Macro- and microscopic findings of ICG fluorescence in liver tumors

Impact of Infrared Indocyanine Green Fluorescence imaging-guided Laparoscopic Hepatectomy on Securing the Resection Margin for Colorectal Liver Metastasis

BACKGROUND

Laparoscopic hepatectomy for colorectal liver metastases (CRLM) is performed worldwide. However, owing to a lack of palpatory information and difficulties associated with accurate intraoperative ultrasonographic diagnosis, the tumor may be exposed at the hepatic transection margin. This study aimed to investigate the pathological significance of near-infrared (NIR) fluorescence imaging with indocyanine green (ICG)-guided laparoscopic hepatectomy and determine its usefulness in securing the resection margin for CRLMs.

METHODS

Fifty-nine patients who underwent laparoscopic hepatectomy for CRLM using NIR fluorescence imaging between February 2017 and June 2021 at Sapporo Medical University Hospital were included. Generally, all patients received intravenous ICG (2.5 mg/body) as a fluorescence agent 1 to 2 days before surgery. During the surgical procedure, real-time NIR fluorescence imaging was repeatedly performed to assess the surgical margins.

RESULTS

Of the 94 tumors in 59 patients, laparoscopic NIR fluorescence imaging identified 56 tumors (59.6%) on the liver surface. Pathological analysis indicated clear margins in 96.6% (57/59) of patients. Examination of paraffin-embedded sections, which were successful in only 20 of 94 cases (21.3%), revealed that there were no tumor cells positive for NIR fluorescence, and the median distance of the continuous fluorescent signal from the tumor margin was 1.074 mm.

CONCLUSIONS

We demonstrated a high R0 rate using NIR fluorescence-guided hepatectomy. This technique has the potential to improve intraoperative tumor identification and tumor margin assurance and reduce the rate of positive resection margins in patients with CRLMs.

Mechanisms of delayed indocyanine green fluorescence and applications to clinical disease processes

BACKGROUND

Delayed indocyanine green fluorescence imaging is under investigation in various clinical disease processes. Understanding the mechanisms of indocyanine green accumulation and retention is essential to correctly interpreting and analyzing imaging data. The purpose of this scoping review was to synthesize what is known about the mechanism of indocyanine green retention at the cellular level to better understand the clinical nuances of delayed indocyanine green imaging and identify critical gaps in our knowledge to guide future studies.

METHODS

We performed a scoping review of 7,087 citations after performing database searches of PubMed, Scopus, the Cochrane Library, and the Web of Science Core Collection electronic databases. Studies were eligible for inclusion if they were peer-reviewed original research discussing the mechanism of indocyanine green retention in the results section in disease processes involving inflammation and/or necrosis, including cancer, and were available in English. Data were extracted using Covidence software.

RESULTS

Eighty-nine studies were included in the final analysis. Several features of indocyanine green retention were identified.

CONCLUSION

We identified several mechanistic features involved in indocyanine green accumulation in diseased tissue that overall had distinct mechanisms of indocyanine green retention in tumors, nontumor inflammation, and necrosis. Our study also reveals new insights on how inflammatory infiltrate influences indocyanine green fluorescence imaging. These findings are noteworthy because they add to our understanding of how fluorescence-guided surgery may be optimized based on the pathology of interest via specific indocyanine green dosing and timing of image acquisition.

FGF19-Based Mini Probe Targeting FGFR4 for Diagnosis and Surgical Navigation of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a frequent malignancy that has a high death rate and a high rate of recurrence following surgery, owing to insufficient surgical resection. Furthermore, HCC is prone to peritoneal metastasis (HCC-PM), resulting in a significant number of tiny cancer lesions, making surgical removal more challenging. As a potential imaging target, FGFR4 is highly expressed in tumors, especially in HCC, but is less expressed in the normal liver. In this study, we used computational simulation approaches to develop peptide I0 derived from FGF19, a particular ligand of FGFR4, and labeled it with the NIRF dye, MPA, for HCC detection. In surgical navigation, the TBR was 9.31 ± 1.36 and 8.57 ± 1.15 in HepG2 in situ tumor and HCC-PM models, respectively, indicating considerable tumor uptake. As a result, peptide I0 is an excellent clinical diagnostic reagent for HCC, as well as a tool for surgically resecting HCC peritoneal metastases.

Correlation Between Indocyanine Green Fluorescence Patterns and Grade of Differentiation of Hepatocellular Carcinoma: A Western Prospective Cohort Study

