ICG Fluorescence

Fig. 36.1

ICG NIR fluorescence explanation

In this chapter, we describe current applications in general surgery: fluorescent cholangiography, lymph node mapping, and assessment of the perfusion of the colonic stumps, colorectal, and gastric tattooing.

Cholangiography Fluorescence of Indocyanine Green

Bile duct injury (BDI) is a rare but serious complication of cholecystectomy. The incidence of these lesions increased from 0.1–0.2 % at the time of open cholecystectomy to 0.4–0.7 % in the era of laparoscopic cholecystectomy. The primary cause of BDI is the misinterpretation of biliary anatomy (71–97 % of cases) [10–14].

The single-incision laparoscopic cholecystectomy (SILC) may be associated with an increased risk of bile duct injuries because of insufficient exposure of Calot’s triangle compared to traditional multiport cholecystectomy.

Single-site robotic cholecystectomy (SSRC) allows easier and safer surgical procedures, similar to those of multiport laparoscopic cholecystectomy, with good exposure of the Calot’s triangle.

However, the difficulty in visualizing the biliary structures can still remain in SSRC, although to a lesser extent with respect to the SILC. This is due to a reduced field of vision and to a forced position of the instruments [15].

Routine IOC to evaluate the biliary anatomy is still recommended by many authors [16], but it has several disadvantages such as a longer operating time, requirement for a multidisciplinary team, staff and patient exposure to radiation, interruption of the workflow, and, in the case of robotic surgery, the need to undock and redock the robot.

ICG NIR cholangiography is a noninvasive method that requires no X-rays or bulky equipment such as the C-arm and permits viewing of the bile duct in real time by alternating between the white light and NIR fluorescent light with a simple switch system.

Recently, several authors have reported the benefits of cholangiography with fluorescence detection of the biliary tract in real time during dissection of the Calot’s triangle with no requirement for catheterization of the biliary tract [17, 18].

Technique

The first dose of 2.5 mg of ICG is administered intravenously during the preparation of the patient, about 30–45 min before surgery. A second dose of 2.5 mg ICG is once again administered intravenously if fluorescence is not detected in the liver about 60 min after the injection of the first dose. The surgery begins in the usual manner for SSRC cholecystectomy. Once a view of the Calot’s triangle is established, the camera is put into fluorescence mode for an initial attempt to identify the biliary anatomy (Figs. 36.2 and 36.3). Then the dissection of the Calot’s triangle begins with the incision of the peritoneum and continues as described in the SSRC chapter, alternatively switching from white to NIR light allowing views of the fluorescent bile ducts in real time. In this way, the surgeon can follow a road map for a safe skeletonization of the cystic duct and cystic artery (Figs. 36.4 and 36.5). The cystic duct may be clipped under fluorescence before sectioning, especially if it is very short and if there are problems in the biliary confluence.

Fig. 36.2

White light view before Calot’s dissection

Fig. 36.3

NIR light view before Calot’s dissection

Fig. 36.4

White with light view after Calot’s dissection (cyst duct and artery sectioned)

Fig. 36.5

NIR light view after Calot’s dissection (cyst duct and artery sectioned)

If there are problems with the vascular anatomy during the cystic artery skeletonization, it is possible to proceed with a further injection of 2.5 mg of ICG and, after 10–20 s, obtain a view of the hepatic and cystic arteries and their divisions and avoid any damage to anomalous branches, especially the branch to the sixth hepatic segment.

During the detachment of the gallbladder from the liver bed, use of fluorescence to define the boundary between the gallbladder and liver bed is useful, especially in cases of thin or an intrahepatic gallbladder and to visualize any aberrant ducts of Luschka (Figs. 36.6, 36.7, 36.8, and 36.9).

Fig. 36.6

White light view of Luschka duct before sectioning

Fig. 36.7

NIR light view of Luschka duct before sectioning

Fig. 36.8

White light view of Luschka duct after sectioning

Fig. 36.9

NIR light view of Luschka duct after sectioning

After the procedure, a final fluorescence view of the operative field may be prudent.

Discussion of Advantages, Limitations, and Relative Contraindications

Advantages

Fluorescent cholangiography, especially during the SSRC, allows safe viewing and immediate and real-time anatomy of the biliary tract and is a further aid to prevent BDI during the procedure.

