3T 非对比自由呼吸呼吸导航冠状动脉心血管磁共振血管造影中使用脂质不敏感二项式离共振激发（LIBRE）。
Noncontrast free-breathing respiratory self-navigated coronary artery cardiovascular magnetic resonance angiography at 3 T using lipid insensitive binomial off-resonant excitation (LIBRE).
机构信息
Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.
Center for Biomedical Imaging, Lausanne, Switzerland.
出版信息
J Cardiovasc Magn Reson. 2019 Jul 11;21(1):38. doi: 10.1186/s12968-019-0543-6.
BACKGROUND
Robust and homogeneous lipid suppression is mandatory for coronary artery cardiovascular magnetic resonance (CMR) imaging since the coronary arteries are commonly embedded in epicardial fat. However, effective large volume lipid suppression becomes more challenging when performing radial whole-heart coronary artery CMR for respiratory self-navigation and the problem may even be exacerbated at increasing magnetic field strengths. Incomplete fat suppression not only hinders a correct visualization of the coronary vessels and generates image artifacts, but may also affect advanced motion correction methods. The aim of this study was to evaluate a recently reported lipid insensitive CMR method when applied to a noncontrast self-navigated coronary artery CMR acquisitions at 3 T, and to compare it to more conventional fat suppression techniques.
METHODS
Lipid insensitive binomial off resonant excitation (LIBRE) radiofrequency excitation pulses were included into a self-navigated 3D radial GRE coronary artery CMR sequence at 3 T. LIBRE was compared against a conventional CHESS fat saturation (FS) and a binomial 1-180°-1 water excitation (WE) pulse. First, fat suppression of all techniques was numerically characterized using Matlab and experimentally validated in phantoms and in legs of human volunteers. Subsequently, free-breathing self-navigated coronary artery CMR was performed using the LIBRE pulse as well as FS and WE in ten healthy subjects. Myocardial, arterial and chest fat signal-to-noise ratios (SNR), as well as coronary vessel conspicuity were quantitatively compared among those scans.
RESULTS
The results obtained in the simulations were confirmed by the experimental validations as LIBRE enabled near complete fat suppression for 3D radial imaging in vitro and in vivo. For self-navigated whole-heart coronary artery CMR at 3 T, fat SNR was significantly attenuated using LIBRE compared with conventional FS. LIBRE increased the right coronary artery (RCA) vessel sharpness significantly (37 ± 9% (LIBRE) vs. 29 ± 8% (FS) and 30 ± 8% (WE), both p < 0.05) and led to a significant increase in the measured RCA vessel length to (83 ± 31 mm (LIBRE) vs. 56 ± 12 mm (FS) and 59 ± 27 (WE) p < 0.05).
CONCLUSIONS
Applied to a respiratory self-navigated noncontrast 3D radial whole-heart sequence, LIBRE enables robust large volume fat suppression and significantly improves coronary artery image quality at 3 T compared to the use of conventional FS and WE.
背景
由于冠状动脉通常嵌入于心外膜脂肪中，因此对于冠状动脉心血管磁共振成像（CMR）来说，稳健且均匀的脂质抑制是强制性的。然而，当进行用于呼吸自导航的径向全心冠状动脉 CMR 时，有效的大容量脂质抑制变得更具挑战性，并且该问题甚至可能在增加磁场强度时加剧。不完全的脂肪抑制不仅会阻碍冠状动脉的正确可视化并产生图像伪影，而且还可能影响先进的运动校正方法。本研究的目的是评估一种最近报道的脂质不敏感 CMR 方法，当应用于 3T 时的非对比性自导航冠状动脉 CMR 采集，并将其与更传统的脂肪抑制技术进行比较。
方法
在 3T 下，将脂质不敏感的二项式离共振激发（LIBRE）射频激发脉冲纳入到自导航的 3D 径向 GRE 冠状动脉 CMR 序列中。LIBRE 与传统的 CHESS 脂肪饱和（FS）和二项式 1-180°-1 水激发（WE）脉冲进行了比较。首先，使用 Matlab 对所有技术的脂肪抑制作用进行数值表征，并在体模和人体志愿者的腿部中进行了实验验证。随后，使用 LIBRE 脉冲以及 FS 和 WE 在 10 名健康受试者中进行了自由呼吸的自导航冠状动脉 CMR。定量比较了这些扫描中的心肌，动脉和胸部脂肪的信噪比（SNR）以及冠状动脉的显影效果。
结果
模拟中获得的结果通过实验验证得到了证实，因为 LIBRE 能够在体外和体内实现 3D 径向成像的近乎完全的脂肪抑制。对于 3T 时的自导航全心冠状动脉 CMR，与传统的 FS 相比，LIBRE 显著降低了脂肪 SNR。LIBRE 显著增加了右冠状动脉（RCA）的血管锐利度（37±9％（LIBRE）比 29±8％（FS）和 30±8％（WE），均 p<0.05），并导致所测量的 RCA 血管长度显著增加（83±31mm（LIBRE）比 56±12mm（FS）和 59±27mm（WE），均 p<0.05）。
结论
应用于呼吸自导航的非对比性 3D 径向全心序列，LIBRE 能够在 3T 时实现强大的大容量脂肪抑制，并与使用传统的 FS 和 WE 相比，显著提高了冠状动脉的图像质量。
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