Adaptive distortion correction techniques for high-field magnetic resonance neuroimaging
Final Report Abstract
The main focus of this project has been the systematic analysis of image distortion and the development of correction techniques. These correction techniques are suitable for various EPI measurements applied to functional MRI and diffusion tensor imaging as well as the compensation of motion induced fluctuations of the magnetic field during time series acquisition. During the course of the project, the focus had been extended to ultra-high magnetic field strength as an additional challenge for EPI. Delays during the transition of one of the applicants (OS) to Magdeburg have delayed and prolonged the project (cost neutrally) and we have made some adjustments to the work plan in order to accommodate the ultra-high field related aspects. A number of developments from this project have meanwhile entered daily routine research scanning protocols at a large number of institutions. This includes in particular the real-time distortion correction during the acquisition. It has been distributed to more than 40 other research laboratories as a “customer-to-customer-package” for scientific purposes free of charge. The positive feedback received from these laboratories demonstrates the quality and success of this project. In addition, a number of methods for the real-time detection of magnetic field variations has been developed and implemented (field maps from EPI raw data, SENSE shimming, field map changes from EPI phase data). These are subsequently being used to dynamically update the distortion correction and ensure proper correction even under temporally varying magnetic field conditions, i.e. during subject motion or breathing. These methods have been tested at 3T and 7T. Further development and evaluation is ongoing to implement these challenging methods into a routine workflow for broader application.
Publications
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“Verfahren zur dynamischen Erfassung und Veränderung der Magnetfeldverteilung bei Messungen der Magnetresonanz (NMR)“ DE-Patent DE 10 2004 038 917; EU-Patent EP 1630568
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Rapid Eddy Current Calibration and Prospective Distortion Correction Methods for Diffusion-Weighted MRI. Proc 13th ISMRM, Miami, USA: 502 (2005)
M. Zaitsev, J. Hennig, O. Speck
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"Automated Correction of EPI Geometric Distortions Applied to Diffusion Tensor Imaging"; Proc. 14th ISMRM, Seattle, USA: 1024 (2006)
M. Zaitsev, J. Hennig, K. A. Il'yasov
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Prospective real-time slice-by-slice motion correction for fMRI in freely moving subjects. Magn. Reson. Mater Phy. 19(2): 55-61 (2006)
O. Speck, J. Hennig and M. Zaitsev
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“Method for dynamic detection and change in the magnetic field distribution in magnetic resonance (NMR) measurements” US-Patent US 2006/0033494
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High-Resolution Single-Shot EPI at 7T. Magn. Reson. Mater Phy. 21(1-2): 73-86 (2008)
O. Speck, J. Stadler, M. Zaitsev
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On dephasing effects in complex projection data: Implications for rapid B0 estimation. Proc. 17th ISMRM, Honolulu, USA: 2792 (2009)
D. N. Splitthoff and M. Zaitsev
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Direct magnetic field estimation based on echo planar raw data. IEEE Trans Med Imaging. Jul; 29(7):1401-11 (2010)
F. Testud, D.N. Splitthoff, O. Speck, J. Hennig, M. Zaitsev
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Robust method for EPI ghost correction. Proc 18th ISMRM, Stockholm, Sweden: 5057 (2010)
F. Godenschweger, M-H In, O. Speck