Background. Most of the available evidence on the use of indocyanine green (ICG) fluorescence in clinical practice consists of articles published by surgeons of the Asian-Pacific area. We performed a prospective cohort study to assess the patterns of ICG fluorescence in Western hepatocellular carcinoma (HCC) counterparts.Methods. From April 2019 to January 2022, a total of 31 consecutive patients who underwent laparoscopic liver resection (LLR) for superficial HCC were enrolled in this prospective study. All patients underwent laparoscopic staging with both laparoscopic ultrasound (LUS) and ICG fluorescence imaging.Results. A total of 38 hepatocellular carcinomas (HCCs) were enrolled: 23 superficial (surfacing at the liver's Glissonian capsule), 5 exophytic, 5 shallow (<8 mm from the hepatic surface) and 5 deep (>10 mm from the hepatic surface). The detection rate with preoperative imaging (abdominal CT/MRI), LUS, ICG fluorescence and combined modalities (ICG and LUS) was 97.4%, 94.9%, 89.7% and 100%, respectively. The five deep seated lesions underwent ultrasound-guided laparoscopic thermal ablation. The other 33 HCCs were treated with minimally invasive liver resection. Intraoperative ultrasound patterns were registered for each single nodule resected. The ICG fluorescence pattern was classified in two types: total fluorescence (all the tumoral tissue showed strong and homogeneous fluorescence), n = 9/33 (27.3%), and non-total fluorescence (partial and rim fluorescence), n = 24/33 (72.7%). There was a statistical correlation between ICG patterns and grade of differentiation. Almost all lesions with uniform fluorescence pattern were well-differentiated HCCs (G1-G2), while partial and rim-type fluorescence pattern were more common among moderately and poorly differentiated HCCs (G3-G4) (88.9% vs 11.1%, 37.5% vs 62.5%, P = .025, respectively).Conclusions. ICG fluorescence imaging could be used to identify early the grade of HCC, ie intraoperatively, thus influencing the intraoperative treatment.

Advantages of a Photodiode Detector Endoscopy System in Fluorescence-Guided Percutaneous Liver Biopsies

Image-guided liver biopsies can improve their success rate when combined with the optical detection of Indocyanine Green (ICG) fluorescence accumulated in tumors. Previous works used a camera coupled to a thin borescope to capture and quantify images from fluorescence emission during procedures; however, light-scattering prevented the formation of sharp images, and the time response for weakly fluorescent tumors was very low. Instead, replacing the camera with a photodiode detector shows an improved temporal resolution in a more compact and lighter device. This work presents the new design in a comparative study between both detection technologies, including an assessment of the temporal response and sensitivity to the presence of background fluorescence.

Detection of Colorectal Liver Metastases Using Near-Infrared Fluorescence Imaging During Hepatectomy: Prospective Single Centre UK Study

INTRODUCTION

Small superficial colorectal liver metastases (CLM) may be difficult to localise intraoperatively, especially during minimally invasive hepatectomy due to reduced tactile feedback and limitations of ultrasound (US). Near-infrared (NIRF) fluorescence imaging is an emerging technology that permits detection of liver tumours after systemic injection of indocyanine green (ICG). Our aim was to report our experience using NIRF to detect CLM.

PATIENTS AND METHODS

Patients with small, superficial resectable CLM received a 10-mg IV bolus of ICG the day before hepatectomy. All patients underwent preoperative liver-specific MRI. CLM were localised intraoperatively using a combination of white light/ultrasound (WL-US) and NIRF. Sensitivity and specificity of NIRF were compared with WL-US.

RESULTS

Between March 2019 and July 2021, NIRF was utilised in 15 patients who underwent hepatectomy (laparoscopic 13, open 2). Thirty-two lesions were detected by MRI (including 3 disappearing CLM), of which 2 were ICG-negative and not resected (1 haemangioma, 1 disappearing CLM). Of 30 resected lesions, the median tumour diameter was 11 mm (range 2-25), median distance from liver surface was 4.5 mm (range 0-20) and all were confirmed CLM on histology (R0 resection rate 71%). Twenty-three of thirty (77%) and twenty-seven of thirty (90%) resected CLM were detected by WL-US and NIRF, respectively. Of 7/30 (23%) resected CLM that were WL-US negative, 5 were ICG-positive. Two resected 'disappearing' CLM were ICG-positive, one of which contained viable cancer cells. Overall, NIRF influenced the operative strategy in 6 patients (43%).

CONCLUSION

Near-infrared fluorescence imaging allows detection of small, superficial colorectal liver metastases that are missed by conventional techniques and warrants further study.

Does Using Indocyanine Green Fluorescence Imaging for Tumors Help in Determining the Safe Surgical Margin in Real-Time Navigation of Laparoscopic Hepatectomy? A Retrospective Study

BACKGROUND

This study aims to investigate whether indocyanine green (ICG) tumor imaging helps determine the safe surgical margin in laparoscopic hepatectomy.

PATIENTS AND METHODS

Eighty-six patients with hepatic malignancies [including hepatocellular carcinoma (HCC) and colorectal liver metastasis (CRLM)] were included in this study. ICG-R15 testing was performed 5-7 days before surgery. Fluorescence staining of the tumor was detected by a fluorescent laparoscope, and the width of fluorescence band surrounding tumor was measured by an electronic vernier caliper.

RESULTS

The positive rate of hepatic malignant lesions successfully stained by ICG fluorescence was 96.0% (95/99). HCC with better differentiation demonstrated non-rim fluorescence patterns, while cases with poor differentiation demonstrated rim patterns. CRLM uniformly demonstrated rim pattern. The width of fluorescence surrounding tumors was 0 in HCC with non-rim patterns. The minimum width of fluorescence surrounding tumors in poor differentiated HCC and CRLM were 2.4 ± 1.9 mm and 2.8 ± 2.5 mm, respectively, with no significant difference (P > 0.05). ICG fluorescence imaging revealed eight small lesions, which were not detected preoperatively in seven patients, of which five lesions were confirmed as malignancies by pathology.

