highest AUC values and sensitivity for IM (AUC = 100%; threshold by Youden-Index ≤ 19 HU) and VNC (0.93; ≥34.1 HU) compared to DE-LB (0.64; ≤63.8; p < 0.001). DECT is suitable for accurate discrimination between IH and BS by calculating iodine maps and VNC images.

Crohn's disease active inflammation assessment with iodine density from dual-energy CT enterography: comparison with endoscopy and conventional interpretation

PURPOSE

To compare terminal ileum (TI) mucosal iodine density obtained at dual-energy CT enterography (DECTE) with conventional CT interpretation and endoscopy in patients with Crohn's disease (CD).

MATERIALS AND METHODS

Twenty-three CD patients (14 men; mean[SD] age:48.1[16.7] years) with endoscopy within 30 days of DECTE were retrospectively identified. An inflammatory bowel disease gastroenterologist reviewed endoscopic images. Two radiologists qualitatively assessed the presence of active TI inflammation. Mean iodine density normalized to the aorta (I%), mean absolute iodine density (I), and iodine density standard deviation (I_SD) from the distal 2 cm ileum (TI) mucosa obtained using semiautomatic prototype software were compared with endoscopic assessment using Mann Whitney tests. The optimal threshold I% and I were determined from receiver operating curves (ROC). Sensitivity and specificity of conventional interpretation and determined iodine thresholds were compared using McNemar's test. Inter-reader agreement was assessed using kappa. A p < 0.05 indicated statistical significance.

RESULTS

Twelve (52.1%) patients had endoscopic active inflammation. I% was 37.9[13.3]% for patients with and 21.7[7.5]% for patients without endoscopic active inflammation (p = 0.001). The optimal ROC threshold 24.6% had 100% sensitivity and 81.8% specificity (AUC = 0.909, 95% CI 0.777-1). I was 2.44[0.73]mg/mL for patients with and 1.77[1.00]mg/mL for patients without active endoscopic inflammation (p = 0.0455). The optimal ROC threshold 1.78 mg/mL I had 91.7% sensitivity and 63.6% specificity (AUC = 0.75, 95% CI 0.532-0.968). I_SD was similar for patients with and without endoscopic active inflammation (0.82[0.33]mg/mL and 0.77[0.28]mg/mL, respectively, p = 0.37). Conventional interpretation sensitivity and specificity (R1/R2) were 83.3%/91.7% and 72.7%/54.5%, respectively (all p > 0.05) with moderate inter-reader agreement (Κ = 0.542[95% CI 0.0202-0.088]).

CONCLUSION

Mean normalized iodine density is highly sensitive and specific for endoscopic active inflammation. DECTE could be considered as a surrogate to endoscopy in CD patients. Despite trends towards improved sensitivity and specificity compared with conventional interpretation, future larger studies are needed.

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

Backgrond and Objective

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

Methods

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

Results

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

Conclusion

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

Supplementary Information

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

Dual energy computed tomography in Crohn's disease: a targeted review

INTRODUCTION

Crohn's disease (CD) is a common chronic inflammatory bowel disease characterized by transmural inflammation and extra-intestinal complications. The diagnosis of CD is made using a combination of clinical, biochemical, endoscopic, imaging and histological features. Among imaging methods, computed tomography enterography (CTE) is the most commonly used. Dual-energy CTE allows objective evaluation of patients with CD. Along with the findings seen in conventional CTE, dual-energy CTE can generate iodine density maps and quantify the iodine content in the involved segments of the bowel, thus providing a measure of the perfusion of the affected bowel. In addition, the virtual monochromatic images generated from dual-energy CTE allow better qualitative evaluation of the mural and extramural findings.

AREAS COVERED

We performed a targeted systemic review of all the studies in the literature to understand the role of dual-energy CT in the diagnosis and assessment of the severity of CD.

EXPERT OPINION

Dual-energy CTE is superior to conventional CTE in the evaluation of CD. Besides quantifying iodine in the pathological segments, other quantitative parameters like the mural thickness of affected bowel segments, the number of segments involved, ulcerations, comb sign, lymphadenopathy, and the mural heterogeneity can also be assessed in dual-energy CTE.

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.

Appendiceal involvement in pediatric inflammatory multisystem syndrome temporally associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2): a diagnostic challenge in the coronavirus disease (COVID) era

BACKGROUND

Many studies on pediatric inflammatory multisystem syndrome temporally associated with severe acute respiratory syndrome coronavirus 2 (PIMS-TS) have described abdominal findings as part of multisystem involvement, with limited descriptions of abdominal imaging findings specific to PIMS-TS.

OBJECTIVE

To perform a detailed evaluation of abdominal imaging findings in children with PIMS-TS.

MATERIALS AND METHODS

We performed a single-center retrospective study of children admitted to our institution between April 2020 and January 2021 who fulfilled Royal College of Paediatrics and Child Health criteria for PIMS-TS and who had cross-sectional abdominal imaging. We studied clinical data, abdominal imaging, laboratory markers, echocardiography findings, treatment and outcomes for these children. We also reviewed the literature on similar studies.

