Morphology enabled dipole inversion (MEDI) from a single‐angle acquisition: Comparison with COSMOS in human brain imaging

TLDR

Magnetic susceptibility differs across brain structures and offers insight into tissue composition, but estimating its distribution from MR phase data is an ill‑conditioned inverse problem that COSMOS solves using multiple orientations, which is often impractical for human studies. The study aims to enhance MEDI by sparsifying edges in susceptibility maps that lack corresponding magnitude image edges. The improved MEDI method sparsifies such edges and its resulting quantitative susceptibility maps are compared qualitatively and quantitatively to COSMOS-generated maps. The improved MEDI maps agree closely with COSMOS, demonstrating its practicality for potential clinical use. Published in Magn Reson Med 2011, © 2011 Wiley‑Liss, Inc.

Abstract

Abstract Magnetic susceptibility varies among brain structures and provides insights into the chemical and molecular composition of brain tissues. However, the determination of an arbitrary susceptibility distribution from the measured MR signal phase is a challenging, ill‐conditioned inverse problem. Although a previous method named calculation of susceptibility through multiple orientation sampling (COSMOS) has solved this inverse problem both theoretically and experimentally using multiple angle acquisitions, it is often impractical to carry out on human subjects. Recently, the feasibility of calculating the brain susceptibility distribution from a single‐angle acquisition was demonstrated using morphology enabled dipole inversion (MEDI). In this study, we further improved the original MEDI method by sparsifying the edges in the quantitative susceptibility map that do not have a corresponding edge in the magnitude image. Quantitative susceptibility maps generated by the improved MEDI were compared qualitatively and quantitatively with those generated by calculation of susceptibility through multiple orientation sampling. The results show a high degree of agreement between MEDI and calculation of susceptibility through multiple orientation sampling, and the practicality of MEDI allows many potential clinical applications. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.