# Photoacoustics can image spreading depolarization deep in gyrencephalic brain

## TL;DR

This paper demonstrates that photoacoustic imaging can effectively visualize spreading depolarization deep within the complex gyrencephalic brain, offering high-resolution, high-contrast insights into brain injury mechanisms.

## Contribution

It introduces a novel hybrid photoacoustic and ultrasonic imaging method for deep, high-resolution visualization of spreading depolarization in complex brains.

## Key findings

- Photoacoustic imaging can detect SD deep in gyrencephalic brain tissue.
- The method provides high spatiotemporal resolution and contrast.
- It enables new insights into SD mechanisms in brain injury.

## Abstract

Spreading depolarization (SD) is a self-propagating wave of near-complete neuronal depolarization that is abundant in a wide range of neurological conditions, including stroke. SD was only recently documented in humans and is now considered a therapeutic target for brain injury, but the mechanisms related to SD in complex brains are not well understood. While there are numerous approaches to interventional imaging of SD on the exposed brain surface, measuring SD deep in brain is so far only possible with low spatiotemporal resolution and poor contrast. Here, we show that photoacoustic imaging enables the study of SD and its hemodynamics deep in the gyrencephalic brain with high spatiotemporal resolution. As rapid neuronal depolarization causes tissue hypoxia, we achieve this by continuously estimating blood oxygenation with an intraoperative hybrid photoacoustic and ultrasonic (PAUS) imaging system. Due to its high resolution, promising imaging depth and high contrast, this novel approach to SD imaging can yield new insights into SD and thereby lead to advances in stroke, and brain injury research.