University of Oulu

Hennig, J., Kiviniemi, V., Riemenschneider, B. et al. 15 Years MR-encephalography. Magn Reson Mater Phy 34, 85–108 (2021).

15 years MR-encephalography

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Author: Hennig, Juergen1,2; Kiviniemi, Vesa3; Riemenschneider, Bruno4;
Organizations: 1Department of Radiology, Medical Physics, Faculty of Medicine, Medical Center University of Freiburg, University of Freiburg, Freiburg, Germany
2Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
3Oulu Functional NeuroImaging Group, Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
4Department of Radiology, Center for Biomedical Imaging, New York University Grossman School of Medicine, New York, NY, USA
5Departments of Radiology and Paediatrics, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 7.7 MB)
Persistent link:
Language: English
Published: Springer Nature, 2021
Publish Date: 2021-04-21


Objective: This review article gives an account of the development of the MR-encephalography (MREG) method, which started as a mere ‘Gedankenexperiment’ in 2005 and gradually developed into a method for ultrafast measurement of physiological activities in the brain. After going through different approaches covering k-space with radial, rosette, and concentric shell trajectories we have settled on a stack-of-spiral trajectory, which allows full brain coverage with (nominal) 3 mm isotropic resolution in 100 ms. The very high acceleration factor is facilitated by the near-isotropic k-space coverage, which allows high acceleration in all three spatial dimensions.

Methods: The methodological section covers the basic sequence design as well as recent advances in image reconstruction including the targeted reconstruction, which allows real-time feedback applications, and—most recently—the time-domain principal component reconstruction (tPCR), which applies a principal component analysis of the acquired time domain data as a sparsifying transformation to improve reconstruction speed as well as quality.

Applications: Although the BOLD-response is rather slow, the high speed acquisition of MREG allows separation of BOLD-effects from cardiac and breathing related pulsatility. The increased sensitivity enables direct detection of the dynamic variability of resting state networks as well as localization of single interictal events in epilepsy patients. A separate and highly intriguing application is aimed at the investigation of the glymphatic system by assessment of the spatiotemporal patterns of cardiac and breathing related pulsatility.

Discussion: MREG has been developed to push the speed limits of fMRI. Compared to multiband-EPI this allows considerably faster acquisition at the cost of reduced image quality and spatial resolution.

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Series: Magnetic resonance materials in physics, biology and medicine
ISSN: 0968-5243
ISSN-E: 1352-8661
ISSN-L: 0968-5243
Volume: 34
Issue: 1; SI
Pages: 85 - 108
DOI: 10.1007/s10334-020-00891-z
Type of Publication: A2 Review article in a scientific journal
Field of Science: 217 Medical engineering
Funding: This work was supported by ERC Advanced Grant European Research Council, Grant agreement 232908. Deutsche Forschungsgemeinschaft. Excellence Cluster BrainLinks-BrainTools, Grant EXC 1086, German Federal Ministry of Education and Research. Grant: 13N9208. German Federal Ministry of Education and Research, Grant 01EQ0605. Deutsche Forschungsgemeinschaft. Reinhard-Kosselleck-Grant He 1875/28-1. Jane ja Aatos Erkko Foundation Grant Academy of Finland Grants 275352, 314497. Open Access funding enabled and organized by Projekt DEAL.
Academy of Finland Grant Number: 275352
Detailed Information: 275352 (Academy of Finland Funding decision)
314497 (Academy of Finland Funding decision)
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