Combined application of voxel-based morphometry and magnetization transfer ratio for group analysis of magnetic resonance images

Magnetic resonance imaging (MRI) is conventionally used for macroscopic qualitative observations. However, increasingly there is a need for quantitative MRI measures, which may lead to enhanced detection sensitivity. Two quantitative techniques that may be used to make neuroanatomical inferences about a population or between different populations are magnetization transfer ratio (MTR) and voxel-based morphometry (VBM).VBM involves the statistical analysis of smoothed segmented white or gray matter maps to reflect increases or decreases in the probability of classifying a voxel as either white or gray matter. MTR provides a measure of the interaction of water and semi-solids within tissue, and thus is indicative of its macromolecular density and microstructural integrity. An MTR group analysis may detect variations of these semi-solid tissue characteristics within or between populations.This thesis investigates the relationship between information attained from VBM and MTR population studies carried out in the context of the Saguenay Youth Study. Additionally, through this study, the effects of age and gender on brain neuroanatomy are explored using the above techniques. The observed age and gender VBM and MTR effects were consistent with existing literature, but also offered new findings. Overall, applying MTR in conjunction with VBM allows for further insight into the origins of specific anatomical changes, and the discovery of areas that undergo within-tissue development without corresponding white or gray matter volume changes