RESULTS

During the study period, 60 PIMS-TS cases were admitted, of whom 23 required abdominal imaging. Most (74%) were from a Black, Asian or minority ethnic background and they had an average age of 7 years (range 2-14 years). All children had fever and gastrointestinal symptoms on presentation with elevated C-reactive protein, D-dimer and fibrinogen. Most had lymphopenia, raised ferritin and hypoalbuminemia, with positive severe acute respiratory syndrome coronavirus 2 immunoglobulin G antibodies in 65%. Free fluid (78%), right iliac fossa mesenteric inflammation (52%), and significantly enlarged mesenteric lymph nodes (52%) were the most common imaging findings. Appendiceal inflammation (30%) and abnormal distal ileum and cecum/ascending colon wall thickening (35%) were also common. All children responded well to medical management alone, with no mortality.

CONCLUSION

In addition to free fluid, prominent lymphadenopathy, and inflammatory changes in the right iliac fossa, we found abnormal long-segment ileal thickening and appendicitis to be frequent findings. Recognition of appendiceal involvement as a component of the PIMS-TS spectrum should help clinicians avoid unnecessary surgical intervention as part of a multidisciplinary team approach.

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.

MRE Evaluation of Intestinal Inflammation: Qualitative and Quantitative Assessment

ABSTRACT

Magnetic resonance enterography (MRE) is a powerful tool for evaluation and management of patients with Crohn disease. Changes of active inflammation of the small bowel can reliably and reproducibly be detected and monitored. Findings indicative of active inflammation include bowel wall thickening, intramural edema and mural hyperenhancement. These changes are most commonly reported qualitatively; however, quantitative indices have also been developed and validated to measure and monitor inflammation both for clinical care and research purposes. This article describes the essential findings of active inflammation on MRE as well as the fundamentals of both qualitative and quantitative assessment and reporting.

Pouch wall thickness and floppy pouch complex

BACKGROUND

Floppy pouch complex (FPC) consists of disease phenotypes in patients with ileal pouches, including pouch prolapse, afferent limb syndrome, enterocele, redundant loop, and pouch folding. Our recent study demonstrated that lower body weight, lower peripouch fat, family history of inflammatory bowel disease (IBD), female gender, and dyschezia are risk factors for FPC patients with IBD. The aims of this study were to assess the relationship between pouch wall thickness and FPC, and to investigate the association between inflamed and non-inflamed pouch wall thickness.

METHODS

This case-control study included all eligible patients with FPC from our prospectively maintained, IRB-approved Pouchitis Registry from 2011 to 2017. We measured pouch wall thickness of fully distended pouches on cross-sectional abdominal and pelvic imaging. Patients with stoma and non-distended pouches were completely excluded. Risk factors for FPC were analyzed.

RESULTS

A total of 140 out of 451 patients from our were found to have fully distended pouches on imaging. Of the 140 patients, 36 (25.7%) were diagnosed as having FPC. We analyzed pouch wall thickness for each subcategory of FPC as well as non-FPC conditions. The thickness of pouch wall was follows: pouch prolapse (N = 19): 1.5 mm (1.5-2.0), afferent limb syndrome (N = 12): 1.5 mm (1.1-2.0), folded pouch (N = 4): 1.5 mm (1.1-1.9), and redundant pouch (N = 2): 1.3 mm (1.0-1.3). The control group (N = 104) consisting of normal pouch, pouchitis, cuffitis, Crohn's disease of the pouch, and pouch sinus with median pouch wall thickness of 1.5 mm, 2.3 mm, 2.0 mm, 2.0 mm, and 1.5 mm, respectively. There were significant differences in pouch wall thickness between normal or non-inflamed pouch versus pouchitis versus cuffitis versus Crohn's disease of the pouch with p values of 0.01, 0.04, 0.05, and 0.049, respectively.

CONCLUSION

Patients with FPC were shown to have thin pouch wall, which those with inflammatory conditions of the pouch tended to have thick pouch wall. These findings will have implications in both diagnosis and investigation of etiopathogenesis of these disorders.

ACR Appropriateness Criteria® Crohn Disease

Three common clinical scenarios involving use of imaging in Crohn disease are covered. These include the initial evaluation of Crohn disease when the diagnosis has not been previously established, the evaluation for anticipated exacerbation of known disease, and the evaluation of disease activity during therapy monitoring. The appropriateness of a given imaging modality for each scenario is rated as one of three categories (usually appropriate, may be appropriate, usually not appropriate) to help guide evaluation. Pediatric presentation of Crohn disease and the appropriateness of imaging are not covered in this document. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Feasibility study using iodine quantification on dual-energy CT enterography to distinguish normal small bowel from active inflammatory Crohn's disease

BACKGROUND

Assessment of Crohn's disease (CD) activity is important to identify patients with active inflammation for therapy management. Quantitative analysis can provide objective measurement of disease presence.

PURPOSE

To evaluate the feasibility of quantitative analysis of contrast-enhanced dual-energy computed tomography (DECT) data in detection of small bowel inflammation in patients with CD with an emphasis on iodine quantification.

