High‐resolution sodium imaging of human brain at 7 T

Qian, Yongxian; Zhao, Tiejun; Zheng, Haoran; Weimer, Jonathan M.; Boada, Fernando E.

doi:10.1002/mrm.23225

Cited by 44 publications

(44 citation statements)

References 26 publications

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“…The total sodium concentration measurements acquired in this study from automated segmentation of white and gray matter analysis are consistent with previous studies, eg, 41.8 ± 6.9 vs. 45.9 ± 3.1 mM, respectively, for WM and 52.1 ± 7.1 vs. 52.7 ± 3.6 mM for GM . WM measurements from the hand‐drawn ROI analysis here are also in agreement with previous studies: for example, Qian et al showed 37.4 ± 2.9 vs. 38.6 ± 8.0 mM here. GM values also showed good agreement with the literature: 47.6 ± 7.1 for the caudate here vs. 52.0 ± 6.0 mM; and 40.9 ± 7.1 for the putamen here vs. 43.0 ± 3.0 mM .…”

Section: Discussionsupporting

confidence: 92%

Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of ²³Na‐MRI across two sites

Riemer

McHugh

Zaccagna

et al. 2019

Magnetic Resonance Imaging

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Background Sodium MRI (23Na‐MRI)‐derived biomarkers such as total sodium concentration (TSC) have the potential to provide information on tumor cellularity and the changes in tumor microstructure that occur following therapy. Purpose To evaluate the repeatability and reproducibility of TSC measurements in the brains of healthy volunteers, providing evidence for the technical validation of 23Na‐MRI‐derived biomarkers. Study Type Prospective multicenter study. Subjects Eleven volunteers (32 ± 6 years; eight males, three females) were scanned twice at each of two sites. Field Strength/Sequence Comparable 3D‐cones 23Na‐MRI ultrashort echo time acquisitions at 3T. Assessment TSC values, quantified from calibration phantoms placed in the field of view, were obtained from white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF), based on automated segmentation of coregistered 1H T1‐weighted images and hand‐drawn regions of interest by two readers. Statistical Tests Coefficients of variation (CoVs) from mean TSC values were used to assess intrasite repeatability and intersite reproducibility. Results Mean GM TSC concentrations (52.1 ± 7.1 mM) were ∼20% higher than for WM (41.8 ± 6.7 mM). Measurements were highly repeatable at both sites with mean scan–rescan CoVs between volunteers and regions of 2% and 4%, respectively. Mean intersite reproducibility CoVs were 3%, 3%, and 6% for WM, GM, and CSF, respectively. Data Conclusion These results demonstrate technical validation of sodium MRI‐derived biomarkers in healthy volunteers. We also show that comparable 23Na imaging of the brain can be implemented across different sites and scanners with excellent repeatability and reproducibility. Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1278–1284.

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Section: Discussionsupporting

confidence: 92%

Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of ²³Na‐MRI across two sites

Riemer

McHugh

Zaccagna

et al. 2019

Magnetic Resonance Imaging

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“…As the sodium T 1 relaxation time is essentially field strength independent, because of the dominant quadrupolar mechanism, the full increase in SNR associated with the increased polarization can be achieved at ultrahigh fields. This has been confirmed in sodium brain studies performed at 7 T and 9.4 T , as well as for a variety of musculoskeletal applications .…”

