Application of indocyanine green in thoracic surgery: A review article

Indocyanine green has been used in clinical practice for a long time because of its many advantages such as stable coloration, safety and cheapness. With the widespread development of thoracoscopic technology, thoracic surgeons have a higher demand for the identification of lesions and tissue structures under the thoracoscope, and the traditional white light imaging can no longer fully meet the needs of thoracic surgeons. In this situation, indocyanine green combined with NIR imaging technology has brought great help to thoracic surgeons. For example, indocyanine green plays an important role in the localization of small pulmonary nodules, the imaging of intersegmental lung planes, the imaging of thoracic ducts, and the assessment of blood supply to the tubular stomach. In this paper, we review the application of indocyanine green in thoracic surgery according to the related research and application at home and abroad.

A Green Lantern for the Surgeon: A Review on the Use of Indocyanine Green (ICG) in Minimally Invasive Surgery

Indocyanine green (ICG) fluorescence imaging has revolutionized surgical practice across various medical and surgical specialties. This article reviews the clinical applications of ICG in abdominal, urological, thoracic, and gynecological surgery. ICG fluorescence imaging has been widely adopted in general surgery for various applications, including perfusion assessment, intraoperative visualization of the ureter, and tumor localization. It is particularly valuable in evaluating anastomotic leaks and aiding in precise tumor resection during minimally invasive surgeries. Studies have shown mixed results on its effectiveness in reducing anastomotic leak rates, highlighting the need for further research. In thoracic surgery, ICG facilitates the identification and resection of pulmonary bullae, as well as the precise localization of pulmonary nodules during video-assisted surgery. In urology, ICG aids in localizing renal tumors and guiding selective arterial occlusion during partial nephrectomy. Its role in identifying the lymphatic pathway in prostate cancer and sentinel lymph node biopsy in gynecological cancer is also discussed. Despite its benefits, the use of ICG fluorescence faces challenges such as limited tissue penetration, the potential for false results, a lack of standardized protocols, and high equipment costs. Nonetheless, it remains a powerful tool that could improve surgical outcomes.

Simultaneous Visualization of Lung Tumor and Intersegmental Plane during Pulmonary Segmentectomy by Intravenous Injection of Indocyanine Green

Segmentectomy is a targeted surgical approach tailored for patients with compromised health and early-stage lung cancer. The key to successful segmentectomy lies in precisely identifying the tumor and intersegmental planes to ensure adequate resection margins. In this study, we aimed to enhance this process by simultaneously visualizing the tumor and intersegmental planes through the intravenous injection of indocyanine green (ICG) at different time points and doses. Lung tumors were detected by intravenous injection of ICG at a dose of 2 mg/kg 12 h before surgery in a rabbit model. Following the dissection of the pulmonary artery, vein, and bronchi of the target segment, 0.6 mg/kg of ICG was injected intravenously to detect the intersegmental plan. Fluorescent images of the lung tumors and segments were acquired, and the fluorescent signal was quantified using the signal-to-background ratio (SBR). Finally, a pilot study of this method was conducted in three patients with lung cancer. In a preclinical study, the SBR of the tumor (4.4 ± 0.1) and nontargeted segments (10.5 ± 0.8) were significantly higher than that of the targeted segment (1.6 ± 0.2) (targeted segment vs. nontarget segment, p < 0.0001; target segment vs. tumor, p < 0.01). Consistent with preclinical results, lung tumors and the intersegmental plane were successfully detected in patients with lung cancer. Consequently, adequate resection margins were identified during the surgery, and segmentectomy was successfully performed in patients with lung cancer. This study is the first to use intravenous ICG injections at different time points and doses to simultaneously detect lung cancer and intersegmental planes, thereby achieving segmentectomy for lung cancer.

Comparative Study of Indocyanine Green Fluorescence Imaging in Lung Cancer with Near-Infrared-I/II Windows

BACKGROUND

We compare the application of intravenous indocyanine green (ICG) fluorescence imaging in lung cancer with near-infrared-I (NIR-I) and near-infrared-II (NIR-II) windows.

METHODS

From March to December 2022, we enrolled patients who received an intravenous injection of ICG (5 mg/kg) 1 day before the planned lung cancer surgery. The lung cancer nodules were imaged by NIR-I/II fluorescence imaging systems, and the tumor-to-normal-tissue ratio (TNR) was calculated. In addition, the fluorescence intensity and signal-to-background ratio (SBR) of capillary glass tubes containing ICG covered with different thicknesses of lung tissue were measured by NIR-I/II fluorescence imaging systems.

