Astronomy derived techniques for super-resolution contrast ultrasound imaging

Contrast enhanced ultrasound provides various advantages when used to image blood perfusion in organs. Ultrasound contrast agents are gas-filled capsulated micro-spheres small enough to go through micro-circulations in human bodies. Imaging of such microbubbles once injected in the body and imaging of the stars present more similarities than one would initially think. Image sharpness is a simple metric of image quality, widely used in astronomy in the past, whose main characteristic is that it takes higher values for in-focus images. This metric combined with the use of a small microscope attachment called diffraction grating, and a maximum-likelihood algorithm has been adopted in biological microscopy, achieving nano-metric depth resolution when tracking the position of small particles. After having taken into consideration all the analogies between optics and acoustics, a similar kind of processing has been done with ultrasound data. First simulated and experimental results demonstrate that this optical method could be translated into ultrasound imaging providing a resolution of almost two orders of magnitude higher that the diffraction limited one. The optical technique will be presented and all the necessary adjustments for the translation to acoustics will be explained in detail.