Advancement of indocyanine green fluorescence imaging technology in laparoscopic surgery for rectal cancer

Abstract

Indocyanine green fluorescence imaging technology has been increasingly utilized in rectal surgery in recent years. As a safe tracer, indocyanine green can facilitate lymph node tracing, assess the blood supply at anastomotic sites, and localize tumour lesions during laparoscopic surgery, thereby resulting in favourable outcomes. This technology helps surgeons to achieve more precise diagnoses and treatments in laparoscopic procedures, thus ultimately benefiting patients. However, the current application of indocyanine green fluorescence imaging technology still lacks standardized regulations, and certain effects remain contentious. This study provides a comprehensive review of the application of indocyanine green in laparoscopic surgery for rectal cancer based on the pertinent literature.

Key Words: Indocyanine green fluorescence; Laparoscopic surgery; Rectal cancer; Lymph node; Blood supply

Core Tip: Indocyanine green fluorescence imaging, which serves as a tracer for lymph node identification, blood supply assessment, and tumour localization, has been increasingly utilized in rectal surgery in recent years. This technique enhances surgical precision and improves patient outcomes. This study reviews the application of indocyanine green in laparoscopic rectal cancer surgery with references to the relevant literature.

INTRODUCTION

Rectal cancer currently ranks as the third most globally prevalent malignant tumour, with an increasing incidence being observed[1]. The advent of minimally invasive surgical techniques has led to the widespread adoption of laparoscopic surgery for rectal cancer, and its therapeutic efficacy has been well established. In recent years, advancements such as total mesorectal excision have become standard surgical practices for middle- and low-position rectal cancers. Additionally, the introduction of neoadjuvant therapy has further alleviated surgical challenges and reduced postoperative recurrence rates. Nevertheless, issues such as incomplete lymph node dissection and postoperative anastomotic fistula continue to pose significant challenges for surgeons regarding traditional laparoscopic rectal cancer surgery. An increased focus on these concerns while improving both short-term and long-term outcomes for patients with rectal cancer remains a critical challenge in clinical practice. Indocyanine green (ICG) fluorescence is a clinically utilized near-infrared imaging agent that is known for its feasibility and safety profile. With ongoing advancements in medical technology, ICG has gradually been applied in tumour surgery and has yielded promising results that suggest favourable prospects for future use. In liver surgery, ICG can effectively delineate the anatomical structures of the liver, thereby facilitating precise hepatectomy. In gynaecological surgery, ICG serves as a valuable tool for assessing the metastasis of pelvic lymph nodes. Moreover, in urological surgery, ICG enables the accurate localization of kidney tumours and renal arteries. The application of ICG can effectively address the aforementioned challenges that are encountered during rectal cancer surgery. This article reviews the application of ICG fluorescence imaging technology in laparoscopic rectal cancer surgery by referencing recent research developments and relevant evidence-based medicine.

THE APPLICATION BASIS OF ICG FLUORESCENCE IMAGING TECHNOLOGY

Traditional dye tracers, such as methylene blue and nanocarbon, exhibit several disadvantages, including localized adhesion, suboptimal imaging quality, and the potential risk of peritoneal infection. ICG is an infrared contrast agent that is known for its excellent biocompatibility. When exposed to external light with wavelengths ranging from 750-800 nm, ICG emits longer wavelengths of near-infrared light. Due to its unique ability to emit light within the near-infrared spectrum, ICG is generally unaffected by self-luminescence, which may arise from haemoglobin and water in the blood components. By leveraging this characteristic, the ICG molecular fluorescence imaging system integrates fluorescence reception imaging with fluorescence excitation to facilitate the generation of ICG fluorescence images. This process employs a computer image processing system in combination with a high-sensitivity near-infrared fluorescence camera and a near-infrared excitation light source. Furthermore, the use of ICG enables real-time imaging during surgical procedures, thereby offering both simplicity and effectiveness.

