What is Fluorescence Guided Surgery?
Fluorescence Guided Surgery (FGS) is a medical imaging technique that uses fluorescent dye to identify anatomic structures during surgical procedures. FGS typically involves three components:
- Fluorescent Dye: The most commonly used fluorescent agent is Indocyanine Green (IGC). ICG has been approved by the FDA in 1959 and has demonstrated to be safe and can be used in different surgical applications.
- An Excitation Source: The ICG is illuminated with a specific light source that causes the dye to glow. This enhances the structure in which the surgeon needs to see.
What are the advantages of Fluorescence Guided Surgery?
Despite many advances in preoperative medical imaging such as CT and MRI scans, surgeons still almost exclusively operate under white (visible) light during their procedures and must rely on their ability to see and feel target tissues. Unfortunately, most human tissue looks very similar under white light, and it can be very difficult to distinguish one tissue from another or to completely remove a target tissue such as a tumor. In addition, a surgeon can only see the topmost layer of tissue under white light while tissues and structures underneath will remain hidden.
FGS essentially gives the surgeon the ability to ‘see’ in a different wavelength of light that would otherwise be invisible to them. By combining this visual ability with the special dyes that glow in those wavelengths surgeons can much more precisely target or avoid certain organs or tissues. In addition, the near-infrared light used in FGS can more easily penetrate human tissues, allowing surgeons to see ‘through’ layers of tissue and organs.
In addition to allowing a surgeon to see what otherwise would be invisible, FGS has the added advantage of being a real-time imaging process. Whereas traditional imaging like X-Rays, CT Scans, and MRI scans can provide excellent images, they are all limited to providing static images.
Think of FGS as being the equivalent of giving a surgeon GPS whereas before they were working with only a map!
How is FGS currently being used?This table from THIS ARTICLE outlines the current clinical and preclinical fluorescence-guided surgery techniques.
|Angiography and Tumor Identification||Coronary artery bypass grafting
Thyroid and parathyroid surgery
|Structures Identification||Ectrahepatic bile ducts
|Lymph Vessels||Evaluation of lymphedema|
What is Fluorescence Cholangiography?
If you have stones in the gallbladder you may require surgery to remove your gallbladder. That procedure is called Laparoscopic Cholecystectomy.
Although the laparoscopic approach has been demonstrated to be very safe, complications may occur. In order to remove the gallbladder, the surgeon needs to identify a small duct (the cystic duct) that connects the gallbladder to the main bile duct. Once the duct is identified, the surgeon cuts the duct in order to completely remove the gallbladder. The bile duct can be misidentified in up to 0.4% of cases, and as a result, the main bile duct can be injured.
In the last few years a new technology has been developed to allow the surgeon to better visualize the ducts. It has been demonstrated that the surgeon can see 3-times better using a technology called near infrared guided (NIR) imaging using a special dye.
In order to better recognize the structures while operating, indocyanine green is intravenously administrated 45 minutes before the procedure starts. This is the time that is required in order for the dye to be excreted into the bile ducts. During the procedure, the surgeon uses a near infrared light to illuminate the extrahepatic biliary ducts.The dye that is in the extahepatic bile ducts glows when it is illuminated with near infrared light illuminating the ducts.
What is the impact of Near Infrared Guided Surgery in plastic procedures?
Surgeons can evaluate the profusion of the flaps. If they find part of the tissue that is not glowing, they can resect it and the reconstruction is going to heal. Otherwise, if part of the non professed tissue is left, the wound won’t heal.
What is Flap Perfusion Evaluation?
It is the determination of the blood supply of the tissue using (ICG) and special surgical equipment.
How can a surgeon evaluate breast reconstruction with ICG?
Once the resection has been performed, the breast is reconstructed with the tissue from another part of the body. The surgeon needs to be sure the selected tissue is well perfused and will be received enough oxygen. The dye will be intravenously administrated and the surgical field will be illuminated with a special light. If the tissue has good blood flow, the injected ICG will glow green helping the surgeon evaluate the vitality of the tissue.
How useful is Fluorescence Guided Surgery in breast cancer procedures?
In some cancers, the sentinel lymph node has to be identified in order to determine the extension of the tumor. Once administered, ICG helps the surgeon locate the sentinel lymph node.
Can ICG be used in Gallbladder Removal Surgery?
When removing the gallbladder, the surgeon needs to identify the structures that connect the gallbladder with the main bile duct. The recognition of those structures is crucial during the procedure. There is a new technique that is called fluorescence cholangiogrpahy which is when your surgeon can identify those structures with light. ICG dye is administrated 45 mins before the procedure. The ICG is extorted by the liver and will go into the ducts that the surgeon needs to identify. During the procedure a special camera is used and those ducts glow making the procedure safer.
What tumors can be detected with ICG?
There are many studies that are reporting the usefulness of FGS to identify tumors. It is best to discuss with your surgeon the use of this technology in specific tumor resections.
Is ICG safe during surgery?
ICG has been used for a long period of time for different applications. It was approved by the FDA in 1959. Currently, ICG is the most commonly dye used for fluorescence guided surgery. Adverse effects of the dye are low.