CONCLUSIONS

Resection along the ICG fluorescence edge can supply a safe surgical margin only for CRLM, but not for HCC. Otherwise, ICG fluorescence tumor imaging can preliminarily determine the pathological type of hepatic malignancies and histological differentiation of HCC and help detect small lesions that cannot be detected preoperatively.

[Modern possibilities of fluorescent imaging in liver surgery]

The article presents a literature review of modern methods of fluorescent navigation in liver surgery. The technique of tumor «staining», mapping of liver segments, fluorescent cholangiography is covered. The own results of the use of indocyanine green in liver surgery are presented.

Indocyanine Green Fluorescence-Guided Surgery for Gastrointestinal Tumors: A Systematic Review

Objective

To conduct a systematic review of the currently available literature on the use of ICG to guide surgical dissection in gastrointestinal (GI) cancer surgery.

Background

Real-time indocyanine green (ICG) fluorescence-guided surgery has the potential to enhance surgical outcomes by increasing patient-tailored oncological precision.

Methods

MEDLINE, PubMed, EMBASE, and Google Scholar were searched for publications on the use of ICG as a contrast agent in GI cancer surgery until December 2020. Perfusion studies were excluded. Quality of the studies was assessed with the Methodological Index for nonrandomized Studies or Jadad scale for randomized controlled trials. A narrative synthesis of the results was provided, with descriptive statistics when appropriate.

Results

Seventy-eight studies were included. ICG was used for primary tumor and metastases localization, for sentinel lymph node detection, and for lymph flow mapping. The detection rate for primary colorectal and gastric tumors was 100% after preoperative ICG endoscopic injection. For liver lesions, the detection rate after intravenous ICG infusion was 80% and up to 100% for lesions less than 8 mm from the liver surface. The detection rate for sentinel lymph nodes was 89.8% for esophageal, 98.6% for gastric, 87.4% for colorectal, and 83.3% for anal tumors, respectively. In comparative studies, ICG significantly increases the quality of D2 lymphadenectomy in oncological gastrectomy.

Conclusion

The use of ICG as a guiding tool for dissection in GI surgery is promising. Further evidence from high-quality studies on larger sample sizes is needed to assess whether ICG-guided surgery may become standard of care.

Tumor visualization and fluorescence angiography with indocyanine green (ICG) in laparoscopic and robotic hepatobiliary surgery - valuation of early adopters from Germany

Objectives

Indocyanine green (ICG) is a fluorescent dye which was initially used for liver functional assessment. Moreover, it is of value for intraoperative visualization of liver segments and bile ducts or primary and secondary liver tumors. Especially in minimally invasive liver surgery, this is essential to enhance the precision of anatomical guided surgery and oncological quality. As early adopters of ICG implementation into laparoscopic and robotic-assisted liver surgery in Germany, we summarize the current recommendations and share our experiences.

Methods

Actual strategies for ICG application in minimally invasive liver surgery were evaluated and summarized during a review of the literature. Experiences in patients who underwent laparoscopic or robotic-assisted liver surgery with intraoperative ICG staining between 2018 and 2020 from the Magdeburg registry for minimally invasive liver surgery (MD-MILS) were evaluated and the data were analyzed retrospectively.

Results

ICG can be used to identify anatomical liver segments by fluorescence angiography via direct or indirect tissue staining. Fluorescence cholangiography visualizes the intra- and extrahepatic bile ducts. Primary and secondary liver tumors can be identified with a sensitivity of 69-100%. For this 0.5 mg/kg body weight ICG must be applicated intravenously 2-14 days prior to surgery. Within the MD-MILS we identified 18 patients which received ICG for intraoperative tumor staining of hepatocellular carcinoma (HCC), cholangiocarcinoma, peritoneal HCC metastases, adenoma, or colorectal liver metastases. The sensitivity for tumor staining was 100%. In 27.8% additional liver tumors were identified by ICG fluorescence. In 39% a false positive signal could be detected. This occurred mainly in cirrhotic livers.

Conclusions

ICG staining is a simple and useful tool to assess individual hepatic anatomy or to detect tumors during minimally invasive liver surgery. It may enhance surgical precision and improve oncological quality. False-positive detection rates of liver tumors can be reduced by respecting the tumor entity and liver functional impairments.

Subregional Radiomics Analysis of PET/CT Imaging with Intratumor Partitioning: Application to Prognosis for Nasopharyngeal Carcinoma

PURPOSE

This work aims to identify intratumoral habitats with distinct heterogeneity based on 2-deoxy-2-[¹⁸F]fluro-D-glucose positron emission tomography (PET)/X-ray computed tomography (CT) imaging, and to develop a subregional radiomics approach to predict progression-free survival (PFS) in patients with nasopharyngeal carcinoma (NPC).

