Ultrasonic elastography in cardiological applications

Aim of project
The aim of this project is to elaborate an automated method for estimation of elastic properties of the cardiac muscle. Development and verification of algorithms enabling to depict internal tissue structure deformation (Strain Imaging SI) and deformation velocity (Strain Rate Imaging, SRI) are envisaged. Both these quantities are related to the contractility of the cardiac muscle and carry important diagnostic information. To solve the problem, the internal tissue displacement estimation on the basis of the sequence of ultrasonic RF or baseband images is proposed, followed by the calculation of the deformation. This is a different approach from the one currently implemented in cardiology, which consists in calculation of SVI images as the spatial gradient of tissue velocity (Tissue Velocity Imaging TVI). However, gradient operator is very sensitive to noise and the result of its application has considerable variance. Moreover, the approach currently applied uses TVI data segments of the size of 5÷10 mm, which leads to averaging the results and reduction of the spatial resolution of SVI images.

As part of the development of the proposed methodology, cardiac phantom studies and in vivo examinations are planned. Application of one-dimensional estimation of deformation is proposed, using the SAD method (Sum of Absolute Differences) and methods based on cross-correlation.

Areas subjected to deformation tracking will be selected by segmentation. Application of standard echocardiographic projections is envisaged.

Expected results
An automated method for imaging of deformation/ deformation velocity appearing in the myocardial muscle is the basic expected result of the project. The results of the project will be published and used in a Ph.D. dissertation.