Changes in dynamic contrast-enhanced pharmacokinetic and diffusion-weighted imaging parameters reflect response to anti-TNF therapy in Crohn's disease

Objective: To investigate the effect of tumour necrosis factor (TNF)-alpha antagonists on MRI dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI) parameters in Crohn's disease (CD). Methods: 42 patients with CD (median age 24 years; 22 females) commencing anti-TNF-alpha therapy with baseline and follow-up (median 51 weeks) 1.5-T MR enterography (MRE) were retrospectively identified. MRE included DCE (n=20) and/or multi-b-value DWI (n=17). Slope of enhancement (SoE), maximum enhancement (ME), area under the time-intensity curve (AUC), Ktrans (transfer constant), ve (fractional volume of the extravascular-extracellular space), apparent diffusion coefficient (ADC) and ADCfast/slow were derived from the most inflamed bowel segments. A physician global assessment of disease activity (remission, mild, moderate and severe) at the time of MRE was assigned, and the cohort was divided into responders and non-responders. Datawere compared using Mann-Whitney U test and analysis of variance. Results: Follow-up Ktrans, ME, SoE, AUC and ADC(ME) changed significantly in clinical responders but not in non-responders, baseline {[median [interquartile range (IQR)]: 0.42 (0.38), 1.24 (0.52), 0.18 (0.17), 17.68 (4.70) and 1.56mm(2) s(-1) (0.39mm(2) s(-1)) vs follow-up [median (IQR): 0.15 (0.22), 0.50 (0.54), 0.07 (0.1), 14.73 (2.06) and 2.14mm(2) s(-1) (0.62mm(2) s(-1) 1), for responders, respectively, p=0.006 to p=0.037}. SoE was higher and ME and AUC lower for patients in remission than for those with severe activity [mean (standard deviation): 0.55 (0.46), 0.49 (0.28), 14.32 (1.32)] vs [0.32 (0.37), 2.21 (2.43) and 23.05 (13.66), respectively p=0.017 to 0.033]. ADC was significantly higher for patients in remission [2.34mm(2) s(-1) (0.67mm(2) s(-1))] than for those with moderate [1.59mm(2) s(-1) (0.26mm2 s(-1))] (p50.005) and severe disease [1.63mm(2) s(-1) (0.21mm(2) s(-1))] (p=0.038). Conclusion: DCE and DWI parameters change significantly in responders to TNF-alpha antagonists and are significantly different according to clinically defined disease activity status. Advances in knowledge: DCE and DWI parameters change significantly in responders to TNF-alpha antagonists in CD, suggesting an effect on bowel wall vascularity.