Toward optimization of imaging system and lymphatic tracer for near-infrared fluorescent sentinel lymph node mapping in breast cancer

Near-infrared fluorescence lymph node template region dissection plus backup lymphadenectomy in open radical cystectomy for bladder cancer using an innovative handheld device: A single center experience

BACKGROUND

The extent of pelvic lymphadenectomy (PLND) as part of radical cystectomy (RC) for bladder cancer (BC) remains unclear. Sentinel-based and lymphangiographic approaches could lead to reduced morbidity without sacrificing oncologic safety.

OBJECTIVE

To evaluate the feasibility and diagnostic value of fluorescence-guided template sentinel region dissection (FTD) using a handheld near-infrared fluorescence (NIRF) camera in open radical cystectomy.

DESIGN, SETTING, AND PARTICIPANTS

After peritumoral cystoscopic injection of indocyanine green (ICG) 21 patients underwent open RC with FTD due to BC between June 2019 and June 2021. Intraoperatively, the FIS-00 Hamamatsu Photonics® NIRF camera was used to identify and resect fluorescent template sentinel regions (FTRs) followed by extended pelvic lymphadenectomy (ePLND) as oncological back-up.

OUTCOME MEASUREMENT AND STATISTICAL ANALYSIS

Descriptive analysis of positive and negative results per template region.

RESULTS AND LIMITATIONS

FTRs were identified in all 21 cases. Median time (range) from ICG injection to fluorescence detection was 75 (55-125) minutes. On average (SD), 33.4 (9.6) lymph nodes were dissected per patient. Considering template regions as the basis of analysis, 67 (38.3%) of 175 resected regions were NIRF-positive, with 13 (7.4%) regions harboring lymph node metastases. We found no metastatic lymph nodes in NIRF-negative template regions. Outside the standard template, two NIRF-positive benign nodes were identified.

CONCLUSION

The concept of NIRF-guided FTD proved for this group all lymph node metastases to be found in NIRF-positive template regions. Pending validation in a larger collective, resection of approximately 40% of standard regions may be sufficient and may result in less morbidity.

Indocyanine green fluorescence versus blue dye, technetium-99M, and the dual-marker combination of technetium-99M + blue dye for sentinel lymph node detection in early breast cancer-meta-analysis including consistency analysis

BACKGROUND

Axillary sentinel lymph node biopsies are standard of care in patients with breast cancer and no clinically apparent metastases. Traditionally, technetium-99m, blue dye, or both have been used to identify sentinel lymph nodes. However, blue dyes miss up to 40% of sentinel lymph nodes, while technetium-99m use is complex, costly, and exposes patients to radiation. Over the past decade, studies have consistently found the biologically inert fluorescent indocyanine green to be 95% to 100% sensitive in detecting breast cancer sentinel lymph nodes, yet indocyanine green remains infrequently used.

METHODS

We conducted an extensive meta-analysis comparing indocyanine green against blue dye, technetium-99m, and the dual-marker combination of technetium-99m + BD. Unlike prior meta-analyses that only assessed either per-case or per-node sentinel lymph node detection, we analyzed the following 5 metrics: per-case and per-node sentinel lymph node detection and metastasis-positive sentinel lymph node sensitivity, and mean number of sentinel lymph nodes/case. We further examined the consistency and magnitude of between-study superiority and statistically significant within-study superiority of each marker against others.

RESULTS

For every metric and analysis approach, indocyanine green was clearly superior to blue dye and at least non-inferior, if not superior, to technetium-99m and technetium-99m + blue dye. Assessing the consistency of superiority by at least 2.0%, indocyanine green was superior to blue dye 73 times versus 1, to technetium-99m 42 times versus 9, and to technetium-99m + blue dye 6 times versus 0. Within-study statistically significant differences favored indocyanine green over blue dye 29 times versus 0 and over technetium-99m 11 times versus 2.

DISCUSSION

For sentinel lymph node detection in patients with breast cancer with no clinically apparent metastases, indocyanine green is clearly and consistently superior to blue dye and either non-inferior or superior to technetium-99m and technetium-99m + blue dye.

A human serum albumin-indocyanine green complex offers improved tumor identification in fluorescence-guided surgery

Background

Complete tumor removal is critical for achieving a good prognosis in patients but remains challenging for surgeons. Near-infrared fluorescence-guided surgery (NIRFGS) enables surgeons to accurately localize tumors in real time and facilitates accurate resection. Indocyanine green (ICG) has been approved by the U.S. Food and Drug Administration and the National Medical Products Administration for many years. Although the application of ICG has progressed for a variety of surgeries, there are inherent limitations to ICG, including poor water solubility and photostability, short blood half-life, and aggregation in blood, resulting in poor imaging performance. We found that mixing ICG with human serum albumin (HSA) preoperatively and then injecting it can improve the imaging performance.

Methods

We prepared fluorescent probes by combining ICG with HSA and identified their optimal ratio via in vitro absorption measurement and emission spectrum characterization of ICG-HSA complex with different mixing ratios and concentration gradients. Subsequently, under the optimal ratio and clinical simulated concentration, we conducted dynamic change analysis of the fluorescence spectral properties after mixing. We then compared the uptake of ICG-HSA in vitro for two different cell types and the imaging performance of different molar ratios of ICG and HSA in mouse models.

Results

Through in vitro absorption and emission spectrum characterization of ICG-HSA mixtures with different mixing ratios and concentration gradients, the optimal ratio of the mixture was obtained (ICG:HSA =4:5). Using this ratio, clinical simulated concentration, and mixing, we completed the dynamic change analysis of the fluorescence spectrum properties. The results verified that HSA can improve the dispersion and stability of ICG in aqueous solution, reduce the proportion of free-state ICG, and thus improve the biodistribution. Moreover, the fluorescence performance of ICG was improved. ICG-HSA and ICG uptake in MDA-MB-231 cells and imaging in vivo showed that HSA increased the enrichment of ICG in tumor compared to ICG alone (ICG-HSAfluorescence intensity =237.3±10.7 vs. ICGfluorescence intensity =127.1±10.7). Compared with ICG alone, ICG-HSA provided a clearer tumor boundary and higher tumor-to-background ratio (TBR) (ICG-HSATBRmax 3.49±0.56 vs. ICGTBRmax 1.94±0.23).

Conclusions

This study suggests that ICG-HSA can achieve higher tumor-to-background contrast with shorter time and can provide an overall superior imaging performance compared to ICG alone, thus exhibiting considerable potential for clinical application.

A Novel Injection Protocol Using Voluven®-Assisted Indocyanine Green with Improved Near-Infrared Fluorescence Guidance in Breast Cancer Sentinel Lymph Node Mapping-A Translational Study

BACKGROUND

Near-infrared (NIR) fluorescence-guided surgery with indocyanine green (ICG) has been demonstrated to provide high sensitivity in sentinel lymph node biopsy (SLNB) for breast cancer but has several limitations, such as unstable pharmacokinetics, limited fluorescence brightness, and undesired diffusion to neighboring tissues. This paper investigates the use of Voluven® as the solvent for ICG fluorescence-guided SLNB (ICG-SLNB).

METHODS

The photophysical properties of ICG in water and Voluven® were evaluated in laboratory experiments and in a mouse model. Nine patients with early breast cancer underwent subareolar injection of diluted ICG (0.25 mg/ml) for ICG-SLNB. Six of the nine patients received ICG dissolved in Voluven® (ICG:Voluven®), while three were administered ICG dissolved in water (ICG:water); a repetitive injection-observation protocol was followed for all patients. The mapping image quality was evaluated.

