Quantitative perfusion assessment using indocyanine green during surgery — current applications and recommendations for future use

Abstract

Purpose Incorrect assessment of tissue perfusion carries a significant risk of complications in surgery. The use of near-infrared (NIR) fluorescence imaging with Indocyanine Green (ICG) presents a possible solution. However, only through quantification of the fluorescence signal can an objective and reproducible evaluation of tissue perfusion be obtained. This narrative review aims to provide an overview of the available quantification methods for perfusion assessment using ICG NIR fluorescence imaging and to present an overview of current clinically utilized software implementations. Methods PubMed was searched for clinical studies on the quantification of ICG NIR fluorescence imaging to assess tissue perfusion. Data on the utilized camera systems and performed methods of quantification were collected. Results Eleven software programs for quantifying tissue perfusion using ICG NIR fluorescence imaging were identified. Five of the 11 programs have been described in three or more clinical studies, including Flow® 800, ROIs Software, IC Calc, SPY-Q™, and the Quest Research Framework®. In addition, applying normalization to fluorescence intensity analysis was described for two software programs. Conclusion Several systems or software solutions provide a quantification of ICG fluorescence; however, intraoperative applications are scarce and quantification methods vary abundantly. In the widespread search for reliable quantification of perfusion with ICG NIR fluorescence imaging, standardization of quantification methods and data acquisition is essential.

Advancing indocyanine green fluorescence flap perfusion assessment via near infrared signal quantification

“… 34 , 35 This could be due to errors in timing, as it is difficult to standardise the inflow/outflow instance without full curve sampling, or because of arbitrary reference point selection for relative comparisons. 19 …”

“…Perfusion patterns extracted from the measurements of intensity and timing of fluorescence in relation to inflow and outflow have been demonstrated to be predictive of flap perfusion related complications, 8 but their application awaits clinical validation. 19 …”

Transcranial cortex-wide imaging of murine ischemic perfusion with large-field multifocal illumination fluorescence microscopy

“…Yet, its outcomes are often compromised by the prolonged scanning times and other well-known safety issues exacerbated in the acutely unwell stroke patients. Although NIR fluorescence imaging suffers from limited penetration as compared to CT and MRI, it has been adopted for various surgical interventions, including vascular, gastrointestinal, cardiac, and reconstructive surgery [25][26][27] . The proposed method could potentially improve the quality of NIR fluorescence imaging and gain additional information for better perfusion assessment in stroke studies.…”

Optimizing Indocyanine Green Dosage for Near-Infrared Fluorescence Perfusion Assessment in Bowel Anastomosis: A Prospective, Systematic Dose-Ranging Study

“…The suitability of lower doses of ICG for NIRF visualization remains unknown, as does the effect of altering the dosage on both subjective visual and objective, software-based perfusion assessment. This is mainly due to the considerable differences in the devices, degrees of imaging environment standardization, and large range of different procedures included into existing studies [14,15]. Lower ICG dosages are likely to improve the accuracy when multiple subsequent intraoperative ICG-NIRF visualizations are performed (such as in anastomotic assessment), besides improving patient safety and reducing costs.…”