PROCEDURES

In total, 128 NPC patients (85 vs. 43 for primary vs. validation cohorts) who underwent pre-treatment PET/CT scan were enrolled retrospectively. Each tumor was partitioned into several phenotypically consistent subregions based on individual- and population-level clustering. For each subregion, 202 radiomics features were extracted to construct imaging biomarker for prognosis via Cox's proportional hazard model combined with forward stepwise feature selection. Relevance of imaging biomarkers and clinicopathological factors were assessed by multivariate Cox regression analysis and Spearman's correlation analysis. To investigate whether imaging biomarkers could provide complementary prognosis information beyond existing predictors, a scoring system was further developed for risk stratification and compared with AJCC staging system.

RESULTS

Three subregions (denoted as S1, S2, and S3) were discovered with distinct PET/CT imaging characteristics in the two cohorts. The prognostic performance of imaging biomarker S3 outperformed the whole tumor (C-index, 0.69 vs. 0.58; log-rank test, p < 0.001 vs. p = 0.552). Imaging biomarker S3 and AJCC stage were identified as independent predictors (p = 0.011 and 0.042, respectively) after adjusting for clinicopathological factors. The scoring system outperformed the traditional AJCC staging system (log-rank test, p < 0.0001 vs. p = 0.0002 in primary cohort and p = 0.0021 vs. p = 0.0277 in validation cohort, respectively).

CONCLUSIONS

Subregional radiomics analysis of PET/CT imaging has the potential to predict PFS in patients with NPC, which also provides complementary prognostic information for traditional predictors.

Consensus Guidelines for the Use of Fluorescence Imaging in Hepatobiliary Surgery

OBJECTIVE

To establish consensus recommendations for the use of fluorescence imaging with indocyanine green (ICG) in hepatobiliary surgery.

BACKGROUND

ICG fluorescence imaging has gained popularity in hepatobiliary surgery in recent years. However, there is varied evidence on the use, dosage, and timing of administration of ICG in clinical practice. To standardize the use of this imaging modality in hepatobiliary surgery, a panel of pioneering experts from the Asia-Pacific region sought to establish a set of consensus recommendations by consolidating the available evidence and clinical experiences.

METHODS

A total of 13 surgeons experienced in hepatobiliary surgery and/or minimally invasive surgery formed an expert consensus panel in Shanghai, China in October 2018. By the modified Delphi method, they presented the relevant evidence, discussed clinical experiences, and derived consensus statements on the use of ICG in hepatobiliary surgery. Each statement was discussed and modified until a unanimous consensus was achieved.

RESULTS

A total of 7 recommendations for the clinical applications of ICG in hepatobiliary surgery were formulated.

CONCLUSIONS

The Shanghai consensus recommendations offer practical tips and techniques to augment the safety and technical feasibility of ICG fluorescence-guided hepatobiliary surgery, including laparoscopic cholecystectomy, liver segmentectomy, and liver transplantation.

Fluorescence imaging in colorectal surgery

BACKGROUND

Fluorescent imaging is an emerging technological tool that can guide surgeons during surgery by highlighting anatomical structures and pathology, and help with intraoperative decision making.

METHODS

A comprehensive review of published literature was performed using the search terms "fluorescence", "imaging" and "colorectal surgery" in PubMed. Only clinical trials that were published in English were included in this review. Ex vivo and animal studies were excluded.

RESULTS

This review demonstrates the use of fluorescence imaging in colorectal surgery in four areas: (1) assessment of tissue perfusion and vasculature; (2) assessment of tumour; (3) lymphatic drainage and (4) identification of the urinary tract. The most commonly used fluorescent dyes are nonspecific, such as indocyanine green and methylene blue, but there is increasing interest in the development of specific fluorescently labelled molecular markers.

CONCLUSION

Fluorescence imaging is a potentially useful tool for colorectal surgery. Early studies on fluorescence imaging have been promising but larger scale randomised controlled trials are warranted to demonstrate the effectiveness and benefits of using fluorescence imaging routinely. The development of molecular dyes that are specific to targets could significantly increase the potential use of fluorescence imaging during surgery.

Identification of liver lesions using fluorescence imaging: comparison of methods for administering indocyanine green

BACKGROUND

Fluorescence imaging using indocyanine green (ICG) enables intraoperatively visualizing liver tumors as fluorescent. This study evaluated the doses and timing of ICG administration for visualizing tumors via fluorescence using near-infrared light camera systems.

METHODS

Consecutive patients who underwent open liver resection for liver tumors from 2016 to 2017 were included. ICG was intravenously injected one-day before surgery at 0.25 mg-intravenous injection (IV), 1.25 mg-IV, 2.5 mg-IV, or 3.75 mg-IV. No additional ICG was administered when patients underwent ICG (0.5 mg/kg) retention test within 10 preoperative days. The ability of fluorescence imaging to enable identifying liver tumors was compared using the PDE-NEO and PINPOINT.