RESULTS

Laboratory experiments and in vivo mouse study showed improved fluorescence and better targeting using Voluven® as the solvent. ICG-SLNB with a repetitive injection-observation protocol was successfully performed in all nine patients. ICG:Voluven® administration had an overall better signal-to-background ratio (SBR) in sequential sentinel lymph nodes. The rates of transportation within the lymphatics were also improved using ICG:Voluven® compared with ICG:water.

CONCLUSIONS

From basic research to animal models to in-human trial, our study proposes a repetitive injection-observation technique with ICG:Voluven®, which is characterized by better transportation and more stable mapping quality for ICG-SLNB in breast cancer patients.

Comparison of Sentinel Lymph Node Biopsy by Blue Dye Conjunction With Indocyanine Green or Radioisotope in Early-Stage Breast Cancer: A Prospective Single-Center Observational Study

Background

Although radioisotope (RI) combined with blue dye (BD) is the standard technique for sentinel lymph node (SLN) biopsy in breast cancer, the use of RI is limited at some institutions due to the specific equipment needed. Indocyanine green (ICG) fluorescence detection has been developed as a potential substitute for RI method. However, reports on the sensitivity of ICG and RI techniques in detecting SLN are inconsistent; hence, the present study was designed to compare the clinical efficacy between the combined method of ICG + BD (ICG-B) and RI + BD (RI-B).

Methods

A prospective observational study was performed that identified 138 breast cancer patients who had undergone lymphatic mapping and SLN biopsy with ICG-B or RI-B. The SLN detection rate, positive SLN counts, and lymph node metastasis between the 2 groups were compared.

Results

A total of 71 patients were recruited in the ICG-B group, while 67 were recruited in the RI-B group. The SLN detection rate was 100% in both the ICG-B and RI-B groups. Lymph node metastasis was found in 13 patients using ICG-B and in 12 patients using the RI-B technique (18.31% vs 17.91%, respectively; P = .61). No significant differences were observed in the positive SLN counts (3.12 ± 2.01 vs 3.33 ± 2.24, P = .37) between the 2 groups.

Conclusions

Indocyanine green combined with BD has an equal efficacy compared with RI plus BD when performing an axillary SLN biopsy in breast cancer. The ICG plus BD procedure is a promising alternative to traditional standard mapping methods.

Investigation of optimizing indocyanine green solution for in vivo lymphatic research using near-infrared fluorescence indocyanine green lymphangiography

Despite the tireless efforts of many researchers in lymphatic research, indocyanine green (ICG) solution conditions suitable for lymphatic circulation tests have not been perfectly established yet. We aimed to investigate the optimal in vivo conditions of ICG solution to avoid photobleaching and quenching effects, which may affect the accuracy of lymphatic circulation evaluation. After ICG fluorescence intensity (or ICG intensity) was assessed under different in vitro conditions, the image quality of brachial lymph nodes (LNs) and collecting lymphatic vessels (LVs) in eight rats was investigated. The in vitro results showed that ICG intensity depends on concentration and time in various solvents; however, the brightest intensity was observed at a concentration of 8-30 μg/mL in all solvents. ICG concentration in the albumin (bovine serum albumin; BSA) solution and rat's plasma showed more than two times higher fluorescence intensity than in distilled water (DW) in the same range. However, saline reduced the intensity by almost half compared to DW. In the in vivo experiment, we obtained relatively high-quality images of the LNs and LVs using ICG in the BSA solution. Even at low concentrations, the result in the BSA solution was comparable to those obtained from high-concentration solutions commonly used in conventional circulation tests. This study provides valuable information about the conditions for optimal ICG intensity in near infrared fluorescence indocyanine green (NIRF-ICG) lymphangiography, which may be useful not only for the diagnosis of lymphatic circulation diseases such as lymphedema but also for preclinical research for the lymphatic system.

Applications of indocyanine green (ICG) fluorescence technology in open surgery: preliminary experience in pediatric surgery

Background

Indocyanine green fluorescence technology (ICG) in pediatric minimally invasive surgery has undergone an important improvement in the last 5 years. However, its use in open surgery is still limited. In this paper, we aim to report our preliminary experience with Rubina® lens ICG fluorescence technology in combination with the IMAGE1 S™ system from KARL STORZ in open excision of masses in children.

Methods

The records of 18 patients undergoing open surgery for head, neck and thorax masses between September and November 2022 were retrospectively reviewed. Rubina® lens ICG fluorescence technology system was used in all the cases. In 10 cases we adopted the holding arm system and in 8 cases the hand-held technique. Data about patients' demographics, surgery and outcomes were collected and analyzed through the following criteria: mass localization, intraoperative time (min), ICG administration (ml), intraoperative complications, postoperative complications.

Results

A total of 18 patients were operated: 4 thyroglossal duct cysts, 3 supraorbital cysts, 2 neck masses, 2 pre-auricular and 2 scalp cysts, 2 gynecomastias, 2 lymphangiomas, 1 nose mass. In all the cases, intralesional injection of 0.5-1 ml of ICG solution was performed peri-operatively. Mean operative time was 58.4 min (35-134 min). Postoperative complications included seroma formation in 2 cases. Surgical pathology reports confirmed complete mass excision in all the cases.

Conclusion

Based on our preliminary experience, ICG fluorescence guided surgery using Rubina® lens system was very helpful also in open surgery procedures. Rubina® lens system permits to have a very low complication rate, a time-saving surgery, a real time reliability of anatomic structures and an excellent clinical safety. In our experience, holding arm system seems more comfortable than hand-held system. However, further cases need to be performed to evaluate the exact role and to identify new indications of this technique in open pediatric surgical procedures.

The magic mirror: a novel intraoperative monitoring method for parathyroid glands

The accurate detection of parathyroid glands (PGs) during surgery is of great significance in thyroidectomy and parathyroidectomy, which protects the function of normal PGs to prevent postoperative hypoparathyroidism and the thorough removal of parathyroid lesions. Existing conventional imaging techniques have certain limitations in the real-time exploration of PGs. In recent years, a new, real-time, and non-invasive imaging system known as the near-infrared autofluorescence (NIRAF) imaging system has been developed to detect PGs. Several studies have confirmed that this system has a high parathyroid recognition rate and can reduce the occurrence of transient hypoparathyroidism after surgery. The NIRAF imaging system, like a magic mirror, can monitor the PGs during surgery in real time, thus providing great support for surgeries. In addition, the NIRAF imaging system can evaluate the blood supply of PGs by utilizing indocyanine green (ICG) to guide surgical strategies. The NIRAF imaging system and ICG complement each other to protect normal parathyroid function and reduce postoperative complications. This article reviews the effectiveness of the NIRAF imaging system in thyroidectomies and parathyroidectomies and briefly discusses some existing problems and prospects for the future.

Indocyanine green combined with methylene blue versus methylene blue alone for sentinel lymph node biopsy in breast cancer: a retrospective study

BACKGROUND

Recent studies have shown that near-infrared (NIR) fluorescence imaging using Indocyanine green (ICG) may improve the efficiency of sentinel lymph node biopsy (SLNB). This study aimed to assess the effectiveness of the combination of ICG and methylene blue (MB) in breast cancer patients undergoing SLNB.

PATIENTS AND METHOD

We evaluated ICG plus MB (ICG + MB) identification effectiveness with MB alone using retrospective analysis. From 2016 to 2020, we collected data on 300 eligible breast cancer patients who got SLNB treatment in our institution by ICG + MB or MB alone. By comparing the distribution of clinicopathological characteristics, the detection rate of sentinel lymph nodes (SLNs) and metastatic SLNs, as well as the total number of SLNs in the two groups, we were able to assess the imaging efficiency.

