Magnetic resonance imaging in animal models of pathologies

This chapter describes the magnetic resonance imaging (MRI) in animal models of pathologies. MRI is a well-recognized tool for in vivo characterization of animal models of human pathologies in preclinical research. It is found that because of its noninvasiveness, high soft contrast, and high space resolution, which can reach 50–100 μm in small laboratory animals, MRI constitutes a powerful morphologic technique. MR signal is sensitive to a number of parameters, including proton density, water proton relaxation times microscopic water self-diffusion, and macroscopic flow. The signal intensities were obtained by the region-of-interest (ROI) analysis. Five transversal contiguous slices were selected across the lesion with the criterion to cover the whole thigh. An operator-defined ROI was manually traced on the muscle of both the infected and the normal leg, avoiding the bone, as well as the subcutaneous edema, which appears strongly hyperintense. The use of localized spectroscopy for characterizing in vivo brown adipose tissue in terms of its content of poly-unsaturated fatty acids is also elaborated.