Indocyanine green fluorescence navigation for hepatocellular carcinoma with bile duct tumor thrombus: a case report

Real-Time Navigation in Liver Surgery Through Indocyanine Green Fluorescence: An Updated Analysis of Worldwide Protocols and Applications

BACKGROUND

Indocyanine green (ICG) fluorescence has seen extensive application across medical and surgical fields, praised for its real-time navigation capabilities and low toxicity. Initially employed to assess liver function, ICG fluorescence is now integral to liver surgery, aiding in tumor detection, liver segmentation, and the visualization of bile leaks. This study reviews current protocols and ICG fluorescence applications in liver surgery, with a focus on optimizing timing and dosage based on clinical indications.

METHODS

Following PRISMA guidelines, we systematically reviewed the literature up to 27 January 2024, using PubMed and Medline to identify studies on ICG fluorescence used in liver surgery. A systematic review was performed to evaluate dosage and timing protocols for ICG administration.

RESULTS

Of 1093 initial articles, 140 studies, covering a total of 3739 patients, were included. The studies primarily addressed tumor detection (40%), liver segmentation (34.6%), and both (21.4%). The most common ICG fluorescence dose for tumor detection was 0.5 mg/kg, with administration occurring from days to weeks pre-surgery. Various near-infrared (NIR) camera systems were utilized, with the PINPOINT system most frequently cited. Tumor detection rates averaged 87.4%, with a 10.5% false-positive rate. Additional applications include the detection of bile leaks, lymph nodes, and vascular and biliary structures.

CONCLUSIONS

ICG fluorescence imaging has emerged as a valuable tool in liver surgery, enhancing real-time navigation and improving clinical outcomes. Standardizing protocols could further enhance ICG fluorescence efficacy and reliability, benefitting patient care in hepatic surgeries.

Indocyanine Green Fluorescence Navigation in Liver Surgery: A Systematic Review on Dose and Timing of Administration

BACKGROUND

Indocyanine green (ICG) fluorescence has proven to be a high potential navigation tool during liver surgery; however, its optimal usage is still far from being standardized.

METHODS

A systematic review was conducted on MEDLINE/PubMed for English articles that contained the information of dose and timing of ICG administration until February 2021. Successful rates of tumor detection and liver segmentation, as well as tumor/patient background and imaging settings were also reviewed. The quality assessment of the articles was performed in accordance with the Scottish Intercollegiate Guidelines Network (SIGN).

RESULTS

Out of initial 311 articles, a total of 72 manuscripts were obtained. The quality assessment of the included studies revealed usually low; only 9 articles got qualified as high quality. Forty articles (55%) focused on open resections, whereas 32 articles (45%) on laparoscopic and robotic liver resections. Thirty-four articles (47%) described tumor detection ability, and 25 articles (35%) did liver segmentation ability, and the others (18%) did both abilities. Negative staining was reported (42%) more than positive staining (32%). For tumor detection, majority used the dose of 0.5 mg/kg within 14 days before the operation day, and an additional administration (0.02-0.5 mg/kg) in case of longer preoperative interval. Tumor detection rate was reported to be 87.4% (range, 43%-100%) with false positive rate reported to be 10.5% (range, 0%-31.3%). For negative staining method, the majority used 2.5 mg/body, ranging from 0.025 to 25 mg/body. For positive staining method, the majority used 0.25 mg/body, ranging from 0.025 to 12.5 mg/body. Successful segmentation rate was 88.0% (range, 53%-100%).

CONCLUSION

The time point and dose of ICG administration strongly needs to be tailored case by case in daily practice, due to various tumor/patient backgrounds and imaging settings.

Targeting Contrast Agents With Peak Near-Infrared-II (NIR-II) Fluorescence Emission for Non-invasive Real-Time Direct Visualization of Thrombosis

Thrombosis within the vasculature arises when pathological factors compromise normal hemostasis. On doing so, arterial thrombosis (AT) and venous thrombosis (VT) can lead to life-threatening cardio-cerebrovascular complications. Unfortunately, the therapeutic window following the onset of AT and VT is insufficient for effective treatment. As such, acute AT is the leading cause of heart attacks and constitutes ∼80% of stroke incidences, while acute VT can lead to fatal therapy complications. Early lesion detection, their accurate identification, and the subsequent appropriate treatment of thrombi can reduce the risk of thrombosis as well as its sequelae. As the success rate of therapy of fresh thrombi is higher than that of old thrombi, detection of the former and accurate identification of lesions as thrombi are of paramount importance. Magnetic resonance imaging, x-ray computed tomography (CT), and ultrasound (US) are the conventional non-invasive imaging modalities used for the detection and identification of AT and VT, but these modalities have the drawback of providing only image-delayed indirect visualization of only late stages of thrombi development. To overcome such limitations, near-infrared (NIR, ca. 700-1,700 nm) fluorescence (NIRF) imaging has been implemented due to its capability of providing non-invasive real-time direct visualization of biological structures and processes. Contrast agents designed for providing real-time direct or indirect visualization of thrombi using NIRF imaging primarily provide peak NIR-I fluorescence emission (ca. 700-1,000 nm), which affords limited tissue penetration depth and suboptimal spatiotemporal resolution. To facilitate the enhancement of the visualization of thrombosis via providing detection of smaller, fresh, and/or deep-seated thrombi in real time, the development of contrast agents with peak NIR-II fluorescence emission (ca. 1000-1,700 nm) has been recently underway. Currently, however, most contrast agents that provide peak NIR-II fluorescence emissions that are purportedly capable of providing direct visualization of thrombi or their resultant occlusions actually afford only the indirect visualization of such because they only provide for the (i) measuring of the surrounding vascular blood flow and/or (ii) simple tracing of the vasculature. These contrast agents do not target thrombi or occlusions. As such, this mini review summarizes the extremely limited number of targeting contrast agents with peak NIR-II fluorescence emission developed for non-invasive real-time direct visualization of thrombosis that have been recently reported.