Search in the Abstract Database

Search Abstracts 2011

* = Presenting author

P046. In vivo T2 relaxometry to assess inflammation and fibrosis in a murine model of inflammatory bowel diseases

C. Breynaert1, T. Dresselaers2, C. Perrier1, S. Vermeire3, P. Rutgeerts3, J. Ceuppens4, U. Himmelreich2, G. Van Assche3

1Division of gastroenterology, Catholic University Leuven, Leuven, Belgium; 2Biomedical NMR unit – MoSAIC, Catholic University Leuven, Leuven, Belgium; 3Division of gastroenterology, Leuven University Hospitals, Leuven, Belgium; 4Experimental immunology, Catholic University Leuven, Leuven, Belgium

Aim: In human Crohn's disease, the value of MRI and CT entero- en colonography as a non invasive assessment tool of transmural inflammation and extraluminal complications is increasingly recognized. However, little is known on the correlate of this in experimental murine ileitis or colitis. The aim of this study was to determine the feasibility of micro (μ)MR imaging in DSS induced acute and chronic colitis to distinguish both inflammatory and fibrotic lesions using in vivo T2 relaxometry.

Material and Methods: DSS colitis was induced in 6 week-old C57BL6/J mice. Three conditions were compared: control mice (n = 2) received normal drinking water, acute colitis mice (n = 2) 2% DSS in the drinking water 7 days prior to scanning and chronic colitis mice (n = 2) 2 cycles of 7 days of DSS followed by 2 weeks of normal drinking water. MR images were acquired with a 9.4T Bruker Biospec system using a 3.5 cm volume resonator. 2D respiration triggered anatomical T2 weighted images and T2 maps were recorded covering the distal part of the colon. Regions of interest delineating the colon wall were identified on T2 weighted images. Histograms were created from T2 maps in 4 slices per animal. After scanning the distal colon was harvested for histology. Collagen deposition was quantified with Martius-Scarlet-Blue staining and measured using ImageJ in 4 cross-sections per mouse.

Results: T2 weighted images and T2 maps were clearly different in the three conditions showing a markedly enlarged colon wall thickness in the acute and chronic model versus the control condition. No difference in MRI derived wall thickness was found between the chronic and acute model (area ratio acute/control: MRI = 1.7, histology = 2.2, chronic/control: MRI = 1.7, histology = 2.9). However, the histograms of the colon T2 values showed a clear shift towards higher values for the acute model but lower values for the chronic model versus the control condition (figure 1). This was confirmed by histology, which showed an increased collagen deposition (figure 2) and more αSMA+ cells in the submucosa of the chronic versus the acute model, indicating more fibrosis and myofibroblast differentiation in chronic colitis compared to acute and normal mice.

Conclusions: These preliminary data suggest a potential role for in vivo MRI T2 relaxometry in distinguishing between inflammatory and fibrotic lesions in a murine model of IBD. It opens perspectives for repeated assessment of fibrotic changes in mice and T2 relaxometry approach should be further explored in patients with Crohn's disease as a non-invasive tool for monitoring and diagnosis of fibrosis.

Figure 1. T2 histograms.

Figure 2. Surface of blue within MSB staining.