Near-infrared fluorescence-guided resection of colorectal liver metastases

Correlation of pathological examination with indocyanine green (ICG) intensity gradients: a prospective study in patients with liver tumor

BACKGROUND

Intraoperative indocyanine green (ICG) fluorescence imaging has been shown to be a new and innovative way to illustrate the optimal resection margin in hepatectomy for hepatocellular carcinoma. This study investigated its accuracy in resection margin determination by looking into the correlation of ICG intensity gradients with pathological examination results of resected specimens.

METHODS

This was a prospective, single-center, non-randomized controlled study. Patients who had liver tumors indicating liver resection were recruited. The hypothesis was that the use of intraoperative near-infrared/ICG fluorescence imaging would be a promising guiding tool for removing hepatocellular carcinoma with a better resection margin. Patients were given ICG (0.25 mg/kg) 1 day before operation. Resected specimens were inspected under a fluorescent imaging system. Biopsies were taken from tumors and normal tissue. Color signals obtained from ICG fluorescence imaging were compared with biopsies for analysis.

RESULTS

Twenty-two patients were recruited for study. The median size of their tumors was 2.25 cm. One patient had resection margin involvement. Under ICG fluorescence, the tumors typically lighted up as yellow color, wrapped by a zone of green color. Tumors of 17 patients (77.3%) displayed yellow color and were confirmed malignancy, while tumors of 12 patients (54.5%) displayed green color and were confirmed malignancy. Receiver operating characteristic curve was used to measure the sensitivity and specificity of the green color to look for a clear resection margin. The area under the curve was 85.3% (p = 0.019, 95% confidence interval 0.696-1.000), with a sensitivity of 0.706 and specificity of 1.000.

CONCLUSION

The use of ICG fluorescence can be helpful in determining resection margins. Resection of tumor should include complete resection of the green zone shown in the fluorescence image.

The Efficacy and Safety of an Indocyanine Green-Macroaggregated Albumin-Hyaluronic Acid Mixture (LuminoMark™) for Surgical Localization of Recurrent Thyroid Cancer

BACKGROUND

The recurrence of thyroid cancer poses challenges compounded by postoperative fibrosis and anatomic changes. By overcoming the limitations of current localizing dye techniques, indocyanine green-macroaggregated albumin-hyaluronic acid (ICG-MAA-HA) mixture dye promises improved localization. This study aimed to evaluate the efficacy and safety of the dye for recurrent thyroid cancer.

METHODS

The nine patients in this study underwent surgery and postoperative ultrasonography. The dye was injected into recurrent lesions in all the patients preoperatively. During surgery, the lesions were confirmed with an imaging system before and after excision. If the lesion was unidentifiable with the naked eye, surgical excision was performed under the corresponding fluorescent guide. Side effects related to the dye injection and completeness of the surgery were evaluated.

RESULTS

No side effects such as bleeding, skin tattooing, or pain during or after the dye injection were reported, and no discoloration occurred that interfered with the surgical field of view during surgery. In three cases (33.3 %), because it was difficult to localize metastatic lesions with the naked eye, the operation was successfully completed using an imaging system. The completeness of the surgical resection was confirmed by ultrasonography after an average of 5 months postoperatively.

CONCLUSION

The study found that ICG-MAA-HA dye effectively located metastatic and recurrent thyroid cancer and had favorable results in terms of minimal procedural side effects and potential for assisting the surgeon. A large-scale multi-institutional study is necessary to prove the clinical significance regarding patient survival and disease control.

Fluorescence-guided minimally-invasive resection of abdominal paragangliomas using indocyanine green

This retrospective study explores the utility of near-infrared (NIR) fluorescence imaging with indocyanine green (ICG) in enhancing the intraoperative identification and guidance for the resection of abdominal paragangliomas. They can be challenging to detect during minimally invasive surgery, due to their anatomical location, varying size and similar appearance in regard to their surrounding tissue. Patients with suspected abdominal paragangliomas planned for a minimally-invasive resection were included. As part of standard of care they received single intravenous dose of 5 mg ICG after abdominal exploration. NIR fluorescence imaging of the anatomical region of the suspected lesion was performed immediately following intravenous administration, to assess fluorescence signals, intraoperative identification, and histopathological correlation. Out of five resected suspicious lesions, four were imaged with NIR fluorescence, pathology confirming four as paragangliomas, the latter turned out to be an adrenal adenoma. NIR fluorescence identified all four lesions, surpassing the limitations of white-light visualization. Homogeneous fluorescence signals appeared 30-60 s post-ICG administration, which lasted up to 30 min. The study demonstrates the feasibility and potential clinical value of fluorescence-guided minimally-invasive resections of abdominal paragangliomas using a single intravenous ICG dose. These findings support the scientific basis for routine use of ICG-fluorescence-guided surgery in challenging anatomical cases, providing valuable assistance in lesion detection and resection.

Semi-automatic standardized analysis method to objectively evaluate near-infrared fluorescent dyes in image-guided surgery

Significance

Near-infrared fluorescence imaging still lacks a standardized, objective method to evaluate fluorescent dye efficacy in oncological surgical applications. This results in difficulties in translation between preclinical to clinical studies with fluorescent dyes and in the reproduction of results between studies, which in turn hampers further clinical translation of novel fluorescent dyes.

Aim

Our aim is to develop and evaluate a semi-automatic standardized method to objectively assess fluorescent signals in resected tissue.

Approach

A standardized imaging procedure was designed and quantitative analysis methods were developed to evaluate non-targeted and tumor-targeted fluorescent dyes. The developed analysis methods included manual selection of region of interest (ROI) on white light images, automated fluorescence signal ROI selection, and automatic quantitative image analysis. The proposed analysis method was then compared with a conventional analysis method, where fluorescence signal ROIs were manually selected on fluorescence images. Dice similarity coefficients and intraclass correlation coefficients were calculated to determine the inter- and intraobserver variabilities of the ROI selections and the determined signal- and tumor-to-background ratios.

Results

The proposed non-targeted fluorescent dyes analysis method showed statistically significantly improved variabilities after application on indocyanine green specimens. For specimens with the targeted dye SGM-101, the variability of the background ROI selection was statistically significantly improved by implementing the proposed method.

Conclusion

Semi-automatic methods for standardized quantitative analysis of fluorescence images were successfully developed and showed promising results to further improve the reproducibility and standardization of clinical studies evaluating fluorescent dyes.

Enhancing visualization and guidance in general surgery: a comprehensive and narrative review of the current cutting-edge technologies and future perspectives

BACKGROUND

In the last decade, there has been a great effort in developing new technologies to enhance surgical visualization and guidance. This comprehensive and narrative review aimed to provide a wide and extensive overview of the current state of the art on this topic and their near-future perspectives linked to the development of artificial intelligence (AI), by focusing on the most recent and relevant literature.

METHODS

A comprehensive and narrative review of the literature was performed by searching specific terms on PubMed/MEDLINE, Scopus, and Embase databases, assessing the current state of the art on this topic.

RESULTS

Fluorescence-guided surgery, contrast-enhanced ultrasound (CEUS), ultra-high frequency ultrasound (UHFUS), photoacoustic imaging (PAI), and augmented reality (AR) are boosting the field of image-guided techniques as the rapid development of AI in surgery is promising a more automated decision-making and surgical movements in the operating room.

CONCLUSION

Fluorescence-guided surgery, CEUS, UHFUS, PAI, and AR are becoming crucial to give surgeons a new level of information during the intervention, with the right timing and sequence, and represent the future of surgery. As many more controlled studies are needed to validate the employment of these technologies, the next generation of surgeons must become more familiar with the basics of AI to better incorporate new tools into the daily surgical practice of the future.

Efficacy and safety of near-infrared fluorescence identification of the thoracic duct during left lateral neck dissection

BACKGROUND

Thoracic duct leaks occur in up to 5% of left lateral neck dissections. No one imaging modality is routinely used to identify the thoracic duct intraoperatively. The goal of our study was to evaluate the efficacy and safety of indocyanine green lymphangiography for intraoperative identification of the thoracic duct compared to traditional methods using ambient and evaluate the optimal timing of indocyanine green administration.

