Beschreibung:
<jats:sec><jats:title>Purpose</jats:title><jats:p>To elucidate the impact of technical and intraindividual reproducibility on the overall variability of myocardial <jats:italic>T</jats:italic><jats:sub>2</jats:sub> relaxation times.</jats:p></jats:sec><jats:sec><jats:title>Materials and Methods</jats:title><jats:p>Thirty healthy volunteers were examined three times (day 1 morning/evening, evening after 2–3 weeks) at 1.5T. During each examination three different <jats:italic>T</jats:italic><jats:sub>2</jats:sub>‐mapping sequences were acquired twice at three slices in short axis view: multi‐echo‐spin‐echo (MESE), <jats:italic>T</jats:italic><jats:sub>2</jats:sub>‐prepared balanced steady‐state free precession (SSFP) (<jats:italic>T</jats:italic><jats:sub>2</jats:sub>prep), and gradient‐spin‐echo with and without fat saturation (GraSE/GraSE<jats:sub>FS</jats:sub>). Repeated measurements were performed for <jats:italic>T</jats:italic><jats:sub>2</jats:sub>prep and GraSE. Segmented <jats:italic>T</jats:italic><jats:sub>2</jats:sub>‐maps were generated for each slice according to the American Heart Association (AHA) 16‐segment model.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The coefficients of variation and intraclass correlation coefficients for intraobserver variability were: 1.3% and 0.89 for <jats:italic>T</jats:italic><jats:sub>2</jats:sub>prep, 1.5% and 0.93 for GraSE, 3.1% and 0.83 for MESE; and for interobserver variability: 3.3% and 0.66 for <jats:italic>T</jats:italic><jats:sub>2</jats:sub>prep, 2.0% and 0.83 for GraSE, 3.6% and 0.77 for MESE. No systematic difference of <jats:italic>T</jats:italic><jats:sub>2</jats:sub> times was observed due to diurnal effects and on long‐term analysis using one‐way analysis of variance (ANOVA) with Tukey‐type multiple comparisons (morning vs. evening scan for <jats:italic>T</jats:italic><jats:sub>2</jats:sub>prep: 52.5 ± 2.4 vs. 51.7 ± 2.7 msec, <jats:italic>P</jats:italic> = 0.119; for GraSE: 58.6 ± 4.0 vs. 58.5 ± 3.8 msec, <jats:italic>P</jats:italic> = 0.984; for GraSE<jats:sub>FS</jats:sub> 57.1 ± 3.2 vs. 57.2 ± 3.9 msec, <jats:italic>P</jats:italic> = 0.998, and for MESE: 53.8 ± 2.7 vs. 53.3 ± 3.3 msec, <jats:italic>P</jats:italic> = 0.541; scans between weeks for <jats:italic>T</jats:italic><jats:sub>2</jats:sub>prep: 51.7 ± 2.7 vs. 51.4 ± 2.4 msec, <jats:italic>P</jats:italic> = 0.873; for GraSE: 58.5 ± 3.8 vs. 58.1 ± 3.4 msec, <jats:italic>P</jats:italic> = 0.736; for GraSE<jats:sub>FS</jats:sub>: 57.2 ± 3.9 vs. 57.0 ± 4.6 msec, <jats:italic>P</jats:italic> = 0.964, and for MESE: 53.3 ± 3.3 vs. 53.4 ± 2.4 msec, <jats:italic>P</jats:italic> = 0.970). ANOVA components, however, demonstrated a greater variance of <jats:italic>T</jats:italic><jats:sub>2</jats:sub> times over multiple timepoints than for repeated measurements within the same scan (variance components of the model fit for intraday variance vs. repeated measurements: <jats:italic>T</jats:italic><jats:sub>2</jats:sub>prep 2.22 vs. 1.36, GraSE 3.76 vs. 2.09, GraSE<jats:sub>FS</jats:sub> 3.96 vs. 1.58, MESE 1.86; and for interweeks variance vs. repeated measurements: <jats:italic>T</jats:italic><jats:sub>2</jats:sub>prep 2.21 vs. 0.80, GraSE 3.20 vs. 2.10, GraSE<jats:sub>FS</jats:sub> 8.82 vs. 1.18, and MESE 4.49).</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Technical reproducibility and intra‐ and interobserver agreement of myocardial <jats:italic>T</jats:italic><jats:sub>2</jats:sub> relaxation times are excellent and intraindividual variation over time is small. Therefore, we consider subject‐related factors to explain most of the interindividual variability of myocardial <jats:italic>T</jats:italic><jats:sub>2</jats:sub> times reported in previous studies. The acknowledgment of this subject‐related, biological variability may be important for the future diagnostic value of <jats:italic>T</jats:italic><jats:sub>2</jats:sub>‐mapping. J. Magn. Reson. Imaging 2016;44:1168–1178.</jats:p></jats:sec>