Fan Qiuyun, Nummenmaa Aapo, Polimeni Jonathan R, Witzel Thomas, Huang Susie Y, Wedeen Van J, Rosen Bruce R, Wald Lawrence L
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA.
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA.
Neuroimage. 2017 Apr 15;150:162-176. doi: 10.1016/j.neuroimage.2017.02.002. Epub 2017 Feb 7.
The parameter selection for diffusion MRI experiments is dominated by the "k-q tradeoff" whereby the Signal to Noise Ratio (SNR) of the images is traded for either high spatial resolution (determined by the maximum k-value collected) or high diffusion sensitivity (effected by b-value or the q vector) but usually not both. Furthermore, different brain regions (such as gray matter and white matter) likely require different tradeoffs between these parameters due to the size of the structures to be visualized or the length-scale of the microstructure being probed. In this case, it might be advantageous to combine information from two scans - a scan with high q but low k (high angular resolution in diffusion but low spatial resolution in the image domain) to provide maximal information about white matter fiber crossing, and one low q but high k (low angular resolution but high spatial resolution) for probing the cortex. In this study, we propose a method, termed HIgh b-value and high Resolution Integrated Diffusion (HIBRID) imaging, for acquiring and combining the information from these two complementary types of scan with the goal of studying diffusion in the cortex without compromising white matter fiber information. The white-gray boundary and pial surface obtained from anatomical scans are incorporated as prior information to guide the fusion. We study the complementary advantages of the fused datasets, and assess the quality of the HIBRID data compared to either alone.
扩散磁共振成像实验的参数选择主要受“k-q权衡”的影响，即图像的信噪比（SNR）要在高空间分辨率（由采集的最大k值决定）或高扩散敏感性（由b值或q矢量影响）之间进行权衡，但通常不能两者兼顾。此外，由于要可视化的结构大小或所探测微观结构的长度尺度不同，不同的脑区（如灰质和白质）可能需要在这些参数之间进行不同的权衡。在这种情况下，结合两次扫描的信息可能会有优势——一次是高q但低k的扫描（扩散方面具有高角分辨率，但图像域具有低空间分辨率），以提供关于白质纤维交叉的最大信息，另一次是低q但高k的扫描（低角分辨率但高空间分辨率），用于探测皮层。在本研究中，我们提出了一种方法，称为高b值和高分辨率综合扩散（HIBRID）成像，用于获取和组合这两种互补类型扫描的信息，目的是在不损害白质纤维信息的情况下研究皮层中的扩散。将从解剖扫描中获得的白-灰边界和软脑膜表面作为先验信息纳入以指导融合。我们研究了融合数据集的互补优势，并评估了HIBRID数据与单独数据相比的质量。