METHODS

We enrolled all patients who underwent left lateral neck dissection at our institution from 2018 to 2022 in this prospective clinical trial. After indocyanine green injection into the dorsum of the foot, we performed intraoperative imaging was performed with a near-infrared fluorescence camera. We reported the data using descriptive statistics.

RESULTS

Of the 42 patients we enrolled, 14 had prior neck surgery, and 3 had prior external beam radiation. We visualized the thoracic duct with ambient light in 48% of patients and with near-infrared fluorescence visualization in 64%. In 17% of patients, we could identify the thoracic duct only using near-infrared fluorescence visualization, which occurred within 3 minutes of injection, and were required to re-dose 5 patients. We visualized the thoracic duct with near-infrared fluorescence in all patients with prior neck radiation and 77% of patients with prior neck surgery. One adverse reaction occurred (hypotension), and 5 intraoperative thoracic duct injuries occurred that were ligated. There with no chylous fistulas postoperatively.

CONCLUSION

This trial demonstrates that near-infrared fluorescence identification of the thoracic duct is feasible and safe with indocyanine green lymphangiography, even in patients with prior neck surgery or radiation.

Exploring Structural-Photophysical Property Relationships in Mitochondria-Targeted Deep-Red/NIR-Emitting Coumarins

Organic fluorophores operating in the optical window of biological tissues, namely in the deep-red and near-infrared (NIR) region of the electromagnetic spectrum, offer several advantages for fluorescence bioimaging applications owing to the appealing features of long-wavelength light, such as deep tissue penetration, lack of toxicity, low scattering, and reduced interference with cellular autofluorescence. Among these, COUPY dyes based on non-conventional coumarin scaffolds display suitable photophysical properties and efficient cellular uptake, with a tendency to accumulate primarily in mitochondria, which renders them suitable probes for bioimaging purposes. In this study, we have explored how the photophysical properties and subcellular localization of COUPY fluorophores can be modulated through the modification of the coumarin backbone. While the introduction of a strong electron-withdrawing group, such as the trifluoromethyl group, at position 4 resulted in an exceptional photostability and a remarkable redshift in the absorption and emission maxima when combined with a julolidine ring replacing the N,N-dialkylaminobenzene moiety, the incorporation of a cyano group at position 3 dramatically reduced the brightness of the resulting fluorophore. Interestingly, confocal microscopy studies in living HeLa cells revealed that the 1,1,7,7-tetramethyl julolidine-containing derivatives accumulated in the mitochondria with much higher specificity. Overall, our results provide valuable insights for the design and optimization of new COUPY dyes operating in the deep-red/NIR region.

High-precision detection and navigation surgery of colorectal cancer micrometastases

Surgical resection is an effective treatment for colorectal cancer (CRC) patients, whereas occult metastases hinder the curative effect. Currently, there is no effective method to achieve intraoperatively diagnosis of tumor-positive lymph nodes (LNs). Herein, we adopt a near-infrared-II (NIR-II) organic donor-pi-acceptor-pi-donor probe FE-2PEG, which exhibits bright fluorescence over 1100 nm, excellent photostability, blood circulation time, and biocompatibility, to achieve high-performance bioimaging with improved temporal and spatial resolution. Importantly, the FE-2PEG shows efficient passive enrichment in orthotopic CRC, metastatic mesenteric LNs, and peritoneal metastases by enhanced permeability and retention effect. Under NIR-II fluorescence-guided surgery (FGS), the peritoneal micrometastases were resected with a sensitivity of 94.51%, specificity of 86.59%, positive predictive value (PPV) of 96.57%, and negative predictive value of 79.78%. The PPV still achieves 96.07% even for micrometastases less than 3 mm. Pathological staining and NIR-II microscopy imaging proved that FE-2PEG could successfully delineate the boundary between the tumor and normal tissues. Dual-color NIR-II imaging strategy with FE-2PEG (1100 ~ 1300 nm) and PbS@CdS quantum dots (> 1500 nm) successfully protects both blood supply and normal tissues during surgery. The NIR-II-based FGS provides a promising prospect for precise intraoperative diagnosis and minimally invasive surgery of CRC.

Deep learning for tumor margin identification in electromagnetic imaging

In this work, a novel method for tumor margin identification in electromagnetic imaging is proposed to optimize the tumor removal surgery. This capability will enable the visualization of the border of the cancerous tissue for the surgeon prior or during the excision surgery. To this end, the border between the normal and tumor parts needs to be identified. Therefore, the images need to be segmented into tumor and normal areas. We propose a deep learning technique which divides the electromagnetic images into two regions: tumor and normal, with high accuracy. We formulate deep learning from a perspective relevant to electromagnetic image reconstruction. A recurrent auto-encoder network architecture (termed here DeepTMI) is presented. The effectiveness of the algorithm is demonstrated by segmenting the reconstructed images of an experimental tissue-mimicking phantom. The structure similarity measure (SSIM) and mean-square-error (MSE) average of normalized reconstructed results by the DeepTMI method are about 0.94 and 0.04 respectively, while that average obtained from the conventional backpropagation (BP) method can hardly overcome 0.35 and 0.41 respectively.

Use of Near-Infrared Fluorescence Techniques in Minimally Invasive Surgery for Colorectal Liver Metastases

Colorectal liver metastases (CRLM) afflict a significant proportion of patients with colorectal cancer (CRC), ranging from 25% to 30% of patients throughout the course of the disease. In recent years, there has been a surge of interest in the application of near-infrared fluorescence (NIRF) imaging as an intraoperative imaging technique for liver surgery. The utilisation of NIRF-guided liver surgery, facilitated by the administration of fluorescent dye indocyanine green (ICG), has gained traction in numerous medical institutions worldwide. This innovative approach aims to enhance lesion differentiation and provide valuable guidance for surgical margins. The use of ICG, particularly in minimally invasive surgery, has the potential to improve lesion detection rates, increase the likelihood of achieving R0 resection, and enable anatomically guided resections. However, it is important to acknowledge the limitations of ICG, such as its low specificity. Consequently, there has been a growing demand for the development of tumour-specific fluorescent probes and the advancement of camera systems, which are expected to address these concerns and further refine the accuracy and reliability of intraoperative fluorescence imaging in liver surgery. While NIRF imaging has been extensively studied in patients with CRLM, it is worth noting that a significant proportion of published research has predominantly focused on the detection of hepatocellular carcinoma (HCC). In this study, we present a comprehensive literature review of the existing literature pertaining to intraoperative fluorescence imaging in minimally invasive surgery for CRLM. Moreover, our analysis places specific emphasis on the techniques employed in liver resection using ICG, with a focus on tumour detection in minimal invasive surgery (MIS). Additionally, we delve into recent developments in this field and offer insights into future perspectives for further advancements.

Preclinical evaluation of molecularly targeted fluorescent probes in perfused amputated human limbs

SIGNIFICANCE

This first-in-kind, perfused, and amputated human limb model allows for the collection of human data in preclinical selection of lead fluorescent agents. The model facilitates more accurate selection and testing of fluorophores with human-specific physiology, such as differential uptake and signal in fat between animal and human models with zero risk to human patients. Preclinical testing using this approach may also allow for the determination of tissue toxicity, clearance time of fluorophores, and the production of harmful metabolites.

AIM

This study was conducted to determine the fluorescence intensity values and tissue specificity of a preclinical, nerve tissue targeted fluorophore, as well as the capacity of this first-in-kind model to be used for lead fluorescent agent selection in the future.

APPROACH

Freshly amputated human limbs were perfused for 30 min prior to in situ and ex vivo imaging of nerves with both open-field and closed-field commercial fluorescence imaging systems.