RESULTS

Fluorescence imaging allowed 131 out of 136 patients in the ICG + MB group to find SLNs. ICG + MB group and MB group had detection rates of 98.5% and 91.5% (P = 0.007, χ² = 7.352), respectively. Besides, the ICG + MB approach was able to produce improved recognition outcomes. What's more, compared with the MB group, the ICG + MB group can identify more lymph nodes (LNs) (3.1 to 2.6, P = 0.000, t = 4.447). Additionally, in the ICG + MB group, ICG could identify more LNs than MB (3.1 vs 2.6, P = 0.004, t = 2.884).

CONCLUSION

ICG has high detection effectiveness for SLNs, and when paired with MB, the detection efficiency can be increased even further. Furthermore, the ICG + MB tracing mode does not involve radioisotopes, which has a lot of promise for clinical use and can take the place of conventional standard detection methods.

Novel color fluorescence imaging for sentinel lymph node detection in oral and oropharyngeal cancer

AIM

Fluorescence imaging (FI) using indocyanine green (ICG) is a noteworthy alternative technique for sentinel lymph node (SLN) detection without radiation exposure in oral cavity and oropharynx cancer. However, conventional FI is monochrome, so the visibility is limited. This study assessed whether color FI using the HyperEye Medical System (HEMS) is feasible as an alternative for SLN detection.

METHODS

Patients with previously untreated cT1-2N0 oral or oropharyngeal cancer who were to undergo primary tumor resection and elective neck dissection (END) in our hospital were enrolled from November 2012 to March 2016. The patients underwent SLN detection for biopsy via the HEMS following the injection of ICG solution around the primary lesion before neck dissection. The visibility and the diagnostic accuracy of the imaging were evaluated.

RESULTS

SLNs were visualized in all eight cases; however, transcutaneous fluorescence detection was not observed in all cases. Utilizing color mode imaging simplified harvest by clearly discriminating SLNs from surrounding structures, while the monochrome mode proved to be more sensitive for detection. Two cases showed occult metastases on both sentinel and regional nodes. The identification and false negative rates were 100% and 0%, respectively. There were no complications incurred due to this method.

CONCLUSION

Our results suggest that color FI with the HEMS allows for the accurate and safe harvest of SLNs with a preparatory skin incision. Although there is room for improvement of sensitivity, this easy-to-handle procedure might provide the potential to expand the role of the ICG method for SLN detection in head and neck cancer.

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

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

Indocyanine green (ICG) fluorescence guide for the use and indications in general surgery: recommendations based on the descriptive review of the literature and the analysis of experience

Indocyanine Green is a fluorescent substance visible in near-infrared light. It is useful for the identification of anatomical structures (biliary tract, ureters, parathyroid, thoracic duct), the tissues vascularization (anastomosis in colorectal, esophageal, gastric, bariatric surgery, for plasties and flaps in abdominal wall surgery, liver resection, in strangulated hernias and in intestinal ischemia), for tumor identification (liver, pancreas, adrenal glands, implants of peritoneal carcinomatosis, retroperitoneal tumors and lymphomas) and sentinel node identification and lymphatic mapping in malignant tumors (stomach, breast, colon, rectum, esophagus and skin cancer). The evidence is very encouraging, although standardization of its use and randomized studies with higher number of patients are required to obtain definitive conclusions on its use in general surgery. The aim of this literature review is to provide a guide for the use of ICG fluorescence in general surgery procedures.

Short-term and long-term outcomes of indocyanine green for sentinel lymph node biopsy in early-stage breast cancer

Background

Indocyanine green (ICG) is becoming a frequently used sentinel lymph node (SLN) tracer of breast cancer in China. However, there is still a lack of data on its safety. We reported the clinical outcome of ICG as a tracer of SLN over a median 67-month follow-up period to evaluate its feasibility in clinically node-negative patients with breast cancer.

Methods

A total of 194 consecutive patients underwent sentinel lymph node biopsy (SLNB) with ICG, radioisotopes (RI) and methylene blue (MB), or with ICG and MB. The SLN mapping data by each tracer was recorded, and safety outcomes were analyzed through follow-up.

Results

With the triad mapping (N = 44), the identification rate of SLN by ICG was 95.5%, slightly higher than that of MB (86.4%) and comparable with RI (95.5%) and combined methods (95.5%, 100%) (p = 0.068). Analysis of all candidates (N = 194) demonstrated that the identification rate of SLN by ICG or by ICG and MB was 99%, significantly higher than that by MB (92.8%) (p < 0.0001). No tracer-related allergic reaction and permanent skin staining of ICG were observed. Local disease progression was reported in 2 of the 194 patients at the ipsilateral axilla. After remedial axillary lymph node dissection, no disease progression was detected at follow-up.

Conclusions

ICG as an SLN tracer is more accurate than MB and comparable to the combined methods and has good clinical safety. ICG can be considered a useful supplement or suitable alternative to traditional tracers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02719-7.

Fluorescent Tracers for In Vivo Imaging of Lymphatic Targets

The lymphatic system continues to gain importance in a range of conditions, and therefore, imaging of lymphatic vessels is becoming more widespread for research, diagnosis, and treatment. Fluorescent lymphatic imaging offers advantages over other methods in that it is affordable, has higher resolution, and does not require radiation exposure. However, because the lymphatic system is a one-way drainage system, the successful delivery of fluorescent tracers to lymphatic vessels represents a unique challenge. Each fluorescent tracer used for lymphatic imaging has distinct characteristics, including size, shape, charge, weight, conjugates, excitation/emission wavelength, stability, and quantum yield. These characteristics in combination with the properties of the target tissue affect the uptake of the dye into lymphatic vessels and the fluorescence quality. Here, we review the characteristics of visible wavelength and near-infrared fluorescent tracers used for in vivo lymphatic imaging and describe the various techniques used to specifically target them to lymphatic vessels for high-quality lymphatic imaging in both clinical and pre-clinical applications. We also discuss potential areas of future research to improve the lymphatic fluorescent tracer design.

Methylene Blue Near-Infrared Fluorescence Imaging in Breast Cancer Sentinel Node Biopsy

Simple Summary

Currently the gold standard for sentinel node biopsy in breast cancer patients is radioactive nanocolloid and a blue dye. In the age of fluorescence guided surgery new fluorophores are used and methylene blue presents some fluorescent properties. This study is the first in a clinical series presenting the possible use of methylene blue as a fluorescent dye for the identification of sentinel nodes in breast cancer sentinel node biopsy. We presented a feasibility of this new method and also in additional experiments because of the quenching effect limitation, found possible dilution of methylene blue presenting improved fluorescence.

Abstract

Introduction: Fluorescence-based navigation for breast cancer sentinel node biopsy is a novel method that uses indocyanine green as a fluorophore. However, methylene blue (MB) also has some fluorescent properties. This study is the first in a clinical series presenting the possible use of MB as a fluorescent dye for the identification of sentinel nodes in breast sentinel node biopsy. Material and methods: Forty-nine patients with breast cancer who underwent sentinel node biopsy procedures were enrolled in the study. All patients underwent standard simultaneous injection of nanocolloid and MB. We visualized and assessed the sentinel nodes and the lymphatic channels transcutaneously, with and without fluorescence, and calculated the signal-to-background ratio (SBR). We also analyzed the corresponding fluorescence intensity of various dilutions of MB. Results: In twenty-three patients (46.9%), the location of the sentinel node, or the end of the lymphatic path, was visible transcutaneously. The median SBR for transcutaneous sentinel node location was 1.69 (range 1.66–4.35). Lymphatic channels were visible under fluorescence in 14 patients (28.6%) prior to visualization by the naked eye, with an average SBR of 2.01 (range 1.14–5.6). The sentinel node was visible under fluorescence in 25 patients (51%). The median SBR for sentinel node visualization with MB fluorescence was 2.54 (range 1.34–6.86). Sentinel nodes were visualized faster under fluorescence during sentinel node preparation. Factors associated with the rate of visualization included diabetes (p = 0.001), neoadjuvant chemotherapy (p = 0.003), and multifocality (p = 0.004). The best fluorescence was obtained using 40 μM (0.0128 mg/mL) MB, but we also observed a clinically relevant dilution range between 20 μM (0.0064 mg/mL) and 100 μM (0.032 mg/mL). Conclusions: For the first time, we propose the clinical usage of MB as a fluorophore for fluorescence-guided sentinel node biopsy in breast cancer patients. The quenching effect of the dye may be the reason for its poor detection rate. Our analysis of different concentrations of MB suggests a need for a detailed clinical analysis to highlight the practical usefulness of the dye.

