# Discovery and visualization of structural biomarkers from MRI using transport-based morphometry

## TL;DR

Transport-based morphometry (TBM) is a novel MRI analysis technique that automatically uncovers subtle brain tissue changes related to aging and fitness without relying on predefined features, enabling detailed visualization and analysis.

## Contribution

The paper introduces TBM, a new image transformation method that fully automates the detection and visualization of complex brain tissue changes from MRI data without prior feature specification.

## Key findings

- TBM successfully identifies aging-related brain changes.
- It reveals potential links between aerobic fitness and brain health.
- The method enables visualization of tissue distribution shifts.

## Abstract

Disease in the brain is often associated with subtle, spatially diffuse, or complex tissue changes that may lie beneath the level of gross visual inspection, even on magnetic resonance imaging (MRI). Unfortunately, current computer-assisted approaches that examine pre-specified features, whether anatomically-defined (i.e. thalamic volume, cortical thickness) or based on pixelwise comparison (i.e. deformation-based methods), are prone to missing a vast array of physical changes that are not well-encapsulated by these metrics. In this paper, we have developed a technique for automated pattern analysis that can fully determine the relationship between brain structure and observable phenotype without requiring any a priori features. Our technique, called transport-based morphometry (TBM), is an image transformation that maps brain images losslessly to a domain where they become much more separable. The new approach is validated on structural brain images of healthy older adult subjects where even linear models for discrimination, regression, and blind source separation enable TBM to independently discover the characteristic changes of aging and highlight potential mechanisms by which aerobic fitness may mediate brain health later in life. TBM is a generative approach that can provide visualization of physically meaningful shifts in tissue distribution through inverse transformation. The proposed framework is a powerful technique that can potentially elucidate genotype-structural-behavioral associations in myriad diseases.