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.

中文翻译：

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使用脂质不敏感二项式偏共振激励 (LIBRE) 在 3 T 下进行非对比自由呼吸呼吸自导航冠状动脉心血管磁共振血管造影。


背景技术由于冠状动脉通常嵌入心外膜脂肪中，因此强有力且均匀的脂质抑制对于冠状动脉心血管磁共振（CMR）成像是必需的。然而，当进行径向全心冠状动脉 CMR 进行呼吸自导航时，有效的大容量脂质抑制变得更具挑战性，并且随着磁场强度的增加，问题甚至可能会加剧。不完全的脂肪抑制不仅阻碍冠状血管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最近报道的脂质不敏感 CMR 方法，该方法应用于 3 T 下的非造影自导航冠状动脉 CMR 采集，并将其与更传统的脂肪抑制技术进行比较。方法 将脂质不敏感二项式非共振激励 (LIBRE) 射频激励脉冲纳入 3 T 的自导航 3D 径向 GRE 冠状动脉 CMR 序列中。LIBRE 与传统 CHESS 脂肪饱和度 (FS) 和二项式 1-180° 进行比较-1 水激发 (WE) 脉冲。首先，使用 Matlab 对所有技术的脂肪抑制进行了数值表征，并在人体志愿者的体模和腿部中进行了实验验证。随后，使用 LIBRE 脉冲以及 FS 和 WE 对 10 名健康受试者进行自由呼吸自导航冠状动脉 CMR。对这些扫描中的心肌、动脉和胸部脂肪信噪比（SNR）以及冠状血管的清晰度进行了定量比较。 结果 模拟中获得的结果得到了实验验证的证实，因为 LIBRE 能够在体外和体内的 3D 径向成像中实现近乎完全的脂肪抑制。对于 3 T 下的自导航全心冠状动脉 CMR，与传统 FS 相比，使用 LIBRE 显着减弱了脂肪 SNR。 LIBRE 显着增加了右冠状动脉 (RCA) 血管清晰度（37 ± 9% (LIBRE) 对比 29 ± 8% (FS) 和 30 ± 8% (WE)，均 p < 0.05），并导致将测得的 RCA 血管长度调整为 (83 ± 31 mm (LIBRE) vs. 56 ± 12 mm (FS) 和 59 ± 27 (WE) p < 0.05）。结论 与使用传统 FS 和 WE 相比，LIBRE 应用于呼吸自导航非对比 3D 径向全心脏序列，能够实现强大的大体积脂肪抑制，并显着提高 3 T 下的冠状动脉图像质量。