A Comparison of Voxel-Based Morphometry and Volumetry Methods in the Context of the Neural Basis of Aggression

The assumption that voxel-based morphometry (VBM) offers an automated substitution for manually-traced volumetry was subjected to empirical evaluation. Data available from a previous volumetry study (Gansler et al. Psychiatry Research: Neuroimaging 171:145–154, 2009) provided the basis for the current study, which assessed for convergence between the methods. Optimized modulated VBM was used to preprocess images (N = 40). Gray matter volume and self-reported aggression associations were tested. Results indicate convergence, as both methods revealed significant negative associations of the left orbitofrontal cortex (OFC) and aggression. VBM detected an additional positive left OFC result not revealed with volumetry, suggesting that VBM may allow greater within-region localization than volumetry. However, the methods differentially deal with error rates and power demands and as such are better conceptualized as complementary than interchangeable.