Functional and multimodal photoacoustic microscopy for brain mapping and surgery

The noninvasive imaging of a brain has led to significant advances for optical techniques in neurosurgery and brain imaging. Previous study reported hemodynamic brain activity is related with neuronal activity. Photoacoustic microscopy (PAM) can detect hemodynamic activity in blood vessels by exciting red blood cells so neuronal activity can be detected by imaging vessels with PAM. Based on the results, we observed the cortical response to electrical stimulations of mouse’s hindlimbs with our functional photoacoustic microscopy (FPAM) system. Especially, based on a fast-speed imaging capability of our FPAM system, we observed instantaneous changes of hemodynamic brain activity by imaging a mouse brain non-invasively with capillary-level resolution while electrically stimulating the mouse’s hindlimbs. For the future studies, the intraoperative surgical photoacoustic microscopy system can be used to monitor the cortical response to electrical stimulations. By integrating FPAM system with surgical microscopy, we developed an intraoperative surgical photoacoustic microscopy system that provides photoacoustic images and enlarged surface view simultaneously. Additionally, by back projecting the acquired photoacoustic images on the ocular lens of the surgical microscopy, surgeons can see both the enlarged surface view and photoacoustic images simultaneously without moving the sight from the ocular lens. Thus, the developed intraoperative surgical photoacoustic microscopy system can be a vital tool for the microsurgeries and neurosurgeries including monitoring the cortical response to electrical stimulations.