Since the 1950s, ICG has been utilized in various applications, including the visualization of the retina and choroid, ophthalmic angiography, liver function assessments, and vascular system evaluations. With advancements in surgical techniques, ICG has been increasingly utilized for vascular imaging and functional assessments. Its applications have gradually expanded to include lymph node tracing, blood supply evaluation, and tumour localization, thereby demonstrating high feasibility and safety[2,3]. The costs of ICG reagents are relatively low, and they are also nonradioactive; thus, no additional protective measures are required during the procedures. Furthermore, ICG does not significantly stain human tissues under visible light conditions, which allows for unobstructed observation and operation during surgery.

Upon administration into the human body, ICG is metabolized by the liver and excreted in its intact molecular form via the bile ducts before being eliminated via faeces. Notably, it does not participate or travel in the enterohepatic circulation. Adverse reactions associated with ICG are infrequent; however, some patients may experience mild symptoms, such as facial flushing or sore throat. More serious reactions can include the development of hives, hypotension, dyspnoea, tachycardia, and anaphylactic shock. Due to its trace iodine content, ICG should be avoided in individuals with known iodine allergies. Since Nagata et al[4] first introduced the use of ICG in colorectal surgery in 2006, it has emerged as a promising tool for both the diagnosis and treatment of colorectal cancer. Furthermore, in recent years, ICG fluorescence imaging technology has been increasingly applied in the context of colorectal cancer surgery.

LYMPH NODE TRACING

Lymph node metastasis from rectal cancer is a primary contributor to recurrence and mortality in patients following surgical intervention. Consequently, comprehensive lymph node dissection within the regional area is crucial for achieving curative resection of rectal cancer. This scenario has significant implications for postoperative staging and the formulation of subsequent treatment strategies. However, there remains a challenge with respect to how to effectively and accurately perform lymph node dissection while enhancing both the positive lymph node detection rate and the total number of dissected lymph nodes, which has consistently been a focal point in rectal cancer surgery.

Compared with traditional nanocarbon methods, ICG demonstrates superior accuracy in identifying sentinel lymph nodes and regional drainage lymph nodes during surgical procedures, as well as a greater capacity for detecting micrometastatic foci. The real-time in vivo imaging capabilities of ICG enable surgeons to accurately locate the regional drainage lymph nodes that are adjacent to tumours under physiological conditions, thereby facilitating effective lymphadenectomy with significant advantages. Typically, ICG lymph node tracing is preoperatively conducted via multiple injection points within the submucosal layer under colonoscopy or intraoperatively conducted around the tumour within the peritoneal cavity. The configuration method involves the dilution of ICG with sterilized water for injection, thus allowing for the preparation of ICG solutions at concentrations of 1.25, 2.5, or 5.0 g/L. Twelve to twenty-four hours prior to the operation, three to four injection sites are selected around the tumour under colonoscopic guidance, and 0.1-0.3 mL of the ICG solution is injected at each site. Additionally, the imaging duration can extend beyond 48 hours. The application method that is used during surgery remains consistent with this approach. Reports have indicated that the use of ICG for lymph node tracing yields a high detection rate during surgery, thereby suggesting its efficacy in guiding the extent of lymphadenectomy and increasing the retrieval of positive lymph nodes[5]. Chand et al[6] employed ICG for intraoperative lymph node tracing and observed visibility of nodes beyond the standard range of dissection; moreover, these nodes were subsequently confirmed to be metastatic after surgery, thereby reducing postoperative recurrence risks among patients. Watanabe et al[7] utilized ICG fluorescence imaging technology and revealed that the lymphatic flow from cancers located in the splenic area of the colon can directly reach regions surrounding the inferior mesenteric artery without traversing through either the left colonic artery or middle colonic artery. This finding challenges the traditional understanding of lymphatic flow pathways and underscores the application value of ICG in elucidating the lymphatic drainage patterns of patients with colorectal cancer.