MATERIAL AND METHODS

DECT enterography was prospectively performed in 20 patients with active CD and in 20 healthy individuals, as the control group. Iodine overlay images were created. Wall thickness, attenuation, absolute iodine density, relative iodine density, and fat fraction were measured in the terminal ileum of all patients by two radiologists. Intraclass correlation coefficients were calculated to assess inter-rater agreement. Parameters were compared between patient groups using mixed model analysis. Receiver operating characteristic (ROC) analysis was performed.

RESULTS

Both absolute and relative iodine density were significantly higher in active disease than in normal small bowel (all P < 0.001). In contrast, measurement of fat fraction was not significantly different in affected terminal ileal loops compared to normal terminal ileum ( P = 0.075). ROC analysis demonstrated a similar excellent diagnostic accuracy of wall thickness, attenuation, and absolute and relative iodine density with area under the ROC curve (AUC) values in the range of 0.96 for attenuation to 1 for relative iodine density.

CONCLUSION

DECT with iodine quantification can be used in distinguishing normal small bowel from active inflammatory CD. Further research should investigate the value of iodine quantification in grading CD activity and in monitoring therapeutic response.

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.

Consensus Recommendations for Evaluation, Interpretation, and Utilization of Computed Tomography and Magnetic Resonance Enterography in Patients With Small Bowel Crohn's Disease

Computed tomography and magnetic resonance enterography have become routine small bowel imaging tests to evaluate patients with established or suspected Crohn's disease, but the interpretation and use of these imaging modalities can vary widely. A shared understanding of imaging findings, nomenclature, and utilization will improve the utility of these imaging techniques to guide treatment options, as well as assess for treatment response and complications. Representatives from the Society of Abdominal Radiology Crohn's Disease-Focused Panel, the Society of Pediatric Radiology, the American Gastroenterological Association, and other experts, systematically evaluated evidence for imaging findings associated with small bowel Crohn's disease enteric inflammation and established recommendations for the evaluation, interpretation, and use of computed tomography and magnetic resonance enterography in small bowel Crohn's disease. This work makes recommendations for imaging findings that indicate small bowel Crohn's disease, how inflammatory small bowel Crohn's disease and its complications should be described, elucidates potential extra-enteric findings that may be seen at imaging, and recommends that cross-sectional enterography should be performed at diagnosis of Crohn's disease and considered for small bowel Crohn's disease monitoring paradigms. A useful morphologic construct describing how imaging findings evolve with disease progression and response is described, and standard impressions for radiologic reports that convey meaningful information to gastroenterologists and surgeons are presented.

Capsule Endoscopy Validation of the Magnetic Enterography Global Score in Patients with Established Crohn's Disease

BACKGROUND AND AIMS

Capsule endoscopy [CE] and magnetic resonance enterography [MRE] are prime modalities for evaluation of the small bowel in Crohn's disease [CD]. Detection of proximal small bowel [SB] inflammation in CD by MRE is challenging. Currently available quantitative MRE scores do not incorporate proximal SB data. The MRE global score [MEGS] was designed for quantitative evaluation of the entire digestive tract; its accuracy in the proximal SB has not previously been evaluated. This study compared the evaluation of the small bowel inflammation by MEGS and CE-derived quantitative score (the Lewis score[LS]).

METHODS

CD patients in stable clinical remission were prospectively recruited and underwent MRE and CE; faecal calprotectin [FC] levels were obtained. MEGS was calculated for each SB segment and the entire SB [SBMEGS]. SB inflammation on CE was quantified using LS. A cumulative Lewis score [C-LS] was calculated based on summation of three tertiles scores.

RESULTS

Fifty patients were included. There was a significant correlation of SBMEGS with LS and C-LS [r = 0.61 and 0.71, both p = 0.001]. The correlation with FC was stronger for MEGS than for LS or C-LS [r = 0.68 vs r = 0.46 vs r = 0.53, all p = 0.001]. The correlation between the proximal LS and MEGS was significant [r = 0.55, p = 0.001]; median MEGS was significantly different in patients, with LS values consistent with mucosal healing, mild and moderate-to-severe inflammation.

CONCLUSIONS

MEGS provides accurate evaluation of the SB and strongly correlates with FC; the main advantage of MEGS is the accurate quantification of proximal SB inflammation unavailable for alternative MRE scores.

Consensus Recommendations for Evaluation, Interpretation, and Utilization of Computed Tomography and Magnetic Resonance Enterography in Patients With Small Bowel Crohn's Disease

Computed tomography and magnetic resonance enterography have become routine small bowel imaging tests to evaluate patients with established or suspected Crohn's disease, but the interpretation and use of these imaging modalities can vary widely. A shared understanding of imaging findings, nomenclature, and utilization will improve the utility of these imaging techniques to guide treatment options, as well as assess for treatment response and complications. Representatives from the Society of Abdominal Radiology Crohn's Disease-Focused Panel, the Society of Pediatric Radiology, the American Gastroenterological Association, and other experts, systematically evaluated evidence for imaging findings associated with small bowel Crohn's disease enteric inflammation and established recommendations for the evaluation, interpretation, and use of computed tomography and magnetic resonance enterography in small bowel Crohn's disease. This work makes recommendations for imaging findings that indicate small bowel Crohn's disease, how inflammatory small bowel Crohn's disease and its complications should be described, elucidates potential extra-enteric findings that may be seen at imaging, and recommends that cross-sectional enterography should be performed at diagnosis of Crohn's disease and considered for small bowel Crohn's disease monitoring paradigms. A useful morphologic construct describing how imaging findings evolve with disease progression and response is described, and standard impressions for radiologic reports that convey meaningful information to gastroenterologists and surgeons are presented. ^©2018, RSNA, AGA Institute, and Society of Abdominal Radiology This article is being published jointly in Radiology and Gastroenterology.

