Objective: The blood-brain barrier (BBB), a vital physiological boundary, is typically considered to be evenly distributed within the central nervous system (CNS). However, our investigation uncovered an intriguing finding: isoflurane (ISO) can induce spatial heterogeneity in BBB permeability. Notably, the type and dosage of inhaled anesthetics significantly affect both the permeability and the spatial heterogeneity of the BBB.

Methods: Conventional BBB evaluation relies on the classic Evans Blue assay with brain tissue in vitro. However, due to limitations in metabolic pathway visualization, monitoring drug metabolism in clinical settings remains challenging. Photoacoustic imaging, a hybrid technique based on the photoacoustic effect, has gained prominence in recent years. It offers several advantages, including rich optical contrast, high ultrasound spatial resolution, and deep tissue penetration. Furthermore, photoacoustic imaging combines the benefits of both tissue imaging and metabolic imaging.

Results and Discussions: This study proposed the use of photoacoustic imaging to monitor the effects of various anesthetic drugs on the central nervous system. By employing photoacoustic computed tomography (PACT) and focused scanning photoacoustic microscopy (PAM), the study visualized key physiological parameters such as drug metabolism and blood-brain barrier integrity in a nondestructive and real-time manner. The findings revealed that sevoflurane, desflurane, and isoflurane have distinct effects on the integrity of the local or overall BBB at equivalent anesthetic doses. These effects were visualized using both photoacoustic and fluorescence imaging techniques.

Conclusions: This finding provides a novel perspective on the spatial distribution characteristics of the BBB and paves the way for future exploration into the therapeutic applications of drugs targeting the central nervous system.