Evaluating Cardiac Function of Tree Shrew (Tupaiabelangeri) using CMR at 7T with 2D Tissue Tracking

OBJECTIVE: To determine the potential value of the two-dimensional (2D) cardiac magnetic resonance imaging (CMR) tissue tracking (CMR-TT) method in assessing the cardiac function of tree shrew at 7T. METHODS: Healthy adult tree shrews (male, n=8) and spraguedawley rats(male, n=8) were selected for this study. CMR was performed to acquire the short-axis images of left ventricle at 7T using the same appropriative coil and cine sequence for all experimental animals. The CMR images were processed using the professional cardiac analysis software, calculating ejection fraction (EF), radial peak sysolic strain (Err), circumferential peak sysolic strain (Ecc), radial peak sysolic displacement (DR), and LVM/BM 〔the ratio of left ventricular mass (LVM) to body mass (BM)〕. RESULTS: Cine imaging for the tree shrews was 100% successful following the CMR protocol for the rats, with clearly visible main segments of cardiac. Significant differences in EF, Err, Ecc and DR were found between the two groups of animals (P < 0.01). The tree shrews has lower EF, Err and Ecc than the rats. Err and Ecc appeared in the fifteenth phase in left ventriclar systole in the tree shrews, compared with the tenth phase in the rats.The tree shrews also had higher LVM/BM than the rats. CONCLUSION: The cardiac function of tree shrew can be assessed using the 2D CMR-TT method despite significant differences across species.