Advances in assessment methods of lymphatic drainage function

The assessment of lymphatic drainage function is essential for understanding the role of the lymphatic system in fluid homeostasis, immunosurveillance and disease processes. Conventional methods of evaluation rely on dynamic visualization with tracers, such as X-ray lymphangiography, lymphoscintigraphy and magnetic resonance lymphangiography. However, these methods have limitations in terms of invasiveness and resolution, and other aspects. Recent advances in optical technologies and nanomaterials technology have enabled the development of noninvasive, high-precision testing methods, such as photoacoustic imaging and optical coherence tomography, which have made it possible to visualize and analyze lymphatic flow rates, tracer clearance rates and functional abnormalities. In addition, the application of artificial intelligence-assisted analysis, multimodal imaging, and targeted nanoprobes has significantly improved the precision and clinical applicability of these methods. In this article, we systematically review the principles, characteristics, clinical applications and preclinical research progress of nine classical or novel lymphatic drainage function testing techniques. We also discuss the advantages and limitations of each technique and explore the future development trend, aiming to provide insights for basic research and clinical practice.