In microsurgery, it is always difficult to accurately identify the blood supply with ease, such as vascular anastomosis, digit replantation, skin avulsion reconstruction and flap transplantation. Near-infrared window I (NIR-I, 700—900 nm) imaging has many clinical applications, whereas near-infrared window II (NIR-II, 1,000–1700 nm) imaging has emerged as a highly promising novel optical imaging modality and used in a few clinical fields recently, especially its penetration distance and noninvasive characteristics coincide with the needs of microsurgery. Therefore, a portable NIR-II imaging instrument and the Food and Drug Administration (FDA) approved indocyanine green (ICG) were used to improve the operation efficiency in microsurgery of 39 patients in this study. The anastomotic vessels and the salvaged distal limbs were clearly visualized after intravenous injection of ICG. The technique enabled identification of perforator vessels and estimation of perforator areas prior to the flap obtention and made it easier to monitor the prognosis. Overall, this study highlights the use of the portable NIR- II imaging with ICG as an operative evaluation tool can enhance the safety and accuracy of microsurgery.
The second near‐infrared biological window two (NIR‐II, 1000–1700 nm) imaging has made remarkable achievements in fluorescence imaging of diseases. Here, this work takes advantage of the rich spectral properties of rare‐earth doped nanoparticles (RENPs) and their capability to present multiple emission peaks in different luminescence regions simultaneously; novel RENPs are synthesized that have emission peaks in the NIR‐II1000nm (1000–1300 nm) region and enhanced emission in the NIR‐IIb (1500–1700 nm) window and are named as NEU‐RENPs. These RENPs with new compositions enable a fair comparison to evaluate their imaging performance in NIR‐II1000nm and NIR‐IIb regions under the same conditions. The imaging abilities of the resulted nanoparticles in NIR‐II1000 nm and NIR‐IIb regions are investigated systematically for local blood vessels, tumor vessels, acute inflammatory vessels, arterial thrombosis, cerebrovascular inflammation, and brain injury models. The results indicate that imaging of NIR‐IIb shows higher resolution and sensitivity than that of NIR‐II1000nm, and it has a stronger ability to accurately distinguish normal and pathological tissues. Interestingly, the fuzzy image of NIR‐II1000nm reveals more information about the background structure of the target, which is difficult to be achieved in NIR‐IIb imaging. The results prove NEU‐RENPs based NIR‐IIb imaging is preferable for biomedical applications.
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