Data_Sheet_1_Super-Resolution Arterial Spin Labeling Using Slice-Dithered Enhanced Resolution and Simultaneous Multi-Slice Acquisition.docx

Purpose: To achieve high spatial resolution (isotropic-2 mm) perfusion imaging using 2D simultaneous multi-slice (SMS) pseudo-continuous arterial spin labeling (pCASL) and slice dithered enhanced resolution (SLIDER) technique for super-resolution reconstruction.
Methods: The SLIDER-SMS pCASL with a multiband factor of 4 was implemented at 3T with three numbers of slice shift (2/3/4) for the slice thickness of 4/6/8 mm, respectively. Super-resolution reconstruction was performed with singular value decomposition and different levels of Tikhonov regularizations. Temporal and spatial signal-to-noise ratio (SNR) as well as spatial blurring effects of super-resolution ASL images were measured in five healthy subjects and compared with those of reference high-resolution ASL images.
Results: Compared to conventional 2D SMS ASL, super-resolution ASL images with isotropic-2-mm resolution yielded 42, 61, and 88% higher spatial SNR, and 18, 55, and 105% higher temporal SNR with slice shift number of 2/3/4, respectively. Spatial blurring effect increased for SLIDER reconstruction from two to four slice shifts.
Conclusion: The proposed SLIDER-SMS pCASL technique can achieve whole-brain high-resolution perfusion images with ∼15-min scan time and improved SNR compared to standard 2D SMS pCASL. Caution needs to be exercised on quantifying and controlling blurring effects of SLIDER reconstruction.

研究目的：采用二维同时多切片（2D simultaneous multi-slice, SMS）伪连续动脉自旋标记（pseudo-continuous arterial spin labeling, pCASL）与切片抖动增强分辨率（slice dithered enhanced resolution, SLIDER）技术开展超分辨率重建，实现各向同性2mm（isotropic-2 mm）空间分辨率的灌注成像。研究方法：在3T磁共振设备上实现多波段因子为4的SLIDER-SMS pCASL序列，分别针对4mm、6mm、8mm的切片厚度设置3种切片移位参数（2/3/4）。采用奇异值分解与不同程度的蒂霍诺夫正则化（Tikhonov regularization）开展超分辨率重建。招募5名健康受试者，对超分辨率动脉自旋标记（arterial spin labeling, ASL）图像的时空信噪比（signal-to-noise ratio, SNR）及空间模糊效应进行测量，并与参考高分辨率ASL图像进行对比。研究结果：与常规二维同时多切片ASL相比，当切片移位参数为2、3、4时，各向同性2mm分辨率的超分辨率ASL图像的空间信噪比分别提升42%、61%、88%，时间信噪比分别提升18%、55%、105%。随着切片移位参数从2增加至4，SLIDER重建的空间模糊效应随之增强。研究结论：相较于标准二维同时多切片pCASL，本研究提出的SLIDER-SMS pCASL技术可在约15分钟的扫描时间内获得全脑高分辨率灌注图像，且信噪比得到改善。但在对SLIDER重建的模糊效应进行量化与控制时需谨慎操作。