RESULTS

In situ, open-field imaging demonstrated a signal-to-background ratio (SBR) of 4.7 when comparing the nerve with adjacent muscle tissue. Closed-field imaging demonstrated an SBR of 3.8 when the nerve was compared with adipose tissue and 4.8 when the nerve was compared with muscle.

CONCLUSIONS

This model demonstrates an opportunity for preclinical testing, evaluation, and selection of fluorophores for use in clinical trials as well as an opportunity to study peripheral pathologies in a controlled environment.

Preoperative planning and intraoperative real-time navigation with indocyanine green fluorescence in robotic liver surgery

PURPOSE

We aimed at exploring indocyanine green (ICG) fluorescence wide spectrum of applications in hepatobiliary surgery as can result particularly useful in robotic liver resections (RLR) in order to overcome some technical limitations, increasing safety, and efficacy.

METHODS

We describe our experience of 76 RLR performed between March 2020 and December 2022 exploring all the possible applications of pre- and intraoperative ICG administration.

RESULTS

Hepatocellular carcinoma and colorectal liver metastases were the most common indications for RLR (34.2% and 26.7% of patients, respectively), and 51.3% of cases were complex resections with high IWATE difficulty scores. ICG was administered preoperatively in 61 patients (80.3%), intraoperatively in 42 patients (55.3%) and in both contexts in 25 patients (32.9%), with no observed adverse events. The most frequent ICG goal was to achieve tumor enhancement (59 patients, 77.6%), with a success rate of 94.9% and the detection of 3 additional malignant lesions. ICG facilitated evaluation of the resection margin for residual tumor and perfusion adequacy in 33.9% and 32.9% of cases, respectively, mandating a resection enlargement in 7.9% of patients. ICG fluorescence allowed the identification of the transection plane through negative staining in the 25% of cases. Vascular and biliary structures were visualized in 21.1% and 9.2% of patients, with a success rate of 81.3% and 85.7%, respectively.

CONCLUSION

RLR can benefit from the routine integration of ICG fluoresce evaluation according to each individual patient and condition-specific goals and issues, allowing liver functional assessment, anatomical and vascular evaluation, tumor detection, and resection margins assessment.

Intraoperative Imaging in Hepatopancreatobiliary Surgery

Hepatopancreatobiliary surgery belongs to one of the most complex fields of general surgery. An intricate and vital anatomy is accompanied by difficult distinctions of tumors from fibrosis and inflammation; the identification of precise tumor margins; or small, even disappearing, lesions on currently available imaging. The routine implementation of ultrasound use shifted the possibilities in the operating room, yet more precision is necessary to achieve negative resection margins. Modalities utilizing fluorescent-compatible dyes have proven their role in hepatopancreatobiliary surgery, although this is not yet a routine practice, as there are many limitations. Modalities, such as photoacoustic imaging or 3D holograms, are emerging but are mostly limited to preclinical settings. There is a need to identify and develop an ideal contrast agent capable of differentiating between malignant and benign tissue and to report on the prognostic benefits of implemented intraoperative imaging in order to navigate clinical translation. This review focuses on existing and developing imaging modalities for intraoperative use, tailored to the needs of hepatopancreatobiliary cancers. We will also cover the application of these imaging techniques to theranostics to achieve combined diagnostic and therapeutic potential.

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.

The Value of Indocyanine Green Image-Guided Surgery in Patients with Primary Liver Tumors and Liver Metastases

INTRODUCTION

Successful R0 resection is crucial for the survival of patients with primary liver cancer (PLC) or liver metastases. Up to date, surgical resection lacks a sensitive, real-time intraoperative imaging modality to determine R0 resection. Real-time intraoperative visualization with near-infrared light fluorescence (NIRF) using indocyanine green (ICG) may have the potential to meet this demand. This study evaluates the value of ICG visualization in PLC and liver metastases surgery regarding R0 resection rates.

MATERIALS AND METHODS

Patients with PLC or liver metastases were included in this prospective cohort study. ICG 10 mg was administered intravenously 24 h before surgery. Real-time intraoperative NIRF visualization was created with the Spectrum^TM fluorescence imaging camera system. First, all liver segments were inspected with the fluorescence imaging system and intraoperative ultrasound for identification of the known tumor, as well as additional lesions, and were compared to preoperative MRI images. PLC, liver metastases, and additional lesions were then resected according to oncological principles. In all resected specimens, the resection margins were analyzed with the fluorescence imaging system for ICG-positive spots immediately after resection. Histology of additional detected lesions, as well as ICG fluorescence compared to histological resection margins, were assessed.

RESULTS

Of the 66 included patients, median age was 65.5 years (IQR 58.7-73.9), 27 (40.9%) were female, and 18 (27.3%) were operated on laparoscopically. Additional ICG-positive lesions were detected in 23 (35.4%) patients, of which 9 (29%) were malignant. In patients with no fluorescent signal at the resection margin, R0 rate was 93.9%, R1 rate was 6.1%, and R2 rate was 0% compared to an ICG-positive resection margin with an R0 rate of 64.3%, R1 rate of 21.4%, and R2 rate of 14.3% (p = 0.005). One- and two-year overall survival rates were 95.2% and 88.4%, respectively.

CONCLUSION

The presented study provides significant evidence that ICG NIRF guidance helps to identify R0 resection intraoperatively. This offers true potential to verify radical resection and improve patient outcomes. Furthermore, implementation of NIRF-guided imaging in liver tumor surgery allows us to detect a considerable amount of additional malignant lesions.

Fluorescence-guided surgery: comprehensive review

BACKGROUND

Despite significant improvements in preoperative workup and surgical planning, surgeons often rely on their eyes and hands during surgery. Although this can be sufficient in some patients, intraoperative guidance is highly desirable. Near-infrared fluorescence has been advocated as a potential technique to guide surgeons during surgery.

METHODS

A literature search was conducted to identify relevant articles for fluorescence-guided surgery. The literature search was performed using Medical Subject Headings on PubMed for articles in English until November 2022 and a narrative review undertaken.

RESULTS

The use of invisible light, enabling real-time imaging, superior penetration depth, and the possibility to use targeted imaging agents, makes this optical imaging technique increasingly popular. Four main indications are described in this review: tissue perfusion, lymph node assessment, anatomy of vital structures, and tumour tissue imaging. Furthermore, this review provides an overview of future opportunities in the field of fluorescence-guided surgery.

CONCLUSION

Fluorescence-guided surgery has proven to be a widely innovative technique applicable in many fields of surgery. The potential indications for its use are diverse and can be combined. The big challenge for the future will be in bringing experimental fluorophores and conjugates through trials and into clinical practice, as well as validation of computer visualization with large data sets. This will require collaborative surgical groups focusing on utility, efficacy, and outcomes for these techniques.

Near-infrared fluorescence imaging of hepatocellular carcinoma cells regulated by β-catenin signaling pathway

Background

Near-infrared fluorescence (NIRF) imaging has recently emerged as a promising tool for noninvasive cancer imaging. However, lack of tumor sensitivity and specificity restricts the application of NIRF dyes in surgical navigation.

Methods

Herein, we investigated the imaging features of NIRF dye MHI-148 and indocyanine green (ICG) in live cell imaging and xenograft nude mice models. TCGA dataset analysis and immunohistochemistry were conducted to investigate the expression of OATPs or ABCGs in hepatocellular carcinoma (HCC) tissues. OATPs or ABCGs were knocked down and overexpressed in HCC cells using transient transfection by siRNA and plasmids or stable transfection by lentivirus. Further, qRT-PCR ,Western blotting and the use of agonists or inhibitors targeting β-catenin signaling pathway were applied to explore its important role in regulation of OATP2B1 and ABCG2 expression.

Results

Here we demonstrated that NIRF dye MHI-148 was biocompatible as indocyanine green (ICG) but with higher imaging intensity and preferential uptake and retention in hepatocellular carcinoma (HCC) cells and tissues. Moreover, our data indicated that membrane transporters OATP2B1 and ABCG2, which regulated by β-catenin signaling pathway, mediated tumor-specific accumulation and retention of MHI-148 in HCC cells. In addition, the treatment with β-catenin inhibitor significantly enhanced the accumulation of MHI-148 in HCC tissues and improved the efficacy of tumor imaging with MHI-148 in vivo.

