Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD 20892-1182, USA.
J Cardiovasc Magn Reson. 2013 Jul 26;15(1):64. doi: 10.1186/1532-429X-15-64.
Cardiovascular magnetic resonance (CMR) T1 mapping indices, such as T1 time and partition coefficient (λ), have shown potential to assess diffuse myocardial fibrosis. The purpose of this study was to investigate how scanner and field strength variation affect the accuracy and precision/reproducibility of T1 mapping indices.
CMR studies were performed on two 1.5T and three 3T scanners. Eight phantoms were made to mimic the T1/T2 of pre- and post-contrast myocardium and blood at 1.5T and 3T. T1 mapping using MOLLI was performed with simulated heart rate of 40-100 bpm. Inversion recovery spin echo (IR-SE) was the reference standard for T1 determination. Accuracy was defined as the percent error between MOLLI and IR-SE, and scan/re-scan reproducibility was defined as the relative percent mean difference between repeat MOLLI scans. Partition coefficient was estimated by ΔR1myocardium phantom/ΔR1blood phantom. Generalized linear mixed model was used to compare the accuracy and precision/reproducibility of T1 and λ across field strength, scanners, and protocols.
Field strength significantly affected MOLLI T1 accuracy (6.3% error for 1.5T vs. 10.8% error for 3T, p<0.001) but not λ accuracy (8.8% error for 1.5T vs. 8.0% error for 3T, p=0.11). Partition coefficients of MOLLI were not different between two 1.5T scanners (47.2% vs. 47.9%, p=0.13), and showed only slight variation across three 3T scanners (49.2% vs. 49.8% vs. 49.9%, p=0.016). Partition coefficient also had significantly lower percent error for precision (better scan/re-scan reproducibility) than measurement of individual T1 values (3.6% for λ vs. 4.3%-4.8% for T1 values, approximately, for pre/post blood and myocardium values).
Based on phantom studies, T1 errors using MOLLI ranged from 6-14% across various MR scanners while errors for partition coefficient were less (6-10%). Compared with absolute T1 times, partition coefficient showed less variability across platforms and field strengths as well as higher precision.
心血管磁共振（CMR）T1 映射指数，如 T1 时间和分区系数（λ），已显示出评估弥漫性心肌纤维化的潜力。本研究的目的是研究扫描仪和场强变化如何影响 T1 映射指数的准确性和精密度/可重复性。
在两台 1.5T 和三台 3T 扫描仪上进行 CMR 研究。制作了八个仿体，以模拟 1.5T 和 3T 时的预对比和对比后心肌和血液的 T1/T2。使用 MOLLI 进行 T1 映射，模拟心率为 40-100 bpm。反转恢复自旋回波（IR-SE）是 T1 测定的参考标准。准确性定义为 MOLLI 和 IR-SE 之间的百分比误差，扫描/重扫可重复性定义为重复 MOLLI 扫描之间的相对平均差异百分比。分区系数由心肌仿体 ΔR1/血液仿体 ΔR1 估计。广义线性混合模型用于比较不同场强、扫描仪和方案下 T1 和 λ 的准确性和精密度/可重复性。
场强显著影响 MOLLI T1 的准确性（1.5T 为 6.3%误差，3T 为 10.8%误差，p<0.001），但不影响 λ 的准确性（1.5T 为 8.8%误差，3T 为 8.0%误差，p=0.11）。两台 1.5T 扫描仪的 MOLLI 分区系数无差异（47.2% vs. 47.9%，p=0.13），三台 3T 扫描仪之间的差异也很小（49.2% vs. 49.8% vs. 49.9%，p=0.016）。与单个 T1 值的测量相比，分区系数的精度（更好的扫描/重扫可重复性）的百分比误差也明显较低（λ 为 3.6%，而预/后血液和心肌值的 T1 值约为 4.3%-4.8%）。
基于仿体研究，使用 MOLLI 的 T1 误差在各种磁共振扫描仪之间为 6-14%，而分区系数的误差较小（6-10%）。与绝对 T1 时间相比，分区系数在平台和场强之间的变化较小，精度较高。
