Scan–Rescan Repeatability and Impact of B<sub>0</sub> and B<sub>1</sub> Field Nonuniformity Corrections in Single‐Point Whole‐Brain Macromolecular Proton Fraction Mapping

Yarnykh, Vasily L.; Kisel, Alena; Khodanovich, M. Yu.

doi:10.1002/jmri.26998

Cited by 20 publications

(27 citation statements)

References 41 publications

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“…Phase images may also be used to derive quantitative susceptibility maps (Acosta-Cabronero et al, 2018 ). Another potential extension would be to calculate the macromolecular proton fraction from the acquired MPM maps (Yarnykh, 2016 ), to acquire an additional marker of myelination with high stability (Yarnykh et al, 2020 ).…”

Section: Discussionmentioning

confidence: 99%

Quantitative Multi-Parameter Mapping Optimized for the Clinical Routine

et al. 2020

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Using quantitative multi-parameter mapping (MPM), studies can investigate clinically relevant microstructural changes with high reliability over time and across subjects and sites. However, long acquisition times (20 min for the standard 1-mm isotropic protocol) limit its translational potential. This study aimed to evaluate the sensitivity gain of a fast 1.6-mm isotropic MPM protocol including post-processing optimized for longitudinal clinical studies. 6 healthy volunteers (35±7 years old; 3 female) were scanned at 3T to acquire the following whole-brain MPM maps with 1.6 mm isotropic resolution: proton density (PD), magnetization transfer saturation (MT), longitudinal relaxation rate (R1), and transverse relaxation rate (R2*). MPM maps were generated using two RF transmit field (B1+) correction methods: (1) using an acquired B1+ map and (2) using a data-driven approach. Maps were generated with and without Gibb's ringing correction. The intra-/inter-subject coefficient of variation (CoV) of all maps in the gray and white matter, as well as in all anatomical regions of a fine-grained brain atlas, were compared between the different post-processing methods using Student's t-test. The intra-subject stability of the 1.6-mm MPM protocol is 2–3 times higher than for the standard 1-mm sequence and can be achieved in less than half the scan duration. Intra-subject variability for all four maps in white matter ranged from 1.2–5.3% and in gray matter from 1.8 to 9.2%. Bias-field correction using an acquired B1+ map significantly improved intra-subject variability of PD and R1 in the gray (42%) and white matter (54%) and correcting the raw images for the effect of Gibb's ringing further improved intra-subject variability in all maps in the gray (11%) and white matter (10%). Combining Gibb's ringing correction and bias field correction using acquired B1+ maps provides excellent stability of the 7-min MPM sequence with 1.6 mm resolution suitable for the clinical routine.

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Section: Discussionmentioning

confidence: 99%

Quantitative Multi-Parameter Mapping Optimized for the Clinical Routine

et al. 2020

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“…Apart from a single MT‐weighted image and its paired normalizing volume, the SP‐MPF composite mapping method requires prior knowledge about R 1 and system imperfections, namely

B_{1}^{+}

and B 0 24 . Hence, any bias in the provided maps shall impact the resulting MPF.…”

Section: Discussionmentioning

confidence: 99%

“…Apart from a single MT-weighted image and its paired normalizing volume, the SP-MPF composite mapping method requires prior knowledge about R 1 and system imperfections, namely B + 1 and B 0 . 24 Hence, any bias in the provided maps shall impact the resulting MPF. As B + 1 and B 0 mapping methods are nowadays readily acquired, T 1sensitive sequences represent the largest bias source within SPGR-based qMT protocols.…”

Section: Discussionmentioning

confidence: 99%

“…Methods to reduce the number of MTw images for 3D-MPF mapping were proposed at 1.5T (humans only), 18 3T (humans and rodents), 10,[18][19][20][21][22] and 11.7T (rodents only). 9,23 Notably, Yarnykh's single-point MPF (SP-MPF) 9,20,21,23,24 method estimates the MPF by constraining the values of other two-pool model parameters, namely the fast crossrelaxation rate constant (R), the T 2 of the restricted pool (T 2,r ), and the product of the relaxation quantities R 1,f and T 2,f of the free pool (R 1,f T 2,f ) using steady-state and MT-prepared spoiled gradient echo sequences, hence, using a single MTw image. The method is, therefore, highly interesting for fast MPF mapping.…”

Section: Introductionmentioning

confidence: 99%

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Determination of optimal parameters for 3D single‐point macromolecular proton fraction mapping at 7T in healthy and demyelinated mouse brain