Conclusions

Our study uncovers a mechanism that links the distribution and expression of the membrane transporters OATP2B1 and ABCG2 to the tumor-specific accumulation of MHI-148, and provides evidence supporting a regulating role of the β-catenin signaling pathway in OATP2B1 and ABCG2- induced retention of MHI-148 inHCC tissues, and strategy targeting key components of MHI-148 transport machinery may be a potential approach to improve HCC imaging.

European Association for Endoscopic Surgery (EAES) consensus on Indocyanine Green (ICG) fluorescence-guided surgery

BACKGROUND

In recent years, the use of Indocyanine Green (ICG) fluorescence-guided surgery during open and laparoscopic procedures has exponentially expanded across various clinical settings. The European Association of Endoscopic Surgery (EAES) initiated a consensus development conference on this topic with the aim of creating evidence-based statements and recommendations for the surgical community.

METHODS

An expert panel of surgeons has been selected and invited to participate to this project. Systematic reviews of the PubMed, Embase and Cochrane libraries were performed to identify evidence on potential benefits of ICG fluorescence-guided surgery on clinical practice and patient outcomes. Statements and recommendations were prepared and unanimously agreed by the panel; they were then submitted to all EAES members through a two-rounds online survey and results presented at the EAES annual congress, Barcelona, November 2021.

RESULTS

A total of 18,273 abstracts were screened with 117 articles included. 22 statements and 16 recommendations were generated and approved. In some areas, such as the use of ICG fluorescence-guided surgery during laparoscopic cholecystectomy, the perfusion assessment in colorectal surgery and the search for the sentinel lymph nodes in gynaecological malignancies, the large number of evidences in literature has allowed us to strongly recommend the use of ICG for a better anatomical definition and a reduction in post-operative complications.

CONCLUSIONS

Overall, from the systematic literature review performed by the experts panel and the survey extended to all EAES members, ICG fluorescence-guided surgery could be considered a safe and effective technology. Future robust clinical research is required to specifically validate multiple organ-specific applications and the potential benefits of this technique on clinical outcomes.

Real-time administration of indocyanine green in combination with computer vision and artificial intelligence for the identification and delineation of colorectal liver metastases

Introduction

Fluorescence guided surgery for the identification of colorectal liver metastases (CRLM) can be better with low specificity and antecedent dosing impracticalities limiting indocyanine green (ICG) usefulness currently. We investigated the application of artificial intelligence methods (AIM) to demonstrate and characterise CLRMs based on dynamic signalling immediately following intraoperative ICG administration.

Methods

Twenty-five patients with liver surface lesions (24 CRLM and 1 benign cyst) undergoing open/laparoscopic/robotic procedures were studied. ICG (0.05 mg/kg) was administered with near-infrared recording of fluorescence perfusion. User-selected region-of-interest (ROI) perfusion profiles were generated, milestones relating to ICG inflow/outflow extracted and used to train a machine learning (ML) classifier. 2D heatmaps were constructed in a subset using AIM to depict whole screen imaging based on dynamic tissue-ICG interaction. Fluorescence appearances were also assessed microscopically (using H&E and fresh-frozen preparations) to provide tissue-level explainability of such methods.

Results

The ML algorithm correctly classified 97.2 % of CRLM ROIs (n = 132) and all benign lesion ROIs (n = 6) within 90-s of ICG administration following initial mathematical curve analysis identifying ICG inflow/outflow differentials between healthy liver and CRLMs. Time-fluorescence plots extracted for each pixel in 10 lesions enabled creation of 2D characterising heatmaps using flow parameters and through unsupervised ML. Microscopy confirmed statistically less CLRM fluorescence vs adjacent liver (mean ± std deviation signal/area 2.46 ± 9.56 vs 507.43 ± 160.82 respectively p < 0.001) with H&E diminishing ICG signal (n = 4).

Conclusion

ML accurately identifies CRLMs from surrounding liver tissue enabling representative 2D mapping of such lesions from their fluorescence perfusion patterns using AIM. This may assist in reducing positive margin rates at metastatectomy and in identifying unexpected/occult malignancies.

Near-infrared Fluorescence Imaging for Detecting Pancreatic Liver Metastasis in an Orthotopic Athymic Mouse Model

BACKGROUND/AIM

Evidence of metastatic disease precludes oncological resection of pancreatic cancer. Near-infrared (NIR) fluorescent labels, such as indocyanine green (ICG), assist in the intraoperative detection of occult and micrometastatic liver disease. The present study aimed to analyse the role of NIR fluorescence imaging using ICG for pancreatic liver disease as proof of concept in an orthotopic athymic mouse model.

MATERIALS AND METHODS

Pancreatic ductal adenocarcinoma was induced by injecting L3.6pl human pancreatic tumour cells into the pancreatic tail of seven athymic mice. After four weeks of tumour growth, ICG was injected into the tail vein and NIR fluorescence imaging was performed at harvest to determine tumour-to-liver ratios (TLR) using Quest Spectrum^® Fluorescence Imaging Platform.

RESULTS

Pancreatic tumour growth and liver metastasis could be visually confirmed for all seven animals. None of the hepatic metastases showed any detectable ICG-uptake. ICG-staining failed to visualize the liver metastases or to increase fluorescence intensity of the rim around the hepatic lesions.

CONCLUSION

ICG-staining fails to visualize liver metastases induced by L3.6pl pancreatic tumour cells in athymic nude mice by NIR fluorescence imaging. Further studies are necessary to delineate the underlying mechanism for insufficient ICG uptake in these pancreatic liver metastases and for the lack of a fluorescent rim around the liver lesions.

Indocyanine green fluorescence patterns of hepatocellular carcinoma correlate with pathological and molecular features

BACKGROUND

Intraoperative Indocyanine Green Dye (ICG) routinely used in hepatobiliary surgery identifies different fluorescent patterns of hepatocellular carcinoma (HCC), a highly heterogeneous cancer. We aimed to correlate these patterns with gene mutations and extensive pathological features beyond the well-known tumor differentiation.

METHODS

Between February 2017 and December 2019, 21 HCC in 16 consecutive patients who underwent intraoperative ICG fluorescence imaging were included. Pathological review was performed by one pathologist blinded to fluorescence features. Random forest machine learning algorithm correlated pathological features of the tumor, peritumoral and non-tumoral liver, and gene mutations from a 28 gene-panel with rim and intra-lesion fluorescence.

RESULTS

Three HCC had negative intra-lesion and rim-like emission, 7 HCC had homogeneous pattern and 11 heterogeneous patterns in whom 3 with rim-like emission. Rim emission was associated with peritumoral vascular changes, lower differentiation and lower serum AFP level. Homogeneous intra-lesion fluorescence was associated with lower necrosis rate, thinner capsule, absence of peritumoral liver changes, and higher serum AFP level. Heterogeneous HCC without rim harbored lesser TP53 and ARID1A mutations.

CONCLUSION

Tumoral and peri-tumoral fluorescence classification of HCC yielded a possible intraoperative pathological and molecular characterization. These preliminary observations could lead to intraoperative refinement in surgical strategy.

Indocyanine green (ICG) fluorescent cholangiography in laparoscopic cholecystectomy: Simplifying time and dose

BACKGROUND

This article aims to analyze and to simplify the optimal dose and time of intravenous indocyanine green (ICG) administration to achieve the identification of the cystic duct and the common bile duct (CBD).

METHODS

A consecutive series of 146 patients was prospectively analyzed and divided into three groups according to the time of ICG administration: at induction of anesthesia group (20-30 min); hours before group (between 2 and 6 h); and the day before group (≥6 h); and two groups according to the dose of ICG: 1 cc (2.5 mg) or weight-based dose (0.05 mg/kg).

