For the first time, next-gen infrared fluorescence imaging helps surgeons see blood perfusion during esophageal surgery

A cross-disciplinary research team has, for the first time, successfully applied NIR-II (1,000–3,000 nm) fluorescence video imaging during esophagectomy—a complex surgical procedure involving the resection of a diseased or cancerous portion of the esophagus, where the most dreaded complication, anastomotic leakage, a gastrointestinal defect at the suture line between the esophagus and the gastric conduit, affects 10–30% of patients and leads to high postoperative morbidity rate and even death.

The team’s findings have been published in Proceedings of the National Academy of Sciences.

In Hong Kong, about 30 patients have already benefited from esophagectomy performed with the aid of this new fluorescence imaging and video analysis technique, with highly promising outcomes to date.

The team was led by Professor Hongjie Dai (Sapientia Eminence Professor, Chair Professor in the Department of Chemistry, Department of Mechanical Engineering and School of Biomedical Sciences, Director of the Materials Institute of Life Sciences and Energy (MILES)) and Professor Simon Ying Kit Law (Chairperson and Cheung Kung-Hai Professor in Gastrointestinal Surgery, Chair Professor in Department of Surgery, the School of Clinical Medicine, HKUMed) at the University of Hong Kong (HKU).

By combining high-clarity NIR-II video imaging with rapid computational video analysis, the HKU research team’s pioneering technology enables operator-independent, objective delineation of boundaries between well-perfused and poorly perfused regions, providing precise guidance for resection and reconstruction to reduce the anastomotic leakage rate.

Challenges of current NIR-I fluorescence imaging in assessing gastric conduit perfusion during esophagectomy

Accurate, operator-independent assessment of tissue perfusion and selection of an optimal anastomotic site during esophagectomy are essential for surgeons to ensure the viability of the gastric conduit and to minimize the risk of anastomotic leakage.

Currently, near-infrared (NIR) fluorescence imaging using conventional dyes, such as indocyanine green (ICG), with a commercially available near-infrared I (NIR-I, 700–900 nm) instrument is used for diagnostics and intraoperative navigation.

Despite its widespread use, NIR-I angiography has several limitations, such as superficial penetration depth, high background signal and lower resolution caused by light scattering and tissue autofluorescence.

Further, assessing perfusion based on the suboptimal images relies heavily on the surgeon’s experience and subjective image interpretation, making it difficult to precisely determine the demarcation line of blood perfusion in the gastric conduit, a process critical to the outcome of the surgery.

Intraoperative NIR-II fluorescence-guided esophagectomy in the operating room

This study represents the first clinical use of NIR-II (1,000–3,000 nm) fluorescence imaging to visualize blood perfusion in the gastric conduits, affording markedly superior contrast and resolution compared to traditional NIR-I imaging.

NIR-II imaging was pioneered by Dai’s team in 2009 with mice, taking advantage of the reduced light scattering and tissue autofluorescence at light wavelengths above 1,000 nm. This breakthrough marks the first successful translation of NIR-II imaging into clinical practice for upper gastrointestinal surgery in human patients.

Highlights of the study include:

1. The building of an imaging system that captures photographic images and NIR-II fluorescence images at the same time
2. Much clearer blood flow images in NIR-II than traditional NIR-I, allowing more precise assessment of blood perfusion
3. The combined use of a rapid intraoperative computational analysis of high-resolution blood perfusion NIR-II videos that identifies well-perfused and poorly perfused regions of the gastric conduits within one minute of dye administration.

Professor Hongjie Dai commented, “This is a great example of cross-disciplinary collaboration for translation of our imaging technique from mouse to man.”

Professor Simon Law added, “This innovation offers objective guidance for surgical decisions in esophagectomy. It enables surgeons to accurately assess blood supply, and remove the poorly perfused portion in order to perform the anastomosis at a well perfused area, thereby reducing the risk of anastomotic leakage. This not only enhances surgical safety but also represents a significant breakthrough in esophagectomy.”

This study is part of Hong Kong’s Research, Academic and Industry Sectors One-plus Scheme (RAISe+), the JC STEM Lab of Nanoscience and Nanomedicine and Materials Institute of Life Sciences and Energy (MILES) in Shenzhen. This RAISe+ project is revolutionizing surgery with advanced dyes and imaging tools that work in the NIR-II window.

This technology gives surgeons “infrared vision” to see tumors, blood vessels, and organs clearly and deeply during operations.

The team’s solution helps overcome current limitations of shallow imaging depth and low image quality, enabling precise tumor removal, ureter detection, and sentinel lymph node identification, making surgeries safer and more effective for patients.