Table 2. FA values.

Radiation dose	Control	0.5 Gy	1.0 Gy	1.5 Gy
Cortex	0.25±0.01	0.24±0.02	0.23±0.02*	0.17±0.02***
Corpus callosum (CC)	0.51±0.04	0.48±0.04	0.40±0.03***	N.D. (Split)
External capsule (EC)	0.59±0.04	0.52±0.04*	0.44±0.05***	0.37±0.06***

The FA (fractional anisotropy) values in the cortex and CC of 4-week-old rats exposed to 1.0 or 1.5 Gy of radiation prenatally were smaller than those of control rats. At 1.5 Gy, FA values were not measured at the CC because the axial fibers were split. FA values in the EC were significantly smaller than those of the control rats at all 3 exposures (0.5, 1.0, or 1.5 Gy).

*, vs. control, P<0.01;

***, vs. control, P<0.001