The lymphatic drainage of lower to middle rectal cancer can occur simultaneously in the upwards, downwards, and lateral directions. The lateral transfer pathway follows the inner aspect of the distal iliac artery, whereby it reaches the lymph nodes surrounding the iliac vessels, which include the internal, obturator, external iliac, and common iliac nodes (Figure 1). According to previous research, the rate of lateral lymph node metastasis in patients with lower to middle rectal cancer may be as high as 26%[8]. Conventional total mesorectal excision typically involves lymph nodes that are located both above and below the iliac vessels but does not address the lateral lymph nodes that are situated outside of the rectal mesentery. Numerous retrospective studies have indicated that lateral lymph node metastasis is a significant risk factor for local recurrence in patients with rectal cancer who have undergone only total mesorectal excision[9]. In cases of pelvic recurrence of rectal cancer, up to 60% of patients may exhibit lateral-type recurrence[10]. Laparoscopic lateral lymph node dissection has emerged as an effective technique for clearing these nodes and can significantly reduce local recurrence rates following surgery while also improving patient outcomes[11].

Figure 1  The vascular supply to the colon.

A prospective randomized controlled trial (JCOG 0212) conducted by Japanese researchers demonstrated that the combination of total mesorectal excision with lateral lymph node dissection substantially decreases the likelihood of lateral local recurrence[12]. Therefore, for patients who are clinically suspected of or diagnosed with metastasis, the performance of concurrent lateral lymph node dissection is advisable. However, various challenges (such as the complex anatomy of the pelvic sidewall, the narrow interpelvic spaces, and oedema resulting from radiotherapy and chemotherapy) considerably complicate the laparoscopic identification and clearance of these laterally located lymph nodes. Therefore, the application of more precise lymph node localization methods to facilitate the clearance of pelvic lymph nodes that are adjacent to the rectum has emerged as a significant challenge that requires resolution. To address this issue, recent advancements in tracer imaging technology have gradually demonstrated the potential value of this technology in clinical applications.

However, lateral lymph node dissection may result in damage to the blood vessels and nerves along the pelvic lateral wall, which increases the incidence of postoperative urinary dysfunction and subsequently diminishes patients’ quality of life. The application of ICG fluorescence imaging technology during lymph node dissection aids in accurately locating target lymph nodes while minimizing unnecessary injury to the surrounding blood vessels and nerves. According to reports, the utilization of ICG can identify lateral lymph nodes in 92% of patients, thereby facilitating lateral lymph node dissection[5]. Moreover, research findings have indicated that, compared with standard total mesorectal excision, nerve-sparing lateral lymph node dissection is associated with a greater prevalence of sexual and urinary function disorders. The preservation of the pelvic plexus nerve during lateral lymph node dissection protects neural structures; additionally, it does not compromise survival benefits, thus enabling most patients to maintain satisfactory urinary function[13] (Table 1).

Table 1 Lymph node tracing.

Ref.	Journal	Year	Application
Nagata et al[4]	Anticancer Res	2006	Colorectal cancer
Dai et al[5]	Front Med (Lausanne)	2022	Lateral pelvic lymph node of rectal cancer
Chand et al[6]	Tech Coloproctol	2018	Colon cancer
Watanabe et al[7]	Int J Colorectal Dis	2017	Splenic flexural colon cancer
Kanemitsu et al[13]	Clin Colon Rectal Surg	2020	Lateral pelvic lymph node of rectal cancer

