Sono-activated ultrasound localization microscopy

Scanned at very high ultrasound frame rates, injectable microbubbles can be activated sequentially as isolated punctual sources of acoustic echoes. These signals can thus be localized far beyond the diffraction limit. The resolution improvement granted by Sono-Activated Ultrasound Localization Microscopy (SAULM) was demonstrated within microfluidic channels 20 times smaller than the imaging wavelength (λ = 870 μm). The width of the channels mapped with SAULM was 13 times smaller than as they appeared under conventional ultrasound imaging. Two channels separated by λ/4.5 could be distinguished. Implementing SAULM in-vivo could lead to a complete reconstruction of the vascular tree down to the smallest capillaries at several centimeter depth.