Abstract
BACKGROUND: Documentation of disease activity in patients affected by Crohn's disease (CD) is mandatory in order to manage patients properly. Magnetic resonance imaging (MRI) is considered the reference cross-sectional technique for the assessment of CD activity. Among MRI findings, layered pattern (LP) of contrast enhancement seems to be one of the most significant signs of severe disease activity; however, it has also been associated with chronic disease and mural fibrosis. AIM: To systematically evaluate the accuracy of LP of contrast enhancement in the diagnosis of active inflammation in patients with CD. METHODS: In February 2019, we searched the MEDLINE and Cochrane Central Register of Controlled Trials databases for studies evaluating the diagnostic accuracy of LP of contrast enhancement on MRI for the detection of active inflammation in patients with CD. To be included, studies had to use histopathologic analysis (endoscopy or surgery) as the reference standard. Risk of bias and applicability concerns of the included studies were evaluated by using items from the Quality Assessment for Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Pooled sensitivity and specificity were determined using a bivariate random-effect model. Heterogeneity was quantified by using the I (2) statistic. Our meta-analysis received no funding, and the review protocol was not published or registered in advance. RESULTS: Of the 1383 studies identified, five articles were finally selected for quantitative and qualitative synthesis (245 patients, 238 of whom had histopathologically confirmed CD, 144 with active inflammation and 94 with inactive disease). The meta-analysis showed a pooled sensitivity of 49.3% (95%CI: 41%-57.8%; I (2): 90.7%) and specificity of 89.1% (95%CI: 81.3%- 94.4%; I (2): 48.6%). Pooled PLR and NLR were 3.3 (95%CI: 1.9-5.7; I (2): 6.1%) and 0.6 (95%CI: 0.5-0.9; I (2) 70.5%), respectively. SDOR was 6.8 (95%CI: 2.6-17.6; I (2): 27.1%). The summary ROC curve showed an area under the curve (AUC) of 0.82 (SE 0.06; Q* 0.76). High risk of bias and applicability concerns were observed in the domains of patient selection for one included study. CONCLUSION: LP on contrast-enhanced MRI is a specific finding to rule out active inflammation in patients with CD. Further studies using a prespecified definition of LP on contrast-enhanced MRI are needed to support our findings.