3D transcranial Dynamic Ultrasound Localization Microscopy in the mouse brain using a Row-Column Array

Abstract

The role of brain hemodynamics in neurodegenerative diseases cannot be fully assessed using existing imaging technologies. Recently, 2D Dynamic Ultrasound Localization Microscopy (DULM) has allowed for the quantitative mapping of the pulsatile flow at sub-wavelength resolution. However, to obtain accurate velocity estimates, 3D imaging is more adapted, especially for complex vascularized organs like the brain. 3D+t DULM is achievable using matrix array probes, but suffers from limitations in terms of cost, device complexity associated with the high channel count, and operating frequencies. Alternatively, Row Column Arrays (RCA) can reduce the number of elements while maintaining a large field of view and high frame rate. Herein, we demonstrate the feasibility of performing 3D+t blood flow measurements in the mouse brain using an RCA and a DULM sequence with a high spatiotemporal resolution. Transcranial images of anesthetized mice (n=7) were acquired at a volume rate of 750 Hz using 42 tilted plane waves. After microbubbles localization and tracking, super-resolved dynamic density and velocity maps of the 3D brain vascular network were obtained. Cortical vessels were segmented and pulsatility in the arteries was significantly higher than in veins for all mice, in accordance with the literature. Our results demonstrate the feasibility and reproducibility of achieving high spatiotemporal resolution volumes of the mouse brain vasculature with DULM using a RCA.