Figure 1.
Regions of interest for entropy and FA measurements: 1, CSF; 2, cortical gray matter; 3, thalamus; 4, putamen; 5, caudate nucleus; 6, corpus callosum; and 7, frontal white matter.
Figure 2.
Comparison between the entropy (A) and the FA map (B) from the same subject.
Gray matter is more visible in the entropy map compared to the FA map.
Table 1.
Entropy changes with number of gradients directions in different brain structures
Figure 3.
Entropy vs. FA in CSF, cerebral gray matter (GM), thalamus (TH), putamen (PU), caudate nucleus (CA), FW, and CC.
The details for gray matter, putamen, caudate nucleus are enlarged from the bottom box area. Error bars indicate one standard deviation (N = 10).
Table 2.
Entropy, FA, corresponding axonal density in the ROIs displayed in Fig1.
Figure 4.
Histograms of diffusion attenuation values in CSF (top) shows high probability of occurrence of attenuation values, causing smaller values of entropy.
Gray matter (middle) and white matter (bottom) show more spread of attenuation values, causing larger entropy.
Figure 5.
Correlation between entropy and axonal density measured from Bielschowsky and Luxol fast blue staining.
Error bars indicate one standard deviation, and N = 5
Figure 6.
Selection of ROIs from frontal white matter (A, FW, top) and corpus callosum (A, CC, bottom), magnified of ROIs from A in FW (B) and CC (C).
The corresponding Bielschowsky and Luxol fast blue staining images in FW (D), and CC (E), respectively, showing axonal density changes in these ROIs.
Figure 7.
The FA (A), diffusion entropy (B), q-ball fiber orientation (C, D) maps overlayed onto entropy, and the Bielshowsky and Luxol fast blue immunoreactive staining images (E-H) measured from the fixed animal brain.
The images in F, G are high magnification images from the box areas in image E as indicated by the numbers in the up right corner in the images of E and F.