Spectral strain rate imaging

This paper presents estimators for spectral strain rate display. The estimators were tested on ultrasonic radio-frequency (RF) data acquired at a frame rate of 323 Hz from the beating heart of a healthy volunteer. The strain rate spectrum from a region of interest was calculated using circular convolution of velocity spectra, or equivalently, Fourier transform of products of RF data packets. An extended method combining several frequency scaled spectra was also implemented. Both processing methods produced strain rate spectrograms which compared well with the conventional strain rate. In some time frames, the strain rate spectrum showed a broad bandwidth, indicating a poor signal.