DOI: 10.5061/dryad.cvdncjt4m
title: Data from: Variations in regional white matter volumetry and microstructure during the post-adolescence period: a cross-sectional study of a cohort of 1,713 university students

description: Human brain white matter undergoes a protracted maturation that continues
 well into adulthood. Recent advances in diffusion-weighted imaging (DWI)
 methods allow detailed characterisations of the microstructural
 architecture of white matter, and they are increasingly utilised to study
 white matter changes during development and ageing. However, relatively
 little is known about the late maturational changes in the microstructural
 architecture of white matter during post-adolescence. Here we report on
 regional changes in white matter volume and microstructure in young adults
 undergoing university-level education. As part of the MRi-Share
 multi-modal brain MRI database, multi-shell, high angular resolution DWI
 data were acquired in a unique sample of 1,713 university students aged 18
 to 26. We assessed the age and sex dependence of diffusion metrics derived
 from diffusion tensor imaging (DTI) and neurite orientation dispersion and
 density imaging (NODDI) in the white matter regions as defined itein the
 John Hopkins University (JHU) white matter labels atlas. We demonstrate
 that while regional white matter volume is relatively stable over the age
 range of our sample, the white matter microstructural properties show
 clear age-related variations. Globally, it is characterised by a robust
 increase in neurite density index (NDI), and to a lesser extent,
 orientation dispersion index (ODI). These changes are accompanied by a
 decrease in diffusivity. In contrast, there is minimal age-related
 variation in fractional anisotropy. There are regional variations in these
 microstructural changes: some tracts, most notably cingulum bundles, show
 a strong age-related increase in NDI coupled with decreases in radial and
 mean diffusivity, while others, mainly cortico-spinal projection tracts,
 primarily show an ODI increase and axial diffusivity decrease. These
 age-related variations are not different between males and females, but
 males show higher NDI and ODI and lower diffusivity than females across
 many tracts. These findings emphasize the complexity of changes in white
 matter structure occurring in this critical period of late maturation in
 early adulthood.
description: The dataset is based on magnetic resonance imaging (MRI) data
 collected as part of the MRiShare database. The anatomical and
 diffusion-weighted imaging data from those under 26 years of age from the
 MRiShare database were processed as described in the associated
 publication. The dataset contains regional white matter (WM) phenotypes
 based on JHU white matter label atlas as described in the paper and
 includes WM volume, mean DTI and NODDI metrics in each region defined in
 the JHU atlas. It also contains quality control (QC) metrics of the
 anatomical and diffusion-weighted imaging data.
description: The dataset can be used with the associated R script
 "MRiShare_Regional_WMproperties_FrSysNeurosci2021.R".
 DATA-SPECIFIC INFORMATION FOR:
 MRiShare_WM_IDPs_FrontSysNeurosci2021.csv 1. Number of
 variables: <br> 258 (plus ID column) 2. Number of
 cases/rows: <br> 1,713 3. Variable
 List: <br> ID: row number Sex: F-females,
 M-males Age: age in years [JHU tract
 abbreviation]_volume (Columns 5-32): JHU regional volume based on SPM12
 (Jacobean-modulated) in mm3 [JHU tract abbreviation]_FA
 (Columns 33-59): JHU regional mean FA [JHU tract
 abbreviation]_MD (Columns 60-86): JHU regional mean MD (in
 mm2/sec) [JHU tract abbreviation]_AD (Columns 87-113):
 JHU regional mean AD (in mm2/sec) [JHU tract
 abbreviation]_RD (Columns 114-140): JHU regional mean RD (in
 mm2/sec) [JHU tract abbreviation]_NDI (Columns
 141-167): JHU regional mean NDI  [JHU tract
 abbreviation]_ODI (Columns 168-194): JHU regional mean ODI 
 [JHU tract abbreviation]_ISOVF (Columns 195-221): JHU regional
 mean IsoVF Columns 222-233: Quality Control (QC)
 metrics related to structural scans<br> -structQC_FLAIRtoT1_coregCF:
 Coregistration cost function for FLAIR to T1w image.
 -structQC_[T1 or FLAIR]_GM_invSNR: Inverse of signal-to-noise
 (SNR) ratio within GM signals in T1w or FLAIR image (based on SPM12
 segmentation). The higher value indicates worse SNR.
