Global and Regional Test-Retest Reproducibility of Native T1 and T2 Mapping in Cardiac Magnetic Resonance Imaging.

BACKGROUND: Mapping of T1 and T2 relaxation times in cardiac MRI is an invaluable tool for the diagnosis and risk stratification of a wide spectrum of cardiac diseases. PURPOSE: To investigate the global and regional reproducibility of native T1 and T2 mapping and to analyze the influence of demographic factors, physiological parameters, slice position, and myocardial regions on reproducibility. STUDY TYPE: Prospective single-center cohort-study. POPULATION: Fifty healthy volunteers (29 female, 21 male) with a mean age of 39.4 ± 13.7 years. FIELD STRENGTH/SEQUENCE: Each volunteer was investigated twice at 1.5 T using a modified look-locker inversion-recovery (MOLLI) sequence (T1 mapping) and a T2-prepared steady-state free precession (SSFP) sequence (T2 mapping). ASSESSMENT: Global T1 and T2 values were quantified for the entire left ventricle in three short-axis slices. Regional T1 and T2 values were measured for each myocardial segment and for myocardial segments grouped by slice position and anatomical region. STATISTICAL TESTS: Test-retest reproducibility was assessed using intraclass correlation coefficient (ICC) and Bland-Altman statistics. A P value < 0.05 was considered statistically significant. RESULTS: Reproducibility was good for global T1 values (ICC 0.88) and excellent for global T2 values (ICC 0.91). Reproducibility of T1 values was excellent (ICC 0.91) for midventricular slice and good for apical (ICC 0.86) and basal slice (ICC 0.81). Reproducibility of T1 mapping values was highest in the septum (ICC 0.90) compared to the anterior (0.81), lateral (0.86), and inferior (0.86) wall. For T2 mapping, reproducibility was good for all slice positions (ICC 0.86 for midventricular, 0.83 for basal, and 0.80 for apical slice). Reproducibility of T2 mapping was significantly lower for the inferior wall (ICC 0.58) than for septum (0.89), anterior (0.85), and lateral (0.87) wall. DATA CONCLUSION: Native T1 and T2 mapping has good to excellent reproducibility with significant regional differences. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.