Quantitative water content mapping at clinically relevant field strengths: A comparative study at 1.5T and 3T

Abbas, Zaheer; Gras, Vincent; Möllenhoff, Klaus; Oros-Peusquens, Ana-Maria; Shah, N. Jon

doi:10.1016/j.neuroimage.2014.11.017

Cited by 50 publications

(65 citation statements)

References 32 publications

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“…The resulting estimates for f in corpus callosum were, as expected, virtually identical for 3T and 7 T (0.266 versus 0.268) and consistent with what would be expected based on the close to 30% fraction of proteins and lipids (and hence an approximately MP fraction of 30%, considering that the hydrogen proton fraction in proteins and lipids is similar to that in water) (Randall 1938, Fatouros and Marmarou 1999). Our estimates furthermore appear consistent with previous MRI measurements of proton density not relying on MT contrast, which found WM water content to be around 70% (Volz, Noth et al 2012, Volz, Noth et al 2012, Mezer, Yeatman et al 2013, Abbas, Gras et al 2015). Nevertheless, our estimate of f is substantially higher than previous MT studies (Davies, Tozer et al 2004, Sled, Levesque et al 2004, Yarnykh and Yuan 2004, Stanisz, Odrobina et al 2005, Yarnykh, Bowen et al 2015).…”

Section: Discussionsupporting

confidence: 91%

Effects of magnetization transfer on T 1 contrast in human brain white matter

2016

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MRI based on T1 relaxation contrast is increasingly being used to study brain morphology and myelination. Although it provides for excellent distinction between the major tissue types of grey matter, white matter, and CSF, reproducible quantification of T1 relaxation rates is difficult due to the complexity of the contrast mechanism and dependence on experimental details. In this work, we perform simulations and inversion-recovery MRI measurements at 3 T and 7 T to show that substantial measurement variability results from unintended and uncontrolled perturbation of the magnetization of MRI-invisible 1H protons of lipids and macromolecules. This results in bi-exponential relaxation, with a fast component whose relative contribution under practical conditions can reach 20%. This phenomenon can strongly affect apparent relaxation rates, affect contrast between tissue types, and result in contrast variations over the brain. Based on this novel understanding, ways are proposed to minimize this experimental variability and its effect on T1 contrast, quantification accuracy and reproducibility.

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Section: Discussionsupporting

confidence: 91%

Effects of magnetization transfer on T 1 contrast in human brain white matter

2016

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“…In contrast, the k WM are similar to literature values (1.4–2 s −1 ) . Compared with estimates based on the nonwater content of tissue (23–26% for GP, 18–21% for Put, and 17–19% for NC ), our MT‐based estimates are somewhat low but not entirely unreasonable given the uncertainty in gray‐matter 1 H content.…”

Section: Discussionsupporting

confidence: 80%

Rapid measurement of brain macromolecular proton fraction with transient saturation transfer MRI

Gelderen

Duyn

2016

Magn. Reson. Med.

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Purpose To develop an efficient MRI approach to estimate the non-water proton fraction (f) in human brain. Methods We implement a brief, efficient MT pulse that selectively saturates the magnetization of the (semi-) solid protons, and monitor the transfer of this saturation to the water protons as a function of delay after saturation. Results Analysis of the transient MT effect with two-pool model allowed robust extraction of f at both 3 T and 7 T. This required estimating the longitudinal relaxation rate constant (R1,MP and R1,WP) for both proton pools, which was achieved with the assumption of uniform R1,MP and R1,WP across brain tissues. Resulting values of f were approximately 50% higher than reported previously, which is partly attributed to MP pulse efficiency and R1,MP being higher than assumed previously. Conclusion Experiments performed on human brain in-vivo at 3 T and 7 T demonstrate the ability of the method to robustly determine f in a scan time of about 5 minutes.

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“…Instead, we selected published data in which researchers carefully measured several tissue‐specific physical parameters, such as their EPs, water content, and relaxation times, by different methodologies, choosing only data that correspond to healthy human adult (ages 20–40 years old) tissues. We obtained average W values from several published water‐content studies , trying to compensate for any measurement discrepancies or biases. The same procedure was used to obtain average T 1 values at 3 T ).…”

Section: Methodsmentioning

confidence: 99%

Electrical conductivity and permittivity maps of brain tissues derived from water content based on T₁‐weighted acquisition

Michel

Hernández

Lee

2016

Magnetic Resonance in Med

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Human brain and phantom EP images suggest that water content is a dominating factor in determining the electrical properties of tissues. Despite possible literature inaccuracies, the proposed method offers EP maps that can provide complementary information to current approaches, to facilitate EPT scans in clinical applications. Magn Reson Med 77:1094-1103, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

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Quantitative water content mapping at clinically relevant field strengths: A comparative study at 1.5T and 3T

Cited by 50 publications

References 32 publications

Effects of magnetization transfer on T 1 contrast in human brain white matter

Effects of magnetization transfer on T 1 contrast in human brain white matter

Rapid measurement of brain macromolecular proton fraction with transient saturation transfer MRI

Electrical conductivity and permittivity maps of brain tissues derived from water content based on T₁‐weighted acquisition

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Quantitative water content mapping at clinically relevant field strengths: A comparative study at 1.5T and 3T

Cited by 50 publications

References 32 publications

Effects of magnetization transfer on T 1 contrast in human brain white matter

Effects of magnetization transfer on T 1 contrast in human brain white matter

Rapid measurement of brain macromolecular proton fraction with transient saturation transfer MRI

Electrical conductivity and permittivity maps of brain tissues derived from water content based on T1‐weighted acquisition

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Electrical conductivity and permittivity maps of brain tissues derived from water content based on T₁‐weighted acquisition