RESULTS

The CBD was better visualized in the at induction of anesthesia group (85.4%), in the hours before group (97.1%) (p = 0.002) and in the 1cc group (p = 0.011). When we analyzed the 1 cc group (n = 126) a greater visualization of the CBD was observed in the at induction of anesthesia group (86.7%) and in the hours before group (97.1%) (p = 0.027).

CONCLUSION

Due to its simplicity and reproducibility, we suggest a dose of 2.5 mg administered 2-6 h before the procedure is the optimal. However, ICG administered 30 min prior to the surgery is enough for adequate visualization of biliary structures.

Retroperitoneal Lymph Node Dissection in Colorectal Cancer with Lymph Node Metastasis: A Systematic Review

The benefits and prognosis of RPLND in CRC have not yet been fully established. This systematic review aimed to evaluate the outcomes for CRC patients with RPLNM undergoing RPLND. A literature search of MEDLINE, EMBASE, EMCare, and CINAHL identified studies from between January 1990 and June 2022 that reported data on clinical outcomes for patients who underwent RPLND for RPLNM in CRC. The following primary outcome measures were derived: postoperative morbidity, disease free-survival (DFS), overall survival (OS), and re-recurrence. Nineteen studies with a total of 541 patients were included. Three hundred and sixty-three patients (67.1%) had synchronous RPLNM and 178 patients (32.9%) had metachronous RPLNM. Perioperative chemotherapy was administered in 496 (91.7%) patients. The median DFS was 8.6-38.0 months and 5-year DFS was 24.4% (10.0-60.5%). The median OS was 25.0-83.0 months and 5-year OS was 47.0% (15.0-87.5%). RPLND is a feasible treatment option with limited morbidity and possible oncological benefit for both synchronous and metachronous RPLNM in CRC. Further prospective clinical trials are required to establish a better evidence base for RPLND in the context of RPLNM in CRC and to understand the timing of RPLND in a multimodality pathway in order to optimise treatment outcomes for this group of patients.

Intra-operative indocyanine green fluorescence imaging in hepatobiliary surgery: a narrative review of the literature as a useful guide for the surgeon

INTRODUCTION

In hepatobiliary surgery, intra-operative indocyanine green (ICG) fluorescence imaging use started in the late 2000s with Japanese surgical teams and is now gaining popularity among surgeons all over the world to improve accuracy and safety of surgical procedures. However, even if ICG fluorescence has been shown to be a safe imaging modality, only a few clinical efficacity studies have been performed and no guidance has been established. This narrative review aims at assessing the potential applications of ICG fluorescence imaging in hepatobiliary surgery.

METHODS

We screened the available international literature to identify the most used applications of ICG fluorescence imaging in hepatobiliary surgery.

RESULTS

Three main fields were identified: biliary duct visualization, hepatic segments' delimitation, and liver tumor detection. Comments, application protocols, prospects, and limitations of each technique were described.

DISCUSSION

These results could guide hepatobiliary surgeons in their use of ICG fluorescence imaging; nevertheless, further prospective studies are needed to assess the sensitivity and specificity of this modality.

Applicability of autofluorescence and fluorescent probes in the trans-surgical of oral carcinomas: A systematic review

Oral cancer represents an important health problem, as it is the sixth most common type of cancer in the world and is associated with high rates of morbidity and mortality. The treatment considered the gold standard for this type of tumor is surgical resection with negative margins, with a distance of at least 5 mm from the tumor. This procedure is strongly associated with local control and disease-specific survival, however, in many cases, large amounts of healthy tissue are removed, resulting in surgical defects, compromising various functions and directly affecting the individual's quality of life. From this perspective, this systematic review aimed to evaluate the use of autofluorescence and fluorescent probes as potential adjuvant techniques to facilitate the delineation of surgical margins for oral cancers. A comprehensive search was performed in Pubmed, Scopus, Web of Science, LIVIVO, Embase, ProQuest Open Access Dissertations & Theses, Open Access Theses and Dissertations, and DART Europe databases, where 1948 articles were found. After the different stages of critical evaluation, 15 articles were selected, eligible for the inclusion criteria. Of these, 7 articles used autofluorescence, 7 used fluorescent probes and 1 article used both methods. As for autofluorescence, the most used device was the VELScope, and indocyanine green was the most used probe. Compared to histopathology, autofluorescence did not obtain significant and/or superiors results. In contrast to fluorescent probes that, most articles showed a good performance of margins during surgical resection, making them a promising alternative. However, it is still necessary to carry out the analysis of more articles, with more significant samples and sensitivity and specificity data to qualify the results.

Novel intraoperative near-infrared imaging strategy to identify abnormalities in the anterior mediastinum

Thoracic surgeons are frequently asked to biopsy suspicious tissues in the anterior mediastinum to discriminate between a reactive versus malignant pathology such as lymph nodes. The most common benign cause of a mediastinal lymph node is a reactive lymph node from a prior infection or inflammatory process such as post-COVID or granulomatous disease. The most common malignant cause is a lymphoproliferative disorder but also metastatic disease from neck, breast and other regional cancers. Biopsies in this location are challenging because they are far from the trachea and the sternum is a barrier to most diagnostic procedures. Thus, a surgical biopsy is frequently required and a common procedure for Thoracic surgeons. Technically, identifying these lesions can be challenging, particularly for small lesions or those in patients with high body mass index. In order to improve contrast between diseased tissue in the anterior mediastinum and surrounding adipose tissue, we have been studying near-infrared imaging during surgery using indocyanine green (ICG) to give contrast to the abnormal tissues and to avoid an unnecessary extended resection. We developed a modified technique to give ICG to a patient during a biopsy in the anterior mediastinum to specifically highlight abnormal tissues. As a proof-of-principle, we present a case of a young woman with a suspicious 2 cm mediastinal lymph node that required surgical biopsy.

Advanced diagnostic and therapeutic strategies in nanotechnology for lung cancer

As a highly invasive thoracic malignancy with increasing prevalence, lung cancer is also the most lethal cancer worldwide due to the failure of effective early detection and the limitations of conventional therapeutic strategies for advanced-stage patients. Over the past few decades, nanotechnology has emerged as an important technique to obtain desired features by modifying and manipulating different objects on a molecular level and gained a lot of attention in many fields of medical applications. Studies have shown that in lung cancer, nanotechnology may be more effective and specific than traditional methods for detecting extracellular cancer biomarkers and cancer cells in vitro, as well as imaging cancer in vivo; Nanoscale drug delivery systems have developed rapidly to overcome various forms of multi-drug resistance and reduce detrimental side effects to normal tissues by targeting cancerous tissue precisely. There is no doubt that nanotechnology has the potential to enhance healthcare systems by simplifying and improving cancer diagnostics and treatment. Throughout this review, we summarize and highlight recent developments in nanotechnology applications for lung cancer in diagnosis and therapy. Moreover, the prospects and challenges in the translation of nanotechnology-based diagnostic and therapeutic methods into clinical applications are also discussed.

Synthesis and application of the fluorescent furan and imidazole probes for selective in vivo and in vitro cancer cell imaging

Development of imaging probes for identification of tumors in the early stages of growth can significantly reduce the tumor-related health hazards and improve our capacity for treatment of cancer. In this work, three different furan and imidazole fluorescent derivatives abbreviated as Cyclo X, SAC and SNO are introduced for in vivo and in vitro imaging of cancer cells. The fluorescence quantum yield values were 0.226, 0.400 and 0.479 for Cyclo X, SAC and SNO, respectively. The excitation and emission wavelengths of maximum intensity were (360, 452), (350, 428) and (350, 432) nm for Cyclo X, SAC and SNO, respectively. The MTT reduction assay was used to estimate the cytotoxic activity of the proposed derivatives against HT-29 (cancer) and Vero (normal) cell lines. Cyclo X showed no cytotoxic effect, while SAC and SNO showed significantly higher cytotoxicity against the tested cell lines than cisplatin as a well-known anticancer drug. In vitro fluorescence microscopic images obtained using HT-29 cells showed that Cyclo X produced very bright images. The in vivo cancer cell imaging using 4T1 tumor-bearing mice revealed that Cyclo X is selectively accumulated in the tumor without distribution in the mice body organs. The spectral and structural stability, large Stokes shift, non-cytotoxicity and high level of selectivity for in vivo imaging are properties that make Cyclo X a suitable candidate to be used for long-term monitoring of cancer cells.

