Recent fluorescence imaging technology applications of indocyanine green in general thoracic surgery

Methods of bronchial stump buttressing in post-pneumonectomy bronchopleural fistula prevention: a systematic review

<b>Introduction:</b> The bronchopleural fistula (BPF) remains one of the most severe complications after pneumonectomy. Several surgical methods may enhance bronchial stump healing and reduce the occurrence of BPF. Usually, surgeons use tissue buttressing, such as intercostal muscle flap (IMF), parietal pleura, pericardium fat pad, or mediastinal fat, to reinforce the bronchial stump. This paper reviews the literature describing the impact of different buttressing tissues on the occurrence of early post-pneumonectomy BPF.<b>Material and methods:</b> We included all studies that described the use of bronchial stump buttressing in patients after pneumonectomy. Studies written in languages other than English were excluded. The search was performed using PubMed, Google Scholar, Embase, COCHRANE databases, and the clinical trial registry on December 1, 2023. We used the following search input: "lung cancer" AND "pneumonectomy" AND ("bronchopleural fistula" OR "BPF") AND ("tissue buttressing" OR "intercostal muscle flap" OR "mediastinal fat pad"). We analysed the types of studies, the numbers of patients, and the most important conclusions. We performed descriptive statistics.<b>Results:</b> Twenty-seven articles on the use of bronchial tissue buttressing were identified. Nine papers were rejected due to small sample size (< 20 patients), surgical operation other than pneumonectomy or lobectomy, or papers older than 30 years. Ultimately, 16 articles were included in the analysis. Among them, three papers highlighted the statistically significant influence of bronchial stump buttressing in reducing the risk of BPF formation. Descriptive statistics were reported in nine studies, and two papers included the assessment of the blood perfusion in the buttressing tissue. Only one study was a randomized trial featuring a control group for comparison.<b>Discussion:</b> Buttressing the bronchial stump remains a controversial issue in thoracic surgery. It could be beneficial for high-risk patients. Among different tissues, the ideal one has still not been identified. Future research should incorporate control groups and intraoperative assessments of the blood supply to the tissue employed for bronchial buttressing.

Advancements in the Management of Postoperative Air Leak following Thoracic Surgery: From Traditional Practices to Innovative Therapies

Background: Postoperative air leak (PAL) is a frequent and potentially serious complication following thoracic surgery, characterized by the persistent escape of air from the lung into the pleural space. It is associated with extended hospitalizations, increased morbidity, and elevated healthcare costs. Understanding the mechanisms, risk factors, and effective management strategies for PAL is crucial in improving surgical outcomes. Aim: This review seeks to synthesize all known data concerning PAL, including its etiology, risk factors, diagnostic approaches, and the range of available treatments from conservative measures to surgical interventions, with a special focus on the use of autologous plasma. Materials and Methods: A comprehensive literature search of databases such as PubMed, Cochrane Library, and Google Scholar was conducted for studies and reviews published on PAL following thoracic surgery. The selection criteria aimed to include articles that provided insights into the incidence, mechanisms, risk assessment, diagnostic methods, and treatment options for PAL. Special attention was given to studies detailing the use of autologous plasma in managing this complication. Results: PAL is influenced by a variety of patient-related, surgical, and perioperative factors. Diagnosis primarily relies on clinical observation and imaging, with severity assessments guiding management decisions. Conservative treatments, including chest tube management and physiotherapy, serve as the initial approach, while persistent leaks may necessitate surgical intervention. Autologous plasma has emerged as a promising treatment, offering a novel mechanism for enhancing pleural healing and reducing air leak duration, although evidence is still evolving. Conclusions: Effective management of PAL requires a multifaceted approach tailored to the individual patient's needs and the specifics of their condition. Beyond the traditional treatment approaches, innovative treatment modalities offer the potential to improve outcomes for patients experiencing PAL after thoracic surgery. Further research is needed to optimize treatment protocols and integrate new therapies into clinical practice.

Intraoperative assessment of anastomotic blood supply using indocyanine green fluorescence imaging following esophagojejunostomy or esophagogastrostomy for gastric cancer

OBJECTIVE

This retrospective study aimed to evaluate the feasibility and safety of intraoperative assessment of anastomotic blood supply in patients undergoing esophagojejunostomy or esophagogastrostomy for gastric cancer using Indocyanine Green Fluorescence Imaging (IGFI).

