The prognostic value, in active ulcerative colitis, of an increased intensity of colonic perivisceral fat signal on magnetic resonance imaging with ferumoxil.

OBJECTIVE: In active ulcerative colitis (UC), magnetic resonance imaging (MRI) with ferumoxil, a superparamagnetic oral contrast agent, accurately evaluates, in our experience, the increased wall thickness and frequently shows a stronger perivisceral fat signal intensity (PFSI). The aim of our study was to evaluate the clinical significance of these MRI findings in active UC. METHODS: Twenty-four consecutive patients affected by moderate pancolitis were enrolled. At entry, each patient underwent MRI with ferumoxil to evaluate wall thickness and PFSI. Two groups of patients were individuated: group A (increased PFSI) and group B (normal PFSI). After obtaining remission, the number of relapses and, at each flare-up, the clinical activity index (CAI) were evaluated in all patients in a 2-yr follow-up period. The mean CAI was calculated at the end of the follow-up in each patient. Where there was colectomy, a complete histological examination of the colon was performed. RESULTS: PFSI was increased in 16 patients (group A) and was normal in the remainder (group B). There was a significant difference of wall thickness, number of relapses/yr, and mean CAI between the two groups of patients. No difference was observed with regard the duration of disease. Six patients of group A and no patient of group B underwent colectomy. The histological evaluation showed an increased thickness of the entire colonic wall with significant changes of the perivisceral fat structures.