First, Ishizawa and then Buchs demonstrated the technical feasibility of fluorescent cholangiography during multiport laparoscopic cholecystectomy, SILC, and SSRC [17, 18].

In our experience, 70 patients underwent SSRC with ICG NIR cholangiography (initial data submitted to Surg Endosc).

We visualized at least 1 biliary duct in 100 % of cases before the dissection of the triangle of Calot and two biliary ducts in 97 % of cases after dissection. The operative time of SSRC with fluorescence compared with that of our SSRC experience without fluorescence was not statistically significant.

Mean hospital stay was 1.1 days. There were no conversions, bile duct injuries, other major complications, or adverse events.

The advantages of this method compared to the traditional radiological IOC are many:

There is no interruption of the workflow in that the images are highlighted on the surgical field during the normal progress of the operation and the surgeon can operate both in white light and fluorescence.
The interpretation of images is simpler because they appear in real time and can be checked with surgical maneuvers of moving structures whilst they are in view. This is in contrast to the traditional IOC images that are fixed on the screen of the radiology equipment with the surgeon working with static information.
It is possible to control the clipping and sectioning of the cystic duct with a clear distinction of the bile ducts.
During the detachment of the gallbladder from the liver bed, its wall can be better highlighted and any aberrant ducts of Luschka easily found.
The fluorescent bile that usually comes out of the stump of the cut cystic duct or of the gallbladder in case of perforation is always clearly visible; therefore, the system could potentially highlight any bile leaks. This use of the ICF fluorescence, however, has not yet been reported.
When needed, the vascular anatomy of the hepatic artery and cystic artery can be shown.
C-arm or other equipment is not needed, thus avoiding the undocking and redocking of the robotic system.
The procedure does not require any additional time compared to normal SSRC.

We can conclude that the procedure is safe and inexpensive; it requires no interaction of multidisciplinary teams, does not expose patients and staff to radiation, and is not burdened by adverse reactions.

Limitations

The current limitations are mainly two:

So far the procedure has not been tested in cases of an emergency cholecystectomy performed for suppurative cholecystitis or gangrenous cholecystitis. The ability of NIR light to reach the deeper, edematous, and inflamed tissues must be studied.
ICG NIR fluorescent cholangiography is optimal for the definition of biliary tree anatomy. The capability of the current system to recognize biliary gallstones or other obstructions has not yet been investigated.

Contraindications

Pregnancy, adverse reaction, or allergy to ICG, iodine, shellfish, or iodine dyes.

Fluorescence for Near-Infrared Imaging During Colorectal Surgery

The advantages of the robotic platform in colorectal cancer surgery have been extensively described in previous chapters. The fluorescence viewing system of the da Vinci HD is able to increase the potential of robot technology in terms of safety and oncologic extent of dissection.

The use of fluorescence in colorectal surgery can be useful for some currently developing applications:

The evaluation of perfusion of the intestinal stumps
Real-time identification of vascular anatomy
Intraoperative lymph node mapping
Tattooing for the localization of tumors of the colon, rectum, etc.

The Evaluation of Perfusion of the Intestinal Stumps

The anastomotic leakage is one of the most feared complications in colorectal surgery [19, 20]. The causes of and pathogenic mechanisms underlying anastomotic leakages have not been fully clarified, but it is considered that the perfusion of the intestinal stump is an important factor [21]. The evaluation of the adequacy of perfusion of the stumps is usually based on the subjective impression of the surgeon that includes parameters such as active bleeding edge of the section, the pulsatility of the mesentery vessels, and lack of discoloration of bowel segments [22].

The loss of tactile feedback, typical of minimally invasive surgery, can make this assessment more difficult compared to open surgery.

Many different solutions have been proposed: laser Doppler flowmetry, visible light spectroscopy, fluorescence laser angiography, narrow band laser imaging techniques, and near-infrared reflection spectroscopy.

The fluorescence system of the da Vinci robot allows HD viewing in real time both for macroscopic vascular anatomy of and perfusion of the microcirculation.

This device can be used to assess the intestinal perfusion and reassure the surgeon in their choice of point section of the bowel during left and right hemicolectomies and anterior resection of the rectum. It can also be useful in nonstandardized colic resections such as the resection of the transverse and left colonic angle in which vascular abnormalities can impair the blood supply.