RESULTS

In this study, 102 patients were enrolled, and the mean age was 59.9 ± 9.2 years. A total of 96 (94.1%) and 98 (96.1%) lung nodules were successfully imaged with NIR-I and NIR-II fluorescence, and the TNR of NIR-II was significantly higher than that of NIR-I (3.9 ± 1.3 versus 2.4 ± 0.6, P < 0.001). In multiple linear regression, solid nodules (P < 0.001) and squamous cell carcinoma (P < 0.001) were independent predictors of a higher TNR of NIR-I/II. When capillary glass tubes were covered with lung tissue whose thickness was more than 2 mm, the fluorescence intensity and the SBR of NIR-II were significantly higher than those of NIR-I.

CONCLUSIONS

We verified the feasibility of NIR-II fluorescence imaging in intravenous ICG lung cancer imaging for the first time. NIR-II fluorescence can improve the TNR and penetration depth of lung cancer with promising clinical prospects.

Efficacy of Near-Infrared Fluorescence Video-Assisted Thoracoscopic Surgery for Small Pulmonary Nodule Resection with Indocyanine Green Inhalation: A Randomized Clinical Trial

BACKGROUND

Small pulmonary nodules (<3 cm) can sometimes be unrecognizable and nonpalpable in video-assisted thoracoscopic surgery (VATS). Near-infrared fluorescence (NIF) VATS after indocyanine green (ICG) inhalation may effectively guide surgeons to locate the nodules.

OBJECTIVE

This study aimed to investigate the safety, feasibility, and efficacy of ICG inhalation-based NIF imaging for guiding small pulmonary nodule resections.

METHODS

Between February and May 2021, the first-stage, non-randomized trial enrolled 21 patients with different nodule depth, ICG inhalation doses, post-inhalation surgery times, and nodule types at a tertiary referral hospital. Between May 2021 and May 2022, the second-stage randomized trial enrolled 56 patients, who were randomly assigned to the fluorescence VATS (FLVATS) or the white-light VATS (WLVATS) group. The ratio of effective guidance and the time consumption for nodule localization were compared.

RESULTS

The first-stage trial proved this new method is safe and feasible, and established a standardized protocol with optimized nodule depth (≤1 cm), ICG dose (0.20-0.25 mg/kg), and surgery window (50-90 min after ICG inhalation). In the second-stage trial, the FLVATS achieved 87.1% helpful nodule localization guidance, which was significantly higher than the WLVATS (59.1%, p < 0.05). The mean nodule locating time (standard deviation) was 1.8 [0.9] and 3.3 [2.3] min, respectively. Surgeons adopting FLVATS were significantly faster (p < 0.01), especially when locating small ground-glass opacities (1.3 [0.6] min vs. 7.0 [3.5] min, p < 0.05). Five of 31 nodules (16.1%) were only detectable by FLVATS, whereas both white light and palpation failed.

CONCLUSIONS

This new method is safe and feasible for small pulmonary nodule resection. It significantly improves nodule localization rates with less time consumption, and hence is highly worthy for clinical promotion. Clinical Trial Registration Chinese Clinical Trial Registry Identifier: ChiCTR2100047326.

Intraoperative Molecular Imaging of Lung Cancer

Intraoperative molecular imaging innovations have been propelled by the development of fluorescent contrast agents that specifically target tumor tissues and advanced camera systems that can detect the specified fluorescence. The most promising agent to date is OTL38, a targeted and near-infrared agent that was recently approved by the Food and Drug Administration for intraoperative imaging for lung cancer.

Use of Indocyanine Green Fluorescence Imaging in Thoracic and Esophageal Surgery

BACKGROUND

Fluorescence imaging using indocyanine green in thoracic and esophageal surgery is gaining popularity because of the potential to facilitate surgical planning, to stage disease, and to reduce postoperative complications. To optimize use of fluorescence imaging in thoracic and esophageal surgery, an expert panel sought to establish a set of recommendations at a consensus meeting.

