In Vivo Multislice Mapping of Myelin Water Content of the Brain with T2* Signal Decay

Introduction: In recent years, substantial interests in quantitative assessment of myelin content in white matter (WM) have emerged for the study on the myelin-related diseases such as multiple sclerosis (MS). One commonly used approach for in vivo myelin quantification is based on the analysis of T2 relaxation time. It has been reported that the T2 spectrum of WM and several myelinated tissue samples consists of three components [1,2]. Since the water trapped in the myelin sheath has the shortest T2 relaxation time among three components, myelin water fraction (MWF) which is the ratio of the amplitude of the shortest T2 component to the total can represent the myelin content in WM. Histopathology studies showed a strong correlation between MWF and the myelin distribution. A single-slice technique based on the CPMG data acquisition has been successfully developed to study the pathology related to demyelination in patients with MS [3]. A new multi-slice technique to estimate MWF using T2* relaxation has also been demonstrated for the in vitro studies [4]. In this abstract, we present the results of in vivo applications of the T2* relaxation analysis technique for multi-slice and high-resolution MWF mapping.