MATERIALS AND METHODS

From January 2019 to October 2021, we conducted a retrospective analysis of patients who had undergone laparoscopic gastrectomy for the treatment of gastric cancer. The patients were consecutively enrolled and categorized into two study groups: the Indocyanine Green Fluorescence Imaging (IGFI) group consisting of 86 patients, and the control group comprising 92 patients. In the IGFI group, intravenous administration of Indocyanine Green (ICG) was performed, and we utilized a fluorescence camera system to assess anastomotic blood supply both before and after the anastomosis.

RESULTS

The demographic characteristics of patients in both groups were found to be comparable. In the IGFI group, the mean time to observe perfusion fluorescence was 26.3 ± 12.0 seconds post-ICG injection, and six patients needed to select a more proximal resection point due to insufficient fluorescence at their initial site of choice. Notably, the IGFI group exhibited a lower incidence of postoperative anastomotic leakage, with no significant disparities observed in terms of pathological outcomes, postoperative recovery, or other postoperative complication rates when compared to the control group (p > 0.05).

CONCLUSION

This study underscores the potential of IGFI as a dependable and pragmatic tool for the assessment of anastomotic blood supply following esophagojejunostomy or esophagogastrostomy for gastric cancer. The use of IGFI may potentially reduce the occurrence of postoperative anastomotic leakage.

Influencing Factors on Intersegmental Identification Adequacy in Segmentectomy with Intraoperative Indocyanine Green (ICG) Intravenous Administration

Accurate identification of the intersegmental plane is essential in segmentectomy, and Indocyanine Green (ICG) assists in visualizing lung segments. Various factors, including patient-related, intraoperative, and technical issues, can influence boundary delineation. This study aims to assess the rate of unsuccessful intersegmental identification and identify the contributing factors. We analyzed cases of lung segmentectomy from April 2020 to March 2023, where intraoperative ICG was intravenously administered during robot-assisted or video-assisted thoracoscopic surgery. Cases where fluorescence extended beyond expected boundaries within 30 s were classified as the "unclear boundary group". This group was then compared to the "clear boundary group". The study encompassed 111 cases, 104 (94%) of which were classified under the "clear boundary group" and 7 (6%) under the "unclear boundary group". The "unclear boundary group" had a significantly lower DLCO (15.7 vs. 11.8, p = 0.03) and DLCO/VA (4.3 vs. 3.0, p = 0.01) compared to the "clear boundary group". All cases in the "unclear boundary group" underwent lower lobe segmentectomy. ICG administration effectively outlines pulmonary segments. Challenges in segment demarcation may occur in cases with low DLCO and DLCO/VA values, particularly during lower lobe segmentectomy.

Robot-assisted segmentectomy with improved modified inflation-deflation combined with the intravenous indocyanine green method

To investigate the perioperative outcomes of patients who underwent robot-assisted thoracoscopic (RATS) segmentectomy for identifying the intersegmental plane (ISP) by improved modified inflation-deflation (MID) combined with near-infrared fluorescence imaging with the intravenous indocyanine green (ICG) method and to assess the feasibility of this method in a large-scale cohort according to the type of segmentectomy performed. We retrospectively analysed the perioperative data of a total of 155 consecutive patients who underwent RATS segmentectomy between April 2020 and December 2021. Data from the operation, including the demarcation status of the intersegmental plane, were analysed retrospectively. The mean operative time and estimated blood loss were 125.56 ± 36.32 min and 41.81 ± 49.18 mL, respectively. Good demarcation of the intersegmental plane was observed in 150 (96.77%) patients, with no correlation with the type of resected segments or the surgical method. Postoperative complications of Clavien-Dindo classification grade 3 or more were observed in 4 patients (2.58%), and no ICG-related adverse events were noted. Demarcation of the intersegmental plane by improved MID combined with ICG is feasible regardless of the type of segmentectomy and can be commonly applied in robot-assisted segmentectomy.

An "AND" Molecular Logic Gate as a Super-Enhancers for De Novo Designing Activatable Probe and Its Application in Atherosclerosis Imaging

Developing activatable fluorescent probes with superlative fluorescence enhancement factor (F/F0 ) to improve the signal-to-noise (S/N) ratio is still an urgent issue. "AND" molecular logic gates are emerging as a useful tool for enhanced probes selectivity and accuracy. Here, an "AND" logic gate is developed as super-enhancers for designing activatable probes with huge F/F0 and S/N ratio. It utilizes lipid-droplets (LDs) as controllable background input and sets the target analyte as variable input. The fluorescence is tremendously quenching due to double locking, thus an extreme F/F0 ratio of target analyte is obtained. Importantly, this probe can transfer to LDs after a response occurs. The target analyte can be directly visualized through the spatial location without a control group. Accordingly, a peroxynitrite (ONOO- ) activatable probe (CNP2-B) is de novo designed. The F/F0 of CNP2-B achieves 2600 after reacting with ONOO- . Furthermore, CNP2-B can transfer from mitochondria to lipid droplets after being activated. The higher selectivity and S/N ratio of CNP2-B are obtained than commercial probe 3'-(p-hydroxyphenyl) fluorescein (HPFin vitro and in vivo. Therefore, the atherosclerotic plaques at mouse models are delineated clearly after administration with in situ CNP2-B probe gel. Such input controllable "AND" logic gate is envisioned to execute more imaging tasks.

