Sentinel Lymph Node Mapping of Liver

Precise and safe pulmonary segmentectomy enabled by visualizing cancer margins with dual-channel near-infrared fluorescence

BACKGROUND

Segmentectomy is a type of limited resection surgery indicated for patients with very early-stage lung cancer or compromised function because it can improve quality of life with minimal removal of normal tissue. For segmentectomy, an accurate detection of the tumor with simultaneous identification of the lung intersegment plane is critical. However, it is not easy to identify both during surgery. Here, the authors report dual-channel image-guided lung cancer surgery using renally clearable and physiochemically stable targeted fluorophores to visualize the tumor and intersegmental plane distinctly with different colors; cRGD-ZW800 (800 nm channel) targets tumors specifically, and ZW700 (700 nm channel) simultaneously helps discriminate segmental planes.

METHODS

The near-infrared (NIR) fluorophores with 700 nm and with 800 nm channels were developed and evaluated the feasibility of dual-channel fluorescence imaging of lung tumors and intersegmental lines simultaneously in mouse, rabbit, and canine animal models. Expression levels of integrin αvβ3, which is targeted by cRGD-ZW800-PEG, were retrospectively studied in the lung tissue of 61 patients who underwent lung cancer surgery.

RESULTS

cRGD-ZW800-PEG has clinically useful optical properties and outperforms the FDA-approved NIR fluorophore indocyanine green and serum unstable cRGD-ZW800-1 in multiple animal models of lung cancer. Combined with the blood-pooling agent ZW700-1C, cRGD-ZW800-PEG permits dual-channel NIR fluorescence imaging for intraoperative identification of lung segment lines and tumor margins with different colors simultaneously and accurately.

CONCLUSION

This dual-channel image-guided surgery enables complete tumor resection with adequate negative margins that can reduce the recurrence rate and increase the survival rate of lung cancer patients.

Nano-tracers for sentinel lymph node detection: current trends in technique and application

Sentinel lymph node (SLN) detection and biopsy is a critical staging component for several cancers. Apart from established methods using dyes or radiolabeled colloids, newer techniques are emerging, like near-infrared fluorescent compounds, targeted molecular radiopharmaceuticals and magnetic nano-tracers. In the overview section of this review, we categorize SLN detection tracers based on their principle of use. We discuss the merits of existing tracers and provide a glimpse of in-development formulations. A subsequent clinical section explores the expanded role of SLN detection in management of various cancers, citing current medical guidelines and the leading conclusions of long-term clinical trials. The concluding section tries to provide a perspective of promising developments and the work required to bring them to clinical fruition.

The LIver SEntinel LYmph-node (LISELY) study: A prospective intraoperative real time evaluation of liver lymphatic drainage and sentinel lymph-node using near-infrared (NIR) imaging with Indocyanine Green (ICG)

Near-infrared (NIR) imaging with Indocyanine green (ICG) has been recently proposed for the sentinel lymph node (SLN) and lymphatic out-flow detection in several tumors. Nowadays its application in primary and secondary liver (LCs) and biliary cancers (BTCs) remains uninvestigated. A proof-of-concept prospective observational study including 18 patients underwent surgery for LCs and BTCs from September 2021 to November 2021 was carried out. The intraoperative NIR imaging with ICG was detected at predefined temporary intervals in order to identify the main lymphatic out-flow and the SLN. In 14 patients (77.8%) the lymphatic outflow pathway was visualized with a median time of 3 min after ICG injection (IQR 3-10). The SLN was detected and confirmed at the histological examination in 12 patients (66.7%). Intraoperative NIR imaging with ICG is a safe and feasible method to identify the lymphatic out-flow and SLN in LCs and BTCs.

Evaluation of perfluoropropane (C3F8)-filled chitosan polyacrylic acid nanobubbles for ultrasound imaging of sentinel lymph nodes and tumors

Accurate sentinel lymph node (SLN) identification is an important prerequisite for sentinel lymph node biopsy (SLNB). However, existing SLN mapping techniques, mainly imaging-guided methods, are severely restricted by the high cost of the instruments, harmful radiation or unsatisfactory imaging depths. Herein, we prepared a new ultrasound contrast agent by filling perfluoropropane (C₃F₈) into chitosan polyacrylic acid nanobubbles for precise SLN identification. The obtained ultrasound contrast agent, coined C₃F₈-CS-PAA nanobubbles, presents a nanometer size with a diameter of approximately 120 nm. The C₃F₈-CS-PAA nanobubbles of desirable size are able to enter lymphatic vessels and accumulate in the sentinel lymph node to enhance ultrasound imaging. As a result, the injection of C₃F₈-CS-PAA nanobubbles can remarkably enhance the ultrasound imaging lymph system, providing image guidance for sentinel lymph node biopsy. Furthermore, it was shown that such C₃F₈-CS-PAA nanobubbles can effectively permeate into the tumor region via the tumor-enhanced permeability and retention (EPR) effect to enhance tumor ultrasound imaging for monitoring tumorigenesis. This work highlights a novel nanoscale ultrasound contrast agent for the lymphatic system and tumor imaging, with great promise for subsequent studies and clinical applications.

