Myocardial effective relaxation time Symbol is commonly regarded as a surrogate for myocardial tissue oxygenation. However, it is legitimate to assume that there are multiple factors that influence Symbol. To this end, this study investigates the relationship between Symbol and cardiac macromorphology given by left ventricular (LV) wall thickness and left ventricular radius, and provides interpretation of the results in the physiological context.Methods:
High spatio-temporally resolved myocardial CINE Symbol mapping was performed in 10 healthy volunteers using a 7.0 Tesla (T) full-body MRI system. Ventricular septal wall thickness, left ventricular inner radius, and Symbol were analyzed. Macroscopic magnetic field changes were elucidated using cardiac phase–resolved magnetic field maps.Results:
Ventricular septal Symbol changes periodically over the cardiac cycle, increasing in systole and decreasing in diastole. Ventricular septal wall thickness and Symbol showed a significant positive correlation, whereas the inner LV radius and Symbol were negatively correlated. The effect of macroscopic magnetic field gradients on Symbol can be considered minor in the ventricular septum.Conclusion:
Our findings suggest that myocardial Symbol is related to tissue blood volume fraction. Temporally resolved Symbol mapping could be beneficial for myocardial tissue characterization and for understanding cardiac (patho)physiology in vivo.