NIR-II Fluorescence Imaging Using Indocyanine Green Provides Early Prediction of Skin Avulsion-Injury in a Porcine Model

Abstract

Purpose Currently, skin avulsion–injury reconstruction is mainly based on subjective evaluation of traditional clinical signs. It frequently results in unnecessary tissue loss and incomplete debridement-related infection. This pilot study aimed to develop a novel near-infrared (NIR) II fluorescence imaging method to assess avulsed skin–perfusion status and thus predict its outcome early. Methods Skin avulsion–injury models were established by avulsing 10×4 cm pedicled flaps on porcine hindlimbs. A clinically available improved NIR-Ι/II multispectral imaging system was applied for NIR imaging using indocyanine green (ICG) fluorescence. Continuous NIR-wavelength filters and dynamic imaging were used to investigate optimal imaging conditions and time window. NIR-Ι/II imaging was synchronously conducted for quality comparison of the two methods. Visual inspection and histological studies were used for assessing the final outcome of avulsed skin. Results NIR-II fluorescence imaging with a 1,100 nm filter obtained satisfactory performance and reached maximum fluorescence intensity at 1 minute after ICG injection. NIR-II imaging clearly visualized the microvascular network in vascularized avulsed skin and revealed “dark areas” in nonvascularized avulsed skin in a real-time fashion. NIR-II fluorescence imaging demonstrated higher resolution than NIR-I imaging, as indicated by ae higher signal-to-background ratio (2.11) and lower full width at half maximum (6.50614). The dark area of avulsed skin on imaging finally developed to necroses that were confirmed by histology. Conclusion NIR-II real-time fluorescence imaging clearly maps the microvascular network and shows the perfusion status of avulsed skin at higher resolution than traditional NIR-I imaging, and thus precisely predicts the outcome of avulsed skin early.

Water soluble chromenylium dyes for shortwave infrared imaging in mice

“…0.05 μmol/kg) ICG for detection of lymph nodes, tumors and vital structures under routine NIR imaging, 37 whereas for SWIR imaging a much larger dose of ICG is required to compensate for the small fraction of the SWIR emission from ICG (0.3 or 0.6 μmol/kg in mouse, pig or human) but still with >100 ms exposure time. 8,21,36,38 Considering that SulfoChrom7 is a bright fluorophore with majority of emission in the SWIR, we anticipate a very small dose of SulfoChrom7 is necessary for SWIR imaging. This represents an advance over ICG, since it is beneficial to introduce as little contrast agent as possible to minimize unnatural interactions and toxicity.…”

In Vivo Imaging Evaluation of Fluorescence Intensity at Tail Emission of Near-Infrared-I (NIR-I) Fluorophores in a Porcine Model

“…Siqi Gao et al recently published a large animal study using a clinically available and improved NIR-Ι/II multispectral imaging system. Authors simultaneously assessed ICG at 800 nm and 1100 nm wavelengths to map the microvascular network and assess the perfusion status on a skin avulsion–injury model [ 23 ].…”

Edaravone promotes viability of random skin flaps via activating PI3K/Akt/mTOR signalling pathway‐mediated enhancement of autophagy

“…Thus, there is a high likelihood that the distal parts of random skin flaps will suffer from necrosis to varying degrees if the length-to-width ratio of skin flaps exceed 1.5-2.0 because of under ischemic conditions. 4,5 Furthermore, ischemia injury is an inevitable pathological process during random skin flap transplantation. 6 It is commonly acknowledged that inflammation, oxidative stress and apoptosis are the main mechanisms of ischemia-referfusion injury, which are important causes of necrosis.…”

“…There is no axial vessels existing in random skin flaps and its blood supply is only from the pedicle bed, so that the length‐to‐width ratio of random skin flaps should not exceed 1.5–2.0, 3 which is a serious limitation for the clinical application of such types of skin flaps. Thus, there is a high likelihood that the distal parts of random skin flaps will suffer from necrosis to varying degrees if the length‐to‐width ratio of skin flaps exceed 1.5–2.0 because of under ischemic conditions 4,5 . Furthermore, ischemia injury is an inevitable pathological process during random skin flap transplantation 6 .…”