A Study of Feasibility of Brain Imaging in Medium- and Small-Sized Animals: Using a Clinical 3T MR System with Three Surface Coils

Purpose: To evaluate which brain MR images obtained with a clinical 3T MR system using surface coils less than 15.4 cm in diameter are best in rabbit and rat models, and to assess the feasibility of the clinical 3T MR machine in the study of morphologic brain in a preclinical study using medium- and small-sized animal models. Materials and Methods: Brain T2-weighted image (T2WI), T1-weighted image (T1WI), diffusion-weighted image (DWI), and susceptibility-weighted image (SWI) were obtained, and MR angiography was performed with a clinical 3T MR system using a rat, a cat, and a knee coil (5, 12, and 15.4 cm in diameter, respectively) in normal rabbits (n = 3) and using a rat and a cat coil in normal rats (n = 3). MR images were assessed qualitatively by consensus of two neuroradiologists and quantitatively using signal-to-noise ratio (SNR) and statistical analysis (using analysis of variance or ttest) in terms of which images obtained with different coils were the best. Brain T2WI, DWI, SWI, and Gd-T1WI MR images were obtained 2 hours after embolization with triolein emulsion infused into the carotid artery in rabbits (n = 3) and rats (n = 3) using the coil which showed highest SNR in the above study, and the images were assessed in terms of abnormal findings and image quality. Results: Brain MR images obtained with the rat coil revealed better image quality and higher SNR compared with those obtained with other coils, and they showed statistical significance (p < 0.05) in rabbits. In rats, brain MR images obtained with the rat coil were better than those obtained with the cat coil in qualitative analysis; however, they revealed no statistical significance except for DWI in quantitative analysis. MR images obtained after triolein emulsion showed T2 hyperintensity and lesional contrast enhancement on Gd-T1WI without evidence of infarction or hemorrhage. Conclusion: The clinical 3T MR system using surface coils for animals enabled us to obtain good quality brain images in medium- and small-sized animal models in the present study. Brain MR images seem to be feasible for the morphologic evaluation in animal models.