Clinical application of indocyanine green fluorescence imaging in laparoscopic lymph node dissection for intrahepatic cholangiocarcinoma: A pilot study (with video)

BACKGROUND

Intrahepatic cholangiocarcinoma is a highly lethal malignancy characterized by lymph node metastasis. This study aimed to evaluate the efficacy of indocyanine green fluorescence for visualization of lymphatic drainage and to assess its clinical application during laparoscopic lymph node dissection for intrahepatic cholangiocarcinoma.

METHODS

All patients with intrahepatic cholangiocarcinoma who underwent laparoscopic left hepatectomy and lymph node dissection between October 2018 and January 2021 were reviewed. The patients were assigned to the indocyanine green group or non-intrahepatic cholangiocarcinoma group based on the staining technique used.

RESULTS

Of 38 patients with left hemiliver intrahepatic cholangiocarcinoma, 20 underwent intrahepatic cholangiocarcinoma tracer-guided laparoscopic radical left hepatectomy; 12 procedures were successful (indocyanine green group). During the same period, 18 patients were treated with traditional laparoscopic resection (control group). Their intraoperative factors were comparable and there were no differences in the incidence or severity of their postoperative complications 30 days after surgery (P > .05). In the indocyanine green group, more lymph nodes were harvested (mean [range]: 7.0 [6.0-8.0] vs 3.5 [3.0-5.0], P < .001) and the proportion of confirmed pathologic lymph nodes was higher (75.0%, 66.7%-87.5% vs 40%, 33.3%-50.0%, P < .001). ICG staining was observed in all (12/12, 100%) patients in the intrahepatic cholangiocarcinoma group at stations 8 and 12, and 9 (9/12, 75%) and 10 (11/12, 91.7%) patients at Stations 13 and 7, respectively.

CONCLUSION

The indocyanine green fluorescence imaging system is feasible, safe, and effective for tracing lymph nodes. It can be used to identify regional lymphatic drainage patterns and help define the scope of lymph node dissection in patients with intrahepatic cholangiocarcinoma.

Comparison of radio-isotope method with 99m technetium and near-infrared fluorescent imaging with indocyanine green for sentinel lymph node detection in endometrial cancer

BACKGROUND

We aimed to compare the detection rate of pelvic sentinel lymph node between the radio-isotope with 99m technetium (99mTc)-labeled phytate and near-infrared fluorescent imaging with indocyanine green in patients with endometrial cancer.

METHODS

This study included 122 patients who had undergone sentinel lymph node mapping using 99mTc and indocyanine green. In the radio-isotope method, sentinel lymph nodes were detected using uterine cervix 99mTc injections the day before surgery. Following injection, the number and locations of the sentinel lymph nodes were evaluated by lymphoscintigraphy. In addition, indocyanine green was injected into the cervix immediately before surgery.

RESULTS

The overall pelvic sentinel lymph node detection rate (at least one pelvic sentinel lymph node detected) was not significantly different between 99mTc (95.9% [117/122]) and indocyanine green (94.3% [115/122]). Similarly, the bilateral sentinel lymph node detection rate was not significantly different between 99mTc (87.7% [107/122]) and indocyanine green (79.5% [97/122]). More than two sentinel lymph nodes per unilateral pelvic lymph node were found in 12.3% (15/122) and 27% (33/122) of cases with 99mTc and indocyanine green, respectively, in the right pelvic side, and 11.5% (14/122) and 32.8% (40/122) of cases with 99mTc and indocyanine green, respectively, in the left pelvic side. indocyanine green showed that there were significantly more than two sentinel lymph nodes in either the left or right pelvic sentinel lymph nodes (P < 0.0001). There was a significant difference in the mean number of total pelvic sentinel lymph nodes between 99mTc (2.2) and indocyanine green (2.5) (P = 0.028) methods.

CONCLUSION

Although indocyanine green is useful for sentinel lymph node identification, we believe it is better to use it in combination with 99mTc until the surgeon is accustomed to it.

