Dataset Information

Deuterium metabolic imaging in the human brain at 9.4 Tesla with high spatial and temporal resolution.

ABSTRACT:

Purpose

To present first highly spatially resolved deuterium metabolic imaging (DMI) measurements of the human brain acquired with a dedicated coil design and a fast chemical shift imaging (CSI) sequence at an ultrahigh field strength of B₀ = 9.4 T. ²H metabolic measurements with a temporal resolution of 10 min enabled the investigation of the glucose metabolism in healthy human subjects.

Methods

The study was performed with a double-tuned coil with 10 TxRx channels for ¹H and 8TxRx/2Rx channels for ²H and an Ernst angle 3D CSI sequence with a nominal spatial resolution of 2.97 ml and a temporal resolution of 10 min.

Results

The metabolism of [6,6'-²H₂]-labeled glucose due to the TCA cycle could be made visible in high resolution metabolite images of deuterated water, glucose and Glx over the entire human brain.

Conclusion

X-nuclei MRSI as DMI can highly benefit from ultrahigh field strength enabling higher temporal and spatial resolutions.

SUBMITTER: Ruhm L

PROVIDER: S-EPMC8591372 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature

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Publications

Deuterium metabolic imaging in the human brain at 9.4 Tesla with high spatial and temporal resolution.

Ruhm Loreen L Avdievich Nikolai N Ziegs Theresia T Nagel Armin M AM De Feyter Henk M HM de Graaf Robin A RA Henning Anke A

NeuroImage 20211009

<h4>Purpose</h4>To present first highly spatially resolved deuterium metabolic imaging (DMI) measurements of the human brain acquired with a dedicated coil design and a fast chemical shift imaging (CSI) sequence at an ultrahigh field strength of B<sub>0</sub> = 9.4 T. <sup>2</sup>H metabolic measurements with a temporal resolution of 10 min enabled the investigation of the glucose metabolism in healthy human subjects.<h4>Methods</h4>The study was performed with a double-tuned coil with 10 TxRx c ...[more]

PMID: 34637905

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Project description:ObjectivesDeuterium (2H) Metabolic Imaging (DMI) is an emerging magnetic resonance technique to non-invasively map human brain glucose (Glc) uptake and downstream metabolism following oral or intravenous administration of 2H-labeled Glc. The achievable spatial resolution is limited due to inherently low sensitivity of DMI. This hinders potential clinical translation. The purpose of this study was to improve the signal-to-noise ratio (SNR) of 3D DMI via a balanced steady state free precession (bSSFP) acquisition scheme combined with fast non-Cartesian spatial-spectral sampling to enable high resolution dynamic imaging of neural Glc uptake and glutamate+glutamine (Glx) synthesis of the human brain at 7T.Materials and methodsSix healthy volunteers (2f/4m) were scanned after oral administration of 0.8 g/kg [6,6']-2H-Glc using a novel density-weighted bSSFP acquisition scheme combined with fast 3D concentric ring trajectory (CRT) k-space sampling at 7T. Time-resolved whole brain DMI datasets were acquired for approximately 80 min (7 min per dataset) after oral 2H-labeled Glc administration with 0.75ml and 0.36ml isotropic spatial resolution and results were compared to conventional spoiled Free Induction Decay (FID) 2H-MRSI with CRT readout at matched nominal spatial resolution.Dynamic DMI measurements of the brain were accompanied by simultaneous systemic Glc measurements of the interstitial tissue using a continuous Glc monitoring (CGM) sensor (on the upper arm). The correlation between brain and interstitial Glc levels was analyzed using linear mixed models.ResultsThe bSSFP-CRT approach achieved SNRs that were up to 3-fold higher than conventional spoiled FID-CRT 2H-MRSI. This enabled a 2-fold higher spatial resolution. Seventy minutes after oral tracer uptake comparable 2H-Glc, 2H-Glx and 2H-water concentrations were detected using both acquisition schemes at both, regular and high spatial resolutions (0.75ml and 0.36 ml isotropic). The mean Areas Under the Curve (AUC) for interstitial fluid Glc measurements obtained using a continuous Glc monitoring (CGM) sensor was 509±65 mM·min. This is 3.4 times higher than the mean AUC of brain Glc measurements of 149±43 mM·min obtained via DMI. The linear mixed models fitted to assess the relationship between CGM measures and brain 2H-Glc yielded statistically significant slope estimates in both GM (β1 = 0.47, p = 0.01) and WM (β1 = 0.36, p = 0.03).ConclusionIn this study we successfully implemented a balanced steady state free precession (bSSFP) acquisition scheme for dynamic whole-brain human DMI at 7T. A 3-fold SNR increase compared to conventional spoiled acquisition allowed us to double the spatial resolution achieved using conventional FID-CRT DMI. Systemic continuous glucose measurements, combined with dynamic DMI, demonstrate significant potential for clinical applications. This could help to improve our understanding of brain glucose metabolism by linking it to time-resolved peripheral glucose levels. Importantly, these measurements are conducted in a minimally invasive and physiological manner.

Project description:Magnetic Resonance Imaging (MRI) of the rodent brain at ultra-high magnetic fields (> 9.4 Tesla) offers a higher signal-to-noise ratio that can be exploited to reduce image acquisition time or provide higher spatial resolution. However, significant challenges are presented due to a combination of longer T1 and shorter T2/T2* relaxation times and increased sensitivity to magnetic susceptibility resulting in severe local-field inhomogeneity artefacts from air pockets and bone/brain interfaces. The Stejskal-Tanner spin echo diffusion-weighted imaging (DWI) sequence is often used in high-field rodent brain MRI due to its immunity to these artefacts. To accurately determine diffusion-tensor or fibre-orientation distribution, high angular resolution diffusion imaging (HARDI) with strong diffusion weighting (b >3000 s/mm2) and at least 30 diffusion-encoding directions are required. However, this results in long image acquisition times unsuitable for live animal imaging. In this study, we describe the optimization of HARDI acquisition parameters at 16.4T using a Stejskal-Tanner sequence with echo-planar imaging (EPI) readout. EPI segmentation and partial Fourier encoding acceleration were applied to reduce the echo time (TE), thereby minimizing signal decay and distortion artefacts while maintaining a reasonably short acquisition time. The final HARDI acquisition protocol was achieved with the following parameters: 4 shot EPI, b = 3000 s/mm2, 64 diffusion-encoding directions, 125×150 μm2 in-plane resolution, 0.6 mm slice thickness, and 2h acquisition time. This protocol was used to image a cohort of adult C57BL/6 male mice, whereby the quality of the acquired data was assessed and diffusion tensor imaging (DTI) derived parameters were measured. High-quality images with high spatial and angular resolution, low distortion and low variability in DTI-derived parameters were obtained, indicating that EPI-DWI is feasible at 16.4T to study animal models of white matter (WM) diseases.

Dataset Information

Deuterium metabolic imaging in the human brain at 9.4 Tesla with high spatial and temporal resolution.

Purpose

Methods

Results

Conclusion

Publications

Deuterium metabolic imaging in the human brain at 9.4 Tesla with high spatial and temporal resolution.

Similar Datasets

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