EVALUATION OF THE BLOOD SUPPLY TO THE ANASTOMOSIS

Anastomotic fistula is a significant complication following rectal cancer surgery, and it can lead to prolonged hospital stays, increased health care costs, elevated mortality rates, and adverse effects on both short-term and long-term patient prognosis. Despite advancements in neoadjuvant therapy, the implementation of total mesorectal excision, improvements in laparoscopic surgical instruments, and improvements in surgical techniques have markedly improved postoperative outcomes for patients with colorectal cancer; however, the incidence of anastomotic leakage has not exhibited a corresponding decline. The occurrence of anastomotic fistula is due to the interplay of multiple factors, with blood supply to the anastomosis being one of the most critical determinants. The vascular supply to the left hemicolon is particularly intricate, as it involves several arteries, including the inferior mesenteric artery, left colonic artery, and middle colonic artery, as well as the marginal artery of Drummond and the arc of Riolan (Figure 2). Variations in or the absence of these vessels can lead to inadequate blood supply to this region. Patients with a history of ischaemic bowel disease or those who have undergone neoadjuvant chemoradiotherapy are at heightened risks for such complications. Compared with postoperative prevention and treatment strategies, the real-time evaluation of blood supply perfusion at the anastomosis site during surgery offers a more precise approach for mitigating the development of postoperative anastomotic fistula. Currently, the clinical assessment of blood supply during surgery primarily relies on surgeon experience; moreover, surgeons evaluate various factors, such as changes in intestinal wall colour before and after anastomosis, bleeding intensity at the intestinal junctions, and capillary filling. However, this method lacks accuracy. During open surgery, the surgeon is able to assess the blood supply of the intestine by examining the vascularity of the mesenteric fat pad and palpating the pulsation of the mesenteric vessels. However, this assessment is not feasible during laparoscopic surgery. Although laser Doppler flowmetry, Doppler colour ultrasound, and oxygen molecular light instruments can be employed to evaluate blood supply during surgical procedures, their clinical application remains limited because of issues related to convenience and a lack of rigorous validation.

Figure 2 Lateral lymph nodes surrounding the rectum. MCA: Middle colic artery; SMA: Superior mesenteric artery; IMA: Inferior mesenteric artery; SRA: Superior rectal artery; LCA: Left colic artery; SA: Sigmoid artery.

ICG fluorescence imaging technology is a straightforward and effective method for evaluating tissue blood flow perfusion during laparoscopic surgery, and it demonstrates high safety and feasibility, as well as promising application prospects. The configuration method involves the dilution of 25 mg of ICG in 10 mL of sterilized water for injection to produce a solution with a concentration of 2.5 g/L ICG. Additionally, the recommended dosage ranges from 0.1-0.3 mg/kg and is administered via intravenous injection. In cases of repeated administrations, the maximum daily dosage should not exceed 5 mg/kg. Following the separation of the proximal intestinal mesentery during laparoscopic procedures, a preexcision line is established, after which ICG is intravenously administered to assess the blood supply at this line. In cases where the blood supply appears to be inadequate, the preexcision line can be repositioned to an area with improved vascularity closer to the distal end. Once anastomosis has been completed, ICG is injected again to evaluate the blood supply at the anastomotic site; if insufficient perfusion is detected, resection of the anastomosis may be necessary, followed by reanastomosis.

In 2010, Kudszus et al[14] pioneered the application of ICG fluorescence imaging technology for assessing the anastomotic blood supply in colorectal cancer surgeries, thereby resulting in a 4% reduction in the incidence of postoperative anastomotic fistulas. The PILLAR II clinical study utilized a fluorescence imaging system to evaluate the anastomotic blood supply in 139 patients who underwent colorectal resection and subsequent reanastomosis due to poor perfusion. Remarkably, no instances of postoperative anastomotic fistulas occurred among these patients; thus, this observation underscores the notion that ICG fluorescence imaging can promptly and effectively identify and address issues related to the anastomotic blood supply, thereby reducing the rates of postoperative complications[15].