Clinical study of combined application of indocyanine green and methylene blue for sentinel lymph node biopsy in breast cancer

OBJECTIVE

This study aims to investigate the feasibility of combined application of indocyanine green (ICG) and methylene blue (MB) for sentinel lymph node biopsy (SLNB) in patients with early breast cancer.

METHODS

A total of 415 patients who underwent SLNB and axillary lymph node dissection were enrolled. Sentinel lymph node (SLN) was assessed in 197 patients with ICG and MB combination method, while, the other 218 patients were detected by MB method alone. During surgery, all SLNs were harvested for pathological examination. Then the detection rate and false negative rate of SLNs were comparatively analyzed between the 2 groups.

RESULTS

In the combined ICG and MB group, the detection rate of SLNs was 96.9%, significantly higher than that of MB group, which was 89.7% (P < .05). Similarly, in combined group, the average number of SLNs per patient was 3.0, much higher than that of MB group, which was 2.1 (P < .05). There was no statistically significant difference in false negative rate between combined group and MB alone group, which was 7.3% and 10.5%, respectively (P = .791).

CONCLUSION

The combined application of ICG and MB for SLNB is much more effective than MB alone in detecting SLNs.

Liver lymphatic drainage patterns follow segmental anatomy in a murine model

The liver’s cellular functions are sustained by a hierarchical, segmentally-organized vascular system. Additionally, liver lymphatic vessels are thought to drain to perihepatic lymph nodes. Surprisingly, while recent findings highlight the importance of organ-specific lymphatics, the functional anatomy of liver lymphatics has not been mapped out. In literature, no segmental or preferential lymphatic drainage patterns are known to exist. We employ a novel murine model of liver lymphangiography and in vivo microscopy to delineate the lymphatic drainage patterns of individual liver lobes. Our data from blue dye liver lymphangiography show preferential lymphatic drainage patterns: Right lobe mainly to hepatoduodenal ligament lymph node 1 (LN1); left lobe to hepatoduodenal ligament LN1 + LN2 concurrently; median lobe showed a more variable LN1/LN2 drainage pattern with increased (sometimes exclusive) mediastinal thoracic lymph node involvement, indicating that part of the liver can drain directly to the mediastinum. Upon ferritin lymphangiography, we observed no functional communication between the lobar lymphatics. Altogether, these results show the existence of preferential lymphatic drainage patterns in the murine liver. Moreover, this drainage can occur directly to mediastinal lymph nodes and there is no interlobar lymphatic flow. Collectively, these data provide the first direct evidence that liver lymphatic drainage patterns follow segmental anatomy.

In Vivo Imaging of Click-Crosslinked Hydrogel Depots Following Intratympanic Injection

In this study, we developed injectable intratympanic hyaluronic acid (HA) depots for the treatment of hearing loss. We prepared an injectable click-crosslinking formulation by modifying HA with tetrazine (HA-TET) and trans-cyclooctene (HA-TCO), which crosslinked to form an HA depot (Cx-HA). Preparation of the click-crosslinking HA formulation was facile, and Cx-HA depot formation was reproducible. Additionally, the Cx-HA hydrogel was significantly stiffer than HA hydrogel. To monitor the degradation pattern of hydrogels, we mixed a zwitterionic near-infrared (NIR) fluorophore (e.g., ZW800-1C) in the click-crosslinking HA formulation. Then, HA-TET and HA-TCO solutions containing ZW800-1C were loaded separately into the compartments of a dual-barrel syringe for intratympanic injection. The Cx-HA depots formed quickly, and an extended residence time in the tympanic cavity was confirmed by performing NIR fluorescence imaging. We have successfully prepared an injectable click-crosslinking HA formulation that has promise as an intratympanic drug depot.

Multi-Wavelength Fluorescence in Image-Guided Surgery, Clinical Feasibility and Future Perspectives

With the rise of fluorescence-guided surgery, it has become evident that different types of fluorescence signals can provide value in the surgical setting. Hereby a different range of targets have been pursued in a great variety of surgical indications. One of the future challenges lies in combining complementary fluorescent readouts during one and the same surgical procedure, so-called multi-wavelength fluorescence guidance. In this review we summarize the current clinical state-of-the-art in multi-wavelength fluorescence guidance, basic technical concepts, possible future extensions of existing clinical indications and impact that the technology can bring to clinical care.