METHODS

The panel included 12 experts in thoracic and upper gastrointestinal surgery from Asia-Pacific countries. Before meeting, 7 focus areas were defined: intersegmental plane identification for sublobar resections; pulmonary nodule localization; lung tumor detection; bullous lesion detection; lymphatic mapping of lung tumors; evaluation of gastric conduit perfusion; and lymphatic mapping in esophageal surgical procedures. A literature search of the PubMed database was conducted using keywords indocyanine green, fluorescence, thoracic, surgery, and esophagectomy. At the meeting, panelists addressed each focus area by discussing the most relevant evidence and their clinical experiences. Consensus statements were derived from the proceedings, followed by further discussions, revisions, finalization, and unanimous agreement. Each statement was assigned a level of evidence and a grade of recommendation.

RESULTS

A total of 9 consensus recommendations were established. Identification of the intersegmental plane for sublobar resections, localization of pulmonary nodules, lymphatic mapping in lung tumors, and assessment of gastric conduit perfusion were applications of fluorescence imaging that have the most robust current evidence.

CONCLUSIONS

Based on best available evidence and expert opinions, these consensus recommendations may facilitate thoracic and esophageal surgery using fluorescence imaging.

Intraoperative Fluorescence Visualization in Thoracoscopic Surgery

We report a clinical case of using indocyanine green inhalation to achieve intraoperative near-infrared fluorescence visualization of pulmonary ground-glass opacity in thoracoscopic wedge resection. The patient underwent thoracoscopic wedge resection under the real-time navigation of a near-infrared fluorescence imaging system with the indocyanine green inhalation performed 85 minutes before the surgery. The nebulized inhalation of indocyanine green (dose of 0.25 mg/kg) successfully guided surgeons to localize the small ground-glass opacity due to a filling defect of the fluorescence. The thoracoscopic near-infrared fluorescence navigation system delineated the tumor margin with high contrast and helped to minimize the damage to lung function.

Near-infrared fluorescence imaging of thoracic duct in minimally invasive esophagectomy

Chylothorax is a serious complication after esophagectomy and there are unmet needs for new intraoperative navigation tools to reduce its incidence. The aim of this study is to explore the feasibility and effectiveness of near-infrared fluorescence imaging (NIR-FI) with indocyanine green (ICG) to identify thoracic ducts (TDs) and chyle leakage during video-assisted thoracoscopic esophagectomy. We recruited 41 patients who underwent thoraco-laparoscopic minimally invasive esophagectomy (MIE) for esophageal cancer in this prospective, open-label, single-arm clinical trial. ICG was injected into the right inguinal region before operations, after which TD anatomy and potential chyle leakage were checked under the near-infrared fluorescence intraoperatively. In 38 of 41 patients (92.7%) using NIR-FI, TDs were visible in high contrast. The mean signal-to-background ratio (SBR) value of all fluorescent TDs was 3.05 ± 1.56. Fluorescence imaging of TDs could be detected 0.5 hours after ICG injection and last up to 3 hours with an acceptable SBR value. The optimal observation time window is from about 1 to 2 hours after ICG injection. Under the guidance of real-time NIR-FI, three patients were found to have chylous leakage and the selective TD ligations were performed intraoperatively. No patient had postoperative chylothorax. NIR-FI with ICG can provide highly sensitive and real-time assessment of TDs as well as determine the source of chyle leakage, which might help reduce TD injury and direct selective TD ligation. It could be a promising navigation tool to reduce the incidence of chylothorax after minimally invasive esophagectomy.

Fluorescence probes for lung carcinoma diagnosis and clinical application

This review provides an overview of the most recent developments in fluorescence probe technology for the accurate detection and clinical therapy of lung carcinoma.

CT-guided placement of microcoil end in the pleural cavity for video-assisted thoracic surgical resection of ground-glass opacity: a retrospective study

BACKGROUND

The aim of the study was to investigate and summarize the effectiveness and safety of CT-guided microcoil localization before video-assisted thoracic surgery (VATS) for the removal of ground-glass opacity (GGO).

METHODS

A total of 147 patients with GGO who were treated at our hospital between January 2019 and February 2021 were retrospectively analyzed. They were divided into two groups according to the final position at the end of the microcoil: intracavity (n = 78) and extracavity (n = 69), which were compared based on puncture complications and influence of the coil end position on VATS.

RESULTS

The proportions of supine and prone positions in the intracavity group were significantly higher than those in the extracavity group (82.1% vs. 66.7%, P < 0.05). The incidence of intrapulmonary hemorrhage, chest pain, and coil displacement in the intracavity group was significantly lower than that in the extracavity group (28.2% vs. 46.4%, 19.2% vs. 39.1%, 1.3% vs. 11.6%, P < 0.05, respectively); however, the incidence of pneumothorax was not significantly different (P > 0.05). The time of VATS and the rate of conversion to thoracotomy in the intracavity group were significantly lower than those in the extracavity group (103.4 ± 21.0 min vs. 112.2 ± 17.3 min, 0% vs. 5.8%, P < 0.05, respectively).

