Advancing in-vivo brain vasculature imaging: Super-resolution 3D ultrasound localization microscopy of the mouse brain and in non-human primate using RCA probes

3D ultrasound localization microscopy (3D-ULM) allows in vivo quantification of blood vessel velocities in the mouse brain using matrix arrays, but it requires complex electronics, and the field of view remains limited [1]. Here, we investigate how low channel count Row-Column Addressing (RCA) probes allow 3D-ULM to be performed in the whole mouse brain non-invasively and in the visual cortex of a non-human primate after craniotomy.An IcoPrime 4D-RCA probe (80+80 elements, 15 MHz, pitch 0.11 mm, Iconeus) was driven by an Iconeus One scanner. For the mouse experiment, the probe was mounted on a 4-axis motor stage, and we used a sequence of 14+14 plane waves transmitted at 28 kHz for 0.5 s (400 repetitions at 1 Hz). Contrast agent (Sonovue) was injected in three boluses of 80 µL each. For the non-human primate experiment, the probe was mounted on an articulated arm, and we used 12+12 plane waves transmitted at 20 kHz for 0.4s (200 repetitions at 0.5 Hz) while maintaining a continuous perfusion of Sonovue. XDoppler beamforming [2], microbubble localization and tracking were applied to the two resulting radiofrequency datasets.Vascular skeletons were estimated and filtered using graph analysis tools [3]. Per-region segment features such as segment radius, length, velocity, and flowrate were extracted thanks to Allen-based registration (mouse) or manual segmentation (primate).Our results demonstrate that RCA is an efficient way to perform large field-of-view 3D ULM with reduced complexity, enabling in-vivo cerebral blood flow quantification at microscopic level, and could be extended to other models.