Variability of myocardial perfusion dark rim Gibbs artifacts due to sub-pixel shifts
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BioMed Central
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Variability of myocardial perfusion dark rim Gibbs artifacts due to sub-pixel shifts Pedro Ferreira*1, Peter Gatehouse1,2, Peter Kellman3, Chiara BucciarelliDucci1,2 and David Firmin1,2 Address: 1National Heart and Lung Institute, Imperial College, London, UK, 2Royal Brompton Hospital, London, UK and 3National Institutes of Health, Bethesda, MD, USA Email: Pedro Ferreira* - [email protected]; Peter Gatehouse - [email protected]; Peter Kellman - [email protected]; Chiara Bucciarelli-Ducci - [email protected]; David Firmin - [email protected] * Corresponding author
Published: 27 May 2009 Journal of Cardiovascular Magnetic Resonance 2009, 11:17
doi:10.1186/1532-429X-11-17
Received: 9 December 2008 Accepted: 27 May 2009
This article is available from: http://www.jcmr-online.com/content/11/1/17 © 2009 Ferreira et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract Background: Gibbs ringing has been shown as a possible source of dark rim artifacts in myocardial perfusion studies. This type of artifact is usually described as transient, lasting a few heart beats, and localised in random segments of the myocardial wall. Dark rim artifacts are known to be unpredictably variable. This article aims to illustrate that a sub-pixel shift, i.e. a small displacement of the pixels with respect to the endocardial border, can result in different Gibbs ringing and hence different artifacts. Therefore a hypothesis for one cause of dark rim artifact variability is given based on the sub-pixel position of the endocardial border. This article also demonstrates the consequences for Gibbs artifacts when two different methods of image interpolation are applied (post-FFT interpolation, and pre-FFT zero-filling). Results: Sub-pixel shifting of in vivo perfusion studies was shown to change the appearance of Gibbs artifacts. This effect was visible in the original uninterpolated images, and in the post-FFT interpolated images. The same shifted data interpolated by pre-FFT zero-filling exhibited much less variability in the Gibbs artifact. The in vivo findings were confirmed by phantom imaging and numerical simulations. Conclusion: Unless pre-FFT zero-filling interpolation is performed, Gibbs artifacts are very dependent on the position of the subendocardial wall within the pixel. By introducing sub-pixel shifts relative to the endocardial border, some of the variability of the dark rim artifacts in different myocardial segments, in different patients and from frame to frame during first-pass perfusion due to cardiac and respiratory motion can be explained. Image interpolation by zero-filling can be used to minimize this dependency.
Background Myocardial perfusion imaging with magnetic resonance, combined
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