CONCLUSION

CT-guided placement of the microcoil is a practical, simple, and convenient localization method before VATS, with a high success rate and few complications. Furthermore, it is a better alternative method to place the end of the coil in the pleural cavity because of the lower complication rate, shorter VATS time, and lower rate of thoracotomy conversion.

Dynamic contrast-enhanced magnetic resonance imaging-based radiomics for the prediction of progression-free survival in advanced nasopharyngeal carcinoma

To establish a multidimensional nomogram model for predicting progression-free survival (PFS) and risk stratification in patients with advanced nasopharyngeal carcinoma (NPC). This retrospective cross-sectional study included 156 patients with advanced NPC who underwent dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Radiomic features were extracted from the efflux rate constant (Ktrans ) and extracellular extravascular volume (Ve ) mapping derived from DCE-MRI. Least absolute shrinkage and selection operator (LASSO) Cox regression analysis was applied for feature selection. The Radscore was constructed using the selected features with their respective weights in the LASSO Cox regression analysis. A nomogram model combining the Radscore and clinical factors was built using multivariate Cox regression analysis. The C-index was used to assess the discrimination power of the Radscore and nomogram. The Kaplan-Meier method was used for survival analysis. Of the 360 radiomic features, 28 were selected (7, 6, and 15 features extracted from Ktrans , Ve, and Ktrans +Ve images, respectively). The combined Radscore k trans +Ve (C-index, 0.703, 95% confidence interval [CI]: 0.571-0.836) showed higher efficacy in predicting the prognosis of advanced NPC than Radscore k trans (C-index, 0.693; 95% CI, 0.560-0.826) and Radscore Ve (C-index, 0.614; 95% CI, 0.481-0.746) did. Multivariable Cox regression analysis revealed clinical stage, T stage, and treatment with nimotuzumab as risk factors for PFS. The nomogram established by Radscore k trans +Ve and risk factors (C-index, 0.732; 95% CI: 0.599-0.864) was better than Radscore k trans +Ve in predicting PFS in patients with advanced NPC. A lower Radscore k trans +Ve (HR 3.5584, 95% CI 2.1341-5.933), lower clinical stage (hazard ratio [HR] 1.5982, 95% CI 0.5262-4.854), lower T stage (HR 1.4365, 95% CI 0.6745-3.060), and nimotuzumab (NTZ) treatment (HR 0.7879, 95% CI 0.4899-1.267) were associated with longer PFS. Kaplan-Meier analysis showed a lower PFS in the high-risk group than in the low-risk group (p<0.0001). The nomogram based on combined pretreatment DCE-MRI radiomics features, NTZ, and clinicopathological risk factors may be considered as a noninvasive imaging marker for predicting individual PFS in patients with advanced NPC.

How effective is indocyanine green (ICG) in localization of malignant pulmonary nodules? A systematic review and meta-analysis

BACKGROUND

Video-Assisted and Robotic-Assisted techniques become constantly more prominent practice in thoracic surgery for lung cancer. Furthermore, the increased frequency in detection of small lung cancers makes the intra-operative identification of these cancers even more challenging. Indocyanine Green (ICG) is one of the most commonly used dyes that assists surgeons identify small lung cancers intra-operatively. Our study aimed to evaluate the effectiveness and safety of ICG in lung cancer detection.

METHODS

We performed a systematic review of the literature by screening the databases of MEDLINE, EMBASE, CENTRAL and Scopus until 30th April 2022 and the first 300 articles of Google Scholar for any suitable grey literature. We included any study that investigated the effectiveness of ICG in lung cancer detection. We excluded studies that explored the use of ICG only in identification of intersegmental planes, lymph node mapping, case reports and non-English articles. We aimed to perform a meta-analysis on test accuracy studies using hierarchical summary receiver operating characteristic (HSROC) and the bivariate random-effects models. In cases where the data for a localization technique was not sufficient for that analysis, it was presented with tables with narrative purposes. Each study was assessed for Risk of Bias (RoB) and Applicability using the QUADAS-2 tool.

