Department of Radiology and Imaging Sciences, Indiana University, School of Medicine, Indianapolis, IN, United States.
Biomedical Engineering and Imaging Institute, Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, United States.
Neuroimage. 2020 Dec;223:117327. doi: 10.1016/j.neuroimage.2020.117327. Epub 2020 Sep 1.
Golden-angle single-shot PROPLLER (GA-SS-PROP) is proposed to accelerate the PROPELLER acquisition for distortion-free diffusion-weighted (DW) imaging. Acceleration is achieved by acquiring one-shot per b-value and several b-values can be acquired along a diffusion direction, where the DW signal follows a bi-exponential decay (i.e. IVIM). Sparse reconstruction is used to reconstruct full resolution DW images. Consequently, apparent diffusion coefficient (ADC) map and IVIM maps (i.e., perfusion fraction (f) and the perfusion-free diffusion coefficient (D)) are obtained simultaneously. The performance of GA-SS-PROP was demonstrated with simulation and human experiments.
A realistic numerical phantom of high-quality diffusion images of the brain was developed. The error of the reconstructed DW images and quantitative maps were compared to the ground truth. The pulse sequence was developed to acquire human brain data. For comparison, fully sampled PROPELLER and conventional single-shot echo planar imaging (SS-EPI) acquisitions were performed.
GA-SS-PROP was 5 times faster than conventional PROPELLER acquisition with comparable image quality. The simulation demonstrated that sparse reconstruction is effective in restoring contrast and resolution. The human experiments demonstrated that GA-SS-PROP achieved superior image fidelity compared to SS-EPI for the same acquisition time and same in-plane resolution (1 × 1 mm).
GA-SS-PROP offers fast, high-resolution and distortion-free DW images. The generated quantitative maps (f, D and ADC) can provide valuable information on tissue perfusion and diffusion properties simultaneously, which are desirable in many applications, especially in oncology. As a turbo spin-echo based technique, it can be applied in most challenging regions where SS-EPI is problematic.
金角单次激发（GA-SS）螺旋桨技术用于加速无失真扩散加权（DW）成像的螺旋桨采集。通过在每个 b 值获取单次激发，并且可以在扩散方向上获取多个 b 值来实现加速，其中 DW 信号遵循双指数衰减（即 IVIM）。稀疏重建用于重建全分辨率 DW 图像。因此，同时获得表观扩散系数（ADC）图和 IVIM 图（即灌注分数（f）和无灌注扩散系数（D））。使用模拟和人体实验证明了 GA-SS-PROP 的性能。
开发了一个高质量脑扩散图像的逼真数值幻影。将重建 DW 图像和定量图的误差与真实值进行了比较。开发了脉冲序列以获取人脑数据。为了进行比较，进行了完全采样的 PROPELLER 和常规单次激发回波平面成像（SS-EPI）采集。
GA-SS-PROP 比传统 PROPELLER 采集快 5 倍，图像质量相当。模拟表明稀疏重建在恢复对比度和分辨率方面是有效的。人体实验表明，在相同的采集时间和相同的平面分辨率（1×1mm）下，GA-SS-PROP 比 SS-EPI 具有更好的图像保真度。
GA-SS-PROP 提供了快速、高分辨率且无失真的 DW 图像。生成的定量图（f、D 和 ADC）可以同时提供组织灌注和扩散特性的有价值信息，这在许多应用中是理想的，特别是在肿瘤学中。作为基于涡轮自旋回波的技术，它可以应用于 SS-EPI 存在问题的大多数具有挑战性的区域。
