MR imaging volumetry of subcortical structures and cerebellar hemispheres in normal persons

BACKGROUND AND PURPOSE: Volume changes in subcortical structures and cerebella have been associated with localization-related epilepsy and psychiatric illnesses. This study evaluated the effect of handedness and sex on the volumes of selected subcortical structures and cerebellar hemispheres in normal persons. METHODS: Volumetric measurements were performed of the caudate heads, thalami, and cerebellar hemispheres in 34 (20 right- and 14 left-handed, 19 female and 15 male) normal persons. Amygdalar and hippocampal volumes were reported previously for these persons. All study participants completed a 10-item handedness questionnaire. The MR imaging sequence was a 3D T1-weighted gradient-echo acquisition of the whole brain (24/6 [TR/TE]; flip angle, 25 degrees). MR images were spatially normalized, and volumes were painted with a 1.0 mm³ resolution cursor on an SGI workstation. The effects of handedness and sex on standardized volumes and right-to-left volume ratios were calculated, and volumes were compared between right and left sides for each structure. RESULTS: Handedness did not affect standardized volumes or asymmetries of the caudate heads, thalami, or cerebellar hemispheres. The volumes of subcortical structures were bilaterally larger in women than in men. Right-to-left asymmetries were significant for the caudate head and cerebellum but not for the thalamus. CONCLUSION: These findings show that women have significantly larger subcortical structures than do men after spatial normalization to account for differences in brain size. Sex-specific normal ranges may be needed for evaluating volume changes related to epilepsy or other disease processes.