RESULTS

We found 30 eligible studies that included a total of 1,776 patients who underwent ICG localization of pulmonary nodules. We identified three ICG localization techniques: CT-guided, endobronchial and intravenous. From the 30 studies, 13 investigated CT-guided localization, 12 explored an endobronchial method while 8 studies administered ICG intravenously the median reported success rate was 94.3% (IQR: 91.4%-100%) and 98.3% (IQR: 94%-100%) for the first two techniques respectively. Intravenous ICG lung cancer localization showed Sensitivity of 88% (95% CI: 59%-0.97%) and Specificity of 25% (95% CI: 0.04%-0.74%). There were 15.2% (150/989) patients who experienced complications from CT guided ICG localization. No ICG-related complications were reported in endobronchial or intravenous techniques.

CONCLUSION

Our study provides a comprehensive review of the literature on ICG localization techniques for lung cancer. Current evidence suggests that ICG is boh effective and safe. Further prospective research with standardized protocols across multiple thoracic units is required in order to accurately validate these findings.

Outcome of Near-infrared Fluorescence-navigated Pulmonary Metastasectomy for Hepatocellular Carcinoma

OBJECTIVES

Pulmonary metastasectomy for hepatocellular carcinoma (HCC) is suitable in highly selected patients. However, complete resection is challenging in HCC patients with multiple lung metastases. We aimed to describe the clinical utility and survival outcome of indocyanine green (ICG) fluorescence-navigated resection of HCC lung metastases.

METHODS

From October 2015 to March 2021, 15 HCC patients with pulmonary metastasis underwent NIR fluorescence imaging thoracoscopic surgery. ICG was administered through peripheral veins preoperatively. All suspected lesions detected by palpation, white-light thoracoscopy or near-infrared (NIR) imaging were resected. After metastasectomy, all patients were followed up at regular intervals of 6-12 months.

RESULTS

A total of 90 metastatic HCC nodules were resected in 15 patients. All patients received sublobar resections, during which 89 lesions were removed by wedge resection and 1 lesion was managed via segmentectomy. Under NIR fluorescence imaging, 81 nodules successfully demonstrated fluorescence during the surgery, while 9 metastatic nodules were undetected. The median signal-to-background ratio (SBR) of the nodules was 3.34. Five patients died and 7 patients relapsed by the end of observation. The median overall survival (OS) and disease-free survival (DFS) were 47.1 months and 17.3 months, respectively. The 1-year OS and DFS rates were 71.1% and 57.8%, respectively.

CONCLUSIONS

ICG fluorescence imaging technology is useful for visualization of the peripheral tumours to assist in pulmonary metastasectomy for HCC. In addition, this technology has the potential to detect the small tumour that are missed in preoperative examinations, which might be beneficial for HCC patients with multiple lung metastases.

Safety and Efficacy of Cone-Beam Computed Tomography-Guided Lung Tumor Localization with a Near-Infrared Marker: A Retrospective Study of 175 Patients

Preoperative localization holds promise for overcoming the limitations of video-assisted thoracoscopic surgery (VATS) in the treatment of impalpable lung nodules. The purpose of this study was to assess the safety and efficacy of cone-beam computed tomography (CBCT)-guided localization using near-infrared (NIR) marking. Between 2017 and 2021, patients presenting with a solitary pulmonary nodule (SPN) who had undergone CBCT-guided lesion localization with indocyanine green (ICG) in a hybrid operating room were included. The primary outcomes were the efficacy of localization and the occurrence of complications. The study cohort consisted of 175 patients with the mean age of 58.76 years. The mean size and depth of the 175 SPNs were 8.34 mm and 5.3 mm, respectively. The mean time required for lesion marking was 14.71 min. Upon thoracoscopic inspection, the NIR tattoo was detected in the vast majority of the study participants (98.3%). An utility thoracotomy to allow digital palpation was required in two of the three patients in whom the tattoo was not identifiable. The perioperative survival rate was 100%, and the mean length of hospital stay was 3.09 days. We conclude that needle localization with ICG injection is a safe and feasible technique to localize SPNs prior to resection.

Near-Infrared Fluorescence Tumor-Targeted Imaging in Lung Cancer: A Systematic Review

Lung cancer is the most common cancer type worldwide, with non-small cell lung cancer (NSCLC) being the most common subtype. Non-disseminated NSCLC is mainly treated with surgical resection. The intraoperative detection of lung cancer can be challenging, since small and deeply located pulmonary nodules can be invisible under white light. Due to the increasing use of minimally invasive surgical techniques, tactile information is often reduced. Therefore, several intraoperative imaging techniques have been tested to localize pulmonary nodules, of which near-infrared (NIR) fluorescence is an emerging modality. In this systematic review, the available literature on fluorescence imaging of lung cancers is presented, which shows that NIR fluorescence-guided lung surgery has the potential to identify the tumor during surgery, detect additional lesions and prevent tumor-positive resection margins.

