Presented in part at the 15th Annual Meeting of ISMRM, Berlin, Germany, 2007.
Image reconstruction by regularized nonlinear inversion—Joint estimation of coil sensitivities and image content†
Article first published online: 5 AUG 2008
Copyright © 2008 Wiley-Liss, Inc.
Magnetic Resonance in Medicine
Volume 60, Issue 3, pages 674–682, September 2008
How to Cite
Uecker, M., Hohage, T., Block, K. T. and Frahm, J. (2008), Image reconstruction by regularized nonlinear inversion—Joint estimation of coil sensitivities and image content. Magn Reson Med, 60: 674–682. doi: 10.1002/mrm.21691
- Issue published online: 24 AUG 2008
- Article first published online: 5 AUG 2008
- Manuscript Accepted: 22 APR 2008
- Manuscript Revised: 21 APR 2008
- Manuscript Received: 28 SEP 2007
- inverse problems;
- iterative reconstruction;
- parallel imaging;
- nonlinear inversion
The use of parallel imaging for scan time reduction in MRI faces problems with image degradation when using GRAPPA or SENSE for high acceleration factors. Although an inherent loss of SNR in parallel MRI is inevitable due to the reduced measurement time, the sensitivity to image artifacts that result from severe undersampling can be ameliorated by alternative reconstruction methods. While the introduction of GRAPPA and SENSE extended MRI reconstructions from a simple unitary transformation (Fourier transform) to the inversion of an ill-conditioned linear system, the next logical step is the use of a nonlinear inversion. Here, a respective algorithm based on a Newton-type method with appropriate regularization terms is demonstrated to improve the performance of autocalibrating parallel MRI—mainly due to a better estimation of the coil sensitivity profiles. The approach yields images with considerably reduced artifacts for high acceleration factors and/or a low number of reference lines. Magn Reson Med, 2008. © 2008 Wiley-Liss, Inc.