Fluorescence Imaging Using Methylene Blue Sentinel Lymph Node Biopsy in Melanoma

Introduction

Fluorescence imaging of sentinel node biopsy in melanoma is a novel method. Both indocyanine green (ICG) and methylene blue (MB) have fluorescent properties. The aim of this study was to present, for the first time in a clinical series of patients, the possible usage of MB as a fluorescent dye for sentinel node biopsy during surgery for melanoma.

Material and methods

Twenty patients with skin melanoma, who were candidates for sentinel node biopsy were enrolled in our study. All patients underwent simultaneous use of standard nanocolloid and blue dye. Transcutaneous visualization of the sentinel node, visualization of lymphatic channels as well as sentinel node fluorescent visualization were all measured. We also performed calculations of Signal to Background ratios (SBR).

Results

In 15% (3/20) of patients, the fluorescent sentinel node was visible through the skin. The median SBR for the sentinel node visualization by fluorescence was 3.15 (range, 2.7–3.5). Lymphatic channels were visible in lymphatic tissue via fluorescence before visualization by the naked eye in 4 patients (20%). The median SBR ratio was 3.69 (range, 2.7–4.2). Sentinel nodes were visible by fluorescence in 13 cases (65%). The median SBR ratio was 2.49 (range, 1.5–5.7). No factors were found to be associated with fluorescent MB visualization of a sentinel node during biopsy.

Conclusion

This is the first clinical study presenting the usefulness of fluorescent sentinel node biopsy in melanoma patients using MB as a fluorophore. Further studies are necessary to provide methods for its’ clinical implementation.

TADF-based NIR-II semiconducting polymer dots for in vivo 3D bone imaging

Intraoperative fluorescence imaging in the second near-infrared (NIR-II) region heralds a new era in image-guided surgery since the success in the first-in-human liver-tumor surgery guided by NIR-II fluorescence. Limited by the conventional small organic NIR dyes such as FDA-approved indocyanine green with suboptimal NIR-II fluorescence and non-targeting ability, the resulting shallow penetration depth and high false positive diagnostic values have been challenging. Described here is the design of NIR-II emissive semiconducting polymer dots (Pdots) incorporated with thermally activated delayed fluorescence (TADF) moieties to exhibit emission maxima of 1064–1100 nm and fluorescence quantum yields of 0.40–1.58% in aqueous solutions. To further understand how the TADF units affect the molecular packing and the resulting optical properties of Pdots, in-depth and thorough density-functional theory calculations were carried out to better understand the underlying mechanisms. We then applied these Pdots for in vivo 3D bone imaging in mice. This work provides a direction for future designs of NIR-II Pdots and holds promising applications for bone-related diseases.

A series of NIR-II fluorescent TADF-incorporated polymer dots were successfully synthesized. The function of the TADF moiety was fully studied and the bio-applications of these polymer dots including bone imaging were also demonstrated.

A novel laparoscopic near-infrared fluorescence spectrum system with indocyanine green fluorescence overcomes limitations of near-infrared fluorescence image-guided surgery

BACKGROUND

Near-infrared (NIR) fluorescence image-guided surgery (FIGS) introduces a revolutionary new approach to address this basic challenge in minimally invasive surgery. However, current FIGS systems have some limitations - the infrared rays cannot detect and visualise thick tissues with low concentrations of the fluorescent agent. We established a novel laparoscopic fluorescence spectrum (LFS) system using indocyanine green (ICG) fluorescence to overcome these limitations.

MATERIALS AND METHODS

Bovine serum albumin (BSA) was conjugated to ICG, and the mixtures were serially diluted at 5 × 10-8-5 × 10-1 mg/mL. We used the LFS system and a NIR camera system (NLS; SHINKO OPTICAL CO., LTD Tokyo, Japan) to determine the optical dilution for the fluorescence detection. BSA was conjugated to ICG (5.0 × 10-2 mg/mL) and used to coat the clips. We attempted to identify the fluorescence-coated clip from the serosal side of the cadaveric porcine stomach tissues using the LFS system and the NIR camera system. We measured the depth of the cadaveric porcine stomach wall at the thickest part that could be confirmed.

RESULTS

We could not visualise fluorescence concentrations <2.5 × 10-3 mg/mL using the NIR camera system. The spectrum was detected at a concentration <2.5 × 10-3 mg/mL. We were able to identify the spectrum of ICG (829 nm) to a 13-mm depth of cadaveric porcine stomach wall by using the LFS system but could not identify the same with the NIR camera system regardless of wall thickness.

CONCLUSIONS

The novel LFS system with NIR fluorescence imaging in this ex vivo and cadaveric porcine model was confirmed useful at deeper depths and lower concentrations. Based on these findings, we anticipate that the LFS system can be integrated and routinely used in minimally invasive surgery.

Near-infrared fluorescence imaging-guided lymphatic mapping in thoracic esophageal cancer surgery

PURPOSE

Identifying the lymphatic drainage pathway is important for accurate lymph node (LN) dissection in esophageal cancer (EC). This study aimed to assess lymphatic drainage mapping in thoracic EC using near-infrared fluorescent (NIRF) imaging with indocyanine green (ICG) and identify its feasibility for intraoperative LN drainage visualization and dissection.

METHODS

From November 2019 to August 2020, esophagectomy was performed using intraoperative NIRF navigation with ICG injected into the esophageal submucosa by endoscopy. All LNs were divided into four groups according to the NIRF status and presence of metastasis: NIRF⁺LN⁺, NIRF⁺LN^-, NIRF^-LN⁺, and NIRF^-LN^-.

RESULTS

Regional LNs were detected in all 84 enrolled patients with thoracic EC. A total of 2164 LNs were removed, and the mean number of dissected LNs was 25.68 ± 12.00. NIRF⁺ LNs were observed in all patients and distributed at 19 LN stations, which formed lymphatic drainage maps. The top five LN stations of NIRF⁺ probability in upper thoracic EC were No. 7, 106ecR, 107, 1, and 106recL; in middle thoracic EC, they were No. 107, 7, 110, 1, and 105; and in lower thoracic EC, they were No. 107, 7, 110, 106recR, and 1. There were no cases of ICG-related adverse events or chylothorax. The 30-day mortality rate was 0%. Major complications included anastomotic fistula (7.14%), pneumonia (4.76%), pleural effusion (13.10%), atelectasis (3.75%), hoarseness (8.33%), and arrhythmia (4.76%).

CONCLUSION

Regional LN mapping of thoracic EC was performed using ICG/NIRF imaging, which showed different preferred LN drainage stations in various anatomical locations of the thoracic esophagus. ICG/NIRF imaging is feasible for intraoperative LN drainage visualization and dissection.

CLINICAL TRIAL REGISTRATION

The clinical trial registration number is NCT04173676 ( http://www.clinicaltrials.gov/ ).

