OBJECTIVETo investigate the correlation between cerebral white matter fraction anisotropy (FA) in normal human adults using the diffusion tensor magnetic resonance (MR) imaging (DTI).

METHODSForty-five adults with normal cerebral white matter MRI findings in 3 age groups (n=15), namely 25 approximately 35 years (young), 45 approximately 55 years (middle-aged) and 65 years or above (elderly), underwent conventional MRI and diffusion tensor MR imaging. FA was measured in different regions of interest (ROIs) including the genu and splenium of the corpus callosum, posterior limb and anterior limb of the internal capsule, centrum semiovale, frontal white matter, thalamus and head of the caudate nucleus.

RESULTSThe FA values of the corresponding regions were similar between the left and right hemispheres. The FA value in the genu of the corpus callosum, centrum semiovale and the frontal white matter decreased with age, showing significant differences between the 3 age groups (P<0.05). The FA value in the splenium of the corpus callosum decreased significantly with age, with significant differences between the elderly and young groups and between the elderly and middle-aged groups (P<0.05). The values in the posterior limb and anterior limb of the internal capsule also decreased significantly with age as shown by comparison between the elderly and young groups (P<0.05). No significant difference was found in the FA value of the thalamus and head of the caudate nucleus between the three groups (P>0.05).

CONCLUSIONThe FA values decrease with age, especially in the genu of corpus callosum, centrum semiovale and frontal white matter. The patient's age and age-related white matter degradation must be considered in DTI-based diagnosis of cerebral diseases.