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P187. MRI T2 relaxometry to image fibrosis in patients with Crohn's disease

C. Breynaert1, T. Dresselaers2, R. Peeters3, I. Roebben3, K. Van Steen4,5, T. Vanuytsel1, V. Ballet1, M. Ferrante1, S. Vermeire1, P. Rutgeerts1, U. Himmelreich2, S. Dymarkowski3, D. Vanbeckevoort3, G. Van Assche1, 1Translational Research in GastroIntestinal Disorders, KU Leuven Department of Clinical and Experimental Medicine, Leuven, Belgium, 2Biomedical MRI, KU Leuven Department of Imaging and Pathology, Leuven, Belgium, 3University Hospitals Leuven, Department of Radiology, Leuven, Belgium, 4Bioinformatics and Modeling, University of Liège GIGA-R, Liège, Belgium, 5Systems and Modeling Unit, University of Liège Montefiore Institute, Liège, Belgium

Background

Non-invasive imaging tools that can assess connective tissue changes and can be applied repetitively, would be a major asset for the management of IBD, especially for the study of treatment efficacy and to predict treatment response. In vivo µMRI T2 relaxometry, a non-invasive imaging tool, allows to discriminate between acute and chronic phases of bowel wall inflammation and fibrosis in murine DSS colitis (Breynaert et al, Plos One 2013). We aimed at assessing the value of MRI T2 relaxometry in patients with Crohn's disease (CD).

Methods

Imaging was performed on a 3 Tesla MR scanner. To determine the T2 a TSE sequence was used with 8 echoes between 15 and 225 ms at 15 ms intervals. To define the normal value of T2 intensity of the rectum, healthy volunteers had a pelvic MRI with acquisition of high resolution T2 weighted images and T2 relaxometry. CD patients in whom a pelvic MRI was indicated for assessment of CD activity were recruited after informed consent for an additional T2 relaxometry. On the T2 map of the pelvis, the rectum was identified on 3 cross-sections per patient and delineated. Within these regions of interest the distribution of the T2 times between 0 and 250 ms was determined using ImageJ. The study was approved by the Ethics Committee of the University Hospitals of Leuven (S53186 - Belgian number B322201111559).

Results

In total, 18 healthy volunteers (10 M) and 17 patients (4 M) were included, 6 patients were excluded because of claustrophobia or early discontinuation of scanning. The mean T2 of the rectum was not significantly different (p = 0.119) between patients [113.0 ms (109.0–120.4)] and volunteers [118.3 ms (115.4–121.3)]. However, analysis of the T2 map of the rectum of CD patients showed a broadening of the histogram to lower values compared to healthy volunteers (p = 0.002).

Figure: T2 map of the rectum of healthy volunteers and CD patients.

Conclusion

T2 relaxometry of the pelvis in patients with CD identifies a histogram shift compared to healthy volunteers consistent with the changes observed in chronic DSS colitis. The data suggest that MRI T2 relaxometry is a promising tool to assess fibrosis in CD. Further investigation of this non-invasive, radiation and IV contrast free imaging tool is warranted.