Adaptive brightness fusion method for intraoperative near-infrared fluorescence and visible images

An adaptive brightness fusion method (ABFM) for near-infrared fluorescence imaging is proposed to adapt to different lighting conditions and make the equipment operation more convenient in clinical applications. The ABFM is designed based on the network structure of Attention Unet, which is an image segmentation technique. Experimental results show that ABFM has the function of adaptive brightness adjustment and has better fusion performance in terms of both perception and quantification. Generally, the proposed method can realize an adaptive brightness fusion of fluorescence and visible images to enhance the usability of fluorescence imaging technology during surgery.

Intraoperative fluorescence molecular imaging accelerates the coming of precision surgery in China

Purpose

China has the largest cancer population globally. Surgery is the main choice for most solid cancer patients. Intraoperative fluorescence molecular imaging (FMI) has shown its great potential in assisting surgeons in achieving precise resection. We summarized the typical applications of intraoperative FMI and several new trends to promote the development of precision surgery.

Methods

The academic database and NIH clinical trial platform were systematically evaluated. We focused on the clinical application of intraoperative FMI in China. Special emphasis was placed on a series of typical studies with new technologies or high-level evidence. The emerging strategy of combining FMI with other modalities was also discussed.

Results

The clinical applications of clinically approved indocyanine green (ICG), methylene blue (MB), or fluorescein are on the rise in different surgical departments. Intraoperative FMI has achieved precise lesion detection, sentinel lymph node mapping, and lymphangiography for many cancers. Nerve imaging is also exploring to reduce iatrogenic injuries. Through different administration routes, these fluorescent imaging agents provided encouraging results in surgical navigation. Meanwhile, designing new cancer-specific fluorescent tracers is expected to be a promising trend to further improve the surgical outcome.

Conclusions

Intraoperative FMI is in a rapid development in China. In-depth understanding of cancer-related molecular mechanisms is necessary to achieve precision surgery. Molecular-targeted fluorescent agents and multi-modal imaging techniques might play crucial roles in the era of precision surgery.

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.

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

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Two lesions fluoresced intraoperatively that were not identified preoperatively.

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

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

Improved visualization of virtual-assisted lung mapping by indocyanine green

Objectives

Virtual-assisted lung mapping (VAL-MAP) is a bronchoscopic marking method of dye application on the surface of the lungs before resecting nonpalpable nodules. However, in some cases, it can be difficult to identify the markings of VAL-MAP on computed tomography and intraoperative thoracoscopy. We developed and assessed the feasibility of indocyanine green VAL-MAP (ICG-VAL-MAP).

Methods

A historical control trial was conducted to investigate the effectiveness of ICG-VAL-MAP for marking visualization compared with that of VAL-MAP. In ICG-VAL-MAP, instead of indigo carmine, ICG and computed tomography contrast agents were used for dye marking, and near-infrared fluorescence endoscopy was employed to visualize the ICG markings. The other processes in VAL-MAP were carried out. The marking visibility was assessed in 3 grades of easy, faint, or not identifiable. We compared the visibility of the markings on computed tomography images and during thoracoscopic operations between VAL-MAP (567 markings in 147 cases) and ICG-VAL-MAP (142 markings in 63 cases).

Results

On the preoperative computed tomography images, ICG-VAL-MAP provided significantly better marking visualization than VAL-MAP (easy/faint/not identifiable = 142/0/0 vs 427/100/30; P < .0001). ICG-VAL-MAP provided significantly better intraoperative markings than VAL-MAP (easy/faint/not identifiable = 141/0/1, respectively, vs 475/50/42, respectively; P < .0001). Regarding complications, pneumothorax occurred in 8 (5.4%) cases of VAL-MAP and zero cases (0%) of ICG-VAL-MAP (P = .12); fever was observed in 7 (5.0%) cases of VAL-MAP and 2 (3.2%) cases of ICG-VAL-MAP (P = .72).

Conclusions

ICG-VAL-MAP provided significantly better visibility of markings than VAL-MAP. It might be useful in the resection of nonpalpable small lung lesions.