A multicentre retrospective study conducted in Japan in 2020 included 422 rectal cancer patients who underwent surgical interventions via ICG fluorescence imaging technology. This investigation revealed that surgical decisions were altered for 5.7% of the patients based on findings from ICG fluorescence imaging assessments, thus consequently leading to a nearly 6% decrease in the incidence of postoperative anastomotic fistulas while also minimizing secondary surgeries and shortening hospital stays[2]. Chan et al[16] conducted a meta-analysis demonstrating that the use of ICG to assess blood supply before and after intestinal resection during surgery can significantly reduce the incidence of postoperative anastomotic fistulas. Moreover, Аlexander et al[17] reported a case of acute ischaemic bowel disease that improved following treatment with laparoscopic ICG fluorescence imaging technology. This scenario represents a rare instance of ICG fluorescence imaging being utilized in the context of ischaemic bowel disease, thereby highlighting its advantages in evaluating local blood supply conditions and enhancing treatment outcomes.

Some researchers have employed spectral analysis software to quantitatively analyse the fluorescence duration and intensity at the anastomotic site, with an aim of obtaining more accurate assessments of blood supply; however, additional clinical data are needed to further substantiate these findings[18]. In low rectal surgeries, wherein the operative space is limited and anastomosis poses challenges, the application of ICG fluorescence imaging technology has been demonstrated to decrease the occurrence of postoperative anastomotic complications[19]. Scholars have integrated robotic surgery with ICG fluorescence imaging technology in cases involving low rectal cancer. This approach not only capitalizes on the superior field visibility and enhanced operability provided by robotic systems but also facilitates improved identification of anatomical layers and evaluation of anastomoses during procedures, thereby increasing surgical safety[20].

When the position of the partial anastomosis is lower and the bowel is thickened or difficult to visualize at the posterior wall of the anastomosis, the use of a laparoscopic fluorescence imaging system for observation may demonstrate challenges. This can subsequently lead to insufficient judgement during surgery. Some scholars have suggested that the utilization of a fluorescent rectal endoscope via the anus may yield more accurate results[21]. However, recent findings from the PILLAR III study indicate that although ICG fluorescence imaging technology can effectively assess the blood supply to the anastomosis in patients, it does not significantly reduce the incidence of anastomotic fistulas[22]. Additionally, a multicentre randomized controlled trial conducted in Italy demonstrated that although ICG fluorescence imaging technology was intraoperatively used to evaluate blood supply and implement timely interventions in participants in the experimental group, there was no significant difference observed in fistula occurrence between this group and the control group[23]. Consequently, further large-sample, multicentre studies are warranted to provide additional evidence-based support regarding the application of ICG for intraoperative assessments of the anastomotic blood supply (Table 2).

Table 2 Evaluation of blood supply to anastomosis.

Ref.	Journal	Year	Application
Kudszus et al[14]	Langenbecks Arch Surg	2010	Colorectal cancer
Jafari et al[15]	J Am Coll Surg	2015	Left colon and rectal cancer
Watanabe et al[2]	Surg Endosc	2020	Rectal cancer
Chan et al[16]	Surgery	2020	Colorectal cancer
Аlexander et al[17]	Int J Surg Case Rep	2019	Acute mesenteric ischemia
Son et al[18]	Surg Endosc	2019	Colorectal cancer
Wada et al[19]	Int J Clin Oncol	2019	Rectal cancer
Skrovina et al[20]	Wideochir Inne Tech Maloinwazyjne	2020	Rectal cancer
Liang et al[21]	Zhonghua Wei Chang Wai Ke Za Zhi	2020	Rectal cancer
Jafari et al[22]	Dis Colon Rectum	2021	Left colon and rectal cancer
De Nardi et al[23]	Surg Endosc	2019	Colorectal cancer

