A new theoretical base for intracranial brain volume normalization in neuroimaging studies

Abstract

In the volumetric studies of the brain, there are often conflicting results due to the presence of confounding factors such as age and gender, and covariates like brain volume. At times, in comparison with a control group, for example, this large variability is enough to confound any effect due to the pathology. For this reason, data are generally corrected or normalized by empirical methods as found in other fields of brain studies. In this study, we proposed a normalization method based on a theoretical approach. This method, based on a simple geometrical brain model, has been tested by a comparison with the empirical ones in 16 brain regions, considering two samples of subjects: 19 dyslexics and 10 healthy controls. The results show a good and interesting agreement between data and model and give a new basis for the single subject brain volume normalization. In particular, it is possible to show how the amygdala and the whole brain volume should be thought of, as linked by shape and physiological relation due to the ratio between their volumes.