Ultrabright Renal-Clearable Cyanine-Protein Nanoprobes for High-Quality NIR-II Angiography and Lymphography

The renal-clearable aspect of imaging agent with minimum toxicity issues and side effects is essential for clinical translation, yet clinical near-infrared-I/II (NIR-I/II) fluorophores with timely renal-clearance pathways are very limited. Herein, we rationally develop the cyanine-protein composite strategy through covalent bonding of β-lactoglobulin (β-LG) and chloride-cyanine dye to produce a brilliant and stable NIR-I/II fluorophore (e.g., β-LG@IR-780). The β-LG acts as a protecting shell with small molecular weight (18.4 kDa) and ultrasmall size (&lt;5 nm), thus endowing the β-LG@IR-780 with excellent biocompatibility and renal excretion. Our β-LG@IR-780 probe enables noninvasive and precise NIR-II visualization of the physiological and pathological conditions of the vascular and lymphatic drainage system, facilitating intraoperative imaging-guided surgery and postoperative noninvasive monitoring. The minimum accumulation of our probes in the main organs improves the overall biosafety. This study provides a facile methodology for new-generation NIR-II fluorophores and largely improves the brightness and pharmacokinetics of small molecular dyes.

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.

The Role of ICG in Robot-Assisted Liver Resections

Introduction: Robotic-assisted liver surgery (RALS) with its known limitations is gaining more importance. The fluorescent dye, indocyanine green (ICG), is a way to overcome some of these limitations. It accumulates in or around hepatic masses. The integrated near-infrared cameras help to visualize this accumulation. We aimed to compare the influence of ICG staining on the surgical and oncological outcomes in patients undergoing RALS. Material and Methods: Patients who underwent RALS between 2014 and 2021 at the Department of General Surgery at the University Hospital Schleswig-Holstein, Campus Kiel, were included. In 2019, ICG-supported RALS was introduced. Results: Fifty-four patients were included, with twenty-eight patients (50.9%) receiving preoperative ICG. Hepatocellular carcinoma (32.1%) was the main entity resected, followed by the metastasis of colorectal cancers (17%) and focal nodular hyperplasia (15.1%). ICG staining worked for different tumor entities, but diffuse staining was noted in patients with liver cirrhosis. However, ICG-supported RALS lasted shorter (142.7 ± 61.8 min vs. 246.4 ± 98.6 min, p < 0.001), tumors resected in the ICG cohort were significantly smaller (27.1 ± 25.0 mm vs. 47.6 ± 35.2 mm, p = 0.021) and more R0 resections were achieved by ICG-supported RALS (96.3% vs. 80.8%, p = 0.075). Conclusions: ICG-supported RALS achieve surgically and oncologically safe results, while overcoming the limitations of RALS.

EGFR-targeted fluorescent imaging using the da Vinci® Firefly™ camera for gallbladder cancer

Background

Fluorescent imaging may aid with the precise diagnosis and treatment of patients with gallbladder cancer. In this study, we sought to demonstrate whether the da Vinci® surgical system and Firefly™ camera could detect EGFR-targeted fluorescent images in orthotopic mouse models of gallbladder cancer.

Methods

An orthotopic mouse model of gallbladder cancer was created by injecting NOZ gallbladder cancer cells mixed with Matrigel into the gallbladder. In vivo imaging of subcutaneous and orthotopic gallbladder tumors was performed after the injection of DyLight 650- or 800-conjugated EGFR antibody.

Results

Western blotting, flow cytometry, and confocal microscopy showed the presence of EGFR in NOZ cells, but not in HEK293 cells. Subcutaneous NOZ cell tumors fluoresced after injection with fluorescent EGFR antibody, but subcutaneous HEK293 tumors did not. Fluorescent EGFR antibody made orthotopic NOZ tumors fluoresce, with an intensity stronger than that in the surrounding normal tissues. Histochemical examination confirmed the location of the tumors inside the gallbladder and adjacent liver parenchyma. Fluorescent signal was also detected in orthotopic gallbladder tumors with Firefly™ camera.

Conclusion

Our study showed that fluorescent EGFR antibodies and the Firefly camera in the da Vinci system can detect fluorescing gallbladder tumors, which demonstrates their potential use for molecular imaging-based prevision surgery in the near future.

Robot-assisted liver resection: the real benefit so far

BACKGROUND

Minimally invasive liver resection is associated with lower perioperative morbidity and shorter hospital stay. However, the added benefit of the robotic platform over conventional laparoscopy is a matter of ongoing investigation.

PURPOSE

The purpose of this narrative review is to provide an up-to-date and balanced evaluation of the benefits and shortcomings of robotic liver surgery for the modern hepatobiliary surgeon.

CONCLUSIONS

Advantages of a robotic approach to liver resection include a shortened learning curve, the ability to complete more extensive or complex minimally invasive operations, and integrated fluorescence guidance. However, the robotic platform remains limited by a paucity of parenchymal transection devices, complete lack of haptic feedback, and added operating time associated with docking and instrument exchange. Like laparoscopic hepatectomy, robotic hepatectomy may provide patients with more rapid recovery and a shorter hospital stay, which can help offset the substantial costs of robot acquisition and maintenance. The oncologic outcomes of robotic hepatectomy appear to be equivalent to laparoscopic and open hepatectomy for appropriately selected patients.

Quantifying the Photochemical Damage Potential of Contrast-Enhanced Fluorescence Imaging Products: Singlet Oxygen Production

The benefits of contrast‐enhancing imaging probes have become apparent over the past decade. However, there is a gap in the literature when it comes to the assessment of the phototoxic potential of imaging probes and systems emitting visible and/or near‐infrared radiation. The primary mechanism of fluorescent agent phototoxicity is thought to involve the production of reactive molecular species (RMS), yet little has been published on the best practices for safety evaluation of RMS production levels for clinical products. We have proposed methods involving a cell‐free assay to quantify singlet oxygen [(SO) a known RMS] generation of imaging probes, and performed testing of Indocyanine Green (ICG), Proflavine, Methylene Blue, IR700 and IR800 at clinically relevant concentrations and radiant exposures. Results indicated that SO production from IR800 and ICG were more than two orders of magnitude below that of the known SO generator Rose Bengal. Methylene Blue and IR700 produced much higher SO levels than ICG and IR800. These results were in good agreement with data from the literature. While agents that exhibit spectral overlap with the assay may be more prone to errors, our tests for one of these agents (Proflavine) appeared robust. Overall, our results indicate that this methodology shows promise for assessing the phototoxic potential of fluorophores due to SO production.

High-precision tumor resection down to few-cell level guided by NIR-IIb molecular fluorescence imaging

Surgical removal of tumors has been performed to combat cancer for over a century by surgeons relying on visual inspection and experience to identify margins between malignant and healthy tissues. Herein, we present a rare-earth down-conversion nanoparticle–anti-CD105 conjugate for cancer targeting and a handheld imager capable of concurrent photographic imaging and fluorescence/luminescence imaging. An unprecedented tumor-to-muscle ratio was achieved by near-infrared-IIb (NIR-IIb, 1,500 to 1,700 nm) imaging during surgery, ∼100 times higher than previous organic dyes for unambiguous determination of tumor margin. The sensitivity/biocompatibility/safety of the probes and instrumentation developed here open a paradigm of imaging-guided surgery at the single-cell level, meeting all major requirements for clinical translation to combat cancer and save human lives.