RESULTS

154 lesions in 82 patients were assessed. The tumor identification rate of PDE-NEO did not differ significantly among dosages. The positive predictive values of PDE-NEO were significantly lower at 3.75 mg-IV (69.0%) than in the control group (92.0%) (p = 0.036) and at 1.25 mg-IV (88.9%) (p = 0.033). The tumor identification rate of PINPOINT was significantly higher at 3.75 mg-IV (82.4%) than at 1.25 mg-IV (60.0%) (p = 0.035). The positive predictive values of PINPOINT did not significantly differ among dosages.

CONCLUSION

Administering 2.5 mg of ICG one-day before surgery can enable identifying tumors via fluorescence imaging when the ICG test was not performed within 10 preoperative days.

Near-Infrared Polymer Dots in the Portal-Hepatic Circulation Achieve Localization of Hepatic Carcinoma In Vivo

The present study aims to use polymer dots to explore whether they can visualize tumor lesions in a diethylnitrosamine (DENA)-induced hepatocellular carcinoma (HCC) model. The HCC rat model was set up, and serum liver function indexes and AFP were tested on days 0, 30, 60, and 90 of the modeling process. After characterization of the polymer dots, they were injected into the rats and mice. The liver, spleen, and kidney of rats and the gallbladder of mice were extracted to verify the metabolic pathways of the polymer dots and their capability of fluorescent localization of HCC and gallbladder by fluorescence imaging. Strong fluorescent emission from the liver appeared immediately and 15 min after the polymer dots were injected through the main portal veins and tail veins of the model rats, respectively. A satisfactory fluorescent imaging effect lasted up to 45 min. Polymer dots circulate through the bloodstream within intrahepatic vessels rather than intracellular areas and can be clearly visualized by using both the pCLE and IVIS spectrum imaging systems. Contrast imaging of HCC lesions without fluorescent emissions was due to the lack of normal portal-hepatic veins within the tumor areas. Fluorescent imaging of the gallbladder could also be detected at 15 min after the polymer dots were injected through the tail veins of mice. The polymer dots had satisfactory fluorescent localization capability for targeted intrahepatic vessels and HCC lesions in vivo and showed potential practical value in hepato-biliary surgery.

Precision Liver Resection: Three-Dimensional Reconstruction Combined with Fluorescence Laparoscopic Imaging

Liver surgery has entered the era of precision surgery. Therefore, how to optimize the resection of lesions and reduce the unnecessary time of liver ischemia and hypoxia have become the focus. A total of 11 patients who underwent fluorescence laparoscopic liver mass resection and preoperative three-dimensional (3D) reconstruction between August 2018 and July 2020 were evaluated. Liver cirrhosis occurred in 3 patients. The mean intraoperative blood loss was 166.8 ± 105.7 mL. The average length of the operation time was 152.0 ± 45.3 minutes. The average intraoperative hilar occlusion time was 9.3 minutes (except for hilar cholangiocarcinoma). The liver function of all patients, except patients with hilar bile duct carcinoma, returned to the preoperative level at 72 hours, and no serious complications occurred. 3D reconstruction combined with fluorescence laparoscopic imaging is safe and effective for precision liver resection.

Fluorescence-guided fiber-optic micronavigation using microscopic identification of vascular boundary of liver segment and tumors

Background: The exact identification of tumor boundaries and related liver segments is especially important for liver tumor surgery. This study aimed to evaluate a new approach for vascular boundary assessment and surgical navigation based on fiber-optic microscopy and microvascular fluorescence labeling.

Methods: Antibody clones with fast binding ability were identified and selected using immunofluorescence. We evaluated the endothelial capture efficacy for an anti-mouse CD31 antibody labeled with different fluorophores and different degrees of labeling ex vivo. Segment boundary identification and navigation potential using endothelial capture were explored by two different fiber-optic microscopy systems. Finally, microvasculature labeling and fiber-optic microscopy were used to identify and treat microscopic liver tumors in vivo.

Results: The following monoclonal antibodies were selected: anti-mouse CD31 (clone 390), anti-mouse CD54 (YN1/1.7.4), anti-human CD31 (WM59), and anti-human CD54 (HA58). These clones showed fast binding to endothelial cells and had long half-lives. The fluorophore choice and the degree of antibody labeling did not significantly affect capture efficacy in an isolated liver perfusion model. The microvascular system was clearly identified with wide-field fiber-optic microscopy after labeling the endothelium with low doses of specific antibodies, and the specifically labeled liver segment could be microscopically dissected. High antibody doses were required for confocal laser endomicroscopy. After microscopically identifying the vascular margin in vivo, tumor thermoablation strongly reduced tumor size or totally eliminated tumors.

Conclusions: We demonstrated that vascular boundaries of liver tumors and locally perfused liver segments were accurately identified and surgical micronavigation was facilitated with fiber-optic microscopy and selected endothelium-specific antibodies.

