Figure 1.
T2-weighted MRI (T2WI) results.
Each row: 3 T2W images representing a consecutive series of brain slices in a typical rat from one of the experimental groups. (A) The first row shows images from a typical control rat. (B) The second-row images are from a typical 0.5-Gy–irradiated rat. (C) The third-row images are from a typical 1.0-Gy–irradiated rat. (D) The bottom-row images are from a typical 1.5-Gy–irradiated rat. The brain size of the animals in the radiation-exposed groups is clearly smaller than that of the control rats. CC, corpus callosum; EC, external capsule; aca, anterior commissure anterior part; LV, lateral ventricle; 3V, 3rd ventricle; CPu, caudate-putamen; Hip, hippocampus; TH, thalamus; ac, anterior commissure; white bar, 5 mm.
Table 1.
Morphological measurements of the brains of radiation-exposed and control rats using MRI.
Figure 2.
Typical diffusion tensor imaging (DTI) MRI results.
Each row: DTI 3-color maps representing a consecutive series of brain slices, in a typical rat from one of the experimental groups. Color maps of tracked fibers were based on the extracted primary direction (red was used for the x-direction, green for the y-direction, and blue for the z-direction). A–D; rows have the same meaning as in Figure 1.
Figure 3.
Typical DTI and KB-staining images.
(A) The first column of color-scale images shows typical coronal DTI rat brain images at CC. (B) The second column shows typical coronal DTI rat brain images at EC. (C) The third column shows typical KB staining images around CC. Rows have the same meaning as in previous figures. EC, external capsule; df, dorsal fornix; Cg, cingulum.
Table 2.
FA values.
Figure 4.
Histological analyses performed using KB, CaBP, and SMI-32 staining in sections of cortex.
(A) The first column shows typical coronal KB images of 6-layered cortex. (B) The second column shows typical coronal CaBP images at the same positions as those used for KB staining. (C) The third column shows typical SMI-32 images at the same positions as those used for KB staining. Rows, progressively higher X-ray dose, 0 Gy at top; white and black bars, 10 µm; Cg, cingulum; df, dorsal fornix; SL, superficial layer; OL, outer layer; IL; inner layer.
Figure 5.
Histological analyses performed using KB, CaBP, and SMI-32 staining in sections of the hippocampus.
(A) Typical images around the hippocampus in sections from control and 1.5-Gy–irradiated rat brains. The upper gray-scale images show typical control and 1.5-Gy–irradiated rat T2WI results. B, C; Typical control (B) and 1.5-Gy–irradiated (C) rat KB images in sections of the hippocampus. D, E; Typical coronal CaBP images in sections of the hippocampus at low and high magnification. F, G; Typical SMI-32 images in sections of the hippocampus. Hip, hippocampus; alv, alveus of the hippocampus; hf, hippocampal fissure; ecm, ectopic neuron mass; f, fimbria of the hippocampus; DG, dentate gyrus; black bars, 50 µm in C and E, and 1 mm in D.
Figure 6.
Correlation analysis: correlations of MRI-determined brain volume, ventricle volume, brain substructure thicknesses, and brain substructure FA (fractional anisotropy) values with radiation dose were evaluated.
A, B; Correlation between radiation dose (0.5, 1.0, or 1.5 Gy) and brain volume (A) and ventricle volume (B). C, D, E; Correlation between dose and thickness of cortex (C), thickness of corpus callosum (D), and thickness of external capsule (E). F, G, H; Correlation between dose and FA values of cortex (F), corpus callosum (G), and external capsule (H).