Document Detail


In vivo study of myocardial elastography under graded ischemia conditions.
MedLine Citation:
PMID:  21285479     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The capability of currently available echocardiography-based strain estimation techniques to fully map myocardial abnormality at early stages of myocardial ischemia is yet to be investigated. In this study, myocardial elastography (ME), a radio-frequency (RF)-based strain imaging technique that maps the full 2D transmural angle-independent strain tensor in standard echocardiographic views at both high spatial and temporal resolution is presented. The objectives were to (1) evaluate the performance of ME on mapping the onset, extent and progression of myocardial ischemia at graded coronary constriction levels (from partial to complete coronary flow reduction), and (2) validate the accuracy of the strain estimates against sonomicrometry (SM) measurements. A non-survival canine ischemic model (n = 5) was performed by gradually constricting the left anterior descending (LAD) coronary blood flow from 0% (baseline blood flow) to 100% (zero blood flow) at 20% increments. An open-architecture ultrasound system was used to acquire RF echocardiograms in a standard full short-axis view at the frame rate of 211 fps, at least twice higher than what is typically used in conventional echocardiographic systems, using a previously developed, fully automated composite technique. Myocardial deformation was estimated by ME and validated against sonomicrometry. ME estimates and maps transmural (1) 2D displacements using RF cross-correlation and recorrelation; and (2) 2D polar (radial and circumferential) strains, derived from 2D (i.e. both lateral and axial) displacement components, at high accuracy. Full-view strain images were shown and found to reliably depict decreased myocardial function in the region at risk at increased levels of coronary flow reduction. The ME radial strain was deemed to be a more sensitive, quantitative, regional measure of myocardial ischemia as a result of coronary flow reduction when compared to the conventional wall motion score index and ejection fraction. Good agreement (0.22% strain bias, 95% limits of agreement) using Bland-Altman analysis and good correlation (r = 0.84) were found between the ME and SM measurements. These findings demonstrate for the first time that ME could map angle-independent strains to non-invasively detect, localize and characterize the early onset of myocardial ischemia, i.e. at 40%, and possibly as low as 20%, LAD flow reduction, which could be further associated with the severity of coronary stenosis.
Authors:
Wei-Ning Lee; Jean Provost; Kana Fujikura; Jie Wang; Elisa E Konofagou
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2011-02-01
Journal Detail:
Title:  Physics in medicine and biology     Volume:  56     ISSN:  1361-6560     ISO Abbreviation:  Phys Med Biol     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-02-02     Completed Date:  2011-05-19     Revised Date:  2014-09-15    
Medline Journal Info:
Nlm Unique ID:  0401220     Medline TA:  Phys Med Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1155-72     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Coronary Circulation
Dogs
Echocardiography / methods*
Elasticity Imaging Techniques / methods*
Heart / physiopathology
Image Processing, Computer-Assisted
Male
Movement
Myocardial Ischemia / physiopathology*,  ultrasonography*
Reproducibility of Results
Stress, Physiological
Stroke Volume
Grant Support
ID/Acronym/Agency:
R01 EB006042/EB/NIBIB NIH HHS; R01 EB006042-03/EB/NIBIB NIH HHS; R01 EB006042-04A1/EB/NIBIB NIH HHS; R01EB006042/EB/NIBIB NIH HHS
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