Meta-analysis Comparing Fluorescence Imaging with Radioisotope and Blue Dye-Guided Sentinel Node Identification for Breast Cancer Surgery

INTRODUCTION

Conventional methods for axillary sentinel lymph node biopsy (SLNB) are fraught with complications such as allergic reactions, skin tattooing, radiation, and limitations on infrastructure. A novel technique has been developed for lymphatic mapping utilizing fluorescence imaging. This meta-analysis aims to compare the gold standard blue dye and radioisotope (BD-RI) technique with fluorescence-guided SLNB using indocyanine green (ICG).

METHODS

This study was registered with PROSPERO (CRD42019129224). The MEDLINE, EMBASE, Scopus, and Web of Science databases were searched using the Medical Subject Heading (MESH) terms 'Surgery' AND 'Lymph node' AND 'Near infrared fluorescence' AND 'Indocyanine green'. Studies containing raw data on the sentinel node identification rate in breast cancer surgery were included. A heterogeneity test (using Cochran's Q) determined the use of fixed- or random-effects models for pooled odds ratios (OR).

RESULTS

Overall, 1748 studies were screened, of which 10 met the inclusion criteria for meta-analysis. ICG was equivalent to radioisotope (RI) at sentinel node identification (OR 2.58, 95% confidence interval [CI] 0.35-19.08, p < 0.05) but superior to blue dye (BD) (OR 9.07, 95% CI 6.73-12.23, p < 0.05). Furthermore, ICG was superior to the gold standard BD-RI technique (OR 4.22, 95% CI 2.17-8.20, p < 0.001).

CONCLUSION

Fluorescence imaging for axillary sentinel node identification with ICG is equivalent to the single technique using RI, and superior to the dual technique (RI-BD) and single technique with BD. Hospitals using RI and/or BD could consider changing their practice to ICG given the comparable efficacy and improved safety profile, as well as the lesser burden on hospital infrastructure.

Recent Developments of ICG-Guided Sentinel Lymph Node Mapping in Oral Cancer

Sentinel lymph node (SLN) biopsy has gained attention as a method of minimizing the extent of neck dissection with a similar survival rate as elective neck dissection in oral cancer. Indocyanine green (ICG) imaging is widely used in the field of surgical oncology. Real-time ICG-guided SLN imaging has been widely used in minimally invasive surgeries for various types of cancers. Here, we provide an overview of conventional SLN biopsy and ICG-guided SLN mapping techniques for oral cancer. Although ICG has many strengths, it still has limitations regarding its potential use as an ideal compound for SLN mapping. The development of novel fluorophores and imaging technology is needed for accurate identification of SLNs, which will allow precision surgery that would reduce morbidities and increase patient survival.

The application of indocyanine green (ICG) and near-infrared (NIR) fluorescence imaging for assessment of the lymphatic system in reconstructive lymphaticovenular anastomosis surgery

INTRODUCTION

Lymphedema has traditionally been managed through noninvasive means with complete decongestive therapy. However, complete decongestive therapy is an intensive program that requires lifelong adherence by patients with lymphedema. More recently, reconstructive surgical procedures have shown promise in improving lymphedema by physiologically restoring lymphatic function. One of these types of procedures, lymphaticovenular anastomosis, relies on technological advances in imaging, particularly indocyanine green lymphangiography.

AREAS COVERED

This article reviews indocyanine green and near-infrared fluorescence imaging. In addition, this article discusses the application of this imaging to the preoperative, intraoperative, and postoperative assessment of the lymphatic system in the setting of lymphaticovenular anastomosis surgery.

EXPERT OPINION

Indocyanine green lymphangiography offers significant advantages over other types of imaging of the lymphatic system. In the future, it is hopeful that additional options for these imaging devices will become available which may increase their accessibility by centers interested in performing reconstructive lymphatic surgery, including in relation to cost. Finally, more studies with higher levels of evidence are needed to better define the long-term outcomes associated with lymphatic surgery including LVA. In this regard, practitioners should fully harness the information conferred by ICG lymphangiography as both a clinical and research tool.

Whole-Body Fluorescence Imaging in the Near-Infrared Window

Fluorescence imaging is one of the most widely used in vivo imaging methods for both fundamental research and clinical practice. Due to the reduced photon scattering, absorption, and autofluorescence in tissues, the emerging near-infrared (NIR) imaging (650-1700 nm) can afford deep tissue imaging with high spatiotemporal resolution and in vivo report the anatomical structures as well as the physiological activities in a whole-body level. Here, we give a brief introduction to fluorescence imaging in the first NIR (NIR-I, 650-950 nm) and second NIR (NIR-II, 1000-1700 nm) windows, summarize the recently developed NIR fluorophores and their applications in whole-body vascular system imaging, precision cancer theranostics, and regenerative medicine. Finally, the clinical applications and future prospects of in vivo NIR fluorescence imaging are also discussed.

Small Molecules for Multi-Wavelength Near-Infrared Fluorescent Mapping of Regional and Sentinel Lymph Nodes in Colorectal Cancer Staging

Assessing lymph node (LN) status during tumor resection is fundamental for the staging of colorectal cancer. Current guidelines require a minimum of 12 LNs to be harvested during resection and ultra-staging regional lymph nodes by sentinel lymph node (SLN) assessment is being extensively investigated. The current study presents novel near-infrared (NIR) fluorescent dyes for simultaneous pan lymph node (PanLN; regional) and SLN mapping. PanLN-Forte was intravenously injected in mice and assessed for accumulation in regional LNs. SLN800 was injected intradermally in mice, after which the collection and retention of fluorescence in SLNs were measured using indocyanine green (ICG) and its precursor, SLN700, as references. LNs in the cervical, inguinal, jejunal, iliac, and thoracic basins could clearly be distinguished after a low dose intravenous injection of PanLN-Forte. Background fluorescence was significantly lower compared to the parent compound ZW800-3A (p < 0.001). SLN700 and SLN800 specifically targeted SLNs with fluorescence being retained over 40-fold longer than the current clinically used agent ICG. Using SLN700 and SLN800, absolute fluorescence in SLN was at least 10 times higher than ICG in second-tier nodes, even at 1 hour post-injection. Histologically, the fluorescent signal localized in the LN medulla (PanLN-Forte) or sinus entry (SLN700/SLN800). PanLN-Forte and SLN800 appear to be optimal for real-time NIR fluorescence imaging of regional and SLNs, respectively.

Comparisons of ICG-fluorescence with conventional tracers in sentinel lymph node biopsy for patients with early-stage breast cancer: A meta-analysis

Radioisotopes (RI) and blue dye (BD) are routinely used markers for staining during sentinel lymph node biopsy (SLNB) in breast cancer. Compared with traditional tracers, tracer performance of indocyanine green (ICG) has been controversial. A total of 21 studies were selected from the PubMed, EMBASE and Cochrane Library databases. Detection ability was judged based on four endpoints: i) The identification rate (IR) of the patients; ii) the IR of the sentinel lymph nodes (SLNs); iii) the IR of the positive SLNs; and iv) the false negative rate (FNR). Compared with BD, ICG was superior in terms of the IR of the patients [odds ratio (OR)=7.17; 95% CI, 3.98-12.94), the IR of the SLNs (OR=8.84; 95% CI, 6.71-11.66) and FNR (OR=0.20; 95% CI, 0.08-0.48) using a fixed-effects model. There was a significant difference in both the IR of the positive SLNs (OR=21.32; 95% CI, 2.84-160.14) and FNR (OR=0.46; 95% CI, 0.23-0.91) in the ICG vs. RI group. Furthermore, when using ICG at the recommended dose, a significant difference was found in the IR of the patients (OR=1.77; 95% CI, 1.09-2.85) and the IR of the SLNs (OR=21.62; 95% CI, 5.23-89.43) using a fixed-effects model. In the ICG vs. BD combined with RI group, there were no differences in either the IR of the patients (OR=5.10; 95% CI, 0.24-107.48) or the IR of SLNs (OR=5.10; 95% CI, 0.60-256.66). In conclusion, ICG was a better tracer compared with BD or RI alone and was not a worse tracer compared with BD combined with RI. The use of the recommended dose of ICG had an improved tracer effect. ICG is expected to be widely used in SLNB in view of its clinical advantages.

