Online Journal
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Journal of Medical Ultrasonics

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2007 - Vol.34

Vol.34 No.04

Original Article(原著)

(0439 - 0448)


Imaging of transient in myocardial contraction and relaxation by measuring strain rate at high temporal resolution

吉新 寛樹1, 長谷川 英之1, 金井 浩1, 田中 元直2

Hiroki YOSHIARA1, Hideyuki HASEGAWA1, Hiroshi KANAI1, Motonao TANAKA2

1東北大学大学院工学研究科電子工学専攻, 2東北厚生年金病院

1Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, 2Tohoku Welfare Pension Hospital

キーワード : myocardial contraction/relaxation, strain rate, phased tracking method, frame rate, <I>in vivo</I> experiments


Purpose: Strain and strain rate imaging have been shown to be useful for assessment of regional myocardial function. However, the mechanism of transition in myocardial contraction and relaxation remains unclear. In this study, we investigated the mechanism by measuring myocardial strain rate at high temporal resolution. Method: The RF data of two young males were acquired in a typical cross-sectional image (the transthoracic parasternal longitudinal-axis view) by scanning ultrasonic beams sparsely to improve temporal resolution. In the periods around the R-wave in electrocardiogram (ECG) and the second heart sound in phonocardiogram (PCG), the phased tracking method was applied to multiple points in the heart wall for estimation of the strain rate. Result: In the case of transition from contraction to relaxation around the second heart sound, the right ventricle (RV) side preceded the left ventricle (LV) side by 15-30 ms in the interventricular septum (IVS), and the epicardium preceded the endocardium by 100-130 ms in the posterior wall. Furthermore, the spatial distribution of strain rate showed that there was a time lag between the apex side and base side in contraction and relaxation. In particular, transition from the apex side to base side was found in the posterior wall. Conclusion: Myocardial strain rate was measured at high temporal resolution. In vivo experimental results showed the possibility of using this method for elucidation of the mechanism in myocardial contraction and relaxation.