Coherent Ultrasound Scattering in the Young Rhesus Macaque Brain: Effects of Exposure to Anesthetics

We report the characterization of the thalamus of fourteen newborn Rhesus macaques using incoherent and coherent ultrasound scattering. Particularly, we study whether sources of coherent scattering could contribute to variability of estimates of the effective scatterer size, ESS, used to detect neurotoxic effects of anesthesia. This characterization is performed by computing the generalized spectrum, the echo-amplitude signal-to-noise ratio, and the echo phase histogram nonuniformity, and comparing their values to those obtained from a reference material with diffuse scattering conditions. Results show that scattering conditions in the thalamus can be described mostly as originating from a low scatterer number density (38% of data) and the presence of specular reflectors (36%). Only 23 % of the data presented diffuse scattering conditions. Specular reflectors were more likely found in data that showed inconclusive results in a previous ESS analysis of the effects of anesthesia. Future work will be focused on implementing coherent scattering descriptors to characterize the thalamus, as well as developing strategies to reduce the effects of this scattering scenario in the estimation of the ESS.