Deuterium metabolic imaging of the human brain in vivo at 7 T

Abstract

Purpose: To explore the potential of deuterium metabolic imaging (DMI) in the human brain in vivo at 7 T, using a multi-element deuterium (² H) RF coil for 3D volume coverage.

Methods: ¹ H-MR images and localized ² H MR spectra were acquired in vivo in the human brain of 3 healthy subjects to generate DMI maps of ² H-labeled water, glucose, and glutamate/glutamine (Glx). In addition, non-localized ² H-MR spectra were acquired both in vivo and in vitro to determine T₁ and T₂ relaxation times of deuterated metabolites at 7 T. The performance of the ² H coil was assessed through numeric simulations and experimentally acquired B₁ ⁺ maps.

Results: 3D DMI maps covering the entire human brain in vivo were obtained from well-resolved deuterated (² H) metabolite resonances of water, glucose, and Glx. The T₁ and T₂ relaxation times were consistent with those reported at adjacent field strengths. Experimental B₁ ⁺ maps were in good agreement with simulations, indicating efficient and homogeneous B₁ ⁺ transmission and low RF power deposition for ² H, consistent with a similar array coil design reported at 9.4 T.

Conclusion: Here, we have demonstrated the successful implementation of 3D DMI in the human brain in vivo at 7 T. The spatial and temporal nominal resolutions achieved at 7 T (i.e., 2.7 mL in 28 min, respectively) were close to those achieved at 9.4 T and greatly outperformed DMI at lower magnetic fields. DMI at 7 T and beyond has clear potential in applications dealing with small brain lesions.

Keywords: 7 Tesla (7 T); brain energy metabolism; deuterium (2H); deuterium metabolic imaging (DMI); glucose; glutamate/glutamine (Glx); human brain; water.