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Additional sampling directions improve detection range of wireless radiofrequency probes.

Published version
Peer-reviewed

Repository DOI


Type

Article

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Authors

Mada, Marius 
Carpenter, T Adrian 
Sawiak, Stephen J 
Williams, Guy B 

Abstract

PURPOSE: While MRI is enhancing our knowledge about the structure and function of the human brain, subject motion remains a problem in many clinical applications. Recently, the use of wireless radiofrequency markers with three one-dimensional (1D) navigators for prospective correction was demonstrated. This method is restricted in the range of motion that can be corrected, however, because of limited information in the 1D readouts. METHODS: Here, the limitation of techniques for disambiguating marker locations was investigated. It was shown that including more sampling directions extends the tracking range for head rotations. The efficiency of trading readout resolution for speed was explored. RESULTS: Tracking of head rotations was demonstrated from -19.2 to 34.4°, -2.7 to 10.0°, and -60.9 to 70.9° in the x-, y-, and z-directions, respectively. In the presence of excessive head motion, the deviation of marker estimates from SPM8 was reduced by 17.1% over existing three-projection methods. This was achieved by using an additional seven directions, extending the time needed for readouts by a factor of 3.3. Much of this increase may be circumvented by reducing resolution, without compromising accuracy. CONCLUSION: Including additional sampling directions extends the range in which markers can be used, for patients who move a lot. Magn Reson Med 76:913-918, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Description

Keywords

head motion, prospective correction, wireless RF markers, Algorithms, Artifacts, Brain, Equipment Design, Equipment Failure Analysis, Fiducial Markers, Head Movements, Humans, Image Enhancement, Magnetic Resonance Imaging, Radio Waves, Reproducibility of Results, Sample Size, Sensitivity and Specificity, Transducers, Wireless Technology

Journal Title

Magn Reson Med

Conference Name

Journal ISSN

0740-3194
1522-2594

Volume Title

Publisher

Wiley
Sponsorship
The project was supported by funding from the Isaac Newton Trust, the Wellcome Trust ISSF, and the Cusanuswerk funding body (Bonn, Germany).