 -structQC_[T1 or FLAIR]_WM_invSNR: Inverse of SNR ratio within WM
 signals in T1w or FLAIR image (based on SPM12 segmentation). The higher
 value indicates worse SNR. -structQC_[T1 or
 FLAIR]_CSF_invSNR: Inverse of SNR ratio within CSF signals in T1w or FLAIR
 image (based on SPM12 segmentation). The higher value indicates worse
 SNR. -structQC_[T1 or FLAIR]_[WMGM or GMWM]_invCNR:
 Inverse of WM-to-GM (for T1w) or GM-to-WM (for FLAIR) contrast-to-noise
 (CNR) ratio (based on SPM12 segmentation). Higher value indicates worse
 CNR. The higher value indicates worse CNR.
 -structQC_[T1 or FLAIR]_GMCSF_invCNR: Inverse of GM-to_CSF CNR
 ratio in T1w or FLAIR image (based on SPM12 segmentation). The higher
 value indicates worse CNR. Higher value indicates worse CNR.
 -structQC_FS6_invEuler: inverse of the Freesurfer's Euler
 number. The higher number indicate poor quality.
 Columns 234-251: QC metrics related to diffusion scans and DTI
 computation -DWIQC_[b0, b300, b1000 or
 b2000]_mean_afni_outlier_post: Mean proportion of outlier voxels based on
 AFNI 3dOutcount tool. -DWIQC_[b0, b300, b1000 or
 b2000]_inv_tSNR: Inverse of temporal SNR for each b value image. The
 higher value indicates lower tSNR. -DWIQC_[b300, b1000
 or b2000]_inv_CNR: Inverse of CNR for each non-zero b value image,
 outputted by Eddy. The higher value indicates worse CNR.
 -DWIQC_shellNS_relative_rms: Mean relative RMS for the entire DWI
 scan computed using relative RMS outputted by Eddy.
 -DWIQC_shellNS_relative_restricted_rms: Mean relative restricted
 RMS for the entire DWI scan computed using relative restricted RMS
 outputted by Eddy. It measures the displacement caused by subject
 motion. -DWIQC_shellNS_eddy_mean_outlier_slices: Mean
 number of outlier slices per volume computed using the number of outlier
 slices outputted by Eddy.
 -DWIQC_shellNS_eddy_mean_outlier_[stdev or sqr_stdev]: Mean
 values of standard deviations off the mean (stdev) or the square root of
 the mean squared (sqr_stdev) difference between the observation and
 prediction, outputted by Eddy. -DTIQC_mean_residuals:
 Mean residuals inside the brain mask when fitting DTI.
 -DTIQC_percent_implausible_voxels: Proportion of physically
 implausible voxels (cf. Tournier et al, 2011) Columns
 252-259: QC metric related to spatial normalisation.
 -NormQC_[wm, FA, MD, AD, RD, ICVF, ODI, or ISOVF]_inv_r2z:
 Inverse of the Fisher Z-transformed Person's correlation r measuring
 the similarity of the individual WM volume, DTI/NODDI scaler maps in
 stereotaxic space to the cohort average map. The higher value indicates
 more deviation from the average map.                      
 4. Missing data codes: <br> Four subjects did not have any
 volumetric or DTI/NODDI values for fornix (FX), as the WM probability map
 did not overlap with this small ROI in the standard space. For the same
 reason, one subject was missing data for the tapetum (TAP). In addition,
 for corticospinal tract (CST; n = 4) and inferior cerebellar peduncle
 (ICP; n = 6) ROIs, mean DTI/NODDI values were not computed in the pipeline
 since these ROIs extended beyond the bounding box of the DWI-derived
 images in the standard space.<br>   DATA-SPECIFIC
 INFORMATION FOR: JHI_27ROI_info.csv 1. Number of
 variables: <br> 6 2. Number of
 cases/rows: <br> 27 3. Variable List: <br>
 tract_name: Long name of the JHU ROI used in the associated
 publication. abb_tract_name: Abbreviated JHU ROI names
 used in the associated publication as well as column names in the
 MRiShare_WM_IDPs_FrontSysNeurosci2021.csv hemi:
 "Both" medially located ROIs and "RL" ROIs present in
 each hemisphere size_group: Arbitrary grouping based on
 the ROI volume of the JHU atlas mori_group: One of the
 four groups based on Mori et al. (2008) that describes the ROIs in the JHU
 atlas. "Brainstem", "Projection",
 "Association", or "Commissural".
 atlas_vol_hemi_averaged: Label volume in the atlas, averaged
 between the two hemispheres for "RL" ROIs that exist ion each
 hemisphere.<br>  <br> 4. Missing data codes: 
 No missing data