Fluorescence navigation with indocyanine green for detecting sentinel lymph nodes in breast cancer

Near infrared fluorescence light imaging for lymphatic flow toward para-aortic lymph node from the Calot's triangle: A prospective exploratory study

BACKGROUND

Metastasis to para-aortic lymph nodes (PAN) in hilar malignancies is considered distant metastasis. Fluorescence imaging using near infrared fluorescence light and indocyanine green (ICG-NIR imaging) are widely employed for identifying the sentinel lymph node, which might be an ideal alternative procedure for whole excisional biopsy of PAN. However, there has been no report about ICG-NIR imaging in hilar malignancies. The purpose of this study was to determine the optimal dose for indocyanine green to detect PAN and to reveal the detection rate of ICG-NIR imaging for lymphatic flow toward regional lymph nodes (RLN) or PAN from the Calot's triangle.

PATIENTS AND METHODS

We enrolled 62 patients with hepato-pancreatic-biliary malignancies in this study. The dose of ICG was optimized in the first 15 patients and the detection rate for RLN and PAN was evaluated in the remaining 47. We observed that the optimal administered dose of ICG for detecting fluorescent signals in PAN was 5 mg/mL.

RESULTS

Using this dose, RLN and PAN fluorescence were detected in 29 of 42 patients. Fluorescent signals were recorded in the lymph nodes (LN) along the bile duct and the posterior surface of the head of the pancreas. We also detected PAN fluorescent signals on the right side of the aorta around the left renal vein. We recommend 5 mg/ml of ICG to visualize lymphatic flow from the hepatoduodenal ligament to PAN using ICG-NIR imaging. However, because detection rate of RLN and PAN were 69%, respectively, further improvement for this procedure will be necessary for clinical application.

Comparison of the indocyanine green dye method versus the combined method of indigo carmine blue dye with indocyanine green fluorescence imaging for sentinel lymph node biopsy in breast conservative therapy for stage ≤IIA breast cancer

BACKGROUND

Fluorescence imaging (FI) is one of the methods to identify sentinel lymph nodes (SLNs). However, the procedure is technically complicated and requires procedural skills, as SLN biopsy must be conducted in dim light conditions. As an improved version of this method, we introduced a combined method (Combined mixed dye and fluorescence; CMF) consisting of indigo carmine blue dye and FI. The direct visualization of SLNs under shadowless surgical light conditions is facilitated by the addition of the blue dye. We compared the SLN detection rates of CMF with that of the indocyanine green (ICG) dye method (ICG-D).

METHODS

A total of 202 patients with stage ≤IIA breast cancer who underwent breast conservative therapy with separate incision from January 2004 to February 2017 were reviewed. Details of the two methods are as follows: (1) ICG-D: 10 mg of ICG was used and the green-stained SLNs were resected via a 3-4 cm axillary incision; (2) CMF: A combination of 5 mg of ICG and 4-8 mg of indigo carmine was used. After a 1.5-2 cm incision was made near the point of disappearance of the fluorescence using Photodynamic Eye (PDE), the blue-stained SLNs were resected under shadowless surgical light conditions.

RESULTS

There were 92 ICG-D and 110 CMF cases. CMF resulted in a significantly higher SLN detection rate than ICG-D (96.4% vs. 83.7%; p = 0.003). This difference was particularly notable in those aged ≥60 years (98.3% vs. 74.3%) and individuals with body mass index (BMI) ≥25 kg/m² (90.3% vs. 58.3%).

CONCLUSION

CMF is an effective method to identify SLNs which is safe and efficient. CMF achieves a high SLN identification rate and most of this procedure is feasible under shadowless surgical light conditions. CMF can reliably perform SLN biopsy even in those aged ≥60 years and individuals with BMI ≥ 25 kg/m².

Noninvasive detection of cancer spread to lymph nodes: A review of molecular imaging principles and protocols

Identification of cancer spread to tumor-draining lymph nodes offers critical information for guiding treatment in many cancer types. Current clinical methods of nodal staging are invasive and can have substantial negative side effects. Molecular imaging protocols have long been proposed as a less invasive means of nodal staging, having the potential to enable highly sensitive and specific evaluations. This review article summarizes the current status and future perspectives for molecular targeted nodal staging.

