Volumetric and multispectral DWI near metallic implants using a non-linear phase Carr-Purcell-Meiboom-Gill diffusion preparation.
Volumetric and multispectral DWI near metallic implants using a non-linear phase Carr-Purcell-Meiboom-Gill diffusion preparation.
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DOI：
10.1002/mrm.29153
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发表时间：
2022-06
影响因子：
3.3
通讯作者：
Hargreaves BA
中科院分区：
文献类型：
--
作者：
Lee PK;Yoon D;Sandberg JK;Vasanawala SS;Hargreaves BA
金属植入物附近的扩散加权（DW）成像尚未得到广泛探索，这主要是由于与透片和面内畸变、不同光谱箱的编码要求增加以及信噪比有限相关的重大挑战。由于通常使用的EPI轨迹由于2 - 20khz范围内的极端非共振失真而完全失败，因此没有广泛采用的临床方案用于金属附近的DW成像。我们提出了一个序列，在临床可行的扫描时间内实现了中等b值（400-500 s/mm2）的金属附近DW成像和体积覆盖。多光谱激励与笛卡尔采样，视角倾斜，和kz相位编码减少面内和通过面非共振伪影，CPMG自旋回波重聚焦列车抵消T2*效应。采用受激回波扩散制备消除了随机相位对重聚焦序列的影响。根翻转Shinnar-Le Roux重聚焦脉冲允许制备高光谱带宽，通过减少覆盖所需光谱范围所需的激发次数来提高成像时间。通过在制备中采用满足CPMG条件的激发来降低B1灵敏度。提出了一种对背景梯度不敏感的ADC量化方法。非线性相位重聚焦脉冲使峰值B1降低46%，从而使射频带宽增加一倍。仿真和模拟实验表明，非线性相位CPMG脉冲对降低了B1灵敏度。在体内的应用证明了与传统多光谱采集的互补对比和与DW-EPI相比更好的可视化。利用三维编码序列可以实现金属附近的体积和多光谱DW成像。
Diffusion weighted (DW) imaging near metal implants has not been widely explored due to substantial challenges associated with through-slice and in-plane distortions, the increased encoding requirement of different spectral bins, and limited SNR. There is no widely adopted clinical protocol for DW imaging near metal since the commonly used EPI trajectory fails completely due to distortion from extreme off-resonance ranging from 2–20 kHz. We present a sequence that achieves DW imaging near metal with moderate b-values (400–500 s/mm2) and volumetric coverage in clinically feasible scan times. Multispectral excitation with Cartesian sampling, View Angle Tilting, and kz phase encoding reduce in-plane and through-plane off-resonance artifacts, and CPMG spin-echo refocusing trains counteract T2* effects. The effect of random phase on the refocusing train is eliminated using a stimulated echo diffusion preparation. Root-flipped Shinnar-Le Roux refocusing pulses permits preparation of a high spectral bandwidth, which improves imaging times by reducing the number of excitations required to cover the desired spectral range. B1 sensitivity is reduced by employing an excitation that satisfies the CPMG condition in the preparation. A method for ADC quantification insensitive to background gradients is presented. Non-linear phase refocusing pulses reduces the peak B1 by 46% which allows RF bandwidth to be doubled. Simulations and phantom experiments show that a non-linear phase CPMG pulse pair reduces B1 sensitivity. Application in vivo demonstrates complementary contrast to conventional multispectral acquisitions and improved visualization compared to DW-EPI. Volumetric and multispectral DW imaging near metal can be achieved with a 3D encoded sequence.
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影响因子：
3.3
作者：
Busse, Reed F.;Brau, Anja C. S.;Vu, Anthony;Michelich, Charles R.;Bayram, Ersin;Kijowski, Richard;Reeder, Scott B.;Rowley, Howard A.
通讯作者：
Rowley, Howard A.
影响因子：
3.3
作者：
Hargreaves BA;Taviani V;Litwiller DV;Yoon D
通讯作者：
Yoon D
影响因子：
2.2
作者：
CONOLLY, S;NISHIMURA, D;GLOVER, G
通讯作者：
GLOVER, G
影响因子：
3.3
作者：
Feldman RE;Islam HM;Xu J;Balchandani P
通讯作者：
Balchandani P
影响因子：
3.3
作者：
Koch, Kevin M.;King, Kevin F.;Hargreaves, Brian A.
通讯作者：
Hargreaves, Brian A.