Imaging of Uncommon Causes of Large-Bowel Obstruction

OBJECTIVE

The most common causes of large-bowel obstruction (LBO) are colon carcinoma and volvulus. Nevertheless, the increased frequency of the condition and widespread use of diagnostic imaging have revealed uncommon causes of LBO. We review the imaging features of the unusual causes of LBO on several imaging modalities, with particular emphasis on CT, along with the current literature.

CONCLUSION

We propose an algorithmic approach to the radiologic evaluation of the uncommon causes of LBO.

Crohn's disease diagnosis, treatment approach, and management paradigm: what the radiologist needs to know

Crohn's disease is one of the major subtypes of idiopathic inflammatory bowel disease and is characterized by chronic transmural intestinal inflammation of the gastrointestinal tract anywhere from mouth to the anus, with a predilection for the small bowel. Cross-sectional imaging with computed tomography and magnetic resonance enterography plays a key role in confirming diagnosis, identifying and managing complications, assessing disease severity, and identifying response to medical therapy. This review will focus on the role of radiologists in the diagnosis and assessment of Crohn's disease. Additionally, a review of current medical therapy approaches, available medications, and side effects will be discussed. The review will also highlight key complications of medical therapy and associated diseases that should be evaluated by the radiologist with cross-sectional imaging.

ACR Appropriateness Criteria Crohn Disease

Crohn disease is a chronic inflammatory disorder involving the gastrointestinal tract, characterized by episodic flares and times of remission. Underlying structural damage occurs progressively, with recurrent bouts of inflammation. The diagnosis and management of this disease process is dependent on several clinical, laboratory, imaging, endoscopic, and histologic factors. In recent years, with the maturation of CT enterography, and MR enterography, imaging has played an increasingly important role in relation to Crohn Disease. In addition to these specialized examination modalities, ultrasound and routine CT have potential uses. Fluoroscopy, radiography, and nuclear medicine may be less beneficial depending on the clinical scenario. The imaging modality best suited to evaluating this disease may change, depending on the target population, severity of presentation, and specific clinical situation. This document presents seven clinical scenarios (variants) in both the adult and pediatric populations and rates the appropriateness of the available imaging options. They are summarized in a consolidated table, and the underlying rationale and supporting literature are presented in the accompanying narrative. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

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.

Intestinal wall thickness detected by multidetector spiral computed tomography enterography predicts the disease severity of Crohn's disease

OBJECTIVE

Multidetector spiral computed tomography enterography (MSCTE) and ileocolonoscopy are used in evaluating inflammatory situation of Crohn's disease (CD) patients. The purpose of this study was to determine the disease severity of CD patients by combining the intestinal wall thickness by MSCTE with ileocolonoscopy.

MATERIAL AND METHODS

This retrospective study included 50 patients with terminal ileal CD. Diagnosis was confirmed based on clinical features, endoscopy, and pathology. Patients underwent both MSCTE and ileocolonoscopy. Ileal wall thickness was measured and the disease severity was evaluated by CD activity index (CDAI). Intestinal mucosal lesions were scored by the simple endoscopic score for CD (SES-CD).

RESULTS

Of the 50 patients with active terminal ileal CD, the comparison of scores between SES-CD and CDAI showed significant association with Spearman's rank correlation coefficient (p < 0.01). There were statistically significant correlation between the wall thickness and the SES-CD (p < 0.0001) as well as CDAI (p < 0.001), respectively, but no significant correlation between the wall thickness and the C-reactive protein (CRP) was found (p = 0.43). Moreover, we found that the wall thickness was preferential to predict the disease severity in the terminal ileal CD.

CONCLUSION

MSCTE, in combination with ileocolonoscopy, is reliable to identify disease severity in CD patients and provides more accurate information in the diagnosis and treatment.

CT and MR enterography in children and adolescents with inflammatory bowel disease

The term inflammatory bowel disease (IBD) is used to describe multiple idiopathic disorders of the gastrointestinal tract. As many as one-quarter of patients with IBD initially present in childhood or adolescence. Multiple methods can be used to diagnose IBD in this age group, including computed tomographic (CT) enterography, magnetic resonance (MR) enterography, small bowel follow-through examination, ileocolonoscopy, and capsule endoscopy. However, CT enterography and MR enterography have become the imaging modalities of choice due to their exquisite image quality, rapid acquisition time, lack of need for bowel preparation, and ability to help diagnose the extraintestinal complications of IBD. In addition to being radiation free, MR enterography can help evaluate peristalsis, has high contrast resolution, and allows the use of diffusion-weighted imaging. The authors discuss the use of CT enterography and MR enterography in the context of pediatric IBD in terms of advantages and disadvantages, protocol, and imaging findings.

