Optimizing Indocyanine Green Fluorescence Angiography in Reconstructive Flap Surgery: A Systematic Review and Ex Vivo Experiments

Abstract

Background. Indocyanine green angiography (ICGA) offers the potential to provide objective data for evaluating tissue perfusion of flaps and reduce the incidence of postoperative necrosis. Consensus on ICGA protocols and information on factors that have an influence on fluorescence intensity is lacking. The aim of this article is to provide a comprehensive insight of in vivo and ex vivo evaluation of factors influencing the fluorescence intensity when using ICGA during reconstructive flap surgery. Methods. A systematic literature search was conducted to provide a comprehensive overview of currently used ICGA protocols in reconstructive flap surgery. Additionally, ex vivo experiments were performed to further investigate the practical influence of potentially relevant factors. Results. Factors that are considered important in ICGA protocols, as well as factors that might influence fluorescence intensity are scarcely reported. The ex vivo experiments demonstrated that fluorescence intensity was significantly related to dose, working distance, angle, penetration depth, and ambient light. Conclusions. This study identified factors that significantly influence the fluorescence intensity of ICGA. Applying a weight-adjusted ICG dose seems preferable over a fixed dose, recommended working distances are advocated, and the imaging head during ICGA should be positioned in an angle of 60° to 90° without significantly influencing the fluorescence intensity. All of these factors should be considered and reported when using ICGA for tissue perfusion assessment during reconstructive flap surgery.

The use of near infrared fluorescence imaging with indocyanine green for vascular visualization in caudal auricular flaps in two cats

“…Our selection of an IV dose of 2.5 mg/cat was based on our previous clinical experience in dogs. In man, IV ICG administration is reported as a standard fixed dose (2.5 mg‐25 mg) or as milligram per body weight dose (0.025‐0.5 mg/kg) 30 . In a recent systematic review of ICG fluorescence angiography, Pruimboom et al 30 reported that a fixed dosing method was used in 60% of studies.…”

“…In man, IV ICG administration is reported as a standard fixed dose (2.5 mg-25 mg) or as milligram per body weight dose (0.025-0.5 mg/kg). 30 In a recent systematic review of ICG fluorescence angiography, Pruimboom et al 30 reported that a fixed dosing method was used in 60% of studies. The dose we selected was well within the reported dog and cat dose ranges (0.54 mg/kg for cat 1, 0.29 mg/kg for cat 2) and provided good visualization of the perforating vessel in both cases.…”

Perfusion Patterns in Patients with Chronic Limb-Threatening Ischemia versus Control Patients Using Near-Infrared Fluorescence Imaging with Indocyanine Green

“…Therefore, in future patient selection and to further understand perfusion patterns, healthy volunteers should be taken into account as well. With regard to the NIR fluorescence intensity analysis, the use of normalized time-intensity curves seems rational since intensity-related parameters are prone to multiple influencing factors, including camera distance and ICG dosage [30,31]. This normalization minimizes the effect of these influencing factors on the measured intensity and contributes to a narrower distribution, as seen in the time-intensity curves in this study.…”

Use of the wearable smart glasses for indocyanine green (ICG) angiography of a flap surgery

“…Wearable technology with heads-up displays has entered the medical field and been used for various medical purposes such as navigation surgery (Shao et al, 2014), education (Guze, 2015), and vital sign monitoring (Liebert, Zayed, Aalami, Tran, & Lau, 2016). In the setting of the reconstructive surgery, near-infrared fluorescence (NIRF) imaging using indocyanine green (ICG), also known as ICG angiography, is used predominantly to assess tissue perfusion in transferred flap (Pruimboom et al, 2019). Our goal in this letter is to describe a new effective method for intraoperative ICG angiography for flap surgery using wearable smart glasses.…”