Dual modal fluorescent colposcope combined with near-infrared fluorescent dye TMTP1-PEG4-ICG to detect cervical lesions

To examine the cervical lesions by using the tumor-targeted near-infrared (NIR) fluorescent dyes TMTP1-PEG4-ICG, a dual modal colposcope with visible reflectance imaging and fluorescence imaging was developed. NIR fluorescence imaging and visible light reflectance imaging were integrated together on a colposcope by designing the specific optics and adopting a dual sensor charge coupled device (CCD) camera. Patients with squamous cell carcinoma, adenocarcinoma, cervical intraepithelial neoplasia (CIN) and cervicitis were examined using this dual modal colposcope to validate its potential of cervical cancer detection. Fluorescent dye TMTP1-PEG4-ICG was applied to the cervix 30 minutes before inspection. The fluorescence images were collected after wiping the unbound fluorescent dye using normal saline. Signal to back ratios (SBR) of the fluorescence images were analyzed and compared with the histological analysis. The results suggest that the fluorescent colposcope combined with tumor-specific near-infrared fluorescent dyes TMTP1-PEG4-ICG could help to evaluate cervical lesions in real time.

Applications of Computational Methods in Biomedical Breast Cancer Imaging Diagnostics: A Review

With the exponential increase in new cases coupled with an increased mortality rate, cancer has ranked as the second most prevalent cause of death in the world. Early detection is paramount for suitable diagnosis and effective treatment of different kinds of cancers, but this is limited to the accuracy and sensitivity of available diagnostic imaging methods. Breast cancer is the most widely diagnosed cancer among women across the globe with a high percentage of total cancer deaths requiring an intensive, accurate, and sensitive imaging approach. Indeed, it is treatable when detected at an early stage. Hence, the use of state of the art computational approaches has been proposed as a potential alternative approach for the design and development of novel diagnostic imaging methods for breast cancer. Thus, this review provides a concise overview of past and present conventional diagnostics approaches in breast cancer detection. Further, we gave an account of several computational models (machine learning, deep learning, and robotics), which have been developed and can serve as alternative techniques for breast cancer diagnostics imaging. This review will be helpful to academia, medical practitioners, and others for further study in this area to improve the biomedical breast cancer imaging diagnosis.

Sentinel lymph node mapping using ICG fluorescence and cone beam CT - a feasibility study in a rabbit model of oral cancer

BACKGROUND

Current sentinel lymph node biopsy (SLNB) techniques, including use of radioisotopes, have disadvantages including the use of a radioactive tracer. Indocyanine green (ICG) based near-infrared (NIR) fluorescence imaging and cone beam CT (CBCT) have advantages for intraoperative use. However, limited literature exists regarding their use in head and neck cancer SLNB.

METHODS

This was a prospective, non-randomized study using a rabbit oral cavity VX2 squamous cell carcinoma model (n = 10) which develops lymph node metastasis. Pre-operatively, images were acquired by MicroCT. During surgery, CBCT and NIR fluorescence imaging of ICG was used to map and guide the SLNB resection.

RESULTS

Intraoperative use of ICG to guide fluorescence resection resulted in identification of all lymph nodes identified by pre-operative CT. CBCT was useful for near real time intraoperative imaging and 3D reconstruction.

CONCLUSIONS

This pre-clinical study further demonstrates the technical feasibility, limitations and advantages of intraoperative NIR-guided ICG imaging for SLN identification as a complementary method during head and neck surgery.

Visualization of lymphatic flow in laparoscopic colon cancer surgery using indocyanine green fluorescence imaging

Intraoperative visualization of lymphatic flow could guide surgeons performing laparoscopic colon cancer surgery on the extent of intestinal resection required. The purpose of this study was to investigate indocyanine green fluorescence imaging for intraoperative detection of lymphatic flow and nodes in such patients. All patients undergoing elective laparoscopic surgery for colorectal cancer from October 2016 to July 2017 were included in this study. Indocyanine green was injected submucosally around the tumors via a colonoscope and lymphatic flow assessed with a laparoscopic near-infrared camera system intraoperatively. Lymphatic flow was visualized perioperatively in 43 of 57 patients (75.4%). The rate of visualized lymphatic flow was significantly higher in patients with a lower clinical stage than in those with a higher clinical stage (p = 0.0103). Among the 14 patients in whom lymphatic flow was not visualized, 10 (71.4%) had cStage III or IV cancer. Our results indicate the potential role of intraoperative navigation in colon cancer surgery in early-stage colon cancers. This method allows the surgeon to clearly identify lymphatic flow during surgery and allows the determination and individualization of the lymph node dissection range.

Indocyanine Green Fluorescence Versus Blue Dye or Radioisotope Regarding Detection Rate of Sentinel Lymph Node Biopsy and Nodes Removed in Breast Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Either blue dye (BD) or radioisotope (RI) is mainly used for sentinel lymph node biopsy (SLNB) in breast cancer patients. Unlike the BD, RI has lower false-negative rate of SLNB. However, its lymphoscintigraphy, difficulty in preoperative injection, and undetected sentinel lymph nodes in some cases cause surgeons to rely only on BD. Currently, indocyanine green (ICG) fluorescence method (ICG-SLNB) is increasingly used as an alternative to the conventional mapping methods in many centers. This systematic review compared ICG with the conventional method of BD or RI in terms of detection rate of SLNB and the number of sentinel lymph nodes (SLNs) removed in.

METHODS

  We searched all relevant studies published between January 2000 and October 2019. All data on for evaluation of SLN detection rate, number of SLNs removed per patient, and tumor positive rate of SLNB were extracted.

RESULTS

A total of 30 studies, including 4,216 SLN procedures were retrieved. There was a statistically significant difference between ICG and BD method in terms of SLN detection rate (OR, 6.73; 95% CI, 4.20-10.78). However, there was no significant difference between ICG and RI in this regard (OR, 0.90; 95% CI, 0.40-2.03). The number of SLNs removed per patient were 2.35 (1.46-5.4), 1.92 (1.0-3.64), and 1.72 (1.35-2.08) for ICG, BD, and RI, respectively. Only in 8 studies, the tumor positive rates in SLNB could be analyzed (ICG, 8.5-20.7%; BD, 12.7-21.4%; RI, 11.3-16%).

CONCLUSION

ICG-SLNB could be an additional or an alternative method for axillary node mapping in breast cancer.<br />.

Indocyanine green fluorescence method for sentinel lymph node biopsy in breast cancer

BACKGROUND/OBJECTIVE

Breast biopsy and analysis of sentinel lymph nodes (SLNs) accurately predict tumor status in the affected basin and help in avoiding unnecessary axillary lymph node dissection, which is associated with remarkable morbidity risk. Blue dye and radioisotope are the most widely used mapping agents, but non-radioactive tracers of comparable accuracy warrant further investigation. This study aimed to investigate utilization of indocyanine green (ICG) fluorescence in sentinel node localization compared with blue dye and to assess the incremental value of ICG.

