McElroy Sarah, Tomi-Tricot Raphael, Cleary Jon, Tan Hsern Ern Ivan, Kinsella Shawna, Jeljeli Sami, Goh Vicky, Neji Radhouene
School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
MR Research Collaborations, Siemens Healthcare Limited, Camberley, UK.
Magn Reson Med. 2025 Apr;93(4):1471-1483. doi: 10.1002/mrm.30357. Epub 2024 Oct 27.
To develop a 3D distortion-free reduced-FOV diffusion-prepared gradient-echo sequence and demonstrate its application in vivo for diffusion imaging of the spinal cord in healthy volunteers.
A 3D multi-shot reduced-FOV diffusion-prepared gradient-echo acquisition is achieved using a slice-selective tip-down pulse in the phase-encoding direction in the diffusion preparation, combined with magnitude stabilizers, centric k-space encoding, and 2D phase navigators to correct for intershot phase errors. The accuracy of the ADC values obtained using the proposed approach was evaluated in a diffusion phantom and compared to the tabulated reference ADC values and to the ADC values obtained using a standard spin echo diffusion-weighted single-shot EPI sequence (DW-SS-EPI). Five healthy volunteers were scanned at 3 T using the proposed sequence, DW-SS-EPI, and a clinical diffusion-weighted multi-shot readout-segmented EPI sequence (RESOLVE) for cervical spinal cord imaging. Image quality, perceived SNR, and image distortion were assessed by two expert radiologists. ADC maps were calculated, and ADC values obtained with the proposed sequence were compared to those obtained using DW-SS-EPI and RESOLVE.
Consistent ADC estimates were measured in the diffusion phantom with the proposed sequence and the conventional DW-SS-EPI sequence, and the ADC values were in close agreement with the reference values provided by the manufacturer of the phantom. In vivo, the proposed sequence demonstrated improved image quality, improved perceived SNR, and reduced perceived distortion compared to DW-SS-EPI, whereas all measures were comparable against RESOLVE. There were no significant differences in ADC values estimated in vivo for each of the sequences.
3D distortion-free diffusion-prepared imaging can be achieved using the proposed sequence.
开发一种三维无畸变的缩小视野扩散准备梯度回波序列，并证明其在健康志愿者脊髓扩散成像中的体内应用。
在扩散准备过程中，通过在相位编码方向上使用切片选择性的向下倾斜脉冲，结合幅度稳定器、中心k空间编码和二维相位导航器来校正各次扫描间的相位误差，实现三维多次激发缩小视野扩散准备梯度回波采集。在所提出的方法中，在扩散模型中评估获得的ADC值的准确性，并与列表中的参考ADC值以及使用标准自旋回波扩散加权单次激发EPI序列（DW-SS-EPI）获得的ADC值进行比较。使用所提出的序列、DW-SS-EPI和临床扩散加权多次激发读出分段EPI序列（RESOLVE）在3T下对五名健康志愿者进行颈椎脊髓成像扫描。由两名放射科专家评估图像质量、感知信噪比和图像畸变。计算ADC图，并将所提出序列获得的ADC值与使用DW-SS-EPI和RESOLVE获得的ADC值进行比较。
在所提出的序列和传统的DW-SS-EPI序列中，在扩散模型中测量到一致的ADC估计值，并且ADC值与模型制造商提供的参考值非常一致。在体内，与DW-SS-EPI相比，所提出的序列显示出改善的图像质量、改善的感知信噪比和减少的感知畸变，而所有测量指标与RESOLVE相当。各序列在体内估计的ADC值没有显著差异。
使用所提出的序列可以实现三维无畸变的扩散准备成像。
