STRUCTURE AND FUNCTION Age-Related Changes in Myocardial Relaxation Using Three-Dimensional Tagged Magnetic Resonance Imaging

Purpose. Marked changes in left ventricular diastolic filling occur with advancing age, but alterations in myocardial movement accompanying these findings have not been previously documented. We aimed to identify differences in myocardial motion during relaxation and diastole using magnetic resonance imaging (MRI), with tagging, which uniquely allows accurate, noninvasive assessment of myocardial movement in three dimensions. Methods. Tagged MRI images from two groups of normal individuals were analyzed using dedicated computer software to provide values for group comparison of apical rotation, torsion, and circumferential and longitudinal strain throughout the cardiac cycle. Results. The mean age of the younger group was 22 years, ðn 1⁄4 15Þ and that of the older group was 69 years, ðn 1⁄4 16Þ: In the older group, peak apical rotation and torsion were increased during systole and significantly more apical rotation, torsion, circumferential, and longitudinal strain persisted during myocardial relaxation and diastole. In addition, peak normalized reversal of apical rotation was reduced (25:1 ^ 1:28 s vs. 26:7 ^ 1:28 s; p 1⁄4 0:001), and there were slower peak rates of circumferential lengthening (76:2 ^ 28% s vs. 142:5 ^ 17% s, p , 0:001) and longitudinal lengthening (62:7 ^ 21% s vs. 122:5 ^ 20% s, p , 0:001). Conclusions. Tagged MRI is a unique, noninvasive imaging method that can identify significant prolongation and reduction of myocardial relaxation in older compared with young normal individuals.