Beyond fluorescence intensity: a Minimum acquisition and reporting standard and emerging technologies for colorectal...

Intraoperative indocyanine green fluorescence angiography (ICG-FA) is increasingly utilized to assess bowel perfusion during colorectal anastomosis. Although recent multicenter randomized trials have yielded mixed findings, pooled randomized evidence and 2025 SAGES guidance indicate an overall benefit, particularly in left-sided and rectal surgery. However, acquisition protocols, interpretation criteria, and reported endpoints remain heterogeneous.

ICG-FA reflects the dynamics of an intravascular dye signal and is affected by injection technique, hemodynamic status, camera geometry, display mode, and platform-specific processing. Visual interpretation shows substantial interobserver variability. Thus, single fluorescence-intensity snapshots are unstable for comparison. In contrast, time-intensity kinetics and spatial heterogeneity measures are more reproducible and physiologically meaningful. Among reported kinetic metrics, the time ratio (TR = T1/2Max/Tmax) is promising. However, current evidence is preliminary and needs multicenter validation.

We propose a practical minimum acquisition and reporting standard for colorectal ICG-FA studies as an expert-opinion framework for future consensus development. This includes consistent reporting of ICG administration, physiological status at assessment, imaging conditions, camera geometry, analysis methodology, measured outcomes, decision impact, and software/version details. We also describe other relevant approaches, such as laser speckle contrast imaging (LSCI), hyperspectral imaging (HSI), and artificial intelligence (AI)-assisted interpretation.

The key question is no longer only whether ICG-FA should be used, but how its signal should be acquired, quantified, interpreted, and reported. Better standardization should improve comparability, support multicenter validation, and clarify where perfusion imaging adds the greatest clinical value.