Abstract :
[en] Background: In a previous study comparing dynamic contrast-enhanced (DCE)-MRI parameters in affected and unaffected segments of Crohn’s disease (CD) patients with those of a control group, we found significantly lower perfusion parameters in unaffected segment of CD patients compared to the unaffected ones of control subjects (Vieujean S, et al. 2021). This led us to consider 2 hypotheses: either there is a constitutional perfusion disorder in CD patients, or it reflects a dynamic disequilibrium between affected and unaffected segments in patients with active disease (and a blood flow diversion to the affected segments). In this latter case, this perfusion parameter in unaffected segment could represent a good indirect marker of disease activity. To distinguish between these two hypothesis, we aimed to assess the perfusional parameters changes in affected and unaffected segments of patients with active disease before after 3 months of treatment.
Methods: in this single-center prospective study, we performed a DCE-MRI in relapsing CD patients for whom a treatment change was required (T0), as well as, at the end of induction. Regions of interest were drawn in affected and unaffected segments and the program (Olea Medical - Canon) provided values for transfer constant (Ktrans), fractional volume of extravascular-extracellular space (Ve), slope of enhancement (SoE), time to maximum enhancement (TME), maximum enhancement (ME) and enhancement ratio (ER) which were determined and compared. The following clinical data were also collected: gender, age, disease duration, Montreal classification, previous surgery, smoking habits, previous IBD treatment, Harvey Bradshaw Index (HBI), c-reactive protein (CRP) and faecal calprotectin (both obtained within a 3-month time window from the MRI). Response to treatment was defined as HBI less than 4 with CRP less than 5 and fecal calprotectin less than 250 µg/g.
Results: A total of 30 CD patients (16 men, mean age ± SD : 40.9 ± 14.3) were included between March 2020 and March 2022 (Table 1). Of these 30 patients, 16 patients underwent MRI before and after 3 months of treatment allowing paired comparisons. Comparisons of affected and unaffected segments in 30 CD patients showed a significant increase of all perfusional parameters in affected segments compared to unaffected, except for TME. Regarding the association with biomarkers, there was a significant negative relationship between KTrans mean and CRP (r=-0.44, p=0.039). We did not observe any significant change in paired comparison after treatment in affected and unaffected segments, including when considering only patients who responded at 3 months.
Conclusion: We did not observe any significant changes in MRI perfusion parameters after medical treatment in CD. This probably reflects a slower change of MRI perfusional parameters compared to clinical of biochemical parameters. These MRI perfusional parameters are thus not appropriate as objective markers of short term response but should be re-examined on the longer term.