Comparative study of intestinal tuberculosis and primary small intestinal lymphoma

AIM: To characterize the clinical, radiological, endoscopic and pathological features of intestinal tuberculosis (ITB) and primary small intestinal lymphoma (PSIL).

METHODS: This was a retrospective study from February 2005 to October 2012 of patients with a diagnosis of ITB (n = 41) or PSIL (n = 37). All patients with ITB or PSIL underwent computed tomography (CT) and pathological examination. Thirty-five patients with ITB and 32 patients with PSIL underwent endoscopy. These patients were followed for a further 18 mo to ascertain that the diagnosis had not changed. Clinical, endoscopic, CT and pathological features were compared between ITB and PSIL patients.

RESULTS: Night sweating, fever, pulmonary TB and ascites were discovered significantly more often in ITB than in PSIL patients (P < 0.05), however, abdominal mass, hematochezia and intestinal perforation were found significantly more frequently in PSIL than in ITB patients (P < 0.05). Ring-like and rodent-like ulcers occurred significantly more often in ITB than in PSIL patients (P < 0.05), however, enterorrhagia and raised lesions were significantly more frequent in PSIL than in ITB patients (P < 0.05). The rate of granuloma was significantly higher in ITB than in PSIL patients (87.8% vs 13.5%, χ² = 43.050, P < 0.05), and the incidence of confluent granulomas with caseous necrosis was significantly higher in ITB than in PSIL patients (47.2% vs 0.0%, χ² = 4.034, P < 0.05). Multi-segmental lesions, mural stratification, mural gas sign, and intestinal stricture were more frequent in ITB than in PSIL patients (P < 0.05), however, a single-layer thickening of bowel wall, single segmental lesions, and intussusception were more common in PSIL than in ITB patients (P < 0.05). Necrotic lymph nodes, comb sign and inflammatory mass were more frequent in ITB than in PSIL patients (P < 0.05). The bowel wall enhancement in ITB patients was greater than that in PSIL patients (P < 0.05), while the thickening and lymph node enlargement in PSIL patients were higher than those in ITB patients (P < 0.05).

CONCLUSION: Combined evaluation of clinical, radiological, endoscopic and pathological features is the key to differentiation between ITB and PSIL.

Magnetic resonance enterography: inflammatory bowel disease and beyond

This article addresses the current technique and protocols for magnetic resonance (MR) enterography, with a primary focus on inflammatory bowel disease (IBD) and a secondary detailed discussion of other diseases of the small bowel beyond IBD. A brief discussion of MR imaging for appendicitis is included, but the evaluation of appendicitis does not require an enterographic protocol. The focused key points and approach presented in this article are intended to enhance the reader's understanding to help improve patient compliance with the MR enterographic studies, overcome challenges, and improve interpretation.

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.

Quantitative measures of comb sign in Crohn's disease: correlation with disease activity and laboratory indications

To determine retrospectively if quantitative measures of the comb sign at CT enterography correlated with laboratory indications in Crohn's disease. We retrospectively included 72 known CD patients (47 male and 25 female patients) and 41 normal controls who had undergone CT enterography (CTE) from 2008 to 2010 and had high-sensitive C reaction protein (Hs-CRP) and erythrocyte sedimentation rate (ESR) results. We divided the 72 CD patients into two groups based on disease activity which was determined by Rutgeerts' score. 41 patients were characterized as active disease while 31 patients were as inactive disease. For each individual, one reformatted coronal CTE image in which the comb sign (vasa recta) was most obviously displayed was selected by two experienced radiologists in a double blind manner. For each image, 20 regions of interest (ROI) with area of 1 cm(2) were drawn and placed over the site where the comb sign exists; the comb sign amount was counted in each ROI and recorded. Total amount of the comb sign were assessed from 20 ROI data. Quantitative comb sign results were compared with Hs-CRP and ESR level. Quantitative comb sign score is significantly higher in the CD group than in the control group at both the arterial stage and venous stage (P < 0.001). Quantitative comb sign score is obviously higher in active CD patients than in inactive CD patients both at arterial stage and venous stage (3.63 vs. 2.86 at arterial stage; 3.53 vs. 2.90 at venous stage). ESR level was well correlated with quantitative comb sign score both at arterial and venous stage whereas Hs-CRP has no significant correlation at either stage. Quantitative comb sign results did well in predicting CD activity with the accuracy rate of 78.4% at arterial stage and 80% at venous stage when using 3.33 as the cutoff of quantitative comb sign score. Quantitative comb sign score is a promising CTE parameter in predicting CD activity and be well correlates with the ESR level.