In vivo fluorescence/luminescence imaging in the near-infrared-IIb (NIR-IIb, 1,500 to 1,700 nm) window under <1,000 nm excitation can afford subcentimeter imaging depth without any tissue autofluorescence, promising high-precision intraoperative navigation in the clinic. Here, we developed a compact imager for concurrent visible photographic and NIR-II (1,000 to 3,000 nm) fluorescence imaging for preclinical image-guided surgery. Biocompatible erbium-based rare-earth nanoparticles (ErNPs) with bright down-conversion luminescence in the NIR-IIb window were conjugated to TRC105 antibody for molecular imaging of CD105 angiogenesis markers in 4T1 murine breast tumors. Under a ∼940 ± 38 nm light-emitting diode (LED) excitation, NIR-IIb imaging of 1,500- to 1,700-nm emission afforded noninvasive tumor–to–normal tissue (T/NT) signal ratios of ∼40 before surgery and an ultrahigh intraoperative tumor-to-muscle (T/M) ratio of ∼300, resolving tumor margin unambiguously without interfering background signal from surrounding healthy tissues. High-resolution imaging resolved small numbers of residual cancer cells during surgery, allowing thorough and nonexcessive tumor removal at the few-cell level. NIR-IIb molecular imaging afforded 10-times-higher and 100-times-higher T/NT and T/M ratios, respectively, than imaging with IRDye800CW-TRC105 in the ∼900- to 1,300-nm range. The vastly improved resolution of tumor margin and diminished background open a paradigm of molecular imaging-guided surgery.

Fluorescence Imaging in Colorectal Surgery: An Updated Review and Future Trends

Fluorescence imaging in colorectal surgery is considered a novel predominantly intraoperative method of ensuring a greater surgical success. The use of fluorescence is linked to advanced tumor visualization and projection of its lymphatics, both vessels and nodes, which results in a higher chance of achieving a total excision. Additionally, iatrogenic complications prove to be reduced using fluorescence during the surgical excision. The combination of fluorescence and artificial intelligence to better facilitate oncological surgery will soon become an established approach in operating rooms worldwide.

Role of Indocyanine Green Fluorescence Imaging in Minimally Invasive Resection of Colorectal Liver Metastases

Indocyanine green (ICG) fluorescence imaging is an easy and reproducible method to detect hepatic lesions, both primary and metastatic. This review reports the potential benefits of this technique as a tactile mimicking visual tool and a navigator guide in minimally invasive liver resection of colorectal liver metastases (CRLM). PubMed and MEDLINE databases were searched for studies reporting the use of intravenous injection of ICG before minimally invasive surgery for CLRM. The search was performed for publications reported from the first study in 2014 to April 2021. The final review included 13 articles: 6 prospective cohort studies, 1 retrospective cohort study, 3 case series, 1 case report, 1 case-matched study, and 1 clinical trial registry. The administered dose ranged between 0.3 and 0.5 mg/kg, while timing ranged between 1 and 14 days before surgery. CRLM detection rate ranged between 30.3% and 100% with preoperative imaging (abdominal computed tomography/magnetic resonance imaging), between 93.3 and 100% with laparoscopic ultrasound, between 57.6% and 100% with ICG fluorescence, and was 100% with combined modalities (ICG and laparoscopic ultrasound) with weighted averages of 77.42%, 95.97%, 79.03%, and 100%, respectively. ICG fusion imaging also allowed to detect occult small-sized lesions, not diagnosed preoperatively. In addition, ICG is effective in real-time assessment of surgical margins by evaluating the integrity of the fluorescent rim around the CRLM.

New Intraoperative Imaging Tools and Image-Guided Surgery in Gastric Cancer Surgery

Innovations and new advancements in intraoperative real-time imaging have gained significant importance in the field of gastric cancer surgery in the recent past. Currently, the most promising procedures include indocyanine green fluorescence imaging (ICG-FI) and hyperspectral imaging or multispectral imaging (HSI, MSI). ICG-FI is utilized in a broad range of clinical applications, e.g., assessment of perfusion or lymphatic drainage, and additional implementations are currently investigated. HSI is still in the experimental phase and its value and clinical relevance require further evaluation, but initial studies have shown a successful application in perfusion assessment, and prospects concerning non-invasive tissue and tumor classification are promising. The application of machine learning and artificial intelligence technologies might enable an automatic evaluation of the acquired image data in the future. Both methods facilitate the accurate visualization of tissue characteristics that are initially indistinguishable for the human eye. By aiding surgeons in optimizing the surgical procedure, image-guided surgery can contribute to the oncologic safety and reduction of complications in gastric cancer surgery and recent advances hold promise for the application of HSI in intraoperative tissue diagnostics.

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.

Hepatic resection using intraoperative ultrasound and near-infrared imaging with indocyanine green fluorescence detects hepatic metastases from gastric cancer: A case report

Introduction and importance

Near-infrared (NIR) imaging with indocyanine green (ICG) is a sensitive intraoperative tool for detecting liver tumors. NIR imaging has been used to distinguish metastatic liver cancer from colon cancer; however, its utility for identifying metastatic lesions from gastric cancer remains unknown. We present a case of advanced gastric cancer with multiple liver metastases, which was diagnosed and treated using intraoperative NIR imaging with ICG.

Case presentation

A 69-year-old man with advanced gastric cancer and simultaneous multiple liver metastases presented with gastric bleeding. He underwent gastrectomy and chemotherapy, which reduced the tumor burden. No new lesions were noted, and the patient was advised to undergo surgical resection of the residual liver metastases. Prior to surgery, 0.5 mg/kg of intravenous ICG was administered. NIR imaging was performed during hepatectomy, which revealed clear green fluorescence in several liver segments, indicating liver metastases. Two lesions were not identified during preoperative magnetic resonance imaging. All fluorescent areas were resected. The tumors identified by both preoperative and fluoresced intraoperatively demonstrated malignant features on histopathological examination. The two lesions that fluoresced intraoperatively but were not identified on preoperative images demonstrated normal liver parenchyma and no signs of malignancy. The patient remains tumor-free 1 year after surgery.

Clinical discussion

This report demonstrates that hepatic metastases from gastric cancer can be diagnosed with intraoperative NIR imaging with ICG.

Conclusions

NIR imaging with ICG can detect liver metastases but may provide false positive results. As the percentage of false positives is high, additional resections must be decided upon carefully.

•

We used intraoperative NIR-ICG imaging to detect gastric cancer liver metastases.

•

Two lesions fluoresced intraoperatively that were not identified preoperatively.

•

Histopathology showed normal liver parenchyma and no malignancy in these lesions.

•

NIR imaging with ICG detects liver metastases but may give false positive results, thus additional resections of liver tumor must be decided on carefully.

Efficacy of Near-Infrared Fluorescence-Guided Hepatectomy for the Detection of Colorectal Liver Metastases: A Randomized Controlled Trial

BACKGROUND

The application of indocyanine green fluorescence-guided hepatectomy for liver metastases from colorectal cancer is in the preliminary stage of clinical practice; thus, its efficacy needs to be determined. This study compared the number of intrahepatic colorectal liver metastases detected intraoperatively and postoperative recovery data between patients who underwent traditional hepatectomy (nonindocyanine green group) and traditional hepatectomy plus intraoperative indocyanine green fluorescence imaging (indocyanine green group).

STUDY DESIGN

Between January 2018 and March 2020, patients with potentially resectable colorectal liver metastases were randomly assigned to the nonindocyanine green or indocyanine green group. The number of intrahepatic colorectal liver metastases identified intraoperatively and based on postoperative recovery data were compared between both groups.

RESULTS

Overall, we recruited 80 patients, among whom 72 eligible patients were randomly assigned. After allocation, 64 patients, comprising 32 in each group, underwent the allocated intervention and follow-up. Compared with the nonindocyanine green group, the mean number of intrahepatic colorectal liver metastases identified intraoperatively in the indocyanine green group was significantly greater (mean [standard deviation], 3.03 [1.58] vs 2.28 [1.35]; p = 0.045), the postoperative hospital stay was shorter (p = 0.012) and the 1-year recurrence rate was also lower (p = 0.017). Postoperative complications and 90-day mortality were comparable, with no statistical differences.

