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WE-E-134-09: Evaluation of the Performance of Cardiac Displacement and Strain Imaging Using Radiofrequency and Envelope Signals.

PURPOSE
Echocardiographic strain imaging is a promising method for detecting deformation of cardiac muscle. In addition to fidelity to the underlying deformation, high spatial and temporal resolution are required for accurate analysis of regional myocardial function. However, all current clinical approaches use speckle-tracking algorithms applied to B-mode images derived from envelope signals. Such approaches are inherently of lower spatial resolution, since they require larger data blocks for deformation tracking due to the absence of phase information.


METHODS
In this study, we evaluate the performance of local strain estimators using B-mode, envelope and radiofrequency signals, utilizing data acquired from a uniformly elastic tissue mimicking phantom, 3D cardiac simulation, and clinical data on a healthy volunteer.


RESULTS
Signal-to-noise ratio improvements using radiofrequency signals for linear and phased array geometries were 5.80 dB and 9.48 dB over that obtained with envelope signals (at peak strain) in phantom studies. Cardiac simulation studies over two cardiac cycles, indicate that the standard deviation of estimated strain using envelope signals from two of the six segments for a short-axis view (anterior and anterolateral) were 48% and 44% higher than that obtained using radiofrequency signals. In a similar manner, analysis on a healthy volunteer also indicate that the standard deviation of the estimated strain using B-mode and envelope signals were 16% and 42% higher than that obtained using radiofrequency signals in the anteroseptal segment, and 45% and 27% in the anterior segment.


CONCLUSION
These results show the significant reduction in the variability of the strain estimated as well as improvements in the spatial resolution and signal-to-noise ratios obtained using radiofrequency signals.