First-in-human liver-tumour surgery guided by multispectral fluorescence imaging in the visible and near-infrared-I/II windows

The second near-infrared wavelength window (NIR-II, 1,000-1,700 nm) enables fluorescence imaging of tissue with enhanced contrast at depths of millimetres and at micrometre-scale resolution. However, the lack of clinically viable NIR-II equipment has hindered the clinical translation of NIR-II imaging. Here, we describe an optical-imaging instrument that integrates a visible multispectral imaging system with the detection of NIR-II and NIR-I (700-900 nm in wavelength) fluorescence (by using the dye indocyanine green) for aiding the fluorescence-guided surgical resection of primary and metastatic liver tumours in 23 patients. We found that, compared with NIR-I imaging, intraoperative NIR-II imaging provided a higher tumour-detection sensitivity (100% versus 90.6%; with 95% confidence intervals of 89.1%-100% and 75.0%-98.0%, respectively), a higher tumour-to-normal-liver-tissue signal ratio (5.33 versus 1.45) and an enhanced tumour-detection rate (56.41% versus 46.15%). We infer that combining the NIR-I/II spectral windows and suitable fluorescence probes might improve image-guided surgery in the clinic.

Novel method of intraoperative liver tumour localisation with indocyanine green and near-infrared imaging

INTRODUCTION

Fluorescence imaging (FI) with indocyanine green (ICG) is increasingly implemented as an intraoperative navigation tool in hepatobiliary surgery to identify hepatic tumours. This is useful in minimally invasive hepatectomy, where gross inspection and palpation are limited. This study aimed to evaluate the feasibility, safety and optimal timing of using ICG for tumour localisation in patients undergoing hepatic resection.

METHODS

From 2015 to 2018, a prospective multicentre study was conducted to evaluate feasibility and safety of ICG in tumour localisation following preoperative administration of ICG either on Day 0-3 or Day 4-7.

RESULTS

Among 32 patients, a total of 46 lesions were resected: 23 were hepatocellular carcinomas (HCCs), 12 were colorectal liver metastases (CRLM) and 11 were benign lesions. ICG FI identified 38 (82.6%) lesions prior to resection. The majority of HCCs were homogeneous fluorescing lesions (56.6%), while CLRM were homogeneous (41.7%) or rim-enhancing (33.3%). The majority (75.0%) of the lesions not detected by ICG FI were in cirrhotic livers. Most (84.1%) of ICG-positive lesions detected were < 1 cm deep, and half of the lesions ≥ 1 cm in depth were not detected. In cirrhotic patients with malignant lesions, those given ICG on preoperative Day 0-3 and Day 4-7 had detection rates of 66.7% and 91.7%, respectively. There were no adverse events.

CONCLUSION

ICG FI is a safe and feasible method to assist tumour localisation in liver surgery. Different tumours appear to display characteristic fluorescent patterns. There may be no disadvantage of administering ICG closer to the operative date if it is more convenient, except in patients with liver cirrhosis.

Improving the Surgical Effect for Primary Liver Cancer with Intraoperative Fluorescence Navigation Compared with Intraoperative Ultrasound

BACKGROUND This study aimed to compare the application value of intraoperative fluorescence navigation technology (FNT) and intraoperative ultrasound (IOUS) in primary liver cancer surgery. MATERIAL AND METHODS Fifty consecutive patients with primary liver cancer scheduled to receive surgical treatment were divided into FNT group and IOUS group. FNT and IOUS were separately used to guide tumor resection and detect new cancerous lesions in the 2 groups. The complete tumor resection rate (R0) resection rate, length of the tumor distance from cutting edge, the diagnostic efficacy of cancerous nodules and the fluorescence imaging characteristics of different types tumors were recorded. RESULTS The R0 resection rate was 100% (25 out of 25 patients) in the FNT group and 96% (24 out of 25 patients) in the IOUS group. In the FNT group, 1 case (4%, 1 out of 25 patients) had cancer tissue that was less than 1 cm from the cutting edge, compared to 7 cases (28%, 7 out of 25 patients) in the IOUS group (P=0.049), which was a significant difference. In the remaining livers of 50 consecutive patients, FNT found 5 new cancerous nodules with a sensitivity of 71.4%, a specificity of 11.1%, and a false-positive rate of 88.9%; for IOUS the results were 42.9%, 88.9%, 11.1%. The fluorescence imaging characteristics of all well-differentiated hepatocellular carcinomas were tumor tissue imaging, but all other types of tumors were ring imaging around the tumor. CONCLUSIONS FNT can improve the R0 resection rate, ensure a safe distance between tumor and cutting edge and can identify more new cancerous nodules compared to IOUS. Thus, FNT could improve the surgical treatment effect for primary liver cancer and hopefully further improve the prognosis of patients.

Fluorescence Imaging for Minimally Invasive Cancer Surgery

This article demonstrates surgical techniques of intraoperative fluorescence imaging using indocyanine green, focusing on its application in minimally invasive hepatobiliary and pancreatic surgery. In this area, indocyanine green fluorescence imaging has been applied to liver cancer identification, fluorescence cholangiography, delineation of hepatic segments, and fluorescence angiography and perfusion assessment. The development of target-specific fluorophores and advances in imaging technology will allow real-time intraoperative fluorescence imaging to develop into an essential intraoperative navigation tool. This property may contribute to enhancing both accuracy and safety of minimally invasive surgery.

