Human Brain-Structure Resolved T1 and T2 Relaxation Time of Proton Metabolites Using 2D and 3D Fast Spectroscopic Imaging Technique

Metabolite T1 and T2 relaxation times are necessary for accurate quantification of the absolute concentration of metabolites and may also be an important pathological index. However, lengthy data acquisition time poses a major challenge to mapping metabolite T1 and T2. In this project, we aim to obtain fast T1 and T2 maps of three major cerebral metabolites: N-acetyl aspartate (NAA), creatine (Cre), and choline (Cho) in clinical acceptable time using a fast spectroscopy imaging technique, called Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI), at 3T MR system. The protocol of less than 30 minutes will be proposed and is expected to improve the applicability in general studies. Data acquisition for two-dimensional and three-dimensional metabolite maps with voxel volume of less than 1 ml will be better for regional evaluation especially in the differentiation between the regional difference in gray and white matter of the brain compared to 8 ml voxel size acquired in single voxel spectroscopy (SVS). Parametric maps of metabolite relaxation times may also be useful as an adjunct to high resolution T1-weighted images to identify brain pathology in patients with neurodegenerative disease and stroke. For the verification we will show that PEPSI spectra at representative regions of interest matched the T1 and T2 values obtained using (SVS) and spectral signal-to-noise ratio (SNR) for estimation of relaxation times will be validated by the Pearson’s correlation coefficients during least square fitting. In addition, the T1 and T2 values of NAA, Cre and Cho, will be compared to those reported in previous studies. Consistent of spatial distributions of metabolites relaxation times will be examined from healthy subjects recruited in this project and we will carefully investigate the disagreement of metabolites T1 and T2 among subjects in terms of sexual and age difference.

Project ID:PB9902-2198
External Project ID:NSC98-2320-B182-003-MY2