Benefit of computed tomography enterography in Crohn's disease: effects on patient management and physician level of confidence

BACKGROUND

Computed tomographic enterography (CTE) has been shown to have a high sensitivity and specificity for active small bowel inflammation. There are only sparse data on the effect of CTE results on Crohn's disease (CD) patient care.

METHODS

We prospectively assessed 273 patients with established or suspected CD undergoing a clinically indicated CTE. Providers were asked to complete pre- and postimaging questionnaires regarding proposed clinical management plans and physician level of confidence (LOC) for the presence or absence of active small bowel disease, fistula(s), abscess(es), or stricturing disease. Correlative clinical, serologic, and histologic data were recorded. Following revelation of CTE results, providers were questioned if CTE altered their management plans, and whether LOC changes were due to CTE findings (on a 5-point scale).

RESULTS

CTE altered management plans in 139 cases (51%). CTE changed management in 70 (48%) of those with established disease, prompting medication changes in 35 (24%). Management changes were made post-CTE in 69 (54%) of those with suspected CD, predominantly due to excluding CD (36%). CTE-perceived changes in management were independent of clinical, serologic, and histologic findings (P < 0.0001). Clinically meaningful LOC changes (2 or more points) were observed in 212 (78%).

CONCLUSIONS

CTE is a clinically useful examination, altering management plans in nearly half of patients with CD, while increasing physician LOC for the detection of small bowel inflammation and penetrating disease. These findings further support the use of CTE in CD management algorithms.

Active Crohn's disease in the small bowel: evaluation by diffusion weighted imaging and quantitative dynamic contrast enhanced MR imaging

PURPOSE

To determine relative diagnostic value of MR diffusion and perfusion parameters in detection of active small bowel inflammation in patients with Crohn's disease (CD).

MATERIALS AND METHODS

We reviewed 18 patients with active CD of terminal ileum (TI) who underwent MR enterography (MRE; including dynamic contrast enhanced MRI and diffusion-weighted MRI). Conventional MRI findings of TI were recorded. Regions of interest were drawn over TI and normal ileum to calculate apparent diffusion coefficient (ADC), the volume transfer constant (K(trans)) and the contrast media distribution volume (v(e)). Receiver operating characteristic analysis was used to determine their diagnostic performance.

RESULTS

Among conventional MR findings, mural thickening and increased enhancement were present in all actively inflamed small bowel. K(trans), v(e), and ADC values differed significantly between actively inflamed TI and normal ileum (0.92 s(-1) versus 0.36 s(-1); 0.31 versus 0.15 ± 0.08; 0.00198 mm(2)/s versus 0.00311 mm(2)/s; P < 0.001). Area under the curve (AUC) for K(trans), v(e), and ADC values ranged from 0.88 to 0.92 for detection of active inflammation. Combining K(trans) and ADC data provided an AUC value of 0.95.

CONCLUSION

Dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted imaging (DWI) provide quantitative measures of small bowel inflammation that can differentiate actively inflamed small bowel segments from normal small bowel in CD. DWI provides better sensitivity compared with DCE-MRI and combination of ADC and K(trans) parameters for analysis can potentially improve specificity.

Systematic review: the use of ultrasonography, computed tomography and magnetic resonance imaging for the diagnosis, assessment of activity and abdominal complications of Crohn's disease

BACKGROUND

Cross-sectional imaging techniques, including ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI), are increasingly used for evaluation of Crohn's disease (CD). Aim  To perform an assessment of the diagnostic accuracy of cross-sectional imaging techniques for diagnosis of CD, evaluation of disease extension and activity and diagnosis of complications, and to provide recommendations for their optimal use.

METHODS

Relevant publications were identified by literature search and selected based on predefined quality parameters, including a prospective design, sample size and reference standard. A total of 68 publications were chosen.

RESULTS

Ultrasonography is an accurate technique for diagnosis of suspected CD and for evaluation of disease activity (sensitivity 0.84, specificity 0.92), is widely available and non-invasive, but its accuracy is lower for disease proximal to the terminal ileum. MRI has a high diagnostic accuracy for the diagnosis of suspected CD and for evaluation of disease extension and activity (sensitivity 0.93, specificity 0.90), and is less dependent on the examiner and disease location compared with US. CT has a similar accuracy to MRI for assessment of disease extension and activity. The three techniques have a high accuracy for identification of fistulas, abscesses and stenosis (sensitivities and specificities >0.80), although US has false positive results for abscesses. As a result of the lack of radiation, US or MRI should be preferred over CT, particularly in young patients.

CONCLUSIONS

Cross-sectional imaging techniques have a high accuracy for evaluation of suspected and established CD, reliably measure disease severity and complications; they may offer the possibility to monitor disease progression.

Prospective comparison of computed tomography enterography and magnetic resonance enterography for assessment of disease activity and complications in ileocolonic Crohn's disease

BACKGROUND

Studies comparing magnetic resonance enterography (MRE) and computerized tomography enterography (CTE) for Crohn's disease (CD) are scarce.

