Digital dynamic discrimination of primary colorectal cancer using systemic indocyanine green with near-infrared endoscopy

Jeffrey Dalli,Niall Hardy,Mohammad Faraz Khan,Anwesha Sarkar,Paul Huxel,Donal F O’Shea,Haseeb A Khokhar,Ronan A Cahill,Eamon Loughman

doi:10.1038/s41598-021-90089-7

Abstract

As indocyanine green (ICG) with near-infrared (NIR) endoscopy enhances real-time intraoperative tissue microperfusion appreciation, it may also dynamically reveal neoplasia distinctively from normal tissue especially with video software fluorescence analysis. Colorectal tumours of patients were imaged mucosally following ICG administration (0.25 mg/kg i.v.) using an endo-laparoscopic NIR system (PINPOINT Endoscopic Fluorescence System, Stryker) including immediate, continuous in situ visualization of rectal lesions transanally for up to 20 min. Spot and dynamic temporal fluorescence intensities (FI) were quantified using ImageJ (including videos at one frame/second, fps) and by a bespoke MATLAB® application that provided digitalized video tracking and signal logging at 30fps (Fluorescence Tracker App downloadable via MATLAB® file exchange). Statistical analysis of FI-time plots compared tumours (benign and malignant) against control during FI curve rise, peak and decline from apex. Early kinetic FI signal measurement delineated discriminative temporal signatures from tumours (n = 20, 9 cancers) offering rich data for analysis versus delayed spot measurement (n = 10 cancers). Malignant lesion dynamic curves peaked significantly later with a shallower gradient than normal tissue while benign lesions showed significantly greater and faster intensity drop from apex versus cancer. Automated tracker quantification efficiently expanded manual results and provided algorithmic KNN clustering. Photobleaching appeared clinically irrelevant. Analysis of a continuous stream of intraoperatively acquired early ICG fluorescence data can act as an in situ tumour-identifier with greater detail than later snapshot observation alone. Software quantification of such kinetic signatures may distinguish invasive from non-invasive neoplasia with potential for real-time in silico diagnosis.

Highlights

As indocyanine green (ICG) with near-infrared (NIR) endoscopy enhances real-time intraoperative tissue microperfusion appreciation, it may dynamically reveal neoplasia distinctively from normal tissue especially with video software fluorescence analysis
NIR cancer identification strategies have concentrated on advanced preprocedural fluorophore administration with visual interrogation planned for many hours or days later at a time when tissue agent concentrations are relatively static[7]
We hypothesized that kinetic characterisation of the evolving dynamic fluorescence intensity (FI) signature at and within cancer deposits could provide discrimination of cancer versus non-cancer even with a passive, non-targeted fluorophore such as ICG12

Summary

Introduction

As indocyanine green (ICG) with near-infrared (NIR) endoscopy enhances real-time intraoperative tissue microperfusion appreciation, it may dynamically reveal neoplasia distinctively from normal tissue especially with video software fluorescence analysis. Analysis of a continuous stream of intraoperatively acquired early ICG fluorescence data can act as an in situ tumour-identifier with greater detail than later snapshot observation alone Software quantification of such kinetic signatures may distinguish invasive from non-invasive neoplasia with potential for real-time in silico diagnosis. Its endolaparoscopic systems are capable of providing multispectral illumination including tissue-penetrating near-infrared (NIR) spectral v ision[3] Such capacity can help characterise tissue intraoperatively with most clinical application far for tissue perfusion assessment using the non-selective fluorophore indocyanine green (ICG)[4,5,6]. Their irregular vascular architecture and lack of a lymphatic recovery system leads to the tumoritropic accumulation of macromolecules such as albumin in solid tumours (in contrast to their rapid clearance in normal tissue)[10] Such characteristics mean even a chemically non-selective perfusate, such as ICG, could functionally discriminate cancer at any site allowing in situ optical delineation. The automated operative perfusion quantification methodology developed and used for this study is available for download so others may test and add to this exploratory work while we continue to expand our clinical series on a collaborative basis

Methods

Results

Conclusion