Department of Biomedical Engineering, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China.
Department of Electrical Engineering, Stanford University, Palo Alto, CA, United States of America.
PLoS One. 2019 Jul 17;14(7):e0219705. doi: 10.1371/journal.pone.0219705. eCollection 2019.
To develop a 7T simultaneous multi-slice (SMS) 2D gradient-echo sequence for susceptibility contrast imaging, and to compare its quality to 3D imaging.
A frequency modulated and phase cycled RF pulse was designed to simultaneously excite multiple slices in multi-echo 2D gradient-echo imaging. The imaging parameters were chosen to generate images with susceptibility contrast, including T2*-weighted magnitude/phase images, susceptibility-weighted images and quantitative susceptibility/R2* maps. To compare their image quality with 3D gradient-echo imaging, both 2D and 3D imaging were performed on 11 healthy volunteers and 4 patients with multiple sclerosis (MS). The signal to noise ratio (SNR) in gray and white matter and their contrast to noise ratio (CNR) was simulated for the 2D and 3D magnitude images using parameters from the imaging. The experimental SNRs and CNRs were measured in gray/white matter and deep gray matter structures on magnitude, phase, R2* and QSM images from volunteers and the visibility of MS lesions on these images from patients was visually rated. All SNRs and CNRs were compared between the 2D and 3D imaging using a paired t-test.
Although the 3D magnitude images still had significantly higher SNRs (by 13.017.6%), the 2D magnitude and QSM images generated significantly higher gray/white matter or globus pallidus/putamen contrast (by 13.387.5%) and significantly higher MS lesion contrast (by 5.9~17.3%).
2D SMS gradient-echo imaging can serve as an alternative to often used 3D imaging to obtain susceptibility-contrast-weighted images, with an advantage of providing better image contrast and MS lesion sensitivity.
开发一种用于磁化率对比成像的 7T 同步多层面（SMS）二维梯度回波序列，并将其质量与 3D 成像进行比较。
设计了一个频率调制和相位循环的射频脉冲，用于在多回波 2D 梯度回波成像中同时激发多个层面。选择成像参数以生成具有磁化率对比的图像，包括 T2*-加权幅度/相位图像、磁化率加权图像和定量磁化率/R2图。为了将其与 3D 梯度回波成像的图像质量进行比较，对 11 名健康志愿者和 4 名多发性硬化症（MS）患者进行了 2D 和 3D 成像。使用成像参数模拟 2D 和 3D 幅度图像的信噪比（SNR）在灰质和白质中的 SNR 和其对比噪声比（CNR）。在志愿者的幅度、相位、R2和 QSM 图像上测量实验 SNR 和 CNR，并对患者这些图像上 MS 病变的可见性进行视觉评分。使用配对 t 检验比较 2D 和 3D 成像之间的所有 SNR 和 CNR。
尽管 3D 幅度图像仍然具有明显更高的 SNR（高 13.017.6%），但 2D 幅度和 QSM 图像产生的灰质/白质或苍白球/壳核对比（高 13.387.5%）和 MS 病变对比（高 5.9~17.3%）明显更高。
2D SMS 梯度回波成像可以作为常用的 3D 成像的替代方法，以获得磁化率对比加权图像，其具有提供更好的图像对比度和 MS 病变敏感性的优势。
