School of Biomedical Engineering and Imaging Sciences, Faculty of Life Sciences and Medicine, King's College London, United Kingdom.
MR Research Collaborations, Siemens Healthcare Limited, Frimley, United Kingdom.
J Magn Reson Imaging. 2019 Aug;50(2):641-654. doi: 10.1002/jmri.26649. Epub 2019 Jan 22.
Myocardial T mapping shows promise for assessment of cardiomyopathies. Most myocardial T mapping techniques, such as modified Look-Locker inversion recovery (MOLLI), generate one T map per breath-held acquisition (9-17 heartbeats), which prolongs multislice protocols and may be unsuitable for patients with breath-holding difficulties.
To develop and characterize novel shortened inversion recovery based T mapping schemes of 2-5 heartbeats.
Prospective.
POPULATION/PHANTOM: Numerical simulations, agarose/NiCl phantom, 16 healthy volunteers, and 24 patients.
FIELD STRENGTH/SEQUENCE: 1.5T/MOLLI.
All shortened T mapping schemes were characterized and compared with a conventional MOLLI scheme (5-(3)-3) in terms of accuracy, precision, spatial variability, and repeatability.
Kruskal-Wallis, Wilcoxon rank sum tests, analysis of variance, Student's t-tests, Bland-Altman analysis, and Pearson correlation analysis.
All shortened schemes provided limited T time variations (≤2% for T times ≤1200 msec) and limited penalty of precision (by a factor of ~1.4-1.5) when compared with MOLLI in numerical simulations. In phantom, differences between all schemes in terms of accuracy, spatial variability, and repeatability did not reach statistical significance (P > 0.71). In healthy volunteers, there were no statistically significant differences between all schemes in terms of native T times and repeatability for myocardium (P = 0.21 and P = 0.87, respectively) and blood (P = 0.79 and P = 0.41, respectively). All shortened schemes led to a limited increase of spatial variability for native myocardial T mapping with respect to MOLLI (by a factor of 1.2) (P < 0.0001). In both healthy volunteers and patients, the two-heartbeat scheme and MOLLI led to highly linearly correlated T times (correlation coefficients ≥0.83).
The proposed two-heartbeat T mapping scheme yields a 5-fold acceleration compared with MOLLI, with highly linearly correlated T times, no significant difference of repeatability, and limited spatial variability penalty at 1.5T. This approach may enable myocardial T mapping in patients with severe breath-holding difficulties and reduce the examination time of multislice protocols.
1 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2019;50:641-654.
心肌 T 映射技术有望用于评估心肌病。大多数心肌 T 映射技术，如改良 Look-Locker 反转恢复（MOLLI），每次呼吸暂停采集生成一个 T 映射（9-17 个心跳），这延长了多层面协议，可能不适合有呼吸暂停困难的患者。
开发和描述 2-5 个心跳的基于新的缩短反转恢复的 T 映射方案。
前瞻性。
人群/体模：数值模拟、琼脂糖/NiCl 体模、16 名健康志愿者和 24 名患者。
磁场强度/序列：1.5T/MOLLI。
所有缩短的 T 映射方案均经过特征描述，并与常规 MOLLI 方案（5-(3)-3）进行比较，比较指标包括准确性、精密度、空间变异性和可重复性。
Kruskal-Wallis、Wilcoxon 秩和检验、方差分析、学生 t 检验、Bland-Altman 分析和 Pearson 相关分析。
在数值模拟中，所有缩短的方案都提供了有限的 T 时间变化（T 时间≤1200 毫秒时≤2%）和有限的精度惩罚（约 1.4-1.5 倍），与 MOLLI 相比。在体模中，所有方案在准确性、空间变异性和可重复性方面的差异均无统计学意义（P>0.71）。在健康志愿者中，所有方案在心肌和血液的固有 T 时间和重复性方面均无统计学差异（P=0.21 和 P=0.87，分别）和血液（P=0.79 和 P=0.41，分别）。与 MOLLI 相比，所有缩短的方案都导致固有心肌 T 映射的空间变异性有有限的增加（增加了 1.2 倍）（P<0.0001）。在健康志愿者和患者中，双心跳方案和 MOLLI 导致 T 时间高度线性相关（相关系数≥0.83）。
与 MOLLI 相比，提出的双心跳 T 映射方案可实现 5 倍加速，具有高度线性相关的 T 时间、无显著重复性差异以及在 1.5T 时空间变异性惩罚有限。该方法可能使有严重呼吸暂停困难的患者进行心肌 T 映射，并减少多层面协议的检查时间。
1 技术功效分期：3 J. Magn. Reson. Imaging 2019;50:641-654.
