Volumetric ultrasound localization microscopy of the whole brain microvasculature

Abstract Technologies to visualize whole organs across scales in vivo are essential for our understanding of biology in health and disease. To date, only post-mortem techniques achieve cellular resolution across entire organs. 2D ultrasound localization microscopy (ULM) suffers from reprojection issues and out-of-plane motion preventing complex blood flow quantification and fast volumetric imaging. Here, we demonstrate for the first time in vivo volumetric ULM. We developed a complete methodological pipeline including a dedicated 3D acquisition sequence, localization, tracking, motion correction and realignment algorithms, as well as post-processing quantification of cerebral blood flow. We illustrate the power of this approach, by revealing the whole rat brain vasculature at a resolution of 12 μm, and cerebral blood flows ranging from 1 to 120 mm/s. Our results pave the way to the investigation of in vivo vascular processes across the mammalian brain in health and disease, in a wide range of contexts and models.