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.

Real-world perioperative outcomes of segmentectomy versus lobectomy for early-stage lung cancer: a propensity score-matched analysis

OBJECTIVES

This study aimed to compare the real-world outcomes of segmentectomy and lobectomy for lung cancer after adjusting for background factors and the extent of lymphadenectomy.

METHODS

This retrospective cohort study used a nationwide database in Japan. The data of patients with clinical stage 0/IA lung cancer who underwent segmentectomy or lobectomy between 2017 and 2019 were retrieved. Short-term postoperative outcomes were compared between the segmentectomy and lobectomy groups using propensity score-matched analysis.

RESULTS

In the total cohort of 59 663 patients, 11 975 and 47 688 patients were in the segmentectomy and lobectomy groups, respectively. After propensity score matching, 8426 matched patients from each group were retrieved. All confounders including age, sex, comorbidities, smoking history, respiratory function, tumour size, clinical stage, affected lobe and extent of lymphadenectomy were appropriately adjusted. The overall complication rate and the cardiopulmonary complication rate were lower in the segmentectomy group than in the lobectomy group (8.5% vs 11.2%, P < 0.001 and 7.5% vs 10.3%, P < 0.001, respectively). The incidence of prolonged air leak was also lower after segmentectomy than after lobectomy (3.6% vs 5.3%). Surgical mortality, operative time and blood loss volume were comparable between the 2 groups.

CONCLUSIONS

The postoperative complication rate was lower with segmentectomy than with lobectomy for early-stage lung cancer.

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.

Progresses in Fluorescence Imaging Guidance for Bone and Soft Tissue Sarcoma Surgery

R0 surgical resection is the preferred treatment for bone and soft tissue sarcoma. However, there is still a lack of precise technology that can visualize bone and soft tissue sarcoma during surgery to assist the surgeon in judging the tumor surgical boundary. Fluorescence imaging technology has been used in the diagnosis of cancer. It is a simple and essentially safe technique that takes no additional time during the operation. Intraoperative fluorescence imaging has potential application prospects in assisting the surgeons in judging the tumor boundary and improving the accuracy of surgical resection. This review mainly starts with clinical studies, animal experimentation, and newly designed probes of intraoperative fluorescence imaging of bone and soft tissue sarcoma, to appraise the application prospects of fluorescence imaging technology in bone and soft tissue sarcoma.

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.

Lipid-Activatable Fluorescent Probe for Intraoperative Imaging of Atherosclerotic Plaque Using In Situ Patch

The surgical removal of lesions is among the most common and effective treatments for atherosclerosis. It is often the only curative treatment option, and the ability to visualize the full extent of atherosclerotic plaque during the operation has major implications for the therapeutic outcome. Fluorescence imaging is a promising approach for the inspection of atherosclerotic plaques during surgery. However, there is no systematic strategy for intraoperative fluorescent imaging in atherosclerosis. In this study, the in situ attachment of a lipid-activatable fluorescent probe (CN-N2)-soaked patch to the outer arterial surface is reported for rapid and precise localization of the atherosclerotic plaque in ApoE-deficient mouse during surgery. Stable imaging of the plaque is conducted within 5 min via rapid recognition of abnormally accumulated lipid droplets (LDs) in foam cells. Furthermore, the plaque/normal ratio (P/N) is significantly enhanced to facilitate surgical delineation of carotid atherosclerotic plaques. Visible fluorescence bioimaging using lipid-activatable probes can accurately delineate plaque sizes down to diameters of <0.5 mm, and the images can be swiftly captured within the stable plaque imaging time window. These findings on intraoperative fluorescent imaging of plaques via the in situ attachment of the CN-N2 patch hold promise for effective clinical applications.