A novel lanthanide-based NIR-II nanoprobe for lung squamous cell carcinoma identification

The morbidity and mortality of lung cancer, particularly squamous cell carcinoma and non-small-cell lung cancer (NSCLC), is significantly higher than other malignant tumors. Currently, there is a lack of a real-time, nonradioactive detection method for early-stage squamous non-small-cell lung cancer diagnosis. In this study, we introduced fluorescence imaging in the second near-infrared (NIR-II) window to identify in vivo lung squamous cell carcinoma for the first time. A novel nanoprobe is constructed based on downconversion nanoparticles (DCNPs) with a fluorescence core (NaErF₄) and an inert shell (NaYF₄) coated via the successive layer-by-layer strategy. The existence of the inert shell reduces the surface defects of DCNPs and inhibits the solvent-quenching effect. Therefore, hydrophilic DCNPs exhibit strong NIR-II fluorescence. After modification with an efficient antibody to the squamous cell carcinoma antigen, DCNPs@anti-SCCA nanoprobes exhibited low cytotoxicity and good biocompatibility. These probes can accurately identify lung squamous carcinoma with high tumor-to-normal-tissue ratio as well as high spatial resolution.

Preoperative computer tomography-guided indocyanine green injection is associated with successful localization of small pulmonary nodules

Background

Localization of small pulmonary nodules (SPNs) is challenging in minimally invasive pulmonary resection, and it is unknown whether computer tomography (CT) guided by indocyanine green (ICG) can provide accurate localization with minimal complications.

Methods

We performed a retrospective study of patients who underwent thoracoscopic resection of pulmonary nodules after CT-guided preoperative localization with ICG from May 2019 to May 2020. Demographics, procedural data, postoperative complications, and pathologic information, were collected, and an analysis of the accuracy and complications after surgery was conducted.

Results

In 471 patients, there was a total of 512 peripheral pulmonary nodules that were ≤2 cm in size. The average time for CT-guided percutaneous ICG injection for localization was 18 minutes, and 98.4% (504/512) of the nodules were successfully localized. The average size of the nodules was 9.1 mm, and the average depth from the pleural surface was 8.9 mm. Overall, 5.9% (28/471) of the patients had asymptomatic pneumothorax after localization, but none needed a tube thoracostomy. All the nodules were resected using video-assisted thoracoscopy technique.

Conclusions

Preoperative CT-guided transthoracic ICG injection is safe and feasible for localization of small lung nodules for minimally invasive pulmonary resection. This technique should be considered for preoperative CT-guided localization of small lung nodules.

Update on Osteosarcoma

PURPOSE OF REVIEW

Osteosarcoma (OSA) is the most common primary tumor of bone, mainly affecting children and adolescents. Here we discuss recent advances in surgical and systemic therapies, and highlight potentially new modalities in preclinical evaluation and prognostication.

RECENT FINDINGS

The advent of neoadjuvant and adjuvant chemotherapy has markedly improved the disease-free recurrence and overall survival of OSA. However, treatment efficacy has been stagnant since the 1980s. This plateau has prompted preclinical and clinical research into in precision surgery, inhaled chemotherapy to increase pulmonary drug concentration without systemic side effects, and novel immunomodulators intended to block molecular pathways associated with OSA proliferation and metastasis. With the advent of novel surgical techniques and new forms and vectors for chemotherapy, it is hoped that OSA treatment outcomes will exceed their currently sustained plateau in the near future.

Indocyanine Green Remains in the Lung for up to 6 Days

Currently there is no explicit guideline for the use of indocyanine green (ICG) in the localization of pulmonary nodules before surgery. How long ICG can remain in vivo is unknown. According to previous reports, ICG can be observed under infrared thoracoscope within 24 hours after injection. We unexpectedly found a case of a 54-year-old man who was injected with ICG under CT guidance, which was still clearly visible under infrared thoracoscopy after 6 days. This unexpected finding suggests that the operation time can be arranged appropriately after local injection with ICG.

Indocyanine green fluorescence imaging for resection of pulmonary metastasis of hepatocellular carcinoma

Background

Indocyanine green (ICG) accumulates in hepatocellular carcinoma (HCC), and tumor fluorescence can be observed under irradiation with near infrared light (NIR). This study investigated the clinical utility of ICG fluorescence imaging during resection of pulmonary metastases of HCC.

