Karl Landheer1, Martin Gajdošík1, Michael Treacy1, Christoph Juchem1,2. 1. Biomedical Engineering, Columbia University Fu Foundation School of Engineering and Applied Science, New York, New York, USA. 2. Radiology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
Abstract
PURPOSE: We aimed to investigate the concentration and effective T2 relaxation time of macromolecules assessed with an ultra-short TE sLASER sequence in 2 brain regions, the occipital and frontal cortex, in both genders at 3T. METHODS: An optimized sLASER sequence was used in conjunction with a double-inversion preparation module to null the metabolites. Eight equally spaced TEs were chosen from 20.1 to 62.1 ms, and the macromolecules were modeled by 10 line broadened singlets. The amplitude of each of the macromolecule signals was extracted at each TE and fit to a monoexponential function to extract the respective effective T2 values. Absolute quantification of the macromolecule resonances was performed using water signal as a reference. A total of 10 young healthy adult subjects (5 females) were scanned, with spectra being obtained from both the frontal and occipital cortex. Differences in the effective T2 relaxation times and concentrations were investigated between both regions and genders. RESULTS: A wide disparity was observed between the effective T2 values of the individual resonances; however, no significant differences between gender or region for any of the measured macromolecule concentration or effective T2 values were found. CONCLUSION: The effective T2 relaxation times and concentration of 10 different macromolecule resonances were measured and found to be well represented by the monoexponential model. These results will be useful for absolute quantification of macromolecules in future studies, or in the generation of synthetic basis sets for optimization or machine learning.
PURPOSE: We aimed to investigate the concentration and effective T2 relaxation time of macromolecules assessed with an ultra-short TE sLASER sequence in 2 brain regions, the occipital and frontal cortex, in both genders at 3T. METHODS: An optimized sLASER sequence was used in conjunction with a double-inversion preparation module to null the metabolites. Eight equally spaced TEs were chosen from 20.1 to 62.1 ms, and the macromolecules were modeled by 10 line broadened singlets. The amplitude of each of the macromolecule signals was extracted at each TE and fit to a monoexponential function to extract the respective effective T2 values. Absolute quantification of the macromolecule resonances was performed using water signal as a reference. A total of 10 young healthy adult subjects (5 females) were scanned, with spectra being obtained from both the frontal and occipital cortex. Differences in the effective T2 relaxation times and concentrations were investigated between both regions and genders. RESULTS: A wide disparity was observed between the effective T2 values of the individual resonances; however, no significant differences between gender or region for any of the measured macromolecule concentration or effective T2 values were found. CONCLUSION: The effective T2 relaxation times and concentration of 10 different macromolecule resonances were measured and found to be well represented by the monoexponential model. These results will be useful for absolute quantification of macromolecules in future studies, or in the generation of synthetic basis sets for optimization or machine learning.
Authors: Steve C N Hui; Tao Gong; Helge J Zöllner; Yulu Song; Saipavitra Murali-Manohar; Georg Oeltzschner; Mark Mikkelsen; Sofie Tapper; Yufan Chen; Muhammad G Saleh; Eric C Porges; Weibo Chen; Guangbin Wang; Richard A E Edden Journal: Magn Reson Med Date: 2021-11-28 Impact factor: 4.668