Section: Introductionsupporting

confidence: 54%

Time-efficient interleaved human²³Na and¹H data acquisition at 7 T

et al. 2015

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The aim of this study was to implement and evaluate a flexible and time-efficient interleaved imaging approach for the acquisition of proton and sodium images of the human knee at 7 T within a clinically relevant timescale. A flexible software framework was established which allowed the interleaving of multiple, different, fully specific absorption ratio (SAR)-validated scans. The system was able to switch between these different scans at flexible time points. The practical example presented consists of interleaved proton (Dixon imaging and T2* mapping) and sodium (mapping the sodium content and fluid-suppressed component separately) sequences with the key idea to perform proton MRI whilst the sodium nuclei relax towards thermal equilibrium, and vice versa. Comparisons were made between these four scans being acquired sequentially in the normal mode of scanner operation and those acquired in an interleaved fashion. Images acquired in the interleaved mode were very similar to those acquired in sequential scans with no image artifacts produced by the slight intra-sequence variation in steady-state magnetization. A reduction in scanning time of almost a factor of two was established using the interleaved scans, allowing such a protocol to be completed within 30 min. Phantom experiments and in vivo scans performed in healthy volunteers and in one patient proved the basic feasibility of this approach. This approach for the interleaving of multiple proton and sodium scans, each with different contrasts, is an efficient method for the design of new practical clinical protocols for sodium MRI.

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“…The diameter of the tube was 2.9 cm and the same sequence protocols as used in vivo were used. In agreement with a previous study by Qian et al [31], signal profiles were taken half-way down the phantom, which can be used to experimentally approximate the FWHM of a symmetric point spread function [11, 31]. As the transition from saline to water is a sharp step-like function, the number of pixels constituting the step in the reconstructed image was measured to estimate resolution.…”

Section: Methodsmentioning

confidence: 69%

Sodium (23Na) ultra-short echo time imaging in the human brain using a 3D-Cones trajectory

Riemer

Solanky

Stehning

et al. 2013

Magn Reson Mater Phy

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ObjectSodium magnetic resonance imaging (23Na-MRI) of the brain has shown changes in 23Na signal as a hallmark of various neurological diseases such as stroke, Alzheimer’s disease, Multiple Sclerosis and Huntington’s disease. To improve scan times and image quality, we have implemented the 3D-Cones (CN) sequence for in vivo 23Na brain MRI.Materials and methodsUsing signal-to-noise (SNR) as a measurement of sequence performance, CN is compared against more established 3D-radial k-space sampling schemes featuring cylindrical stack-of-stars (SOS) and 3D-spokes kooshball (KB) trajectories, on five healthy volunteers in a clinical setting. Resolution was evaluated by simulating the point-spread-functions (PSFs) and experimental measures on a phantom.ResultsAll sequences were shown to have a similar SNR arbitrary units (AU) of 6–6.5 in brain white matter, 7–9 in gray matter and 17–18 AU in cerebrospinal fluid. SNR between white and gray matter were significantly different for KB and CN (p = 0.046 and <0.001 respectively), but not for SOS (p = 0.1). Group mean standard deviations were significantly smaller for CN (p = 0.016). Theoretical full-width at half-maximum linewidth of the PSF for CN is broadened by only 0.1, compared to 0.3 and 0.8 pixels for SOS and KB respectively. Actual image resolution is estimated as 8, 9 and 6.3 mm for SOS, KB and CN respectively.ConclusionThe CN sequence provides stronger tissue contrast than both SOS and KB, with more reproducible SNR measurements compared to KB. For CN, a higher true resolution in the same amount of time with no significant trade-off in SNR is achieved. CN is therefore more suitable for 23Na-MRI in the brain.

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High‐resolution sodium imaging of human brain at 7 T

Cited by 44 publications

References 26 publications

Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of ²³Na‐MRI across two sites

Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of ²³Na‐MRI across two sites

Time-efficient interleaved human²³Na and¹H data acquisition at 7 T

Sodium (23Na) ultra-short echo time imaging in the human brain using a 3D-Cones trajectory

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High‐resolution sodium imaging of human brain at 7 T

Cited by 44 publications

References 26 publications

Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of 23Na‐MRI across two sites

Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of 23Na‐MRI across two sites

Time-efficient interleaved human23Na and1H data acquisition at 7 T

Sodium (23Na) ultra-short echo time imaging in the human brain using a 3D-Cones trajectory

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Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of ²³Na‐MRI across two sites

Measuring tissue sodium concentration: Cross‐vendor repeatability and reproducibility of ²³Na‐MRI across two sites

Time-efficient interleaved human²³Na and¹H data acquisition at 7 T