Sui Ran, Chen Lin, Li Yuguo, Huang Jianpan, Chan Kannie W Y, Xu Xiang, van Zijl Peter C M, Xu Jiadi
F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland, USA.
Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Magn Reson Med. 2021 Aug;86(2):893-906. doi: 10.1002/mrm.28770. Epub 2021 Mar 27.
To develop a steady-state saturation with radial readout chemical exchange saturation transfer (starCEST) for acquiring CEST images at 3 Tesla (T). The polynomial Lorentzian line-shape fitting approach was further developed for extracting amideCEST intensities at this field.
StarCEST MRI using periodically rotated overlapping parallel lines with enhanced reconstruction-based spatial sampling was implemented to acquire Z-spectra that are robust to brain motion. Multi-linear singular value decomposition postprocessing was applied to enhance the CEST SNR. The egg white phantom studies were performed at 3T to reveal the contributions to the 3.5 ppm CEST signal. Based on the phantom validation, the amideCEST peak was quantified using the polynomial Lorentzian line-shape fitting, which exploits the inverse relationship between Z-spectral intensity and the longitudinal relaxation rate in the rotating frame. The 3D turbo spin echo CEST was also performed to compare with the starCEST method.
The amideCEST peak showed a negligible peak B dependence between 1.2 µT and 2.4 µT. The amideCEST images acquired with starCEST showed much improved image quality, SNR, and motion robustness compared to the conventional 3D turbo spin echo CEST method with the same scan time. The amideCEST contrast extracted by the polynomial Lorentzian line-shape fitting method trended toward a stronger gray matter signal (1.32% ± 0.30%) than white matter (0.92% ± 0.08%; P = .02, n = 5). When calculating the magnetization transfer contrast and T -corrected rotating frame relaxation rate maps, amideCEST again was not significantly different for white matter and gray matter.
Rapid multi-slice amideCEST mapping can be achieved by the starCEST method (< 5 min) at 3T by combing with the polynomial Lorentzian line-shape fitting method.
开发一种采用径向读出化学交换饱和转移（starCEST）的稳态饱和技术，用于在3特斯拉（T）场强下采集CEST图像。在此场强下，进一步发展了多项式洛伦兹线形拟合方法以提取酰胺CEST信号强度。
实施使用周期性旋转重叠平行线并基于增强重建的空间采样的starCEST MRI，以获取对脑运动具有鲁棒性的Z谱。应用多线性奇异值分解后处理来提高CEST信噪比。在3T场强下进行蛋清体模研究，以揭示对3.5 ppm CEST信号的贡献。基于体模验证，使用多项式洛伦兹线形拟合对酰胺CEST峰进行定量，该方法利用了Z谱强度与旋转坐标系中纵向弛豫率之间的反比关系。还进行了3D快速自旋回波CEST以与starCEST方法进行比较。
酰胺CEST峰在1.2 µT至2.4 µT之间显示出可忽略不计的峰B依赖性。与具有相同扫描时间的传统3D快速自旋回波CEST方法相比，使用starCEST采集的酰胺CEST图像在图像质量、信噪比和运动鲁棒性方面有显著改善。通过多项式洛伦兹线形拟合方法提取的酰胺CEST对比度显示，灰质信号（1.32% ± 0.30%）比白质信号（0.92% ± 0.08%；P = 0.02，n = 5）更强。在计算磁化传递对比度和T校正旋转坐标系弛豫率图时，白质和灰质的酰胺CEST再次无显著差异。
通过结合多项式洛伦兹线形拟合方法，starCEST方法可在3T场强下实现快速多切片酰胺CEST成像（< 5分钟）。