LOCALIZATION OF DISTANT METASTASES

The liver serves as the primary target organ for haematogenous metastasis in patients with colorectal cancer. Although the surgical resection of liver metastases is an effective treatment approach, some patients continue to experience recurrence after surgery. This may be attributed to the challenges associated with the preoperative detection of microscopic metastases via imaging modalities and the difficulty in intraoperatively identifying these metastases. ICG has emerged as a valuable tool for visualizing liver metastases and was utilized even prior to its application in colon and rectal cancers. For the localization of liver metastases originating from colorectal cancer, an intravenous injection of 0.5 mg/kg of a 2.5 g/L ICG solution can be administered 24 hours prior to the surgical procedure. Ishizawa et al[24] were among the first researchers to report the use of ICG for visualizing liver metastases in 12 cases of colorectal cancer with hepatic involvement; notably, 6 cases exhibited clear visualization of liver metastases, thus demonstrating high sensitivity. Additionally, researchers conducted a retrospective analysis involving clinical data from 15 patients diagnosed with colorectal cancer liver metastasis and reported that the use of ICG during surgery significantly increased the detection rate of these lesions[25]. According to the literature, ICG fluorescence imaging can identify liver metastases with a minimum diameter of 1 mm during surgical procedures; however, due to the limited penetration depth of this imaging technology, it is recommended that deep-seated lesions be assessed in conjunction with intraoperative ultrasound techniques[26]. Therefore, ICG can be utilized during laparoscopic colorectal cancer surgery to identify liver metastases, thus facilitating timely intraoperative management or subsequent postoperative treatment.

Similar to liver metastases, small peritoneal metastatic lesions are challenging to detect and can easily result in recurrence following surgery in patients with rectal cancer. Barabino et al[27] employed ICG to visualize peritoneal metastatic lesions in ten patients with colorectal cancer metastasizing to the peritoneum, whereby they achieved a visualization rate of 72.4% for lesions confirmed by pathology as being metastatic cancer. Therefore, the use of ICG for real-time imaging during surgical procedures has the potential to identify peritoneal micrometastatic lesions that are often difficult to discern either preoperatively or intraoperatively, thus allowing for the removal of these lesions and thereby increasing the survival rates of rectal cancer patients. However, relatively few studies have investigated the application of ICG in cases of peritoneal metastasis. In addition, a single-centre study indicated that quantitative ICG seems to be useful for the assessment of nonmucinous colorectal peritoneal metastases[28] (Table 3).

Table 3 Localization of extraperitoneal metastases from rectal cancer.

Ref.	Journal	Year	Application
Ishizawa et al[24]	Cancer	2009	Liver metastasis
Patel et al[25]	J Gastrointest Cancer	2023	Liver metastasis
Piccolo et al[26]	J Laparoendosc Adv Surg Tech A	2021	Liver metastasis
Barabino et al[27]	Eur J Surg Oncol	2016	Peritoneal metastasis
González-Abós et al[28]	Dis Colon Rectum	2022	Peritoneal metastasis

LIMITATIONS AND APPLICATION PROSPECTS

Despite the increasing application of ICG fluorescence imaging technology in surgical procedures, several factors can influence surgeons’ judgements during operations. These factors include the amount of injected ICG, observation time, injection site, injection method, fluorescence intensity, external lighting conditions, distance between the laparoscopic lens and the tissue or organ, and individual patient differences. Insufficient fluorescence intensity of ICG may impair the surgeon’s evaluation of the blood supply to anastomoses, thus potentially leading to postoperative complications such as anastomotic fistulas. Indeed, the fluorescence intensity is correlated with the administered dosage; however, a standardized injection protocol and optimal concentration for ICG have yet to be established. Reports have indicated that even when ICG fluorescence imaging is employed to intraoperatively assess blood supply, some patients still experience postoperative anastomotic fistulas due to nonstandardized injection techniques and observation times[29].

According to previous studies, the imaging times following ICG injections can vary across different vascular systems (ranging from several seconds to a few minutes). Consequently, if the optimal imaging time cannot be established, it may adversely affect the assessment of blood supply at the anastomotic site. Importantly, for patients undergoing neoadjuvant chemoradiotherapy, potential damage to lymphatic vessels caused by preoperative treatment may hinder the visibility of the lymph nodes that are detectable with ICG during surgery, thereby impacting the effectiveness of ICG imaging. Ankersmit et al[30] conducted a meta-analysis that demonstrated insufficient diffusion of fluorescence dye around tumours in colorectal surgeries, which led to suboptimal localization of lymph nodes and tumour visualization. In clinical practice, advanced-stage tumours may exhibit challenges such as thrombosis in lymphatic vessels due to cancer emboli. This scenario can result in the partial enlargement of lymph nodes that are not visible or lead to the partial invasion of tumours into the intestinal wall, which obstructs lymphatic drainage and manifests as false-positive results. Therefore, targeted lymphadenectomy remains necessary during surgery based on individual circumstances.

