Tensor estimation was then performed, and Fractional Anisotropy (FA), Axial Diffusivity (AD), Radial Diffusivity (RD), and b0 maps were computed and saved (while applying a skull-stripped mask generated in ROI Editor for the b0 image of each participant). The FA and b0 maps of each participant were then used for Large Deformation Diffeomorphic Metric Mapping (LDDMM) [27], and regions of interest (ROIs) were generated for each participant as follows. The b0 and FA maps of each participant were first transformed linearly (using affine Automated Image Registration (AIR) transformation, with trilinear interpolation) and then non-linearly (using LDDMM, with cascading alpha of 0.01, 0.005, and 0.002), in order to match as well as possible the corresponding Johns Hopkins University MNI-space single participant skull-stripped templates (JHU_MNI_SS_b0_ss and JHU_MNI_SS_FA_ss). A detailed atlas of the white matter tracts and gray matter ROIs had been previously constructed by [27] based on the data from the participant used in the Johns Hopkins University MNI-space single participant skull-stripped templates. Next, the inverse transformation algorithms (inverse LDDMM and then inverse AIR) were applied to the ROI atlas (JHU_MNI_SS_WMPM_TypeII), in order to obtain ROIs that are within each participant's original brain space. To ensure the proper execution of the algorithms, the ROIs generated were visually inspected for accuracy. The mean FA, AD, and RD values for the ROIs were then extracted in ROI Editor. For further analyses, we focused on the measures FA, AD, and RD of all available white matter tract ROIs (27 tracts in each hemisphere; for a complete list see the list of Abbreviations at the end of the paper). Sample ROIs are shown in Figure 1.
gray atlas of human anatomy pdf 38
For these purposes, the atlas comes with brain tissue and structurelabels including cortical gray matter, white matter, subcorticalgray matter structures, CSF, lateral ventricles, brainstem, andcerebellum labels, and more. In addition, gestational age weeks21-30 include labels for developing white matter layers, includingthe subplate, intermediate zone, and ventricular zone. An updateof the atlas, including a week 38 template and an additionalregionally divided cortex parcellation was released in February2018. Future plans include expanding the atlas to include earliergestational ages. Please check back for updates. 2ff7e9595c
Commenti