Newman Benjamin T, Dhollander Thijs, Reynier Kristen A, Panzer Matthew B, Druzgal T Jason
Department of Radiology and Medical Imaging, School of Medicine, University of Virginia, Charlottesville, Virginia.
Brain Institute, University of Virginia, Charlottesville, Virginia.
Magn Reson Med. 2020 Oct;84(4):2161-2173. doi: 10.1002/mrm.28242. Epub 2020 Feb 28.
Several recent studies have used a three-tissue constrained spherical deconvolution pipeline to obtain quantitative metrics of brain tissue microstructure from diffusion-weighted MRI data. The three tissue compartments, consisting of white matter, gray matter, and CSF-like (free water) signals, are potentially useful in the evaluation of brain microstructure in a range of pathologies. However, the reliability and long-term stability of these metrics have not yet been evaluated.
This study examined estimates of whole-brain microstructure for the three tissue compartments, in three separate test-retest cohorts. Each cohort had different lengths of time between baseline and retest, ranging from within the same scanning session in the shortest interval to 3 months in the longest interval. Each cohort was also collected with different acquisition parameters.
The CSF-like compartment displayed the greatest reliability across all cohorts, with intraclass correlation coefficient (ICC) values being above 0.95 in each cohort. White matter-like and gray matter-like compartments both demonstrated very high reliability in the immediate cohort (both ICC > 0.90); however, this declined in the 3-month interval cohort to both compartments having ICC > 0.80. Regional CSF-like signal fraction was examined in bilateral hippocampus and had an ICC > 0.80 in each cohort.
The three-tissue constrained spherical deconvolution techniques provide reliable and stable estimates of tissue-microstructure composition, up to 3 months longitudinally in a control population. This forms an important basis for further investigations using three-tissue constrained spherical deconvolution techniques to track changes in microstructure across a variety of brain pathologies.
最近的几项研究使用了三组织约束球面反卷积流程，从扩散加权磁共振成像（MRI）数据中获取脑组织微观结构的定量指标。由白质、灰质和脑脊液样（自由水）信号组成的三个组织部分，在一系列病理状态下对脑微观结构的评估中可能是有用的。然而，这些指标的可靠性和长期稳定性尚未得到评估。
本研究在三个独立的重测队列中，对三个组织部分的全脑微观结构估计值进行了检查。每个队列在基线和重测之间的时间长度不同，从最短间隔的同一扫描会话内到最长间隔的3个月。每个队列也采用不同的采集参数进行收集。
脑脊液样部分在所有队列中显示出最高的可靠性，每个队列的组内相关系数（ICC）值均高于0.95。白质样和灰质样部分在即时队列中均显示出非常高的可靠性（两者ICC均>0.90）；然而，在3个月间隔队列中，这两个部分的可靠性均下降，ICC>0.80。对双侧海马的区域脑脊液样信号分数进行了检查，每个队列的ICC>0.80。
在对照人群中，三组织约束球面反卷积技术可纵向提供长达3个月的可靠且稳定的组织微观结构组成估计值。这为进一步利用三组织约束球面反卷积技术追踪各种脑部病变中微观结构的变化奠定了重要基础。
