Compartment-specific estimation of T2 and T2* with diffusion-PEPTIDE MRI

TL;DR

This paper introduces a novel MRI technique using diffusion-PEPTIDE to simultaneously estimate compartment-specific T2 and T2* in the human brain, improving microstructure imaging accuracy.

Contribution

It develops a new method combining relaxometry and diffusion imaging to jointly estimate T2 and T2* in vivo, which was not previously possible.

Findings

First in vivo estimation of compartmental T2 and T2*

Demonstrates accuracy and precision through simulations

Provides a new tool for neuroimaging studies

Abstract

We present a microstructure imaging technique for estimating compartment-specific T2 and T2* simultaneously in the human brain. Microstructure imaging with diffusion MRI (dMRI) has enabled the modelling of intra-neurite and extra-neurite diffusion signals separately allowing for the estimation of compartment-specific tissue properties. These compartment-specific properties have been widely used in clinical studies. However, conventional dMRI cannot disentangle differences in relaxations between tissue compartments, causing biased estimates of diffusion measures which also change with TE. To solve the problem, combined relaxometry-diffusion imaging methods have been developed in recent years, providing compartmental T2-diffusion or T2*-diffusion imaging respectively, but not T2 and T2* together. As they provide complementary information, a technique that can estimate both jointly with diffusion is appealing to neuroimaging studies. The aim of this work is to develop a method to map compartmental T2-T2*-diffusion simultaneously. Using an advanced MRI acquisition called diffusion-PEPTIDE, a novel microstructure model is proposed and a multi-step fitting method is developed to estimate parameters of interest. We demonstrate for the first time that compartmental T2, T2* can be estimated simultaneously from in vivo data. we further show the accuracy and precision of parameter estimation with simulation.