The research progress of label-free optical imaging technology in intraoperative real-time navigation of parathyroid glands.

Intraoperative misidentification or vascular injury to the parathyroid glands can lead to hypoparathyroidism and hypocalcemia, resulting in serious postoperative complications. Therefore, functional localization of the parathyroid glands during thyroid (parathyroid) surgery is a key focus and challenge in thyroid surgery. The current clinical prospects of various optical imaging technologies for intraoperative localization, identification, and protection of parathyroid glands varies. However, "Label-free optical imaging technology" is increasingly favored by surgeons due to its simplicity, efficiency, safety, real-time capability, and non-invasiveness. This manuscript focuses on the relatively well-researched near-infrared autofluorescence (NIRAF) and NIRAF-combined studies including those integrating laser speckle imaging, artificial intelligence(AI) optimization, hardware integration, and optical path improvements. It also briefly introduces promising technologies, including Laser-Induced Fluorescence (LIF), Hyperspectral Imaging (HSI), Fluorescence Lifetime Imaging (FLIm), Laser-Induced Breakdown Spectroscopy (LIBS), Optical Coherence Tomography (OCT), and Dynamic Optical Contrast Imaging (DOCI). While these technologies are still in early stages with limited clinical application and standardization, current research highlights their potential for improving intraoperative parathyroid identification. Future studies should focus on refining these methods for broader clinical use.