Optical Imaging in the Second Near Infrared Window for Vascular Bioimaging

Abstract Optical imaging in the second near infrared region (NIR‐II, 1000–1700 nm) provides higher resolution and deeper penetration depth for accurate and real‐time vascular anatomy, blood dynamics, and function information, effectively contributing to the early diagnosis and curative effect assessment of vascular anomalies. Currently, NIR‐II optical imaging demonstrates encouraging results including long‐term monitoring of vascular injury and regeneration, real‐time feedback of blood perfusion, tracking of lymphatic metastases, and imaging‐guided surgery. This review summarizes the latest progresses of NIR‐II optical imaging for angiography including fluorescence imaging, photoacoustic (PA) imaging, and optical coherence tomography (OCT). The development of current NIR‐II fluorescence, PA, and OCT probes (i.e., single‐walled carbon nanotubes, quantum dots, rare earth doped nanoparticles, noble metal‐based nanostructures, organic dye‐based probes, and semiconductor polymer nanoparticles), highlighting probe optimization regarding high brightness, longwave emission, and biocompatibility through chemical modification or nanotechnology, is first introduced. The application of NIR‐II probes in angiography based on the classification of peripheral vascular, cerebrovascular, tumor vessel, and cardiovascular, is then reviewed. Major challenges and opportunities in the NIR‐II optical imaging for vascular imaging are finally discussed.