MRI-Based Radiomic Signature Identifying Secondary Loss of Response to Infliximab in Crohn's Disease.

Up to 50% of patients with Crohn's disease (CD) experience secondary loss of response (SLR) to infliximab. Patients with SLR may show clinical signs of iron deficiency as a result of inflammation despite being iron-replete. The magnetic resonance imaging (MRI)-based radiomic index, R2, can detect changes in iron metabolism. Therefore, the R2 parameter has considerable potential for detection of SLR to infliximab. The aims of this study were to explore the correlation between R2 and inflammation and to develop a non-invasive nomogram based on R2 to identify SLR to infliximab in patients with CD. Three hundred and twenty-two infliximab-treated patients with CD who underwent magnetic resonance enterography within 2 weeks before or after 54 weeks of infliximab therapy were divided into training and validation datasets at a ratio of 8:2. Point-biserial analysis was conducted to confirm the relationship between R2 and inflammation. A multivariate logistic regression model was created using R2, CRP and hemoglobin (OR, 1.10, 1.04 and 0.98; < 0.05). Receiver-operating characteristic curves and the Hosmer-Lemeshow test were used to assess the performance of the model. A correlation between R2 and inflammation was identified. Different trends in R2 and iron status indices were observed between patients with responsive and non-responsive CD, which is worthy of further study. The model was converted to a visualized nomogram that had a good ability to discriminate the outcomes of infliximab therapy with an area under the curve of 0.723 (95% CI, 0.661-0.785) in the training dataset and 0.715 (95% CI, 0.587-0.843) in the validation dataset. We confirmed a correlation between R2 and inflammation in patients with CD. Based on the MRI-based radiomic signature, a novel nomogram was established and validated to facilitate individualized identification of SLR to infliximab in patients with CD.