Higher order reconstruction for MRI in the presence of spatiotemporal field perturbations

Despite continuous hardware advances, MRI is frequently subject to field perturbations that are of higher than first order in space and thus violate the traditional k‐space picture of spatial encoding. Sources of higher order perturbations include eddy currents, concomitant fields, thermal drifts, a...

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Vydáno v:Magnetic resonance in medicine Ročník 65; číslo 6; s. 1690 - 1701
Hlavní autoři: Wilm, Bertram J., Barmet, Christoph, Pavan, Matteo, Pruessmann, Klaas P.
Médium: Journal Article
Jazyk:angličtina
Vydáno: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.06.2011
Témata:
algebraic image reconstruction
Algorithms
Brain Mapping - methods
diffusion imaging
DTI
Echo-Planar Imaging
Eddy current correction
Feasibility Studies
Humans
Image Processing, Computer-Assisted - methods
magnetic field monitoring
Magnetic Resonance Imaging - instrumentation
Magnetic Resonance Imaging - methods
Phantoms, Imaging
ISSN:0740-3194, 1522-2594, 1522-2594
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Popis
Shrnutí:Despite continuous hardware advances, MRI is frequently subject to field perturbations that are of higher than first order in space and thus violate the traditional k‐space picture of spatial encoding. Sources of higher order perturbations include eddy currents, concomitant fields, thermal drifts, and imperfections of higher order shim systems. In conventional MRI with Fourier reconstruction, they give rise to geometric distortions, blurring, artifacts, and error in quantitative data. This work describes an alternative approach in which the entire field evolution, including higher order effects, is accounted for by viewing image reconstruction as a generic inverse problem. The relevant field evolutions are measured with a third‐order NMR field camera. Algebraic reconstruction is then formulated such as to jointly minimize artifacts and noise in the resulting image. It is solved by an iterative conjugate‐gradient algorithm that uses explicit matrix‐vector multiplication to accommodate arbitrary net encoding. The feasibility and benefits of this approach are demonstrated by examples of diffusion imaging. In a phantom study, it is shown that higher order reconstruction largely overcomes variable image distortions that diffusion gradients induce in EPI data. In vivo experiments then demonstrate that the resulting geometric consistency permits straightforward tensor analysis without coregistration. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Bibliografie:ArticleID:MRM22767
istex:0F2D5F3F86A424474A03188E149BB869AD7C1823
Philips Healthcare
ark:/67375/WNG-4H89VRMC-M
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:0740-3194
1522-2594
1522-2594
DOI:10.1002/mrm.22767