T1 mapping data are generally acquired in patients' diastolic phase, wherein their myocardium is the thinnest in the cardiac cycle. However, the analysis of the thin myocardium may cause errors in image registrations and settings related to the region of interest. In this study, we validated systolic T1 mapping using the saturation recovery with individualized delay time (SR-IDT) method and compared it with conventional diastolic T1 mapping. Both diastolic and systolic T1 mappings were performed in the mid-ventricular plane in 10 healthy volunteers (35 ± 9 years, 9 males) and 29 consecutive patients with cardiac diseases (68 ± 14 years, 19 males). Comparison of the myocardial T1 value at diastole and systole was performed with both the Pearson correlation coefficient (r) and the Bland-Altman analysis. Additionally, the systolic myocardial T1 value was compared between the volunteers and patients by using Tukey's test. Pearson correlation analysis demonstrated a strong positive correlation between diastolic and systolic T1 values (r = 0.88, P < 0.001). The Bland-Altman plot suggested that left ventricular T1 values in the diastole and systole showed high agreement (mean difference and 95% limits of agreement = 17 ± 104 ms). Further, systolic T1 values with SR-IDT in patients in the late gadolinium enhancement (LGE) group were significantly higher than those in the control group (1585 ± 118 ms vs 1469 ± 69 ms; P = 0.024). Therefore, the proposed systolic T1 mapping with the SR-IDT, which was validated with respect to the conventional diastolic method, is a useful clinical tool for the quantitative characterization of the myocardium.
Keywords: Cardiovascular magnetic resonance imaging; Myocardium; Saturation recovery; Systole; T1 mapping.