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

Role of Dual Energy Computed Tomography in Inflammatory Bowel Disease

Dual-energy computed tomography (DECT), which allows material-based differential X-ray absorption behavior from near simultaneously acquired low- and high-kilovolt datasets is finding increasing applications in the evaluation of bowel diseases. In patients with inflammatory bowel disease, DECT techniques permit both qualitative and quantitative assessment. Particularly in patients with Crohn's disease, monoenergetic and iodine specific images have been explored. This article focuses on the principles and applications of DECT in inflammatory bowel disease along with review of its limitations and challenges.

Agreement between real-time elastography and delayed enhancement magnetic resonance enterography on quantifying bowel wall fibrosis in Crohn's disease

BACKGROUND

the assessment of fibrosis in Crohn's disease (CD) bowel lesions helps to guide therapeutic decisions. Real-time elastography (RTE) and delayed-enhancement magnetic resonance enterography (DE-MRE) have demonstrated good accuracy in quantifying CD-related ileal fibrosis as compared with histological examination. To date no study has compared DE-MRE and RTE.

AIMS

we aimed to evaluate the agreement between RTE and DE-MRE on quantifying CD-related ileal fibrosis.

METHODS

consecutive patients with ileal or ileocolonic CD underwent RTE and DE-MRE. Ileal fibrosis was quantified by calculating the strain ratio (SR) at RTE and the 70s-7 min percentage of enhancement gain (%EG) of both mucosa and submucosa at DE-MRE. A SR ≥2 was applied to define severe fibrosis. Clinically relevant outcomes occurring at follow-up were recorded.

RESULTS

40 CD patients were enrolled. A significant linear correlation was observed between SR and submucosal %EG (r = 0.594, p < 0.001). Patients with severe fibrosis (SR ≥2) had significantly higher submucosal %EG values than patients with low/moderate fibrosis (median values 26.4% vs. 9.5%, p < 0.001). During a median 43.8-month follow-up relevant disease outcomes occurred more frequently in the severe-fibrosis group (75% vs. 36%, HR 5.4, 95% CI 1.2-24.6, p = 0.029).

CONCLUSIONS

the study demonstrates an excellent agreement between RTE and DE-MRE in assessing ileal fibrosis in CD.

Machine learning for selecting patients with Crohn's disease for abdominopelvic computed tomography in the emergency department

BACKGROUND

Patients with Crohn's disease (CD) frequently undergo abdominopelvic computed tomography (APCT) in the emergency department (ED). It's essential to diagnose clinically actionable findings (CAF) as they may need immediate intervention, frequently surgical. However, repeated APCT's includes increased ionizing radiation exposure. Guidance regarding APCT performance is mostly clinical and empiric.

AIMS

We used a machine learning (ML) approach for predicting CAF on APCT in the ED.

METHODS

We performed a retrospective cohort study of patients with CD who presented to the ED and underwent APCT. CAF were defined as bowel obstruction, perforation, intra-abdominal abscess or complicated fistula. ML was used to predict the probability of having CAF on APCT, using routine clinical variables.

RESULTS

Of 101 admissions included, 44 (43.5%) had CAF on APCT. ML successfully identified patients at low (NPV 91.6%, CI-95% 90.6-92.5) and high (PPV 92.8%, CI-95%, 92.3-93.2) risk for CAF (AUROC = 0.774), using beats-per-minute, mean arterial pressure, neutrophil-to-lymphocyte ratio and sex. This allowed the construction of a risk stratification scheme according to patients' probability for CAF on APCT.

CONCLUSION

We present a novel artificial intelligence-based approach, utilizing readily available clinical variables to better select patients with CD in the ED for APCT. This might reduce the number of APCTs performed, avoiding related hazards while ensuring high-risk patients undergo APCT.

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.

Correlation between ultrasound consolidated score and simple endoscopic score for determining the activity of Crohn's disease

OBJECTIVES

The aim of this study was to develop an ultrasound consolidated score (UCS) in determining the activity of Crohn's disease (CD) and evaluate it with reference to simple endoscopic score (SES).