Methods

From April 2010 to June 2018, six patients with suspected pulmonary metastasis of HCC were enrolled prospectively. Prior to surgery, all patients underwent the ICG hepatic function test following intravenous administration of ICG (0.5 mg/kg body weight). During surgery, metastatic HCC was identified by observation of ICG fluorescence, allowing assessment of the surgical margin. Tumor fluorescence was also evaluated on cut sections.

Results

A total of 11 metastatic HCCs were resected in six patients at nine operations. Eight lesions were removed by wedge resection and 3 lesions were managed by lobectomy. During surgery, tumor fluorescence could be confirmed through the visceral pleura in 6 out of 7 lesions treated by wedge resection, while NIR irradiation was difficult for 1 lesion. For these 6 lesions, the median distance from the tumor to the visceral pleura and the median surgical margin were 0 mm (range, 0-2 mm) and 14 mm (range, 11-17 mm), respectively. When cut sections were examined, all tumors emitted fluorescence. All lesions were histologically confirmed to be metastatic HCC.

Conclusions

In patients with pulmonary metastasis of HCC, ICG fluorescence imaging is useful for identifying the tumor and securing its margin when the lesion is peripheral and wedge resection is planned.

Endoscopic Cerenkov luminescence imaging and image-guided tumor resection on hepatocellular carcinoma-bearing mouse models

Detecting deep tumors inside living subject is still challenging for Cerenkov luminescence imaging (CLI). In this study, a high-sensitivity endoscopic CLI (ECLI) system was developed with a dual-mode deep cooling approach to improve the imaging sensitivity. System was characterized through a series of ex vivo studies. Furthermore, subcutaneous and orthotropic human hepatocellular carcinoma (HCC) mouse models were established for ECLI guided tumor resection in vivo. The results showed that the ECLI system had spatial resolution (62.5 μm) and imaging sensitivity (6.29 × 10^-2 kBq/μl ¹⁸F-FDG). The in vivo experimental data from the HCC mouse models demonstrated that the system was effective to intraoperatively guide the surgery of deep tumors such as liver cancer. Overall, the developed system exhibits promising potential for the applications of tumor precise resection and novel nanoprobe based optical imaging.

Intraoperative fluorescence imaging in thoracic surgery

Intraoperative fluorescence imaging (IFI) can improve real-time identification of cancer cells during an operation. Phase I clinical trials in thoracic surgery have demonstrated that IFI with second window indocyanine green (TumorGlow^® ) can identify subcentimeter pulmonary nodules, anterior mediastinal masses, and mesothelioma, while the use of a folate receptor-targeted near-infrared agent, OTL38, can improve the specificity for diagnosing tumors with folate receptor expression. Here, we review the existing preclinical and clinical data on IFI in thoracic surgery.

Image-guided video-assisted thoracoscopic small lung tumor resection using near-infrared marking

BACKGROUND

Localization of non-visible, non-palpable small pulmonary nodules during video-assisted thoracoscopic surgery (VATS) remains challenging. We sought to investigate the feasibility and safety of image-guided video-assisted thoracoscopic surgery (iVATS) with near-infrared (NIR) marking in a hybrid operating room (OR).

METHODS

Both localization and surgery were performed by a single team of thoracic surgeons. Diluted indocyanine green (ICG; quantity: 0.3-0.5 mL; dye concentration: 0.125 mg/mL) was injected percutaneously to pinpoint the tumor's location under cone beam computed tomography (CBCT) guidance using a laser-guided navigation system. Real-time fluorescence images were intraoperatively obtained using a NIR thoracoscopic camera to guide subsequent resection.

RESULTS

Between March and December 2017, 26 patients underwent NIR marking of small pulmonary nodules for iVATS. The median tumor size was 7 mm (interquartile range [IQR] 5.3-10.8 mm), whereas their median distance from the pleural surface was 5 mm (IQR 0.3-10.5 mm). Seven nodules (35%) were solid, whereas 17 (65%) were ground-glass opacities. All lesions were identifiable on intraoperative CBCT. The median time required for NIR localization was 13 min. An NIR(+) "tattoo" was identified in all cases, and no intraoperative conversion to thoracotomy occurred. The final pathological diagnoses were primary lung cancer (n = 11), metastatic cancer (n = 6), and benign lung tumor (n = 9). Adverse events were not observed, and the median length of post-operative stay was 4 days (IQR 3-4 days).

CONCLUSIONS

Our data show that iVATS with NIR marking is useful, has no adverse effects, and can successfully localize difficult-to-identify small pulmonary nodules.