Interobserver Agreement in MR Enterography for Diagnostic Assessment in Patients with Crohn's Disease

Interobserver variation in the interpretation of magnetic resonance enterography in Crohn's disease

OBJECTIVES

To evaluate interobserver variability for diagnosis of disease presence and extent of small bowel and colonic Crohn's disease using MR enterography (MRE).

METHODS

Data from the first 73 consecutive patients (mean age 32, 33F, 28 new diagnosis, 45 suspected relapse) recruited to a multicentre, prospective diagnostic accuracy trial evaluating MRE for small bowel Crohn's disease were each read independently by three (from a pool of 20) radiologists. Radiologists documented presence and segmental location of small bowel Crohn's disease and recorded morphological mural/extramural parameters for involved segments. Per patient percentage agreement for disease presence and extent were calculated against an outcome-based construct reference standard (averaged between pairs of readers). Prevalence-adjusted bias-adjusted κ (PABAK) was calculated.

RESULTS

Agreement for small bowel disease presence for new diagnosis/relapsed patients was 68%(κ = 0.36)/ 78% (κ = 0.56) and 43%(κ = 0.14)/ 53% for disease extent (κ = 0.07), respectively. For disease presence, all three radiologists agreed correctly with the reference standard in 41/59 (69%) of patients with small bowel involvement, and in 8/14 (57%) cases of without small bowel disease. Agreement was highest for multisegment disease, greater than 5 cm in length, with mural thickness>6 mm, and increased mural T2 signal. Agreement for colonic disease presence was 61% (κ = 0.21 fair agreement) for new diagnosis/ 60% (κ = 0.20, slight agreement) for relapsed patients.

CONCLUSION

There is a reasonable agreement between radiologists for small bowel disease presence using MRE for newly diagnosed Crohn's disease, and patients with suspected relapse, respectively. Agreement is lower for disease extent.

ADVANCES IN KNOWLEDGE

There is reasonable agreement between radiologists for small bowel disease presence using MRE for newly diagnosed (68%) Crohn's disease, and patients with suspected relapse (78%). Agreement is lower for disease extent (43% new diagnosis and 53% suspected relapse).

Magnetic resonance enterography compared with ultrasonography in newly diagnosed and relapsing Crohn's disease patients: the METRIC diagnostic accuracy study

BACKGROUND

Magnetic resonance enterography and enteric ultrasonography are used to image Crohn's disease patients. Their diagnostic accuracy for presence, extent and activity of enteric Crohn's disease was compared.

OBJECTIVE

To compare diagnostic accuracy, observer variability, acceptability, diagnostic impact and cost-effectiveness of magnetic resonance enterography and ultrasonography in newly diagnosed or relapsing Crohn's disease.

DESIGN

Prospective multicentre cohort study.

SETTING

Eight NHS hospitals.

PARTICIPANTS

Consecutive participants aged ≥ 16 years, newly diagnosed with Crohn's disease or with established Crohn's disease and suspected relapse.

INTERVENTIONS

Magnetic resonance enterography and ultrasonography.

MAIN OUTCOME MEASURES

The primary outcome was per-participant sensitivity difference between magnetic resonance enterography and ultrasonography for small bowel Crohn's disease extent. Secondary outcomes included sensitivity and specificity for small bowel Crohn's disease and colonic Crohn's disease extent, and sensitivity and specificity for small bowel Crohn's disease and colonic Crohn's disease presence; identification of active disease; interobserver variation; participant acceptability; diagnostic impact; and cost-effectiveness.

