OCT-PAM dual-mode imaging to evaluate early ischemic stroke in rats

Early diagnosis of ischemic stroke is crucial for timely intervention and saving brain function. The mechanisms of stroke are complex, involving multiple parameters such as blood flow perfusion, tissue status, and oxygenation levels. These parameters interact with each other, necessitating multiple systems to evaluate. The animal model must be moved among systems for various systems monitoring, which complicates the operation and may induce additional interference. Here, we propose a non-contact all-optic OCT-PAM dual-mode imaging system for monitoring rat cortex states. The compact probe enables facilitating long-term multi-parameter observation. Using the system, we quantitatively monitored the state of the rat cortex of ischemic stroke during the acute phase, including blood perfusion density, vessel diameter, vessel length, optical attenuation coefficient, and photoacoustic absorption. We observed reduced perfusion in the affected cortex, contralateral perfusion increases, and vasodilation, suggesting collateral circulation activation. Additionally, increased optical attenuation and photoacoustic absorption in the stroke area were linked to blood-brain barrier changes. This OCT-PAM system and its quantitative analysis method offer a promising tool for early ischemic stroke diagnosis and exploring underlying molecular and cellular mechanisms.