Real-Time Fluorescence Imaging in Thoracic Surgery

Near-infrared (NIR) fluorescence imaging provides a safe and cost-efficient method for immediate data acquisition and visualization of tissues, with technical advantages including minimal autofluorescence, reduced photon absorption, and low scattering in tissue. In this review, we introduce recent advances in NIR fluorescence imaging systems for thoracic surgery that improve the identification of vital tissues and facilitate the resection of tumorous tissues. When coupled with appropriate NIR fluorophores, NIR fluorescence imaging may transform current intraoperative thoracic surgery methods by enhancing the precision of surgical procedures and augmenting postoperative outcomes through improvements in diagnostic accuracy and reductions in the remission rate.

Real-Time Imaging of Vaccine Biodistribution Using Zwitterionic NIR Nanoparticles

Efficient and timely delivery of vaccine antigens to the secondary lymphoid tissue is crucial to induce protective immune responses by vaccination. However, determining the longitudinal biodistribution of injected vaccines in the body has been a challenge. Here, the near-infrared (NIR) fluorescence imaging is reported that can efficiently enable the trafficking and biodistribution of vaccines in real time. Zwitterionic NIR fluorophores are conjugated on the surface of model vaccines and tracked the fate of bioconjugated vaccines after intradermal administration. Using an NIR fluorescence imaging system, it is possible to obtain time-course imaging of vaccine trafficking through the lymphatics, observing notable uptake in lymph nodes with minimal nonspecific tissue interactions. Flow cytometry analysis confirmed that the uptake in lymph nodes by antigen presenting cells was highly dependent on the hydrodynamic diameter of vaccines. These results demonstrate that the combination of a real-time NIR fluorescence imaging system and zwitterionic fluorophores is a powerful tool to determine the fate of vaccine antigens. Since such non-specific vaccine uptake causes serious adverse reactions, this method is not only useful for optimization of vaccine design, but also for safety evaluation of clinical vaccine candidates.

Oncologic Impact of Lymph Node Dissection for Intrahepatic Cholangiocarcinoma: a Propensity Score-Matched Study

BACKGROUND

Intrahepatic cholangiocarcinoma is a malignancy of the intrahepatic biliary tree. Although surgical resection is the mainstay of treatment for this tumor, the impact of lymph node dissection during hepatectomy is controversial. In this study, we evaluated the impact of lymph node dissection during surgical resection for intrahepatic cholangiocarcinoma.

METHODS

Records from 170 patients who underwent radical hepatectomy for intrahepatic cholangiocarcinoma from January 2000 to December 2014 were retrospectively reviewed. Twenty-two patients who underwent R1 resection or had distant metastasis at the time of surgery were excluded. Using propensity score matching (matched factors: differentiation, lymphovascular invasion, perineural invasion, and T stage), the patients were divided into two groups: no dissection (n = 34) or lymph node dissection (n = 34). Disease-free survival and overall survival were compared between groups.

RESULTS

There was a marginally significant difference between the two groups with respect to the disease-free survival (no dissection vs. lymph node dissection: 20.0 [4.2-35.8] months vs. 64.0 [27.3-120.8] months, p = 0.077). Overall survival was significantly longer in the lymph node dissection group (no dissection vs. lymph node dissection: 44.0 [31.1-56.9] months vs. 90.0 [51.1-158.9] months, p = 0.027).

CONCLUSION

Radical surgery including an adequate lymph node dissection area and suitable harvested lymph nodes appears to improve oncologic outcomes for intrahepatic cholangiocarcinoma.

Molecular fluorescence-guided surgery of peritoneal carcinomatosis of colorectal origin: A narrative review

Patients with peritoneal carcinomatosis (PC) from colorectal origin may undergo cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) as a curative approach. One major prognostic factor that affects survival is completeness of cytoreduction. Molecular Fluorescence Guided Surgery (MFGS) is a novel intraoperative imaging technique that may improve tumor identification in the future, potentially preventing over- and under-treatment in these patients. This narrative review outlines a chronological overview of MFGS development in patients with PC of colorectal origin.

Multivalent Mannose-Decorated NIR Nanoprobes for Targeting Pan Lymph Nodes

Lymphadenectomy is a prerequisite for most malignancies to define the precise staging of cancer, as well as resect the possible metastases completely. While it improves prognosis, lymphadenectomy often causes postoperative edema or bleeding because of unclear surgical margins. In this study, we synthesized near-infrared (NIR) fluorescent nanoprobes with conjugating various mannose moieties on the surface to target macrophages in the lymph node. Armed with these NIR nanoprobes, we demonstrated the feasibility of intraoperative pan lymph nodes (PLN) mapping and real-time optical imaging under the NIR fluorescence imaging system. We found that even single mannose-conjugated ZW800-1 showed specific uptake in lymph nodes within 4 h, and multiple mannose-employed polyrotaxanes highlighted PLN efficiently with low background signals in major organs. This technology can help surgeons perform lymphadenectomy with ease and safety by identifying all regional lymph nodes proficiently after a single intravenous injection of NIR nanoprobes.