Quantitative analysis of liver tumors at different stages using microscopic hyperspectral imaging technology

Liver cancer has one of the highest rates of human morbidity and mortality. However, in terms of pathology, liver cancer is traditionally clinically diagnosed based on observation of microscopic images of pathological liver sections. This paper investigates in vitro samples of rat models of bile duct carcinoma and presents a quantitative analysis method based on microscopic hyperspectral imaging technology to evaluate liver cancers at different stages. The example-based feature extraction method used in this paper mainly includes two algorithms: a morphological watershed algorithm is applied to find object and segment pathological components of pathological liver sections at different stages, and a support vector machine algorithm is implemented for liver tumor classification. Majority/minority analysis is utilized as the postclassification tool to eliminate small plaques from the preliminary classification results. Then, pseudocolor synthesis in RGB color space is used to produce the final results. The experimental results show that this method can effectively calculate the percent tumor areas in liver biopsies at different time points, that is, 3.338%, 11.952%, 15.125%, and 23.375% at 8, 12, 16, and 20 weeks, respectively. Notably, through tracking analysis, the processed results of 8-week images showed the possibility for early diagnosis of the liver tumor.

Indocyanine green-based fluorescence imaging in visceral and hepatobiliary and pancreatic surgery: State of the art and future directions

In recent years, the use of fluorescence-guided surgery (FGS) to treat benign and malignant visceral, hepatobiliary and pancreatic neoplasms has significantly increased. FGS relies on the fluorescence signal emitted by injected substances (fluorophores) after being illuminated by ad hoc laser sources to help guide the surgical procedure and provide the surgeon with real-time visualization of the fluorescent structures of interest that would be otherwise invisible. This review surveys and discusses the most common and emerging clinical applications of indocyanine green (ICG)-based fluorescence in visceral, hepatobiliary and pancreatic surgery. The analysis, findings, and discussion presented here rely on the authors' significant experience with this technique in their medical institutions, an up-to-date review of the most relevant articles published on this topic between 2014 and 2018, and lengthy discussions with key opinion leaders in the field during recent conferences and congresses. For each application, the benefits and limitations of this technique, as well as applicable future directions, are described. The imaging of fluorescence emitted by ICG is a simple, fast, relatively inexpensive, and harmless tool with numerous different applications in surgery for both neoplasms and benign pathologies of the visceral and hepatobiliary systems. The ever-increasing availability of visual systems that can utilize this tool will transform some of these applications into the standard of care in the near future. Further studies are needed to evaluate the strengths and weaknesses of each application of ICG-based fluorescence imaging in abdominal surgery.

A practical guide for the use of indocyanine green and methylene blue in fluorescence-guided abdominal surgery

Near-infrared (NIR) fluorescence imaging is gaining clinical acceptance over the last years and has been used for detection of lymph nodes, several tumor types, vital structures and tissue perfusion. This review focuses on NIR fluorescence imaging with indocyanine green and methylene blue for different clinical applications in abdominal surgery with an emphasis on oncology, based on a systematic literature search. Furthermore, practical information on doses, injection times, and intraoperative use are provided.

Diagnostic accuracy of indocyanine green fluorescence imaging and multidetector row computed tomography for identifying hepatocellular carcinoma with liver explant correlation

AIM

Indocyanine green (ICG)-fluorescence imaging is useful for detecting hepatocellular carcinoma (HCC) during surgery, but its accuracy has not been compared to that of multidetector row computed tomography (MDCT) with liver explant correlation. The aim of the present study was to clarify the precise diagnostic accuracy of ICG-fluorescence imaging for detecting HCC in a whole explant liver survey.

METHODS

Thirty-three patients with end-stage liver disease (mean age, 53 years) were prospectively enrolled in the present study. The mean Model for End-stage Liver Disease score was 14.6. One month before and 1 week prior to living donor liver transplantation, all patients underwent MDCT and administration of ICG. Following whole liver resection, the explanted liver was sliced. Gross examination and ICG-fluorescence imaging of both sides of the cut specimen was carried out and all focal liver lesions were recorded.

RESULTS

Pathologic examination diagnosed 18 of 84 focal liver lesions as HCC. Of those, MDCT and ICG-fluorescence imaging diagnosed 12 and 13 HCCs, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MDCT were 66.7%, 92.4%, 70.6%, 91.0%, and 86.9%, respectively, compared with those of ICG-fluorescence imaging at 72.2%, 31.8%, 22.4%, 80.8%, and 40.5%, respectively.

CONCLUSION

The sensitivity of ICG-fluorescence imaging for detecting HCC with liver explant correlation was similar to that of MDCT. However, ICG-fluorescence imaging had low specificity in the setting of decompensated cirrhotic explant liver correlation.

