Fig 1.
Representative in-plane cross sections from a single subject showing unprocessed raw diffusion image data (4 shot, centric ordered, 2 averages, 25 coronal slices with slice thickness = 500 μm, 250 × 250 μm in plane resolution, FOV 40 x 40 mm, matrix size = 160 x 160, TE = 25 ms, TR = 5.0 s), and corresponding scalar image maps of the following NODDI values: Orientation Dispersion Index (ODI), Neurite Density Index (NDI), and Isotropic Volume Fraction (IsoVF).
Fig 2.
Region of interest (ROI) values for ODI, NDI and IsoVF in both the scan and rescan conditions for several representative brain regions.
Each box represents the range from 25th to 75th percentile (Interquartile Range) with the median depicted by the line within the box. The whiskers shown extend to the maximum and minimum value of each measurement.
Fig 3.
Mean coefficient of variation (CV) for each ROI.
Values for the between subject condition represent the mean ± standard deviation within each ROI averaged over a scan-rescan protocol. Values for the within subject condition represent the mean ± standard deviation within each ROI averaged over the eight subjects.
Fig 4.
Whole brain average between subject CV maps and histogram.
Values for the between subject condition represent the mean CV within each voxel for the scan and rescan conditions averaged over the two scans. The resulting histogram has been extracted from the averaged scans. Heat maps from a representative slice show the regional variation for each metric.
Fig 5.
Whole brain average within subject CV maps and histogram.
Values for the within subject condition represent the mean CV within each voxel for each subject averaged over all eight subjects. The resulting histogram has been extracted from the averaged scans. Heat maps from a representative slice show the regional variation for each metric.
Fig 6.
Voxel-wise between and within subject CV histograms within each representative ROI.
Voxel-wise values for the between subject condition represents the mean CV within each ROI for both the scan and rescan conditions averaged over the two scans. Voxel-wise values for the within subject condition represent the mean CV within each ROI averaged over the eight subjects.
Fig 7.
Whole brain voxel-wise histograms representing the i) number of subjects necessary to detect a statistically significant effect with a change in the given metric of 5%, 10%, 15% and 20% and ii) the minimum detectable effect with each metric under a scan-rescan study design given group sample sizes of 6, 8 and 10.
Note the varied scales for the IsoVF metric in each category as opposed to the ODI and NDI metrics.