Quantification of changes in myocardial T1 * values with exercise cardiac MRI using a free-breathing non-electrocardiograph radial imaging.
Quantification of changes in myocardial T1 * values with exercise cardiac MRI using a free-breathing non-electrocardiograph radial imaging.
复制标题
使用自由呼吸非心电图径向成像通过运动心脏 MRI 量化心肌 T1 * 值的变化。
DOI：
10.1002/mrm.29346
复制
发表时间：
2022
影响因子：
3.3
通讯作者：
Nezafat,Reza
中科院分区：
文献类型：
--
作者：
Guo,Rui;Qi,Haikun;Amyar,Amine;Cai,Xiaoying;Kucukseymen,Selcuk;Haji-Valizadeh,Hassan;Rodriguez,Jennifer;Paskavitz,Amanda;Pierce,Patrick;Goddu,Beth;Thompson,RichardB;Nezafat,Reza
目的使用径向成像开发和评估自由呼吸非心电图 (ECG) 心肌 T1* 映射序列，以量化运动心脏 MRI (Ex-CMR) 中休息和运动之间心肌 T1* 的变化（T1* 反应性）。方法使用饱和脉冲开发自由运行 T1* 序列，然后进行三个 Look-Locker 反转恢复实验。每个 Look-Locker 使用低翻转角破坏梯度回波读数连续采集数据作为径向轨迹。以~100ms的时间分辨率进行自我导航，以回顾性地提取呼吸运动。使用经验模型对记录的心电图信号回顾性检测每个心动周期的舒张中期阶段。进行多次测量以获得平均值，以减少自由呼吸采集的影响。最后，通过低秩加稀疏约束算法选取并重建在舒张中期和呼气末获取的数据。通过模拟、模型和静息时和生理运动后的体内研究来评估该序列的性能。结果数值模拟表明，T1* 的变化与 T1 的变化相关；然而，呼吸运动等其他因素可能会影响 T1* 测量。使用自由运行 T1* 映射序列测量的体模 T1* 值与自旋回波 T1 值具有良好的相关性，并且对心率不敏感。在 Ex-CMR 研究中，运动后测得的 T1* 反应性为 10%，并随着时间的推移而下降。结论 自由运行的 T1* 映射序列允许对生理运动引起的心肌 T1* 变化进行自由呼吸的非心电图量化。尽管绝对心肌 T1* 值对各种混杂因素（例如 B1 和 B0 不均匀性）敏感，但对其变化的量化可能有助于揭示运动时的心肌组织特性。
PurposeTo develop and evaluate a free breathing non‐electrocardiograph (ECG) myocardial T1* mapping sequence using radial imaging to quantify the changes in myocardial T1* between rest and exercise (T1*reactivity) in exercise cardiac MRI (Ex‐CMR).MethodsA free‐running T1* sequence was developed using a saturation pulse followed by three Look‐Locker inversion‐recovery experiments. Each Look‐Locker continuously acquired data as radial trajectory using a low flip‐angle spoiled gradient‐echo readout. Self‐navigation was performed with a temporal resolution of ∼100 ms for retrospectively extracting respiratory motion. The mid‐diastole phase for every cardiac cycle was retrospectively detected on the recorded electrocardiogram signal using an empirical model. Multiple measurements were performed to obtain mean value to reduce effects from the free‐breathing acquisition. Finally, data acquired at both mid‐diastole and end‐expiration are picked and reconstructed by a low‐rank plus sparsity constraint algorithm. The performance of this sequence was evaluated by simulations, phantoms, and in vivo studies at rest and after physiological exercise.ResultsNumerical simulation demonstrated that changes in T1* are related to the changes in T1; however, other factors such as breathing motion could influence T1* measurements. Phantom T1* values measured using free‐running T1* mapping sequence had good correlation with spin‐echo T1values and was insensitive to heart rate. In the Ex‐CMR study, the measured T1* reactivity was 10% immediately after exercise and declined over time.ConclusionThe free‐running T1* mapping sequence allows free‐breathing non‐ECG quantification of changes in myocardial T1* with physiological exercise. Although, absolute myocardial T1* value is sensitive to various confounders such as B1and B0inhomogeneity, quantification of its change may be useful in revealing myocardial tissue properties with exercise.