Soustelle

Antal

Lamy

et al. 2020

Magnetic Resonance in Med

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To determine optimal constrained tissue parameters and off-resonance sequence parameters for single-point macromolecular proton fraction (SP-MPF) mapping based on a comprehensive quantitative magnetization transfer (qMT) protocol in healthy and demyelinated living mice at 7T. Methods: Using 3D spoiled gradient echo-based sequences, a comprehensive qMT protocol is performed by sampling the Z-spectrum of mice brains, in vivo. Provided additional T 1 , B + 1 and B 0 maps allow for the estimation of qMT tissue parameters, among which three will be constrained, namely the longitudinal and transverse relaxation characteristics of the free pool (R 1,f T 2,f), the cross-relaxation rate (R) and the bound pool transverse relaxation time (T 2,r). Different sets of constrained parameters are investigated to reduce the bias between the SP-MPF and its reference based on the comprehensive protocol. Results: Based on a whole-brain histogram analysis about the constrained parameters, the optimal experimental parameters that minimize the global bias between reference and SP-MPF maps consist of a 600° and 6 kHz off-resonance irradiation pulse. Following a Bland-Altman analysis over regions of interest, optimal constrained parameters were R 1,f T 2,f = 0.0129, R = 26.5 s −1 , and T 2,r = 9.1 µs, yielding an overall MPF bias of 10 −4 (limits of agreement [−0.0068;0.0070]) and a relative variation of 0.64% ± 5.95% between the reference and the optimal single-point method across all mice. Conclusion: The necessity of estimating animal model-and field-dependent constrained parameters was demonstrated. The single-point MPF method can be reliably applied at 7T, as part of routine preclinical in vivo imaging protocol in mice.

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“…MPF maps were reconstructed according to a single-point synthetic reference algorithm ( Yarnykh, 2016 ) with correction of B 1 field nonuniformity using custom-written C-language software with previously determined ( Yarnykh, 2012 ) constraints for the non-adjustable two-pool model parameters. Correction of B 0 field inhomogeneity was not applied because of a negligible effect of B 0 -related errors on MPF measurements ( Yarnykh et al, 2020 ). Prior to map reconstruction, individual echo images in each data set were averaged to increase SNR ( Helms and Dechent, 2009 ).…”

Section: Methodsmentioning

confidence: 99%

Myelin development in cerebral gray and white matter during adolescence and late childhood

et al. 2021

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Myelin development during adolescence is becoming an area of growing interest in view of its potential relationship to cognition, behavior, and learning. While recent investigations suggest that both white matter (WM) and gray matter (GM) undergo protracted myelination during adolescence, quantitative relations between myelin development in WM and GM have not been previously studied. We quantitatively characterized the dependence of cortical GM, WM, and subcortical myelin density across the brain on age, gender, and puberty status during adolescence with the use of a novel macromolecular proton fraction (MPF) mapping method. Whole-brain MPF maps from a cross-sectional sample of 146 adolescents (age range 9–17 years) were collected. Myelin density was calculated from MPF values in GM and WM of all brain lobes, as well as in subcortical structures. In general, myelination of cortical GM was widespread and more significantly correlated with age than that of WM. Myelination of GM in the parietal lobe was found to have a significantly stronger age dependence than that of GM in the frontal, occipital, temporal and insular lobes. Myelination of WM in the temporal lobe had the strongest association with age as compared to WM in other lobes. Myelin density was found to be higher in males as compared to females when averaged across all cortical lobes, as well as in a bilateral subcortical region. Puberty stage was significantly correlated with myelin density in several cortical areas and in the subcortical GM. These findings point to significant differences in the trajectories of myelination of GM and WM across brain regions and suggest that cortical GM myelination plays a dominant role during adolescent development.

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Scan–Rescan Repeatability and Impact of B₀ and B₁ Field Nonuniformity Corrections in Single‐Point Whole‐Brain Macromolecular Proton Fraction Mapping

Cited by 20 publications

References 41 publications

Quantitative Multi-Parameter Mapping Optimized for the Clinical Routine

Quantitative Multi-Parameter Mapping Optimized for the Clinical Routine

Determination of optimal parameters for 3D single‐point macromolecular proton fraction mapping at 7T in healthy and demyelinated mouse brain

Myelin development in cerebral gray and white matter during adolescence and late childhood

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Scan–Rescan Repeatability and Impact of B0 and B1 Field Nonuniformity Corrections in Single‐Point Whole‐Brain Macromolecular Proton Fraction Mapping

Cited by 20 publications

References 41 publications

Quantitative Multi-Parameter Mapping Optimized for the Clinical Routine

Quantitative Multi-Parameter Mapping Optimized for the Clinical Routine

Determination of optimal parameters for 3D single‐point macromolecular proton fraction mapping at 7T in healthy and demyelinated mouse brain

Myelin development in cerebral gray and white matter during adolescence and late childhood

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Product

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Scan–Rescan Repeatability and Impact of B₀ and B₁ Field Nonuniformity Corrections in Single‐Point Whole‐Brain Macromolecular Proton Fraction Mapping