Towards high frame rate cardiac ultrasonography - a circular wave imaging approach

Analysis and quantification of both intracardiac blood flow and myocardial motion by Doppler ultrasound (US) are of major interest to early detect heart failure. Furthermore these medical examinations are becoming part of daily clinical setups. Although noninvasive measures are yielded by conventional US Doppler, these are incomplete since only the velocity components along the US beam direction are captured. In addition, because one usually needs to cover a large sector in cardiac imaging, frame rates (typically <; 50 fps) offered by standard focused US are generally too low to fully describe the intracavitary blood flow and tissue motion. For the same last reason, alternate techniques such as speckle tracking and/or echo-PIV (particle image velocimetry) are also currently limited by a reduced frame rate. The objective of this in vitro study was to demonstrate the capability of ultrafast circular wave imaging to provide accurate time-resolved vector flow mapping over a wide deep sector scan. Circular wave imaging was chosen in the context of potential cardiac applications, where wide regions of interest (ROI) are required but only small intercostal acoustic windows are available.