METHODS

The aim of this study was to prospectively compare the sensitivity, specificity, and accuracy of abdominal MRE and CTE to assess disease activity and complications (fistulas, strictures) in ileocolonic CD. A total of 44 patients (23 male; 21 female; mean age 44) with ileocolonic CD underwent both MR and CT in a short time interval (mean 5 days). A 16-slice CT with intravenous contrast and an MRI with oral and paramagnetic intravenous contrast were performed. Ileocolonoscopy was used as the reference standard. Sensitivity values of CT and MR for detection of extraenteric signs of disease were compared with the McNemar test, with results of imaging studies, surgery, and physical examination as reference standards.

RESULTS

No significant differences in sensitivity, specificity, and accuracy were observed between MRE and CTE regarding the following parameters at the patient level: localization of CD (P = 1.0), bowel wall thickening (P = 1.0), bowel wall enhancement (P = 1.0), enteroenteric fistulas (P = 0.08), detection of abdominal nodes (P = 1.0), and perivisceral fat enhancement (P = 0.31). MR was significantly superior compared to CT in detecting strictures (P = 0.04). Per segment analysis showed that MRE was significantly superior to CTE in detecting ileal wall enhancement (P = 0.02).

CONCLUSIONS

MR and CT are equally accurate to assess disease activity and bowel damage in CD. MR may be superior to CT in detecting intestinal strictures and ileal wall enhancement. MR may represent an alternative technique to CT in assessing ileocolonic CD.

New concepts in intestinal imaging for inflammatory bowel diseases

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

Validation of a lower radiation computed tomography enterography imaging protocol to detect Crohn's disease in the small bowel

BACKGROUND

The purpose was to validate a lower radiation dose computed tomography enterography (CTE) imaging protocol to detect the presence of Crohn's disease (CD) in the small bowel using two different reference standards and to identify a prediction model based on CTE signs for the presence of active CD.

METHODS

This retrospective study included patients with known or suspected CD who underwent CTE between January and October 2006 according to a lower radiation dose protocol. Two gastrointestinal radiologists blindly and independently classified each CTE as being active or inactive. Reference standards included ileocolonoscopy ± biopsy and a comprehensive clinical reference standard (retrospectively created by a gastroenterologist, also including history, physical, follow-up course, and subsequent endoscopy, imaging, or surgery). Logistic regression was used to identify CTE findings that predicted the presence of active CD based on the combined clinical reference standard.

RESULTS

In all, 137 patients underwent CTE and ileocolonoscopy. Using an endoscopic reference standard, the sensitivity of CTE to detect active CD for the two readers was 81% and 89%, respectively. Using the clinical reference standard, the sensitivity of CTE to detect active CD was 89% and 98%, respectively. For both readers the sensitivity of CTE increased by 8%-9% when using the comprehensive reference standard. Multivariate analysis showed that a combination of mural thickness and hyperenhancement best predicted active CD (area under the curve [AUC] = 0.92-0.93, P < 0.0001).

CONCLUSIONS

Lower radiation dose CTE exams are sensitive for the detection of active small bowel CD. The combination of mural thickness and hyperenhancement are the best radiologic predictors of active CD.

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

PURPOSE

The purpose of this study was to determine whether CT enterography (CTE) changes of Crohn's disease (CD) after treatment correlated with clinical remission.

MATERIALS AND METHODS

We retrospectively studied 50 known CD patients (male: 35; female: 15) with clinical remission in a period of 3 years (2005-2008). CD was diagnosed by clinical, enteroscopic and pathologic manifestations. Clinical remission was identified by experienced gastroenterologists using the combing criteria of clinical, endoscopy and laboratory tests. First CTE and endoscopy exams were performed during their first hospitalization in our hospital meanwhile CD diagnosis was made during that time. Repeated CTE and endoscopy exams were done after treatment. CTE findings were determined by two experienced radiologists with double-blind approach. Each patient was analyzed for the CTE parameters including bowel wall attenuation, bowel wall thickening (>3mm), bowel wall thickening types (type A: multilayered mural stratification; type B: two layers with strong mucosal enhancement and prominent low-density submucosa; type C: two layers without strong mucosal enhancement; type D: homogeneous enhancement) comb sign, luminal stenosis (mild: luminal diameter 2-3 cm; moderate: luminal diameter 1-2 cm; severe: luminal diameter<1cm) and the presence of extraenteric complications (such as fistulas and abscess). All the quantitative parameters were measured three times by each review.

RESULTS

After treatment, bowel wall thickening was attenuated in 88% of CD patients. Thickness of bowel wall was decreased from 8.8 ± 2.8mm to 6.4 ± 1.9 mm (P<0.001). CT value of bowel wall in portal stage was also declined from 90.0 ± 15.4 (HU) to 73.4 ± 14.2 (HU (P<0.001). The percentage of patients with type A or B bowel wall thickening was decreased from 78.7% to 35.4%, while those with type C or D thickening was increased from 21.2% to 64.6% (P<0.001). The percentage of patients with comb sign was decreased from 88% to 60% (P=0.001). The percentage of patients with moderate or severe luminal stenosis was reduced from 74% to 32% (P<0.001). The ROC (receiver operating characteristic) analysis showed bowel wall attenuation (A(z)=0.89) and bowel wall thickness (A(z)=0.81) were the two best parameters to predict disease activity, and combining of these two values was better than using them solely (κ=0.71, P<0.001). The bowel wall attenuation (OR=9.56, P<0.001) and bowel wall thickness (OR=3.32, P=0.001) were significantly correlated with the disease activity in the following logistic regression analysis.

