In Vivo Quantitative MRI T1 and T2 Measurements of the Human Brain at 0.064 T

Published

May 20, 2023

Author(s)

Kalina Jordanova, Michele Martin, Stephen Ogier, Megan Poorman, Katy Keenan

Abstract

Object : Tissue relaxation of the brain is measured in vivo at 0.064 T. This work contributes to research efforts targeted at measuring quantitative magnetic resonance imaging properties of the human body at lower field strengths, thereby increasing the clinical utility of quantitative methods at new magnetic field strengths. Materials and Methods: T_1 and T_2 relaxation were measured in vivo for ten healthy volunteers at 0.064 T. The T_1 mapping protocol used six inversion recovery sequences and was optimized for in vivo imaging at 0.064 T. The T_2 mapping protocol used a T_2 -weighted 3D FSE sequence with 10 echo times. To validate the mapping protocols, T_1 and T_2 of ten chemical samples were measured at 0.064 T on both the Hyperfine system and on a separate electromagnet system. T_1 and T_2 maps are reported for white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) using both an automatic segmentation algorithm that was developed by this study and manually segmented regions. Results: The automatic segmentation algorithm resulted in larger T_1 and T_2 estimates than the manual segmentation. Manual segmentation resulted in T_1 of 0.259 s ± 0.0315 s for WM, 0.393 s ± 0.0217 s for GM, 1.723 s ± 0.584 s for CSF. Manual segmentation resulted in T_2 of 0.0813 s ± 0.0035 s for WM, 0.108 s ± 0.0223 s for GM, 1.166 s ± 0.338 s for CSF. Discussion: T_1 and T_2 relaxation measurements for healthy brain tissue are measured and presented at 0.064 T. It was difficult to measure relaxation in CSF, largely due to partial volume effects in the brain due to the 5 mm slice thickness of the measurement protocols. Future studies should take care to remove partial volume effects, especially for in vivo measurements at low field where larger slice thicknesses are often used.

Citation

Magnetic Resonance Materials in Physics Biology and Medicine

Volume

36

Pub Type

Journals

Download Paper

https://doi.org/10.1007/s10334-023-01095-x

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Keywords

Magnetic Resonance Imaging

Citation

Jordanova, K. , Martin, M. , Ogier, S. , Poorman, M. and Keenan, K. (2023), In Vivo Quantitative MRI T1 and T2 Measurements of the Human Brain at 0.064 T, Magnetic Resonance Materials in Physics Biology and Medicine, [online], https://doi.org/10.1007/s10334-023-01095-x, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935902 (Accessed December 4, 2024)