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Sensitivity and resolution improvement for in vivo magnetic resonance current-density imaging of the human brain

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Purpose: Magnetic resonance current-density imaging (MRCDI) combines MRI with low-intensity transcranial electrical stimulation (TES; 1-2 mA) to map current flow in the brain. However, usage of MRCDI is still hampered by low measurement sensitivity and image quality. Methods: Recently, a multigradient-echo–based MRCDI approach has been introduced that presently has the best-documented efficiency. This MRCDI approach has now been advanced in three directions and has been validated by phantom and in vivo experiments. First, the importance of optimum spoiling for brain imaging was verified. Second, the sensitivity and spatial resolution were improved by using acquisition weighting. Third, navigators were added as a quality control measure for tracking physiological noise. Combining these advancements, the optimized MRCDI method was tested by using 1 mA TES for two different injection profiles. Results: For a session duration of 4:20 min, the new MRCDI method was able to detect TES-induced magnetic fields at a sensitivity level of 84 picotesla, representing a twofold efficiency increase against our original method. A comparison between measurements and simulations based on personalized head models showed a consistent increase in the coefficient of determination of ΔR2 = 0.12 for the current-induced magnetic fields and ΔR2 = 0.22 for the current flow reconstructions. Interestingly, some of the simulations still clearly deviated from the measurements despite the strongly improved measurement quality. This highlights the utility of MRCDI to improve head models for TES simulations. Conclusion: The achieved sensitivity improvement is an important step from proof-of-concept studies toward a broader application of MRCDI in clinical and basic neuroscience research.

Original languageEnglish
Article number28944
JournalMagnetic Resonance in Medicine
Issue number6
Pages (from-to)3131-3146
Number of pages16
Publication statusPublished - Dec 2021

Bibliographical note

Funding Information:
The financial support of the Lundbeck Foundation (grant nos. R288‐2018‐236 to C.G. and R244‐2017‐196 and R313‐2019‐622 to A.T.), the Max Planck Society, and the German Research Foundation (Reinhart Koselleck Project, DFG SCHE 658/12) is gratefully acknowledged. H.R.S. holds a 5‐year professorship in precision medicine at the Faculty of Health Sciences and Medicine, University of Copenhagen, which is sponsored by the Lundbeck Foundation (grant no. R186‐2015‐2138).

Publisher Copyright:
© 2021 International Society for Magnetic Resonance in Medicine

    Research areas

  • acquisition-weighted in vivo brain imaging, current-induced magnetic field, magnetic resonance current-density imaging, navigators, spoiled multiecho-gradient echo, Brain/diagnostic imaging, Magnetic Resonance Imaging, Algorithms, Magnetic Resonance Spectroscopy, Humans, Phantoms, Imaging

ID: 71681119