Koay Cheng Guan, Yeh Ping-Hong, Ollinger John M, İrfanoğlu M Okan, Pierpaoli Carlo, Basser Peter J, Oakes Terrence R, Riedy Gerard
National Intrepid Center of Excellence (NICoE), Bethesda, MD, USA; Section on Tissue Biophysics and Biomimetics, NICHD, National Institutes of Health, Bethesda, MD, USA; NorthTide Group, LLC, USA.
National Intrepid Center of Excellence (NICoE), Bethesda, MD, USA; The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA.
Neuroimage. 2016 Feb 1;126:151-63. doi: 10.1016/j.neuroimage.2015.11.046. Epub 2015 Nov 27.
The purpose of this work is to develop a framework for single-subject analysis of diffusion tensor imaging (DTI) data. This framework is termed Tract Orientation and Angular Dispersion Deviation Indicator (TOADDI) because it is capable of testing whether an individual tract as represented by the major eigenvector of the diffusion tensor and its corresponding angular dispersion are significantly different from a group of tracts on a voxel-by-voxel basis. This work develops two complementary statistical tests based on the elliptical cone of uncertainty, which is a model of uncertainty or dispersion of the major eigenvector of the diffusion tensor. The orientation deviation test examines whether the major eigenvector from a single subject is within the average elliptical cone of uncertainty formed by a collection of elliptical cones of uncertainty. The shape deviation test is based on the two-tailed Wilcoxon-Mann-Whitney two-sample test between the normalized shape measures (area and circumference) of the elliptical cones of uncertainty of the single subject against a group of controls. The False Discovery Rate (FDR) and False Non-discovery Rate (FNR) were incorporated in the orientation deviation test. The shape deviation test uses FDR only. TOADDI was found to be numerically accurate and statistically effective. Clinical data from two Traumatic Brain Injury (TBI) patients and one non-TBI subject were tested against the data obtained from a group of 45 non-TBI controls to illustrate the application of the proposed framework in single-subject analysis. The frontal portion of the superior longitudinal fasciculus seemed to be implicated in both tests (orientation and shape) as significantly different from that of the control group. The TBI patients and the single non-TBI subject were well separated under the shape deviation test at the chosen FDR level of 0.0005. TOADDI is a simple but novel geometrically based statistical framework for analyzing DTI data. TOADDI may be found useful in single-subject, graph-theoretic and group analyses of DTI data or DTI-based tractography techniques.
这项工作的目的是开发一个用于扩散张量成像（DTI）数据单受试者分析的框架。这个框架被称为纤维束方向与角弥散偏差指标（TOADDI），因为它能够逐体素地测试由扩散张量的主特征向量所代表的单个纤维束及其相应的角弥散是否与一组纤维束有显著差异。这项工作基于不确定性椭圆锥开发了两种互补的统计检验方法，不确定性椭圆锥是扩散张量主特征向量的不确定性或弥散模型。方向偏差检验用于检查单个受试者的主特征向量是否在由一组不确定性椭圆锥形成的平均不确定性椭圆锥内。形状偏差检验基于单个受试者的不确定性椭圆锥与一组对照的标准化形状度量（面积和周长）之间的双尾Wilcoxon-Mann-Whitney双样本检验。在方向偏差检验中纳入了错误发现率（FDR）和错误非发现率（FNR）。形状偏差检验仅使用FDR。结果发现TOADDI在数值上是准确的，在统计上是有效的。对两名创伤性脑损伤（TBI）患者和一名非TBI受试者的临床数据与从一组45名非TBI对照获得的数据进行了测试，以说明所提出框架在单受试者分析中的应用。在两项检验（方向和形状）中，上纵束的额叶部分似乎与对照组有显著差异。在选定的FDR水平为0.0005时，TBI患者和单个非TBI受试者在形状偏差检验下得到了很好的区分。TOADDI是一个简单但新颖的基于几何的统计框架，用于分析DTI数据。TOADDI可能在DTI数据的单受试者、基于图论的和组分析或基于DTI的纤维束成像技术中有用。