Intraoperative Near-Infrared Fluorescence Imaging of Thymus in Preclinical Models

BACKGROUND

There are currently no thymus-specific contrast agents for biomedical imaging. Thus, finding ectopic thymic tissue during certain operations is extremely difficult. The purpose of the present study was to determine if near-infrared (NIR) fluorescence imaging could provide high sensitivity, real-time identification of thymic tissue during the operation.

METHODS

After initial in vivo screening of a 315-compound NIR fluorophore library for thymic uptake, methylene blue and five different 700-nm emitting candidate molecules were injected into CD-1 mice for quantitation of the signal-to-background ratio as a function of kinetics and dosing. Results were confirmed in 35-kg Yorkshire pigs. Dual-channel NIR imaging was also performed using a variety of 800-nm emitting NIR fluorophores targeted to various tissues in the mediastinum and neck.

RESULTS

The compound Oxazine 170 demonstrated the highest signal-to-background ratio (≥3) for thymic tissue relative to mediastinal fat, heart, lung, muscle, thyroid gland, and parathyroid gland, with peak signal-to-background ratio occurring 4 h after 1 intravenous injection of a human equivalent dose of approximately 7 mg. Simultaneous dual-channel NIR imaging permitted unambiguous identification of the thymus from surrounding tissues, such as endocrine glands and lymph nodes.

CONCLUSIONS

In mouse and pig, NIR fluorescence imaging using Oxazine 170 permits high sensitivity, real-time identification of thymic tissue for surgical procedures requiring its resection or avoidance. The performance of Oxazine 170 for imaging human thymic tissue is currently not known.

Near-Infrared Illumination of Native Tissues for Image-Guided Surgery

Our initial efforts to prepare tissue-specific near-infrared (NIR) fluorescent compounds generated successful correlation between physicochemical properties and global uptake in major organs after systemic circulation and biodistribution. Herein, we focus on the effects on biodistribution based on modulating electronic influencing moieties from donating to withdrawing moieties at both the heterocyclic site and through meso-substitution of pentamethine cyanine fluorophores. These selected modifications harnessed innate biodistribution pathways through the structure-inherent targeting, resulting in effective imaging of the adrenal glands, pituitary gland, lymph nodes, pancreas, and thyroid and salivary glands. These native-tissue contrast agents will arm surgeons with a powerful and versatile arsenal for intraoperative NIR imaging in real time.

From Conventional Radiotracer Tc-99(m) with Blue Dye to Indocyanine Green Fluorescence: A Comparison of Methods Towards Optimization of Sentinel Lymph Node Mapping in Early Stage Cervical Cancer for a Laparoscopic Approach

BACKGROUND

The credibility of sentinel lymph node (SLN) mapping is becoming increasingly more established in cervical cancer. We aimed to assess the sensitivity of SLN biopsy in terms of detection rate and bilateral mapping in women with cervical cancer by comparing technetium-99 radiocolloid (Tc-99(m)) and blue dye (BD) versus fluorescence mapping with indocyanine green (ICG).

METHODS

Data of patients with cervical cancer stage 1A2 to 1B1 from 5 European institutions were retrospectively reviewed. All centers used a laparoscopic approach with the same intracervical dye injection. Detection rate and bilateral mapping of ICG were compared, respectively, with results obtained by standard Tc-99(m) with BD.

RESULTS

Overall, 76 (53 %) of 144 of women underwent preoperative SLN mapping with radiotracer and intraoperative BD, whereas 68 of (47 %) 144 patients underwent mapping using intraoperative ICG. The detection rate of SLN mapping was 96 % and 100 % for Tc-99(m) with BD and ICG, respectively. Bilateral mapping was achieved in 98.5 % for ICG and 76.3 % for Tc-99(m) with BD; this difference was statistically significant (p < 0.0001).

CONCLUSIONS

The fluorescence SLN mapping with ICG achieved a significantly higher detection rate and bilateral mapping compared to standard radiocolloid and BD technique in women with early stage cervical cancer. Nodal staging with an intracervical injection of ICG is accurate, safe, and reproducible in patients with cervical cancer. Before replacing lymphadenectomy completely, the additional value of fluorescence SLN mapping on both perioperative morbidity and survival should be explored and confirmed by ongoing controlled trials.