Application of photoacoustic imaging in tumor diagnosis and surgical treatment.

Photoacoustic imaging (PAI) is an emerging hybrid modality that combines high-contrast optical imaging with high-resolution ultrasound imaging, offering significant potential for tumor diagnosis and surgical guidance. This review provides a concise and focused overview of the principles, technological advancements, and clinical applications of PAI in oncology. We begin by introducing the basic mechanism of PAI, including the photoacoustic effect and the differentiation between the NIR-I and NIR-II imaging windows. The review then systematically examines the role of PAI in preoperative tumor characterization, intraoperative margin assessment, and vascular involvement detection. Emphasis is placed on how PAI enables label-free, real-time visualization of tumor microenvironments, including hemoglobin distribution, oxygen saturation, and nuclear morphology. Key technological innovations, such as multispectral optoacoustic tomography (MSOT) and optical-resolution photoacoustic microscopy (OR-PAM), are discussed with a focus on their inherent depth-resolution trade-offs. We also highlight recent advances in exogenous contrast agents and their potential for molecular imaging. critically evaluating their stability, toxicity, and translational hurdles. By synthesizing current evidence and directly addressing key technical and clinical limitations-including penetration depth, laser safety, reconstruction artifacts, and lack of standardization-this review provides a comprehensive and critical evaluation of PAI's capabilities, limitations, and future directions in tumor diagnosis and surgical treatment.