CONCLUSIONS

Indocyanine green fluorescence imaging significantly increases the number of intrahepatic colorectal liver metastases identified and reduces postoperative hospital stay and 1-year recurrence rate without increasing hepatectomy-related complications and mortality rates.

The complementary value of intraoperative fluorescence imaging and Raman spectroscopy for cancer surgery: combining the incompatibles

A clear margin is an important prognostic factor for most solid tumours treated by surgery. Intraoperative fluorescence imaging using exogenous tumour-specific fluorescent agents has shown particular benefit in improving complete resection of tumour tissue. However, signal processing for fluorescence imaging is complex, and fluorescence signal intensity does not always perfectly correlate with tumour location. Raman spectroscopy has the capacity to accurately differentiate between malignant and healthy tissue based on their molecular composition. In Raman spectroscopy, specificity is uniquely high, but signal intensity is weak and Raman measurements are mainly performed in a point-wise manner on microscopic tissue volumes, making whole-field assessment temporally unfeasible. In this review, we describe the state-of-the-art of both optical techniques, paying special attention to the combined intraoperative application of fluorescence imaging and Raman spectroscopy in current clinical research. We demonstrate how these techniques are complementary and address the technical challenges that have traditionally led them to be considered mutually exclusive for clinical implementation. Finally, we present a novel strategy that exploits the optimal characteristics of both modalities to facilitate resection with clear surgical margins.

Intra-operative assessment of the vascularisation of a cross section of the meniscus using near-infrared fluorescence imaging

PURPOSE

The purpose of this study was to assess whether the vascularisation of the meniscus could be visualised intra-operatively using near-infrared fluorescence (NIRF) imaging with indocyanine green (ICG) in patients undergoing total knee arthroplasty (TKA).

METHODS

The anterior horn (i.e., Cooper classification: zones C and D) of the meniscus that was least affected (i.e., least degenerative) was removed during TKA surgery in ten patients to obtain a cross section of the inside of the meniscus. Thereafter, 10 mg of ICG was injected intravenously, and vascularisation of the cross section of the meniscus was assessed using the Quest spectrum NIRF camera system. We calculated the percentage of patients in whom vascularisation was observed intra-operatively using NIRF imaging compared to immunohistochemistry.

RESULTS

Meniscal vascularisation using NIRF imaging was observed in six out of eight (75%) patients in whom vascularisation was demonstrated with immunohistochemistry. The median extent of vascularisation was 13% (interquartile range (IQR) 3-28%) using NIRF imaging and 15% (IQR 11-23%) using immunohistochemistry.

CONCLUSION

This study shows the potential of NIRF imaging to visualise vascularisation of the meniscus, as vascularisation was observed in six out of eight patients with histologically proven meniscal vascularisation.

LEVEL OF EVIDENCE

IV.

Emerging Technologies for the Detection of Cancer Micrometastasis

The most efficient way to treat tumors is through surgery. However, many cancer patients have a poor prognosis even when they undergo radical excision at an early stage. Micrometastasis is one of the most critical factors that induced this situation. Undetected micrometastasis can lead to the failure of initial treatment. Therefore, preoperative and intraoperative detection of micrometastasis could have a significant clinical influence on the prognosis and optimal therapy for cancer patients. Additionally, to achieve this goal, researchers have aimed to create more effective detection technologies. Herein, we classify the currently reported micrometastasis detection technologies, introduce some representative samples for each technology, including the limitations, and provide future directions to overcome the limitations.

A study on setting standards for near-infrared fluorescence-image guided surgery (NIRFGS) time lapse monitoring based on preoperative liver function assessment

Background

This study aimed to explore the relationship between the fluorescence intensity of indocyanine green (ICG) in near-infrared fluorescence guided surgery (NIRFGS) and preoperative liver function indicators.

Methods

A total of 12 4T1 tumor-bearing mice were used for model establishment. Intraperitoneal injection (i.p.) of 20% carbon tetrachloride (CCl₄) corn oil solution (50 µL) was given to mice in the liver injury model group, 24 hours after injection, the model was established, while the control group received 0% CCl₄ corn oil solution (50 µL) (n=6 for each group). Additionally, doses of 8 mg/kg and 1 mg/kg of free ICG were injected intravenously (i.v.) (n=3 in each group). Fluorescence was imaged in vivo using an NIR fluorescence imaging system at different time points (1, 2, 4, 8, 12, 24, 48, and 72 h) after injection.

Results

The absolute fluorescence intensity of mice in the liver injury model group was stronger than that in the control group. Mice in the liver injury model group had the same clearance rate of ICG from the tumor as normal mice. However, the background clearance rate was slower than that of normal mice, which prolonged the optimal tumor to background ratio (TBR) time. Correlation analysis was also used to determine which preoperative liver function parameters were most correlated with hepatic ICG clearance.

Conclusions

Liver injury does not significantly affect the maximum TBR, but prolongs the optimal TBR time, and at the same time, a wider and more stable surgical window will appear. This study showed that a prolonged surgical start time is feasible according to preoperative liver function testing using NIR fluorescence imaging technology.

Essential updates 2020/2021: Current topics of simulation and navigation in hepatectomy

With the development of three‐dimensional (3D) simulation software, preoperative simulation technology is almost completely established. The remaining issue is how to recognize anatomy three‐dimensionally. Extended reality is a newly developed technology with several merits for surgical application: no requirement for a sterilized display monitor, better spatial awareness, and the ability to share 3D images among all surgeons. Various technology or devices for intraoperative navigation have also been developed to support the safety and certainty of liver surgery. Consensus recommendations regarding indocyanine green fluorescence were determined in 2021. Extended reality has also been applied to intraoperative navigation, and artificial intelligence (AI) is one of the topics of real‐time navigation. AI might overcome the problem of liver deformity with automatic registration. Including the issues described above, this article focuses on recent advances in simulation and navigation in liver surgery from 2020 to 2021.

Cancer-Targeted Azo Dye for Two-Photon Photodynamic Therapy in Human Colon Tissue

Inappropriate cancer management can be prevented by simultaneous cancer diagnosis, treatment, and real-time assessment of therapeutic processes. Here, we describe the design of a two-photon (TP) photosensitizer (PS), ACC-B, for high temporal and spatioselective near-infrared cancer therapy. ACC-B consisting of a biotin unit significantly enhanced the cancer sensitivity of the PS. Upon TP irradiation, ACC-B generated reactive oxygen species (ROS) through the type I photodynamic therapy (PDT) process and triggered highly selective cancer ablation. In addition, fluorescence microscopy images revealed that ACC-B-loaded live human colon tissues showed a marked difference in ACC-B uptake between normal and cancer tissues, and this property was used for real-time imaging. Upon 770 nm TP treatment, ACC-B generated ROS efficiently in live colon cancer tissues with high spatial selectivity. During PDT, ACC-B can provide in situ spatioselective visualization of cellular behavior and molecular information for therapeutic assessment in specific regions.

Augmented Reality and Image-Guided Robotic Liver Surgery

Artificial intelligence makes surgical resection easier and safer, and, at the same time, can improve oncological results. The robotic system fits perfectly with these more or less diffused technologies, and it seems that this benefit is mutual. In liver surgery, robotic systems help surgeons to localize tumors and improve surgical results with well-defined preoperative planning or increased intraoperative detection. Furthermore, they can balance the absence of tactile feedback and help recognize intrahepatic biliary or vascular structures during parenchymal transection. Some of these systems are well known and are already widely diffused in open and laparoscopic hepatectomies, such as indocyanine green fluorescence or ultrasound-guided resections, whereas other tools, such as Augmented Reality, are far from being standardized because of the high complexity and elevated costs. In this paper, we review all the experiences in the literature on the use of artificial intelligence systems in robotic liver resections, describing all their practical applications and their weaknesses.