Indocyanine Green Angiography Predicts Tissue Necrosis More Accurately Than Thermal Imaging and Near-Infrared Spectroscopy in a Rat Perforator Flap Model

Abstract

Background: Clinical examination alone is neither sensitive nor specific for predicting flap necrosis, so several technologies, including indocyanine green angiography, thermal imaging (using the FLIR ONE), and near-infrared spectroscopy, have been developed to supplement perfusion assessment. This study aims to compare the accuracy of these three methods for intraoperatively predicting clinical flap necrosis in a rat perforator flap model. The authors hypothesized that near-infrared spectroscopy, assessing oxygenation rather than direct perfusion, would yield significantly different predictions. Methods: A 10 × 3-cm epigastric perforator flap was elevated in 14 adult male rats weighing 250 ± 50 g. Flap perfusion was assessed immediately after flap elevation using thermal imaging, near-infrared spectroscopy, and indocyanine green angiography. Measurements were correlated to the clinical endpoint and gold standard of flap necrosis on postoperative day 7. Results: All three technologies detected significant differences in perfusion along flap length (all p < 0.001), and were associated with significant differences in the odds of developing flap necrosis (all p < 0.001). The areas under the receiver operating characteristic curves were 0.948 for indocyanine green angiography as an absolute value, 0.873 for relative changes with thermal imaging, and 0.792 for tissue oxygenation. The sensitivity, specificity, and accuracy for indocyanine green angiography measured as an absolute value were the highest at 97.8, 87.5, and 92 percent, respectively. Conclusions: Indocyanine green angiography most accurately predicted flap necrosis in this study; however, tissue oximetry and thermal imaging were also capable of predicting necrosis and represented potentially less expensive or more readily available alternatives for objective perfusion assessment. Additional research can further delineate their roles and cost-efficacy in clinical practice.

Evaluation of the Influence of Short Tourniquet Ischemia on Tissue Oxygen Saturation and Skin Temperature Using Two Portable Imaging Modalities

“…Therefore, small measurement inaccuracies must be assumed. For example, thermal imaging using FLIR ONE in a rat perforator model showed a sensitivity, specificity, and accuracy with a temperature difference of 80.8, 83.6, and 82 percent, respectively [ 45 ]. The assessment of burn wounds showed that the FLIR ONE was highly reliable, but with moderate validity [ 46 ].…”

Utility of Indocyanine Green Angiography for Preventing Pre-expanded Extended Lower Trapezius Myocutaneous Flap Necrosis: How to Make the Correct Decision for Hypoperfused Areas

“…Previous studies indicate that ICGA is a valuable adjunct that can assess flap perfusion and identify HPAs. 4,6,9,12 Komorowska-Timek and Gurtner 24 reported that prophylactic excision of HPAs can minimize the incidence of mastectomy flap necrosis and impaired healing.…”

“…8 A recent study suggested that indocyanine green angiography (ICGA) appears to be the most accurate of these tools. 9 Since Still et al 10 first used ICGA to evaluate flap perfusion in 1999, this technique has been adapted for plastic and reconstructive surgeries. 11,12 The benefits of ICGA in assessing tissue perfusion to aid clinical decision-making have been demonstrated in mastectomy skin flaps, 13 free flaps, 12 and pedicle flaps.…”

Hyperintensity of integrin‐targeted fluorescence agent IntegriSense750 accurately predicts flap necrosis compared to Indocyanine green

“…Most of the small animal model studies using ICG as a tool for assessing flap viability have taken place in rats. [15][16][17][18] Although the results have been promising in these select studies, it is important to appreciate the different mechanisms by which these studies quantify necrosis.…”