Lipid Droplet-Specific Probe for Rapidly Locating Atherosclerotic Plaques and Intraoperative Imaging via In Situ Spraying

The ability to visualize the full extent of atherosclerotic plaques during surgery has major implications for therapeutic outcomes. Fluorescence imaging is a promising approach for atherosclerotic plaque inspection during surgery. However, a specific strategy for the intraoperative fluorescence imaging of atherosclerosis has not been established. This study presents an in situ spraying aerosol of a lipid droplet-specific probe to rapidly and precisely locate atherosclerotic plaques during surgery. Stable imaging of the plaque was achieved within 5 min by nebulizing the aqueous solution of the lipid droplet-specific probe (CN-PD) into 3 μm droplets and rapidly permeating it in situ. The visible fluorescence bioimaging of CN-PD can accurately delineate the plaque margins and size even with a diameter ≤0.5 mm, which are capable of being swiftly captured during the stable plaque imaging window (>2 h). This strategy combines the consideration of a specific probe design and an efficient in situ delivery, which results in weak interference from the background signals. Therefore, the plaque-to-normal tissue ratio (P/N) is sufficient to facilitate the surgical delineation of carotid atherosclerotic plaques. The originality of the intraoperative fluorescence imaging of the plaques via in situ delivery of the lipid droplet-specific probe holds promise for effective clinical application.

Optimization of Sentinel Lymph Node Imaging Methodology Using Anionic Liposome and Hyaluronidase

The sentinel lymph node (SLN) is the first lymph node into which lymphatic fluid from tumor tissues flows. The development of a highly sensitive probe for detecting SLNs is desired for the lymph node dissection through intraoperative biopsy. We have previously shown that anionic liposomes tend to accumulate in lymph nodes and that macrophage uptake of liposomes contributes to their accumulation. In the present study, we found that among anionic lipids, phosphatidylserine (PS)-containing liposomes were substantially taken up by macrophages. We identified a new lipid composition to improve the SNL-selectivity of liposome accumulation based on Design-of-Experiment. The optimized PS-containing particles were more selectively accumulate to SLN lymph nodes than existing imaging agents indocyanine green. These results indicate the effectiveness of PS-containing anionic particles in SLN imaging.

Development of Sentinel LN Imaging with a Combination of HAase Based on a Comprehensive Analysis of the Intra-lymphatic Kinetics of LPs

The sentinel lymph node (LN) is the first LN to which lymph fluid flows from tumor tissue. We identified the key parameters of liposomes (LPs) that affect their accumulation in regional (primary) LNs with minimum leakage to its connecting (secondary) LNs by a comprehensive analysis of the LN-to-LN trafficking of LPs with various surface charges and various sizes. We used a lymphatic flow-modified (LFM) mouse that allows for the chronological analysis of inguinal (primary) LN-to-axillary (secondary) LN at the body surface. As a result, the anionic medium-sized LPs (130 nm on average) exhibited the highest accumulation in the primary LNs. A mechanism-based analysis revealed that CD169-positive macrophages in LNs were the dominant cell population that captures anionic LPs. Sentinel LN imaging was also performed by the intratumoral injection of fluorescent medium-sized anionic LPs using a breast cancer orthotopic model. In comparison with the typically used contrast agent indocyanine green, the anionic LPs were detected in sentinel LNs with a high sensitivity. Additionally, the co-injection of hyaluronidase significantly improved the sensitivity of detection of the fluorescent LPs in sentinel LNs. In conclusion, medium-sized anionic LPs combined with hyaluronidase represents a potent strategy for investigating sentinel LNs.

A method to identify pulmonary intersegmental planes with intravenous vitamin B2 injection

PURPOSE

The present study investigated whether the pulmonary intersegmental planes could be identified with the intravenous injection of vitamin B₂ using a fluorescent camera and whether this method can be used instead of the inflation-deflation technique or the intravenous indocyanine green (ICG) method.

METHODS

In experiment 1, the vitamin B₂ was intravenously injected to visualize the pulmonary intersegmental plane and perform segmentectomy, and the visualized pulmonary intersegmental line was then compared to the inflation-deflation line in six pigs. In experiment 2, using six pigs, the fluorescent area and duration of fluorescence were compared after the intravenous injection of vitamin B₂ and ICG in the same animals.

RESULTS

In all animals in experiment 1, it was possible to clearly detect yellow-green fluorescence in the lung, in segments other than the one intended for resection, for at least 60 min. Moreover, the line visualized with vitamin B₂ fluorescence matched the inflation-deflation line in all animals. In experiment 2, the area of vitamin B₂ fluorescence corresponded to the area of ICG fluorescence in each animal.

CONCLUSIONS

The visualization of fluorescence after the intravenous injection of vitamin B₂ using a fluorescent camera was a simple, safe, and accurate method for detecting intersegmental planes in a pig model. This method can be an alternative to the inflation-deflation technique and the intravenous ICG method.