Mapping Myelocytoarchitectual Anatomy in vivo using Quantitative MRI

Dr Christian Lambert, Clinical Lecturer in Neurology
St George’s University of London

Ex vivo, brain regions are defined using the spatial distribution of neuronal cell populations (cytoarchitecture) and myelination density (myeloarchitecture). The precise location and size of these architecturally defined regions are highly variable between individuals and do not precisely align to visible cortical landmarks, yet have quantifiable impact on function and behaviour.

In vivo brain anatomy is usually delineated using T1w MRI. Standard processing pipelines either parse this data into three canonical tissue types (grey, white and CSF), or warp manually defined templates based on gross anatomical landmarks. Consequently, a significant degree of true anatomical variability is lost.

QMRI (qMRI) provides quantitative and specific biomarkers of tissue microstructure. Here I will present qMRI based “quantitative segmentation” pipelines to map architectural anatomy at an individual subject level. Focusing mainly on brainstem and subcortical structures, I will show how these methods are approaching in vivo histology, and will demonstrate the application of these techniques in both health and disease.