Evaluation of the predictive value of Dynamic MRI in determining treatment response in perianal fistulizing Crohn*s disease before and after treatment with Infliximab

Crohn*s disease (CD) is a chronic, segmental, transmural inflammatory bowel
disease (IBD). Perianal fistulas are reported to occur in up one third of
patients. MR imaging is an effective imaging modality in the evaluation of
patients with perianal CD as it can accurately demonstrate localization and
extent of disease including clinically undetected fistula or abscess. Many
patients with perianal Crohn*s disease are treated with Infliximab, a
monoclonal antibody against tumor necrosis factor. Infliximab has been shown to
reduce the number of Crohn related fistulas. Clinical evaluation is inaccurate
in determing treatment response. Initial studies have shown the potential of
MRI in establishing the presence or absence of treatment response.
In order to provide a more accurate disease index Van Assche et al developed an
MRI-based score of disease severity based on static MRI for patients with
perianal fistulizing CD. This score has limitations (reproducibility, no
external validation). A recent pilotstudy from the AMC has shown that dynamic
contrast-enhanced MRI (DCE-MRI) before treatment can possibly add valuable
information about disease activity in perianal CD. We want to determine with
this study the potential value of MRI, now that we can assess the whole course
of the fistula with the use of 3T MRI (In the previous study we could only
evaluate some selectected slices) and the possibility of this technique to
predict during and immediately after treatment the response/remission.

To study whether dynamic MRI can predict treatment response and long term
outcome in patients with Crohn*s disease.

Prospective observational study. We will study a cohort of consecutive patients
with perianal Crohn*s disease with DCE-MRI before and after remission induction
therapy with Infliximab after 6 weeks, 12 weeks, and 1 year.

MRI is a routine examination in patients with Crohn*s disease and is routinely
performed with intravenous contrast medium.
Patients will undergo 4 MRI scans as part of their clinical follow-up. For this
study a 5 minute additional MRI sequence will be performed during each of the
MRI scans. The scan will last 45 minutes. Also they have to fill in the PDAI
after each MRI scan. This will cost 5 minutes (total of 20 minutes). patients
have to undergo a venapuncture three times, one time for study purposes only.
No side-effects or risks have been reported for MR imaging provided that contra
indications are considered. Some patients may experience claustrophobia.