Authors: Yanurita Dwihapsari J P Mostert J M Hoogduin
Publish Date: 2010/08/05
Volume: 39, Issue: 3, Pages: 251-260
Abstract
One of the drawbacks of scanning patients using multiplevoxel spectroscopic imaging is the long acquisition time This is especially true when one is interested in obtaining absolute metabolite concentrations which requires acquisition of unsuppressed water spectra in addition to the suppressed spectra In our experiment turbo spectroscopic imaging TSI method with acquisition of three echoes per excitation was applied to reduce scanning time without lowering the spatial resolution In 15 relapsingremitting multiple sclerosis patients mean age 3707 years mean disease duration 767 years an MRSI scan at the level of centrum semiovale was obtained The scan time was approximately 7 min including the unsuppressed spectra Tissue water was used as an internal concentration reference to obtain absolute metabolite concentrations of Nacetylaspartate NAA creatine Cr and choline Cho The peak areas were corrected for differences in transversal and longitudinal relaxation times and a water concentration of 555 M was assumed A threedimensional highresolution T 1 scan was acquired and used to segment tissue in gray matter GM white matter WM and cerebrospinal fluid using FSL’S FAST segmentation method a software library of the automated segmentation tool by the Center of Functional MRI of the Brain Oxford UK Finally a regression analysis was employed to address the metabolite concentrations and ratios in GM and WM respectively Our study shows that the metabolite concentrations NAA Cho Cr and metabolite ratios NAA/Cr and Cho/Cr in GM and WM obtained using the methods discussed earlier are comparable to the results found in other studies of similar patient groups It also shows that TSI method can be used to obtain the absolute metabolite ratios in a reasonable scan time
Keywords: