Improved Liver R2* Mapping by Averaging Decay Curves

Abstract Liver R2* mapping is often degraded by the low signal-to-noise ratio (SNR) especially in the presence of severe iron. This study aims to improve liver R2* mapping at low SNRs by averaging decay curves before the process of curve-fitting. Independently filtering echo images by nonlocal means...

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Autores principales:	Xinyuan Zhang, Jie Peng, Changqing Wang, Yanqiu Feng, Qianjin Feng, Xinzhong Li, Wufan Chen, Taigang He
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/68ac8403468e4abf9a6056e12f084827
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spelling	oai:doaj.org-article:68ac8403468e4abf9a6056e12f0848272021-12-02T15:06:15ZImproved Liver R2* Mapping by Averaging Decay Curves10.1038/s41598-017-05683-52045-2322https://doaj.org/article/68ac8403468e4abf9a6056e12f0848272017-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-05683-5https://doaj.org/toc/2045-2322Abstract Liver R2* mapping is often degraded by the low signal-to-noise ratio (SNR) especially in the presence of severe iron. This study aims to improve liver R2* mapping at low SNRs by averaging decay curves before the process of curve-fitting. Independently filtering echo images by nonlocal means (NLM) demonstrated improved quality of R2* mapping, but may introduce new errors due to the nonlinear nature of the NLM filter, during which the averaging weights may vary with different image contents at multiple echo times. In addition, the image denoising effect of the NLM may decline when no sufficient similar patches are available. To overcome these drawbacks, we proposed to filter decay curves instead of images. In this novel scheme, decay curves were averaged in a local window, each with a weight assigned according to the curve-similarity measured by the distance between one of the neighboring curves and the targeted one. The proposed method was tested on simulated, phantom and patient data. The results demonstrate that the proposed method can provide more accurate R2* mapping compared with the NLM algorithm, and hence has the potential to improve diagnosis and therapy in patients with liver iron.Xinyuan ZhangJie PengChangqing WangYanqiu FengQianjin FengXinzhong LiWufan ChenTaigang HeNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-11 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Xinyuan Zhang Jie Peng Changqing Wang Yanqiu Feng Qianjin Feng Xinzhong Li Wufan Chen Taigang He Improved Liver R2* Mapping by Averaging Decay Curves
description	Abstract Liver R2* mapping is often degraded by the low signal-to-noise ratio (SNR) especially in the presence of severe iron. This study aims to improve liver R2* mapping at low SNRs by averaging decay curves before the process of curve-fitting. Independently filtering echo images by nonlocal means (NLM) demonstrated improved quality of R2* mapping, but may introduce new errors due to the nonlinear nature of the NLM filter, during which the averaging weights may vary with different image contents at multiple echo times. In addition, the image denoising effect of the NLM may decline when no sufficient similar patches are available. To overcome these drawbacks, we proposed to filter decay curves instead of images. In this novel scheme, decay curves were averaged in a local window, each with a weight assigned according to the curve-similarity measured by the distance between one of the neighboring curves and the targeted one. The proposed method was tested on simulated, phantom and patient data. The results demonstrate that the proposed method can provide more accurate R2* mapping compared with the NLM algorithm, and hence has the potential to improve diagnosis and therapy in patients with liver iron.
format	article
author	Xinyuan Zhang Jie Peng Changqing Wang Yanqiu Feng Qianjin Feng Xinzhong Li Wufan Chen Taigang He
author_facet	Xinyuan Zhang Jie Peng Changqing Wang Yanqiu Feng Qianjin Feng Xinzhong Li Wufan Chen Taigang He
author_sort	Xinyuan Zhang
title	Improved Liver R2* Mapping by Averaging Decay Curves
title_short	Improved Liver R2* Mapping by Averaging Decay Curves
title_full	Improved Liver R2* Mapping by Averaging Decay Curves
title_fullStr	Improved Liver R2* Mapping by Averaging Decay Curves
title_full_unstemmed	Improved Liver R2* Mapping by Averaging Decay Curves
title_sort	improved liver r2* mapping by averaging decay curves
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/68ac8403468e4abf9a6056e12f084827
work_keys_str_mv	AT xinyuanzhang improvedliverr2mappingbyaveragingdecaycurves AT jiepeng improvedliverr2mappingbyaveragingdecaycurves AT changqingwang improvedliverr2mappingbyaveragingdecaycurves AT yanqiufeng improvedliverr2mappingbyaveragingdecaycurves AT qianjinfeng improvedliverr2mappingbyaveragingdecaycurves AT xinzhongli improvedliverr2mappingbyaveragingdecaycurves AT wufanchen improvedliverr2mappingbyaveragingdecaycurves AT taiganghe improvedliverr2mappingbyaveragingdecaycurves
_version_	1718388516844470272

Improved Liver R2* Mapping by Averaging Decay Curves

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