Phase Imaging : a novel tool for myelin quantification

Introduction: Accurate myelin quantification is of prime importance not only in animal models of adult cerebral white matter disease but also in neonatal models of brain injury. Its quantification by MRI would provide a non-invasive tool to evaluate the impact of injury on myelination and the efficacy of neuroprotective treatments. To date, there is no readily available fast MRI-technique for myelin quantification at high field using high resolution multiple slices. Although diffusion anisotropy has been shown to reflect myelin integrity in adult animal models, it is not the case in the developing brain where significant anisotropy can be found in non-myelinated tracks. It is known that phase images acquired with gradient-recalled echo is greatly enhanced at high field and is affected mainly by tissue lipid, iron and microstructure, but not by tissue cerebral blood flow as initially postulated . The purpose of this study was to investigate the relevance of phase imaging in detecting and quantifying myelination in developing rats at 9.4 Tesla.