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KMID : 1038720190300040139
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Progress in Medical Physics
2019 Volume.30 No. 4 p.139 ~ p.149
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Assessment of the Cerebrospinal Fluid Effect on the Chemical Exchange Saturation Transfer Map Obtained from the Full Z-Spectrum in the Elderly Human Brain
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Park Soon-Chan
Jang Joon
Oh Jang-Hoon
Ryu Chang-Woo
Jahng Geon-Ho
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Abstract
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Purpose: With neurodegeneration, the signal intensity of the cerebrospinal fluid (CSF) in the brain increases. The objective of this study was to evaluate chemical exchange saturation transfer (CEST) signals with and without the contribution of CSF signals in elderly human brains using two different 3T magnetic resonance imaging (MRI) sequences.
Methods: Full CEST signals were acquired in ten subjects (Group I) with a three-dimensional (3D)-segmented gradient-echo echo-planar imaging (EPI) sequence and in ten other subjects (Group II) with a 3D gradient and spin-echo (GRASE) sequence using two different 3T MRI systems. The segmented tissue compartments of gray and white matter were used to mask the CSF signals in the full CEST images. Two sets of magnetization transfer ratio asymmetry (MTRasym) maps were obtained for each offset frequency in each subject with and without masking the CSF signals (masked and unmasked conditions, respectively) and later compared using paired t-tests.
Results: The region-of-interest (ROI)-based analyses showed that the MTRasym values for both the 3D-segmented gradient-echo EPI and 3D GRASE sequences were altered under the masked condition compared with the unmasked condition at several ROIs and offset frequencies.
Conclusions: Depending on the imaging sequence, the MTRasym values can be overestimated for some areas of the elderly human brain when CSF signals are unmasked. Therefore, it is necessary to develop a method to minimize this overestimation in the case of elderly patients.
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KEYWORD
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CEST, Cerebrospinal fluid signal, MTR asymmetry, Sequence type, Brain-tissue degeneration
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