Inter-subject registration and application of the SIGMA rat brain atlas for regional labeling in functional ultrasound imaging.

Background: Recent advances using functional ultrasound (fUS) imaging have opened new avenues to evaluate brain activity through the regional monitoring of cerebral blood volume (CBV) dynamics. In particular, this technology paves the way for understanding physiological or pathological cerebral processes or exploring the pharmacological profiles of new drugs targeting brain disorders. One of the main difficulties of this technology is the lack of standardized and validated tools, in particular relevant brain atlases, to help improving the accuracy, automation and reproducibility of fUS data analysis.

New Method: Here, we demonstrate the possibility to use the MRI-validated SIGMA brain atlas in rat to perform fast and precise analysis of CBV changes in numerous functionally relevant regions of interest using fUS imaging. We applied this atlas to a dataset obtained in anesthetized rats evaluating the cerebral effects of atomoxetine, a norepinephrine reuptake inhibitor currently marketed in attention-deficit/hyperactivity-disorder.

Results: This approach enabled to show the subregional effects of atomoxetine in the rat with very few inter-individual differences in some areas, such as the dentate gyrus.

Conclusions: We show the feasibility of inter-individual registration of 2D pharmaco-fUS data and subsequent detailed analysis using the SIGMA atlas.