BACKGROUND: Quantification of the longitudinal- and transverse relaxation time in the myocardium has shown to provide important information in cardiac diagnostics. Methods for cardiac relaxation time mapping generally demand a long breath hold to measure either T1 or T2 in a single 2D slice. In this paper we present and evaluate a novel method for 3D interleaved T1 and T2 mapping of the whole left ventricular myocardium within a single breath hold of 15 heartbeats. METHODS: The 3D-QALAS (3D-quantification using an interleaved Look-Locker acquisition sequence with T2 preparation pulse) is based on a 3D spoiled Turbo Field Echo sequence using inversion recovery with interleaved T2 preparation. Quantification of both T1 and T2 in a volume of 13 slices with a resolution of 2.0x2.0x6.0 mm is obtained from five measurements by using simulations of the longitudinal magnetizations Mz. This acquisition scheme is repeated three times to sample k-space. The method was evaluated both in-vitro (validated against Inversion Recovery and Multi Echo) and in-vivo (validated against MOLLI and Dual Echo). RESULTS: In-vitro, a strong relation was found between 3D-QALAS and Inversion Recovery (R = 0.998; N = 10; p < 0.01) and between 3D-QALAS and Multi Echo (R = 0.996; N = 10; p < 0.01). The 3D-QALAS method showed no dependence on e.g. heart rate in the interval of 40-120 bpm. In healthy myocardium, the mean T1 value was 1083 ± 43 ms (mean ± SD) for 3D-QALAS and 1089 ± 54 ms for MOLLI, while the mean T2 value was 50.4 ± 3.6 ms 3D-QALAS and 50.3 ± 3.5 ms for Dual Echo. No significant difference in in-vivo relaxation times was found between 3D-QALAS and MOLLI (N = 10; p = 0.65) respectively 3D-QALAS and Dual Echo (N = 10; p = 0.925) for the ten healthy volunteers. CONCLUSIONS: The 3D-QALAS method has demonstrated good accuracy and intra-scan variability both in-vitro and in-vivo. It allows rapid acquisition and provides quantitative information of both T1 and T2 relaxation times in the same scan with full coverage of the left ventricle, enabling clinical application in a broader spectrum of cardiac disorders.
展开▼
机译：背景：量化心肌的纵向和横向弛豫时间已显示出在心脏诊断中的重要信息。心脏舒张时间映射的方法通常需要屏住呼吸才能测量单个2D切片中的T1或T2。在本文中，我们提出并评估了一种新的方法，该方法可在15次心跳的一次屏息内对整个左心室心肌进行3D交错T1和T2映射。方法：3D-QALAS（使用带有T2准备脉冲的交错式Look-Locker采集序列进行3D量化）基于3D损坏的Turbo场回波序列，该过程使用带有T2交错准备的反演恢复。通过使用纵向磁化强度Mz的五次测量，可以得到13个切片中T1和T2的定量，分辨率为2.0x2.0x6.0 mm。重复该采集方案三次以采样k空间。对该方法进行了体外评估（针对Inversion Recovery和Multi Echo进行了验证）和体内评估（针对MOLLI和Dual Echo进行了验证）。结果：在体外，发现3D-QALAS与反转恢复之间有很强的关系（R = 0.998； N = 10； p <0.01）以及3D-QALAS与Multi Echo之间的相关性（R = 0.996； N = 10； p < 0.01）。 3D-QALAS方法显示不依赖于例如心率在40-120 bpm之间。在健康心肌中，3D-QALAS的平均T1值为1083±43 ms（MOLLI）为1089±54 ms，而3D-QALAS的平均T2值为50.4±3.6 ms和Dual的T2值为50.3±3.5 ms回声。十名健康志愿者的3D-QALAS和MOLLI（N = 10; p = 0.65）和3D-QALAS和Dual Echo（N = 10; p = 0.925）的体内舒张时间没有显着差异。结论：3D-QALAS方法在体外和体内均显示出良好的准确性和扫描内变异性。它可以快速采集并在同一扫描中提供T1和T2弛豫时间的定量信息，并完全覆盖左心室，从而可以在更广泛的心脏疾病中进行临床应用。
展开▼
