Modern laparoscopic surgery is rapidly developing in the direction of minimally invasive technologies with improved visualization. One of the most promising methods for increasing the accuracy of intraoperative navigation is the use of near infrared (NIR) fluorescence imaging using indocyanine green (ICG). This method allows for clear visualization of vessels, lymph nodes, tumor boundaries and organ structures in real time, which significantly improves surgical outcomes and reduces risks for patients.
Near infrared fluorescence imaging (NIR) is a modern imaging method that significantly expands the capabilities of laparoscopic surgery. It is based on the use of contrast agents that can glow in response to irradiation with light of a certain wavelength. For this, special dyes are used, in particular indocyanine green (ICG), which fluoresces in response to infrared light in the range of 750-800 nm. It is this spectral range – from 650 to 900 nm – that is called the "optical window", because biological tissues have minimal light absorption in it: hemoglobin and water almost do not interfere with the passage of rays, which allows light to penetrate to a depth of 1-2 cm. As a result, the surgeon gets the opportunity to see structures that are inaccessible under normal lighting.
After administration, ICG quickly binds to blood plasma lipoproteins and circulates in the vascular bed. Due to its size and chemical properties, the molecule does not go beyond the vessels and does not accumulate in the intercellular space. This ensures a clear, localized glow only where there are actually blood or lymphatic structures. During surgery, a laparoscopic camera equipped with an infrared light source and a sensitive sensor captures the fluorescence emitted by ICG. The resulting image is processed in real time and superimposed on a regular video image from the endoscope, forming a combined image where anatomical structures are clearly visible together with ICG-illuminated objects.
This method allows to significantly improve the visualization of important structures, in particular, vessels, bile ducts, lymph nodes, tumor borders. Due to the high signal-to-background ratio (i.e. the clarity of the glow against the background of fluorescent tissues), high precision and safety of surgical intervention are achieved. The near infrared spectrum also has minimal interference from natural tissue autofluorescence, which further increases the contrast of the image.
Indocyanine green is the only fluorescent contrast agent in the NIR range approved by the FDA for intravenous use. Due to its amphiphilic nature, the ICG molecule quickly binds to plasma lipoproteins and is distributed through the blood and tissue fluid without penetrating beyond the vascular bed. This ensures the highest specificity and safety of the method.
The main advantages of ICG:
Light penetration depth
Infrared light (650–900 nm) penetrates 1–2 cm deep into tissues — more than visible light.
Real time image
Fluorescence is displayed on the monitor during surgery without delay.
Increased safety of surgery
Allows precise detection of vessels, lymph nodes, bile ducts, tumor boundaries, etc.
The lack of tactile control is compensated by visualization.
In laparoscopy, where the surgeon does not feel the tissues with his hands, visualization provides critical information.
High signal-to-background ratio
Minimal tissue autofluorescence provides a clear, contrasting image.
• Image fusion
Fluorescent image is superimposed on regular RGB video – the surgeon sees anatomy and functional areas simultaneously.
• No additional access or probing required
Visualization is performed through existing laparoscopic ports without additional invasion.
• Suitable for various surgical areas
Hepatobiliary, oncogynecology, colorectal, thoracic, urology, assessment of anastomotic perfusion.
• High biocompatibility, low toxicity, rapid elimination.
• Stable in dry form, easy to store and prepare.
• Possibility of mass production at low cost.
• High signal-to-background ratio, which increases image contrast.
1. Hepatobiliary surgery
ICG allows visualization of liver segments, tumor outlines, vascular architecture and bile ducts. This is extremely useful in liver resections and cholecystectomies, when precise identification of the bile ducts and vessels is required.
2. Gynecological surgery
In gynecologic oncology, ICG is used for mapping lymph nodes in tumors of the cervix and body of the uterus. This allows minimizing the volume of surgical intervention and reduce the risk of complications while maintaining oncological radicality.
3. Gastrointestinal surgery
ICG is used to assess perfusion during gastric or colon resection.
It is also used to detect lymph nodes and tumors.
4. Thoracic surgery
Fluorescence imaging helps to visualize lung segments and identify lymph nodes during lung surgery.
5. Urology
During laparoscopic or robotic-assisted nephrectomy or prostatectomy, ICG allows visualization of renal vessels, urethra, and tumors, as well as lymph node dissection.
6. Detection of peritoneal metastases
ICG can help identify small foci of peritoneal metastases that are not always visible during conventional endoscopy.
The use of ICG in laparoscopic surgery is an important step in next-generation imaging. Its safety, high accuracy and ease of use make fluorescence imaging a valuable tool in both routine and oncological surgery. Combining laparoscopy with infrared fluorescence guidance allows for increased surgical precision and improved patient prognosis.