RESULTS

Out of the 518 participants assessed, 335 entered the trial, with 51 excluded, giving a final cohort of 284 (133 and 151 in new diagnosis and suspected relapse cohorts, respectively). Across the whole cohort, for small bowel Crohn's disease extent, magnetic resonance enterography sensitivity [80%, 95% confidence interval (CI) 72% to 86%] was significantly greater than ultrasonography sensitivity (70%, 95% CI 62% to 78%), with a 10% difference (95% CI 1% to 18%; p = 0.027). For small bowel Crohn's disease extent, magnetic resonance enterography specificity (95%, 95% CI 85% to 98%) was significantly greater than ultrasonography specificity (81%, 95% CI 64% to 91%), with a 14% difference (95% CI 1% to 27%). For small bowel Crohn's disease presence, magnetic resonance enterography sensitivity (97%, 95% CI 91% to 99%) was significantly greater than ultrasonography sensitivity (92%, 95% CI 84% to 96%), with a 5% difference (95% CI 1% to 9%). For small bowel Crohn's disease presence, magnetic resonance enterography specificity was 96% (95% CI 86% to 99%) and ultrasonography specificity was 84% (95% CI 65% to 94%), with a 12% difference (95% CI 0% to 25%). Test sensitivities for small bowel Crohn's disease presence and extent were similar in the two cohorts. For colonic Crohn's disease presence in newly diagnosed participants, ultrasonography sensitivity (67%, 95% CI 49% to 81%) was significantly greater than magnetic resonance enterography sensitivity (47%, 95% CI 31% to 64%), with a 20% difference (95% CI 1% to 39%). For active small bowel Crohn's disease, magnetic resonance enterography sensitivity (96%, 95% CI 92% to 99%) was significantly greater than ultrasonography sensitivity (90%, 95% CI 82% to 95%), with a 6% difference (95% CI 2% to 11%). There was some disagreement between readers for both tests. A total of 88% of participants rated magnetic resonance enterography as very or fairly acceptable, which is significantly lower than the percentage (99%) of participants who did so for ultrasonography. Therapeutic decisions based on magnetic resonance enterography alone and ultrasonography alone agreed with the final decision in 122 out of 158 (77%) cases and 124 out of 158 (78%) cases, respectively. There were no differences in costs or quality-adjusted life-years between tests.

LIMITATIONS

Magnetic resonance enterography and ultrasonography scans were interpreted by practitioners blinded to clinical data (but not participant cohort), which does not reflect use in clinical practice.

CONCLUSIONS

Magnetic resonance enterography has higher accuracy for detecting the presence, extent and activity of small bowel Crohn's disease than ultrasonography does. Both tests have variable interobserver agreement and are broadly acceptable to participants, although ultrasonography produces less participant burden. Diagnostic impact and cost-effectiveness are similar. Recommendations for future work include investigation of the comparative utility of magnetic resonance enterography and ultrasonography for treatment response assessment and investigation of non-specific abdominal symptoms to confirm or refute Crohn's disease.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN03982913.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 42. See the NIHR Journals Library website for further project information.

A comparison of automated segmentation and manual tracing in estimating hippocampal volume in ischemic stroke and healthy control participants

Manual quantification of the hippocampal atrophy state and rate is time consuming and prone to poor reproducibility, even when performed by neuroanatomical experts. The automation of hippocampal segmentation has been investigated in normal aging, epilepsy, and in Alzheimer's disease. Our first goal was to compare manual and automated hippocampal segmentation in ischemic stroke and to, secondly, study the impact of stroke lesion presence on hippocampal volume estimation. We used eight automated methods to segment T1-weighted MR images from 105 ischemic stroke patients and 39 age-matched controls sampled from the Cognition And Neocortical Volume After Stroke (CANVAS) study. The methods were: AdaBoost, Atlas-based Hippocampal Segmentation (ABHS) from the IDeALab, Computational Anatomy Toolbox (CAT) using 3 atlas variants (Hammers, LPBA40 and Neuromorphometics), FIRST, FreeSurfer v5.3, and FreeSurfer v6.0-Subfields. A number of these methods were employed to re-segment the T1 images for the stroke group after the stroke lesions were masked (i.e., removed). The automated methods were assessed on eight measures: process yield (i.e. segmentation success rate), correlation (Pearson's R and Shrout's ICC), concordance (Lin's RC and Kandall's W), slope 'a' of best-fit line from correlation plots, percentage of outliers from Bland-Altman plots, and significance of control-stroke difference. We eliminated the redundant measures after analysing between-measure correlations using Spearman's rank correlation. We ranked the automated methods based on the sum of the remaining non-redundant measures where each measure ranged between 0 and 1. Subfields attained an overall score of 96.3%, followed by AdaBoost (95.0%) and FIRST (94.7%). CAT using the LPBA40 atlas inflated hippocampal volumes the most, while the Hammers atlas returned the smallest volumes overall. FIRST (p = 0.014), FreeSurfer v5.3 (p = 0.007), manual tracing (p = 0.049), and CAT using the Neuromorphometics atlas (p = 0.017) all showed a significantly reduced hippocampal volume mean for the stroke group compared to control at three months. Moreover, masking of the stroke lesions prior to segmentation resulted in hippocampal volumes which agreed less with manual tracing. These findings recommend an automated segmentation without lesion masking as a more reliable procedure for the estimation of hippocampal volume in ischemic stroke.

