The advent of the genomic age is revolutionizing the experimental cardiovascular research irreversibly. Dissecting molecular switches that control the changes of cardiac physiology with transgenic mouse models has proven to offer important insights into the control of cardiac function. The integration of novel MR tissue tracking techqniques with these genetically manipulated mice may allow comprehensive characterization of contractile dysfunction non-invasively at the earliest diseased stages, thus facilitate our understanding of the pathogenesis of human cardiac diseases.
In the current thesis, we aimed at developing fast and accurate MR tissue tracking techniques and applying them for the assessment of ventricular function in transgenic mouse models of cardiac diseases. First, spatial modulation of magnetization (SPAMM) tagging was implemented in the mouse heart; and a 3D SPAMM tagging analysis method was developed based on harmonic phase (HARP) and homogeneous strain analysis. Using this 3D tagging analysis method, longitudinal strain and circumferential-longitudinal shear was quantified in addition to the 2D ventricular wall strain. Second, to improve the limited tagging resolution of existing SPAMM techniques, a HARP-based high-resolution tagging analysis method was proposed in mouse. The utility of such method was demostrated by quantifying the transmural heterogeneity of the left ventricle. Third, a 2D multi-phase displacement encoding with stimulated echoes (DENSE) imaging and analysis method was developed which allows direct and automatic Lagrangian strain quantification with high spatial and temporal resolution. Additionally, the utility of this multi-phase DENSE method was demonstrated in mouse both at baseline and with high workload. Functional enhancement was identified upon dobutamine stimulation both at the global and the regional levels. Fourth, for the evaluation of longitudinal wall motion within the short axis (SA) plane, 2D multi-phase DENSE imaging method was extended to the third dimension. Last, the application of MR tagging and DENSE methods was investigated in diabetic mouse hearts with cardiac-specific GLUT1-overexpression. Normalized cardiac function was found in diabetic mice with enhanced glucose metabolism through GLUT1-overexpression. Our results demonstrated the capability of MR tagging and DENSE in delineating left ventricular function in the mouse heart.