Moreover, individual differences among patients may significantly influence the metabolism and excretion of ICG, thereby affecting its imaging efficacy. For example, the half-life of ICG is extended in elderly patients and in those patients with renal insufficiency, whereas it is reduced in younger patients and in individuals with liver dysfunction. To effectively address these individual variations in clinical practice, several measures can be implemented. First, individualized ICG dosing regimens can be developed based on factors such as patient age, sex, health status, and liver function. By adjusting both the dosage and timing of injections, the metabolism and excretion of ICG within the patient’s body can be optimized to enhance imaging outcomes. Second, the improvement of the detection sensitivity of imaging devices to accommodate low-dose ICG applications is essential. This enhancement can help to mitigate instances of suboptimal imaging results caused by attenuation effects from ICG within the body. Third, prior to conducting ICG imaging procedures, a thorough evaluation of liver and kidney function indicators should be performed to determine appropriate dosages and injection intervals for each patient. By implementing these strategies, individual differences can be effectively managed, thereby ultimately improving both the accuracy and safety associated with ICG imaging.

The application of ICG in laparoscopic surgery is progressively advancing. When ICG is combined with emerging technologies, its potential applications may be further expanded. In laparoscopic procedures, the integration of intraoperative navigation technology enables surgeons to obtain real-time fluorescence images of the surgical field during operations, thereby facilitating more precise localization of diseased tissues and allowing for the formulation of more rational surgical strategies. Ryu et al[31] employed intraoperative fluorescence navigation technology in laparoscopic left-sided colon and rectal cancer surgery. Additionally, they conducted evaluations of blood flow, fluorescence clip marking procedures, ureteral navigation procedures and fluorescence vessel navigation procedures to identify and evaluate both lesions and the surrounding tissue structures. The findings demonstrated significant efficacy and contributed to a reduction in the incidence of postoperative complications. Moreover, the incorporation of machine learning and artificial intelligence significantly enhances the utility of ICG in laparoscopic surgery. By training machine learning models, clinicians can leverage feature information from ICG fluorescence imaging to automatically identify and analyse pathological tissues. This approach not only improves diagnostic accuracy but also provides avenues for personalized treatment options. In laparoscopic rectal cancer surgeries, the use of ICG fluorescence imaging in conjunction with machine learning techniques allows surgeons to determine resection margins with greater precision, thereby ensuring both thoroughness and safety during the procedures[32]. Concurrently, artificial intelligence can assist physicians by monitoring changes in ICG fluorescence imaging in real time throughout the operation, thus enabling prompt detection and management of any abnormalities that may arise. This ability for real-time monitoring not only enhances surgical safety but also provides valuable decision support during operations. The integration of ICG with intraoperative navigation systems, as well as machine learning and artificial intelligence technologies, demonstrates significant potential to improve both the accuracy and safety of surgical interventions while also offering possibilities for tailored treatments. As these technologies continue to advance and develop, the application of ICG in laparoscopic rectal surgery is expected to become increasingly comprehensive and sophisticated.

CONCLUSION

In conclusion, ICG fluorescence imaging technology has proven to be a valuable tool for lymph node tracing, assessment of the blood supply at anastomotic sites, and localization of distant metastatic lesions during laparoscopic rectal cancer surgery. However, the operating procedures for ICG fluorescence imaging remain to be clearly defined, and certain effects require further validation. Therefore, it is essential to conduct more prospective multicentre studies and establish standardized operating guidelines to facilitate the broader adoption of ICG in the future.