METHODS

From June 2014 to June 2017, 66 patients with CD were retrospectively enrolled in this study. Each patient underwent endoscopy and transabdominal ultrasound (US) examination. The morphological symmetry, echogenicity of bowel wall, bowel wall layer structure, echogenicity of peri-bowel fat, bowel wall thickness (BWT), and Limberg type on power Doppler US were assessed with transabdominal US, and an UCS scoring system was developed based on these characteristics. Endoscopic results were used as the reference standard and SES was calculated to determine the CD activity. Receiver operating characteristic curve analysis was performed to assess the diagnostic performance for determining CD activity and the correlation between UCS and SES was assessed using Spearman correlation analysis.

RESULTS

330 intestinal segments in 66 patients were included. The UCS of the segments in the remission phase ranged from 3.0 to 9.0 (mean, 3.6 ± 0.9) whereas in the active phase from 3.0 to 20.0 (mean, 10.6 ± 4.0) (p < 0.001). The cut-off value of UCS was 6. The associated area under ROC curve, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 0.980, 88.3%, 95.5%, 93.8%, 91.3%, and 92.3%, respectively. The correlation coefficient between UCS and SES was 0.90, which was higher than the correlation coefficient of 0.83 between BWT and SES.

CONCLUSIONS

The newly developed UCS with transabdominal US has a good performance and potentially provides an effective alternative for evaluating the activity of CD.

ADVANCES IN KNOWLEDGE

UCS is an effective method to evaluate the activity of CD because it provides comprehensive information of the disease. Therefore, it could be employed as an alternative for diagnosis of CD.

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.

Quantitative Analysis of Apparent Diffusion Coefficient for Disease Assessment in Paediatric Inflammatory Bowel Disease

OBJECTIVE

The aim of the study was to establish an apparent diffusion coefficient (ADC) cut-off value to classify active and non-active lesions in inflammatory bowel disease.

METHODS

We reviewed 167 paediatric magnetic resonance enterographies executed for suspected inflammatory bowel disease by using a 1.5- and 3-T scanner. We assessed the presence and activity of the disease by using morphologic and functional parameters such as the ADC. Each patient could have more than 1 examinations. Quantitative assessment of disease activity in the ADC map was measured placing 3 regions of interest in the areas of highest inflammation and the mean value was calculated, patients without sign of inflammation were assessed at 2 standardised site. Ileocolonoscopy, esophagogastroduodenoscopy, surgery, and video-capsule endoscopy were used as standards of reference.

RESULTS

We enrolled 34 patients and 35 examinations: radiological findings of disease were identified in 29 examinations and 44 lesions were detected. Six patients had negative results and ADC assessment was taken at the terminal ileum and cecum. A total of 56 bowel segments were included in the study. Image analysis revealed 39 active lesions (69.6%) and their ADC values were lower compared to the ones of non-active segments. For each scanner a cut-off value was found (sensitivity: 0.91, specificity: 0.89 for 1.5 T and 0.81 for 3 T). Inter-rater agreement on disease activity between ADC values and magnetic resonance enterography results and between ADC values and the standard of reference were very good.

CONCLUSIONS

ADC can provide a scanner-based quantitative measurement of disease activity.

Unmet needs of Italian physicians managing patients with inflammatory bowel disease

BACKGROUND

Little is known about the unmet needs of physicians caring for patients with inflammatory bowel disease (IBD).

AIMS

This study explored the practical difficulties and needs for professional updating of Italian IBD physicians.

METHODS

A questionnaire was distributed to 600 physicians attending IG-IBD meetings.

RESULTS

280 physicians completed the questionnaire (46.7%). On a 5-point Likert scale (from 1, strongly disagree to 5, strongly agree), they identified the most problematic issues in managing IBD patients as increasing bureaucracy (3.9), lack of extra-gastroenterological IBD expertise (3.4), lack of diagnostic techniques (3.1) and budget limitations (2.9). The most lacking techniques, ranked from 1 (greatest need) to 9 (lowest need), were: anti-drug antibody and trough level assays (2.7), device-assisted enteroscopy (3.1), exploration under anaesthesia (3.2), MR enterography (3.2), and bowel ultrasonography (3.3). About professional updating, respondents indicated (on a 5-point Likert scale) that helpful topics were practical medicine (4.3), managing difficult patients (4.1), and guidelines (4.0). The most desired modality for updating was residential courses on clinical practice (4.3).

CONCLUSION

Several factors potentially limit the best management of IBD patients in Italy. Satisfying these unmet needs could improve care for IBD patients.