CONCLUSION

Therapeutic effect of CD and disease activity can be properly evaluated by CTE.

Enterografia por tomografia computadorizada: experiência inicial na avaliação das doenças do intestino delgado

OBJETIVO: O objetivo deste estudo é demonstrar a importância da enterografia por tomografia computadorizada (entero-TC) e como este exame pode contribuir na elucidação diagnóstica e avaliação clínica de pacientes com doenças do intestino delgado. MATERIAIS E MÉTODOS: Análise retrospectiva de 35 pacientes submetidos a entero-TC realizadas em aparelho multidetector de 16 canais, entre maio de 2008 e março de 2009. Utilizou-se meio de contraste iodado venoso e oral neutro (polietilenoglicol). As principais indicações foram avaliação de doença de Crohn, diarreia de origem indeterminada e suspeita de neoplasias. RESULTADOS: Houve boa correlação dos achados à entero-TC relacionados à atividade da doença em pacientes com doença de Crohn, quando comparados com dados clínicos, laboratoriais e endoscópicos. Em 15 casos identificaram-se alterações compatíveis com doença de Crohn, 9 deles sugerindo atividade. Dos pacientes com diarreia, o exame elucidou a maioria dos casos. Identificaram-se dois casos de tumor carcinoide. CONCLUSÃO: A entero-TC é método simples e eficaz para estudo das doenças inflamatórias/neoplásicas do intestino delgado, sobretudo na avaliação da doença de Crohn, indicando atividade da doença. Uma de suas principais vantagens é a possibilidade de avaliação de alterações mesentéricas e extraintestinais associadas.

Effect of altering automatic exposure control settings and quality reference mAs on radiation dose, image quality, and diagnostic efficacy in MDCT enterography of active inflammatory Crohn's disease

OBJECTIVE

The purpose of our study was to determine whether the MDCT enterography dose can be reduced by changing automatic exposure control (AEC) setting and quality reference milliampere-seconds (mAs) without altering subjective image quality or efficacy in active inflammatory Crohn's disease.

SUBJECTS AND METHODS

This is a prospective study of 2,310 MDCT enterography procedures performed using 16- and 64-MDCT in three cohorts (original, intermediate, and final dose levels). For 16-MDCT, the original and intermediate dose level quality reference mAs was 200, and weight-based (1 pound [0.45 kg] = 1 mAs) for the final dose level. For 64-MDCT, the original dose level quality reference mAs was 260; the mAs was 220 for intermediate and weight-based for the final dose level. For the intermediate and final dose levels, AEC was changed from strong to weak increase for obese and weak to strong decrease for slim patients. Demographic data and volume CT dose index (CTDI(vol)) were analyzed. Three readers evaluated the cases for image quality and efficacy differentiating normal from active inflammatory Crohn's disease.

RESULTS

For 16-MDCT, CTDI(vol) decreased from 12.82 to 10.14 mGy and 10.14 to 8.7 mGy between original to intermediate and intermediate to final dose levels. For 64-MDCT, the CTDI(vol) decreased from 15.72 to 11.42 mGy and 11.42 to 9.25 mGy between original to intermediate and intermediate to final dose levels. Images were rated suboptimal or nondiagnostic more often in the intermediate dose level (p < 0.05) but not in the final. There was no reduction in diagnostic efficacy as measured by area under the ROC curve (p > 0.1443 except for one comparison with one reader).

CONCLUSION

Substantial dose reduction can be achieved using weight-based quality reference mAs and altering AEC settings without affecting diagnostic efficacy in active inflammatory Crohn's disease of the terminal ileum. However, subjective image quality can be compromised at these dose settings, depending on radiologist preference.

CT enterography

Conventional radiologic and endoscopic evaluations of the small bowel are often limited by the length, caliber, and motility of the small bowel loops. The development of new multidetector-row CT scanners, with faster scan times and isotropic spatial resolution, allows high-resolution multiphasic and multiplanar assessment of the bowel, bowel wall, and lumen. CT Enterography (CTE) is a variant of routine abdominal scanning, geared toward more sustained bowel filling with oral contrast material, and the use of multiplanar images, that can enhance gastrointestinal (GI) tract imaging. This article examines the techniques and clinical applications of CTE in comparison with CT enteroclysis, focusing on Crohn disease, obscure GI bleeding, GI tumors, acute abdominal pain, and bowel obstruction.

CT enterography of pediatric Crohn disease

CT enterography is an important tool in the noninvasive diagnosis and follow-up of pediatric Crohn disease. This imaging modality is particularly useful for assessing extent of disease (including both intestinal and extraintestinal manifestations), response to medical therapy, and disease-related complications. The purpose of this article is to provide a contemporary review of CT enterography technique as well as the spectrum of intestinal and extraintestinal findings in pediatric Crohn disease.