Beyond the margins: real-time detection of cancer using targeted fluorophores

Over the past two decades, synergistic innovations in imaging technology have resulted in a revolution in which a range of biomedical applications are now benefiting from fluorescence imaging. Specifically, advances in fluorophore chemistry and imaging hardware, and the identification of targetable biomarkers have now positioned intraoperative fluorescence as a highly specific real-time detection modality for surgeons in oncology. In particular, the deeper tissue penetration and limited autofluorescence of near-infrared (NIR) fluorescence imaging improves the translational potential of this modality over visible-light fluorescence imaging. Rapid developments in fluorophores with improved characteristics, detection instrumentation, and targeting strategies led to the clinical testing in the early 2010s of the first targeted NIR fluorophores for intraoperative cancer detection. The foundations for the advances that underline this technology continue to be nurtured by the multidisciplinary collaboration of chemists, biologists, engineers, and clinicians. In this Review, we highlight the latest developments in NIR fluorophores, cancer-targeting strategies, and detection instrumentation for intraoperative cancer detection, and consider the unique challenges associated with their effective application in clinical settings.

Targeted near infrared hyperthermia combined with immune stimulation for optimized therapeutic efficacy in thyroid cancer treatment

Treatment of thyroid cancer has incurred much focus because of its high prevalency. As a new strategy treating thyroid cancer, hyperthermia takes several advantages compared with surgery or chemotherapy, including minimal invasion, low systematic toxicity and the ability to enhance the immunogenicity of cancer cells with the expression Hsp70 which serves as Toll-like receptors-4 (TLR-4 agonist). However, Hsp70 as a molecular chaperone can protect cells from heat induced apoptosis and therefore compromise the tumor killing effect of hyperthermia. In this study, to solve this problem, a combined hyperthermia therapy was employed to treat thyroid cancer. We prepared a probe with the tumor targeting agent AG to monitor thyroid tumor issue and generate heat to kill tumor cells in vivo. At the same time Quercetin (inhibitor of HSP70) and lipopolysaccharide (LPS) (agonist of TLR-4) were used for the combined hyperthermia therapy. The results showed that compared with free IR820, AG modification facilitated much enhanced cellular uptake and greatly pronounced tumor targeting ability. The combined therapy exhibited the most remarkable tumor inhibition compared with the single treatments both in vitro and in vivo. These findings verified that the new therapeutic combination could significantly improve the effect of hyperthermia and shed light on a novel clinical strategy in thyroid cancer treatment.

Laparoscopic detection and resection of occult liver tumors of multiple cancer types using real-time near-infrared fluorescence guidance

BACKGROUND

Tumor recurrence after radical resection of hepatic tumors is not uncommon, suggesting that malignant lesions are missed during surgery. Intraoperative navigation using fluorescence guidance is an innovative technique enabling real-time identification of (sub)capsular liver tumors. The objective of the current study was to compare fluorescence imaging (FI) and conventional imaging modalities for laparoscopic detection of both primary and metastatic tumors in the liver.

METHODS

Patients undergoing laparoscopic resection of a malignant hepatic tumor were eligible for inclusion. Patients received standard of care, including preoperative CT and/or MRI. In addition, 10 mg indocyanine green was intravenously administered 1 day prior to surgery. After introduction of the laparoscope, inspection, FI, and laparoscopic ultrasonography (LUS) were performed. Histopathological examination of resected suspect tissue was considered the gold standard.

RESULTS

Twenty-two patients suspected of having hepatocellular carcinoma (n = 4), cholangiocarcinoma (n = 2) or liver metastases from colorectal carcinoma (n = 12), uveal melanoma (n = 2), and breast cancer (n = 2) were included. Two patients were excluded because their surgery was unexpectedly postponed several days. Twenty-six malignancies were resected in the remaining 20 patients. Sensitivity for various modalities was 80 % (CT), 84 % (MRI), 62 % (inspection), 86 % (LUS), and 92 % (FI), respectively. Three metastases (12 %) were identified solely by FI. All 26 malignancies could be detected by combining LUS and FI (100 % sensitivity).

CONCLUSION

This study demonstrates added value of FI during laparoscopic resections of several hepatic tumors. Although larger series will be needed to confirm long-term patient outcome, the technology already aids the surgeon by providing real-time fluorescence guidance.

Indocyanine green delivery systems for tumour detection and treatments

Indocyanine green (ICG) is a cyanine compound that displays fluorescent properties in the near infrared region. This dye is employed for numerous indications but nowadays its major application field regards tumour diagnosis and treatments. Optical imaging by near infrared fluorescence provides news opportunities for oncologic surgery. The imaging of ICG can be useful for intraoperative identification of several solid tumours and metastases, and sentinel lymph node detection. In addition, ICG can be used as an agent for the destruction of malignant tissue, by virtue of the production of reactive oxygen species and/or induction of a hyperthermia effect under irradiation. Nevertheless, ICG shows several drawbacks, which limit its clinical application. Several formulative strategies have been studied to overcome these problems. The rationale of the development of ICG containing drug delivery systems is to enhance the in vivo stability and biodistribution profile of this dye, allowing tumour accumulation and resulting in better efficacy. In this review, ICG containing nano-sized carriers are classified based on their chemical composition and structure. In addition to nanosystems, different formulations including hydrogel, microsystems and others loaded with ICG will be illustrated. In particular, this report describes the preparation, in vitro characterization and in vivo application of ICG platforms for cancer imaging and treatment. The promising results of all systems confirm their clinical utility but further studies are required prior to evaluating the formulations in human trials.