Magnetic resonance enterographic predictors of one-year outcome in ileal and ileocolonic Crohn's disease treated with anti-tumor necrosis factor antibodies

The aim of the study was to assess the role of magnetic resonance enterography (MRE) in predicting one-year efficacy of anti-tumor necrosis factor antibodies - infliximab (IFX), adalimumab (ADA) in Crohn’s disease (CD) patients primarily responding to therapy. We performed retrospective analysis among 61 CD patients who had undergone a successful IFX/ADA induction therapy and were treated with maintenance doses. All patients underwent MRE at week 0. We assessed which MRE features were predictive for steroid-free remission at week 52, and which were associated with a secondary loss of response. 44 patients were in steroid-free remission at week 52, 17 - were secondary non-responders. The ROC curve showed that bowel thickening with contrast enhancement analyzed together at week 0 were associated with steroid-free remission at week 52 (p = 0.01; AUC 0.67). Bowel stenosis with or without prestenotic dilatation [OR 5.8 (95% CI 1.4 – 25) and 2.4 (95% CI 1.2 – 5) respectively; p = 0.01] and the presence of intra-abdominal fistulas [OR 1.4 (95% CI 1.1 – 2); p = 0.004] were related to secondary non-response. A high baseline inflammatory activity detected by MRE predicts one-year response in CD after IFX/ADA. In case of bowel stenosis, intra-abdominal fistulas, other therapeutic options should be considered.

Magnetic resonance enterography of Crohn's disease

Magnetic resonance enterography (MRE) has been reported to be a useful modality for the evaluation of luminal inflammation and extraintestinal complications in Crohn's disease (CD). A recent study indicated that the diagnostic ability of MRE was comparable to the diagnostic ability of other devices, such as ileocolonoscopy. MRE can be performed repeatedly because there is no radiation exposure. Therefore, MRE is useful as a method of follow-up for younger patients with established CD. It is useful for evaluating the efficacy of medical treatments, such as biologics. MRE can detect small intestinal lesions even if the endoscope does not pass through the stenosis. The concerns of availability of expertise and the costs associated with MRE should be addressed so MRE can be widely used for CD patients in the near future.

Magnetic resonance enterography: state of the art

Crohn's disease is a chronic inflammatory bowel disease of the gastrointestinal tract manifested by frequent periods of relapses and remissions of symptoms. The small bowel is most frequently affected. Progression of transmural inflammation can lead to stricturing or penetrating complications. At the time of diagnosis, approximately 10% of patients have disease beyond the reach of the colonoscope. Imaging can aid in clinical evaluation by depicting small bowel involvement and extraenteric disease. Magnetic resonance enterography (MRE) has emerged as a valuable tool and is being used with increasing frequency for the diagnosis and management of Crohn's disease. This article will discuss the current state of the art in MRE. In addition to reviewing the literature reporting its utility, we will present case examples illustrating how MRE best depicts the various findings of Crohn's disease within 4 imaging categories of disease: active inflammatory, fibrostenotic, fistulizing/perforating, and reparative or regenerative. We will present additional important clinical considerations in routine use of MRE, including implications for monitoring disease activity and response to treatment, cost-effectiveness, and appropriate use in the context of the American College of Radiology Appropriateness Criteria.