Assessment of myocardial regional strain and strain rate by tissue tracking in B-mode echocardiograms (original) (raw)
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European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology, 2000
The non-invasive quantification of regional myocardial function is an important goal in clinical cardiology. Myocardial thickening/thinning indices is one method of attempting to define regional myocardial function. A new ultrasonic method of quantifying regional deformation has been introduced based on the principles of 'strain' and 'strain rate' imaging. These new imaging modes introduce concepts derived from mechanical engineering which most echocardiographers are not familiar with. In order to maximally exploit these new techniques, an understanding of what they measure is indispensable. This paper will define each of these modalities in terms of physical principles and will give an introduction to the principles of data acquisition and processing required to implement ultrasonic strain and strain rate imaging. In addition, the current status of development of the technique and its limitations will be discussed, together with examples of potential clinical applic...
The Journal of the Acoustical Society of America, 2008
Methods for imaging of strain rate in the heart wall are useful for quantitative evaluation of regional heart function. We developed a method which can accurately measure the heart wall motion along an ultrasonic beam based on phase changes in RF echoes. However, there are some components in the wall motion which are not along each ultrasonic beam. Therefore, the measurement of motion in the direction perpendicular (lateral) to the beam has been required in addition to that in the axial direction. However some unsolved problems remain in estimation of the distribution of lateral motion of the wall. In this study, two-dimensional displacement was estimated by 2-D cross-correlation between RF echoes. Important parameters, the sizes of a region-of-interest and search region, which determine tracking accuracy, were adaptively optimized by referring to instantaneous wall velocities, in the respective cardiac phases. The correlation coefficient between the lateral displacement estimated by the 2-D tracking with optimized parameters in longitudinal-axis view and in apical view (corresponding to lateral displacement in longitudinal-axis view) separately and accurately estimated by the 1-D phase-based method was 0.93. These results show possibility of this method for accurate measurement of twodimensional heart motion to assess the regional myocardial strain rate.
We present a new method for measuring global longitudinal strain and global longitudinal strain rate from 2D echocardiograms using a logarithmic-transform correlation (LTC) method. Traditional echocardiography strain analysis depends on user inputs and chamber segmentation, which yield increased measurement variability. In contrast, our approach is automated and does not require cardiac chamber segmentation and regularization, thus eliminating these issues. The algorithm was benchmarked against two conventional strain analysis methods using synthetic left ventricle ultrasound images. Measurement error was assessed as a function of contrast-to-noise ratio (CNR) using mean absolute error and root-mean-square error. LTC showed better agreement to the ground truth for strain (πΉπ = π. π1) and strain rate (πΉπ = π. 85) as compared to conventional algorithms (strain (πΉπ = π. 07), strain rate (πΉπ = π. 07)) and was unaffected by CNR. A 200% increase in strain measurement accuracy was observed...
Journal of the American Society of Echocardiography, 2004
We sought to assess the feasibility of 2-dimensional strain, a novel software for real-time quantitative echocardiographic assessment of myocardial function. Methods: Conventional and a novel non-Dopplerbased echocardiography technique for advanced wall-motion analysis were performed in 20 patients with myocardial infarction and 10 healthy volunteers from the apical views. Two-dimensional strain is on the basis of the estimation that a discrete set of tissue velocities are present per each of many small elements on the ultrasound image. This software permits real-time assessment of myocardial velocities, strain, and strain rate. These parameters were also compared with Doppler tissue imaging measurements in 10 additional patients.
2006
One-dimensional strain imaging has been shown to be angle dependent. To address this problem, a new methodology, 2D-strain, has become available. The aim of this study was to validate this methodology in an in vivo set-up against sonomicrometry. In five open chest sheep, ultrasound gray-scale images were acquired of the inferolateral wall from two different angles. The longitudinal and radial strain components were simultaneously extracted using the novel 2D-strain methodology. The extracted values were compared with sonomicrometry using Bland-Altman statistics and correlation coefficients. A good agreement was found for the longitudinal strain component, while, for the radial strain estimates, the accuracy was less. 2D-strain is a fast and accurate tool to assess longitudinal strain from apical views. Further improvements are needed for the method to be sufficiently accurate in estimating the deformation perpendicular or close to perpendicular to the ultrasound beam. (E-mail: stian.langeland@uz.kuleuven.be)
2008 IEEE Ultrasonics Symposium, 2008
Methods for imaging of strain rate in the heart wall are useful techniques for the quantitative evaluation of regional myocardial function. However, a mechanism of the transitions between myocardial contraction and relaxation is unclear. Except for a method based on ECG triggering, a required high temporal resolution was realized by scanning the heart wall sparsely at the expense of the lateral spatial resolution. Therefore, the spatial resolution in measurement of the transition of myocardial contraction / relaxation in the lateral direction have been limited. In this study, the RF data was acquired in a typical cross-sectional view (interventricular septum (IVS) longitudinal-axis view) based on parallel beam forming (PBF). A wide transmitted beam scanned 7 different directions sparsely and 16 receiving beams were created in each transmit. The typical cross-sectional image was realized to obtain with high spatial (the angle between neighbor beams was 0.375 degree) and temporal (the frame rate (FR) was 1020 Hz) resolution. In addition, the strain rate was obtained by spatial differentiation of the velocity distribution along the ultrasonic beam using the phased tracking method applied to multiple points in the heart wall. Slight spatial transition of contraction / relaxation in the axial and lateral directions during a very short period less than 10 ms was able to visualized by PBF. On the other hand, the transition in only the axial direction was visualized by sparse scan. Measurement of myocardial strain rate at high temporal and spatial resolutions was achieved using PBF. In vivo experimental results show a possibility of this method for elucidation of the transition of myocardial contraction and relaxation in two dimensions. It is supposed that such transition corresponds to the propagation of myocardial excitation along the conduction system of the heart (from sinoatrial node to Purkinje fibers).