METHODS

A total of 39 consecutive patients underwent sentinel lymph node biopsy (SLNB) (40 cases: 38 unilateral and 1 bilateral) with combined blue dye and ICG for localization. The obtained fluorescence images of the lymphatic system were investigated.

RESULTS

All 84 lymph nodes removed in 40 procedures were identified by ICG, but only 37 were identified by blue dye. The ICG method identified an average of 2.1 SLNs in 39 of 40 cases with a detection rate of 97.5%, but only 0.93 SLN per case with blue dye. Subcutaneous lymphatic channel patterns were also detected by fluorescent imaging in 37 procedures, which all revealed lymphatic drainage toward the axilla except in one case with internal mammary pathway.

CONCLUSION

This study demonstrated the accuracy and safety of ICG for SLNB and its superiority to blue dye method in SLN localization. Therefore, ICG fluorescence method is safe and effective addition in breast clinical settings, wherein blue dye alone is used.

Real-time near-infrared fluorescence imaging mediated by blue dye in breast cancer patients

BACKGROUND

Near-infrared (NIR) fluorescence imaging has recently been introduced to the sentinel lymph node (SLN) mapping because of the benefits of the SLN biopsy, such as providing real-time and high-resolution optical guidance. Methylene blue is available and less expensive as an SLN mapping tracer. Our study aims to identify SLN through the NIR fluorescence imaging system mediated by blue dye.

METHODS

Early-stage breast cancer patients were prospectively enrolled. All participants received a subareolar or peritumoral injection of 1 mL methylene blue (MB) before surgery. The MB fluorescence system was set immediately after injection. SLNs were searched and removed under the guidance of fluorescence and blue dye.

RESULTS

We identified SLN adequately with the help of real-time lymphography and blue dye. Symbolic lymphatic drainage patterns were also observed.

CONCLUSION

NIR fluorescence imaging mediated by blue dye has benefits on the identification of lymph vessels, the location of SLN, and the patterns of breast lymphatic flow.

Timing of indocyanine green injection prior to laparoscopic colorectal surgery for tumor localization: a prospective case series

Background

Accurate identification of tumor sites during laparoscopic colorectal surgery helps to optimize oncological clearance. We aimed to assess the timing of the local injection preoperatively and clarify the usefulness and limitation of tumor site marking using indocyanine green (ICG) fluorescence imaging.

Methods

Consecutive patients who underwent primary colorectal cancer surgery from September 2017 to January 2019 were included. Preoperatively, lower endoscopy was used to inject the ICG solution into the submucosal layer near the tumor. During laparoscopic surgery, ICG fluorescence marking as the tumor site marking was detected using a laparoscopic near-infrared camera system. The detection rate and factors associated with successful intraoperative ICG fluorescence visualization including the interval between local injection and surgery were evaluated.

Results

One hundred sixty-five patients were enrolled. Using the laparoscopic near-infrared system, the intraoperative detection rates of ICG marking were 100% for ICG injection within 6 days preoperatively, 60% for injection between 7 and 9 days preoperatively, and 0% for injection earlier than 10 days preoperatively. There were no complications associated with ICG marking. Additionally, this method did not disturb the progress of the surgical procedure because injected ICG in the submucosal layer did not cause any tissue inflammation, and if ICG spilled into the serosa, it was invisible by white light.

Conclusion

Advantages of ICG fluorescence tumor site marking were high visibility of infrared imaging during laparoscopic colorectal surgery and minimal adverse events of surgery. One of the most important findings regarding practical use was a rapid decrease in fluorescence marking visibility if one week passed from the time of ICG local injection.

Use of indocyanine green fluorescence compared to radioisotope for sentinel lymph node biopsy in early-stage breast cancer: systematic review and meta-analysis

BACKGROUND

In early-stage breast cancer, indocyanine green (ICG)-fluorescence based sentinel lymph node (SLN) detection is being considered. This is a meta-analysis of SLN detection rates and sensitivity of ICG-fluorescence compared to radioisotope (RI), to evaluate its clinical applicability.

DATA SOURCES

Systematic review of full-text articles from PubMed and Scopus, of women with early breast cancer who underwent SLN mapping using ICG and RI concurrently was performed. The meta-analysis was performed using the Mantel-Haenszel method.

RESULTS

2301 patients from 19 studies were included. No significant difference was observed between ICG and RI for SLN detection (OR0.90,95%CI0.66-1.24) or sensitivity (OR1.23,95%CI0.73-2.05) with heterogeneity between studies (I² = 58%,P = 0.003). Sensitivity of dual mapping (ICG + RI) was significantly better compared to single mapping with RI (OR3.69,95%CI1.79-7.62) or ICG (OR3.32,95%CI1.52-7.24) alone with no heterogeneity between studies (I² = 0%,P = 0.004).

CONCLUSION

ICG-fluorescence could complement RI method or provide alternative in centers with poor accessibility to RI lymphoscintigraphy.

Optical and Optoacoustic Imaging

The present chapter summarizes progress with optical methods that go beyond human vision. The focus is on two particular technologies: fluorescence molecular imaging and optoacoustic (photoacoustic) imaging. The rationale for the selection of these two methods is that in contrast to optical microscopy techniques, both fluorescence and optoacoustic imaging can achieve large fields of view, i.e., spanning several centimeters in two or three dimensions. Such fields of views relate better to human vision and can visualize large parts of tissue, a necessary premise for clinical detection. Conversely, optical microscopy methods only scan millimeter-sized dimensions or smaller. With such operational capacity, optical microscopy methods need to be guided by another visualization technique in order to scan a very specific area in tissue and typically only provide superficial measurements, i.e., information from depths that are of the order of 0.05-1 mm. This practice has generally limited their clinical applicability to some niche applications, such as optical coherence tomography of the retina. On the other hand, fluorescence molecular imaging and optoacoustic imaging emerge as more global optical imaging methods with wide applications in surgery, endoscopy, and non-invasive clinical imaging, as summarized in the following. The current progress in this field is based on a volume of recent review and other literature that highlights key advances achieved in technology and biomedical applications. Context and figures from references from the authors of this chapter have been used here, as it reflects our general view of the current status of the field.

Near-infrared fluorescence imaging for sentinel lymph node identification in colon cancer: a prospective single-center study and systematic review with meta-analysis

Background

Near-infrared (NIR) fluorescence imaging has the potential to overcome the current drawbacks of sentinel lymph node mapping (SLNM) in colon cancer. Our aim was to provide an overview of current SLNM performance and of factors influencing successful sentinel lymph node (SLN) identification using NIR fluorescence imaging in colon cancer.

Methods

A systematic review and meta-analysis was conducted to identify currently used methods and results. Additionally, we performed a single-center study using indocyanine green (ICG) as SLNM dye in colon cancer patients scheduled for a laparoscopic colectomy. SLNs were analyzed with conventional hematoxylin-and-eosin staining and additionally with serial sectioning and immunohistochemistry (extended histopathological assessment). A true-positive procedure was defined as a tumor-positive SLN either by conventional hematoxylin-and-eosin staining or by extended histopathological assessment, independently of regional lymph node status. SLN procedures were determined to be true negatives if SLNs and regional lymph nodes revealed no metastases after conventional and advanced histopathology. SLN procedures yielding tumor-negative SLNs in combination with tumor-positive regional lymph nodes were classified as false negatives. Sensitivity, negative predictive value and detection rate were calculated.

