1.5T 和 3T 场强下基于径向自由运行快速间断稳态（FISS）序列的自带脂肪抑制 5D 全心 MRI
Natively fat-suppressed 5D whole-heart MRI with a radial free-running fast-interrupted steady-state (FISS) sequence at 1.5T and 3T.
机构信息
Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.
Advanced clinical imaging technology, Siemens Healthcare AG, Lausanne, Switzerland.
出版信息
Magn Reson Med. 2020 Jan;83(1):45-55. doi: 10.1002/mrm.27942. Epub 2019 Aug 27.
PURPOSE
To implement, optimize, and test fast interrupted steady-state (FISS) for natively fat-suppressed free-running 5D whole-heart MRI at 1.5 tesla (T) and 3T.
METHODS
FISS was implemented for fully self-gated free-running cardiac- and respiratory-motion-resolved radial imaging of the heart at 1.5T and 3T. Numerical simulations and phantom scans were performed to compare fat suppression characteristics and to determine parameter ranges (number of readouts [NR] per FISS module and TR) for effective fat suppression. Subsequently, free-running FISS data were collected in 10 healthy volunteers and images were reconstructed with compressed sensing. All acquisitions were compared with a continuous balanced steady-state free precession version of the same sequence, and both fat suppression and scan times were analyzed.
RESULTS
Simulations demonstrate a variable width and location of suppression bands in FISS that were dependent on TR and NR. For a fat suppression bandwidth of 100 Hz and NR ≤ 8, simulations demonstrated that a TR between 2.2 ms and 3.0 ms is required at 1.5T, whereas a range of 3.0 ms to 3.5 ms applies at 3T. Fat signal increases with NR. These findings were corroborated in phantom experiments. In volunteers, fat SNR was significantly decreased using FISS compared with balanced steady-state free precession (P < 0.05) at both field strengths. After protocol optimization, high-resolution (1.1 mm ) 5D whole-heart free-running FISS can be performed with effective fat suppression in under 8 min at 1.5T and 3T at a modest scan time increase compared to balanced steady-state free precession.
CONCLUSION
An optimal FISS parameter range was determined enabling natively fat-suppressed 5D whole-heart free-running MRI with a single continuous scan at 1.5T and 3T, demonstrating potential for cardiac imaging and noncontrast angiography.
目的
在 1.5T 和 3T 下实现、优化和测试自由运行 5D 全心脏磁共振的快速中断稳态（FISS），并对其进行天然脂肪抑制。
方法
在 1.5T 和 3T 下，对完全自主门控的自由运行心脏和呼吸运动分辨的心脏径向成像进行了 FISS 实现。进行了数值模拟和体模扫描，以比较脂肪抑制特性，并确定有效脂肪抑制的参数范围（每个 FISS 模块和 TR 的读取次数 [NR]）。随后，在 10 名健康志愿者中采集了自由运行的 FISS 数据，并使用压缩感知进行了图像重建。所有采集均与同一序列的连续平衡稳态自由进动版本进行了比较，并对脂肪抑制和扫描时间进行了分析。
结果
模拟结果表明，FISS 中的抑制带的宽度和位置是可变的，这取决于 TR 和 NR。对于脂肪抑制带宽为 100Hz 和 NR≤8，模拟结果表明在 1.5T 下需要 TR 在 2.2ms 到 3.0ms 之间，而在 3T 下则需要 3.0ms 到 3.5ms 的范围。脂肪信号随 NR 增加而增加。这些发现在体模实验中得到了证实。在志愿者中，与平衡稳态自由进动相比，FISS 显著降低了脂肪 SNR（P<0.05），在两种场强下均如此。在方案优化后，在 1.5T 和 3T 下，可以在不到 8 分钟的时间内以适度的扫描时间增加完成具有有效脂肪抑制的高分辨率（1.1mm）5D 全心脏自由运行 FISS，与平衡稳态自由进动相比具有潜在的心脏成像和非对比血管造影能力。
结论
确定了最优的 FISS 参数范围，可在 1.5T 和 3T 下实现天然脂肪抑制的 5D 全心脏自由运行 MRI，具有单次连续扫描的潜力，可为心脏成像和非对比血管造影提供潜在的应用。
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