Imaging two-dimensional tissue form factor in Synthetic Transmit Aperture ultrasound imaging

<p dir="ltr">Tissue microstructure reflects its physiological and pathological state. It can be described by the form factor—the Fourier transform of the autocorrelation function of density and sound-speed fluctuations in the medium. This paper derived an equation relating a system-independent local 2D form factor of a region of interest (ROI) to the 2D power spectrum of the ROI's ultrasound image in Synthetic Transmit Aperture Ultrasound Imaging. We then validated the equation using Field II simulations. After that, we demonstrated that the directivity of a medium can be inferred from the 2D spectra of ultrasound images, using both simulation and experimental data. </p>