Results

This systematic review and meta-analysis included 8 studies describing 227 SLN procedures. A pooled sensitivity of 0.63 (95% CI 0.51–0.74), negative predictive value 0.81 (95% CI 0.73–0.86) and detection rate of 0.94 (95% CI 0.85–0.97) were found. Upstaging as a result of extended histopathological assessment was 0.15 (95% CI 0.07–0.25). In our single-center study, we included 30 patients. Five false-negative SLNs were identified, resulting in a sensitivity of 44% and negative predictive value of 80%, with a detection rate of 89.7%. Eight patients had lymph node metastases, in three cases detected after extended pathological assessment, resulting in an upstaging of 13% (3 of 23 patients with negative nodes by conventional hematoxylin and eosin staining).

Conclusions

Several anatomical and technical difficulties make SLNM with NIR fluorescence imaging in colon cancer particularly challenging when compared to other types of cancer. As a consequence, reports of SLNM accuracy vary widely. Future studies should try to standardize the SLNM procedure and focus on early-stage colon tumors, validation of tracer composition, injection mode and improvement of real-time optical guidance.

Electronic supplementary material

The online version of this article (10.1007/s10151-019-02107-6) contains supplementary material, which is available to authorized users.

Nanotechnology in Oral Cavity Carcinoma: Recent Trends and Treatment Opportunities

Oral cavity carcinoma (OCC) remains an ongoing public health problem. Emerging nanotechnology provides alternative treatment approaches. This review covers the up-to-date literature in the human OCC treatment field. We explored the growing body of evidence to reveal novel and highly promising diagnostic and therapeutic applications of nanotechnology in this field. Various types of nanoparticles have been tested for applications in OCC. Imaging modalities in addition to nanocarriers are discussed. The encouraging contribution of lymphotropic nanoparticles contrast in the diagnosis of metastatic cervical lymph nodes needs to be confirmed. The development of the sentinel lymph node procedure and photodynamic therapy may lead to breakthrough therapies in order improve clinical outcomes and quality of life. In this perspective, cancer nanotechnology has the potential to revolutionize the treatment of OCC patients.

Improved generative adversarial networks using the total gradient loss for the resolution enhancement of fluorescence images

Because of the optical properties of medical fluorescence images (FIs) and hardware limitations, light scattering and diffraction constrain the image quality and resolution. In contrast to device-based approaches, we developed a post-processing method for FI resolution enhancement by employing improved generative adversarial networks. To overcome the drawback of fake texture generation, we proposed total gradient loss for network training. Fine-tuning training procedure was applied to further improve the network architecture. Finally, a more agreeable network for resolution enhancement was applied to actual FIs to produce sharper and clearer boundaries than in the original images.

Near-Infrared Contrast Agents for Bone-Targeted Imaging

Background

For the bone-specific imaging, a structure-inherent targeting of bone tissue recently has been reported a new strategy based on incorporation of targeting moieties into the chemical structure of near-infrared (NIR) contrast agents, while conventional methods require covalent conjugation of bone-targeting ligands to NIR contrast agents. This will be a new approach for bone-targeted imaging by using the bifunctional NIR contrast agents.

Methods

The goal of this review is to provide an overview of the recent advances in optical imaging of bone tissue, highlighting the structure-inherent targeting by developing NIR contrast agents without the need for a bone-targeting ligand such as bisphosphonates.

Results

A series of iminodiacetated and phosphonated NIR contrast agents for the structure-inherent targeting of bone tissue showed excellent bone-targeting ability in vivo without non-specific binding. Additionally, the phosphonated NIR contrast agents could be useful in the diagnosis of bone metastasis.

Conclusion

By developing bone-targeted NIR contrast agents, optical imaging of bone tissue makes it very attractive for preclinical studies of bone growth or real-time fluorescence guided surgery resulting in high potential to shift the clinical paradigms.

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.

Technological Advances in Lymphatic Surgery: Bringing to Light the Invisible

Lymphatic surgery has become an integral and flourishing component of the field of plastic surgery. The diversity of ongoing technological innovations in perioperative imaging, including intraoperative dyes and cameras, allows plastic surgeons to work at the supermicrosurgical level. This study aims to highlight innovations that have shaped and will continue to revolutionize the perioperative management of the lymphatic surgery patient in the future. As additional advances emerge, we need a systematic and objective way to evaluate the efficacy and clinical integration readiness of such technologies. Undoubtedly, these technologies will help lymphatic surgery trend toward increasing objectivity, which will be critical for continued evolution and advancement.

Network meta-analysis of novel and conventional sentinel lymph node biopsy techniques in breast cancer

Background

The aim of this network meta‐analysis was to compare the performance of blue dye alone or in combination with radioisotope (technetium‐99m, Tc) with three novel techniques for sentinel lymph node detection in breast cancer: indocyanine green fluorescence (ICG), superparamagnetic iron oxide (SPIO) nanoparticles and contrast‐enhanced ultrasound imaging (CEUS).

Methods

PubMed, Embase, the Cochrane Library, China Knowledge Research Integrated Database, ClinicalTrials.gov and OpenGrey databases were searched up to 31 November 2017, without language restriction. Studies that compared the detection performance of at least one of the novel methods (ICG, SPIO and CEUS) with that of traditional methods (blue dye and/or radioisotope) were included in network meta‐analysis.

Results

Thirty‐five studies were included. Pooled risk ratios (RRs) for Tc (1·09, 95 per cent c.i. 1·04 to 1·15), ICG (1·12, 1·07 to 1·16) and SPIO (1·09, 1·01 to 1·18) showed statistically better performance in detecting sentinel lymph nodes than blue dye alone. ICG had the lowest false‐negative rate, with a RR of 0·29 (0·16 to 0·54), followed by Tc (RR 0·44, 0·20 to 0·96) and SPIO (RR 0·45, 0·14 to 1·45), with blue dye alone as the reference group.

Conclusion

SPIO or ICG alone are superior to blue dye alone and comparable to the standard dual‐modality technique of blue dye with Tc.

Intraoperative Sentinel Node Mapping in the Colon: Potential and Pitfalls

Sentinel lymph node mapping (SLNM) may play a significant role in future delivery of colon cancer surgery because of an increase in early-stage, node-negative disease due to national bowel cancer screening programmes. Traditionally, colon lymphatic drainage has not been thought relevant as the operative approach cannot be tailored. Recent advances in local and endoscopic risk-reducing interventions for colonic malignancy have caused a rethink in approach. SLNM was initially attempted with blue dye techniques with limited success. Technological improvement has allowed surgeons to use near-infrared (NIR) light and NIR active tracers such as indocyanine green. This review provides an overview of the current status of intraoperative lymph node mapping in the colon, identifies challenges to the delivery of the techniques, and discusses potential solutions that may help SLNM play a role in improving the delivery of surgical care for patients with colon cancer.

Molecular design of near-infrared fluorescent Pdots for tumor targeting: aggregation-induced emission versus anti-aggregation-caused quenching

Semiconducting polymer dots (Pdots) have recently emerged as a new type of ultrabright fluorescent probe that has been proved to be very useful for biomedical imaging. However, Pdots often suffer from serious fluorescence aggregation-caused quenching (ACQ) especially for near-infrared (NIR) fluorescent Pdots. This article compared two strategies to overcome the ACQ effect in near-infrared emissive Pdot systems: aggregation-induced emission (AIE) and anti-aggregation-caused quenching (anti-ACQ). The results show that the anti-ACQ platform outperforms the AIE system. The fluorescence quantum yield of anti-ACQ-based Pdots can be over 50% and the average per-particle brightness of the Pdots is about 5 times higher than that of the commercially available quantum dots. To help understand why the monomer conformations could greatly affect the optical properties of Pdots, molecular dynamics simulations were performed for the first time in such complicated Pdot systems. To demonstrate applications for in vivo fluorescence imaging, both microangiography imaging on living zebrafish embryos and specific tumor targeting on mice were performed. We anticipate that these studies will pave the way for the design of new highly fluorescent Pdot systems.