Novel thoracoscopic navigation surgery for neonatal chylothorax using indocyanine-green fluorescent lymphography

BACKGROUND

Postoperative chylothorax after surgery for esophageal atresia/tracheoesophageal fistula (TEF) is a rare but serious complication, especially in neonates. This study aimed to identify the thoracic duct and ligate chylous leakage sites, using thoracoscopic navigation of an indocyanine-green (ICG)-based near-infrared (NIR) fluorescence imaging system.

METHODS

From November 2014 to April 2017, thoracoscopic intraoperative ICG-NIR imaging was performed in 10 newborns (11 surgeries) with first TEF operation or with persistent postoperative chylothorax after TEF operation. NIR imaging was performed 1h after an inter-toe injection of ICG. Thoracoscopic ligations against the NIR-detected leakage sites were performed with sutures.

RESULTS

The thoracic duct or lymphatic leakage was directly visualized in each patient. In 8 surgeries with first thoracoscopic TEF operation, one case had suspected minor chylous leakage without postoperative chylothorax. Another case with no chylous leakage at the first operation resulted in chylothorax at postoperative day 11. In three neonates with postoperative chylothorax, leakage points were detected near the ablation site of the azygos vein during the first operation. These points were properly ligated, and postoperative chylous leakage ceased with no adverse events.

CONCLUSIONS

Thoracoscopic ICG-NIR imaging encourages the repair of refractory chylothorax and seems reliable.

LEVEL OF EVIDENCE

IV.

Comparison of sentinel lymph node biopsy guided by blue dye with or without indocyanine green in early breast cancer

BACKGROUND

There were limited data available for a head-to-head comparison of the identification rate and survival between the combined method of indocyanine green fluorescence and blue dye versus the traditional blue dye alone method for sentinel lymph node (SLN) biopsy.

METHODS

From January 2013 to December 2015, 523 eligible breast cancer patients were included in this nonrandomized prospective analysis. The identification rates, the number of SLNs identified, and the disease-free survival (DFS) between the two mapping methods were compared.

RESULTS

The identification rate of SLNs was significantly higher with the combined method than that with the blue dye alone method (99.2% vs 93.3%, respectively; P < 0.001). The average number of SLNs identified per patient in the combined method group was 3.7 ± 2.4, which was more than that in the blue dye alone group (3.2 ± 1.6; P = 0.004). With a median follow-up of 29 months, 0.5% patients in the combined group, and 1.3% patients in the blue dye group had axillary recurrences. The DFS between the two groups showed no significant difference (P = 0.161).

CONCLUSION

The combined method achieved a higher identification rate and lower rate of axillary recurrence compared to the blue dye alone method.

Real-time navigation system for sentinel lymph node biopsy in breast cancer patients using projection mapping with indocyanine green fluorescence

BACKGROUND

Inability to visualize indocyanine green fluorescence images in the surgical field limits the application of current near-infrared fluorescence imaging (NIR) systems for real-time navigation during sentinel lymph node (SLN) biopsy in breast cancer patients. The aim of this study was to evaluate the usefulness of the Medical Imaging Projection System (MIPS), which uses active projection mapping, for SLN biopsy.

METHODS

A total of 56 patients (59 procedures) underwent SLN biopsy using the MIPS between March 2016 and November 2017. After SLN biopsy using the MIPS, residual SLNs were removed using a conventional NIR camera and/or radioisotope method. The primary endpoint of this study was identification rate of SLNs using the MIPS.

RESULTS

In all procedures, at least one SLN was detected by the MIPS, giving an SLN identification rate of 100% [95% confidence interval (CI) 94-100%]. SLN biopsy was successfully performed without operating lights in all procedures. In total, 3 positive SLNs were excised using MIPS, but were not included in the additional SLNs excised by other methods. The median number of SLNs excised using the MIPS was 3 (range 1-7). Of procedures performed after preoperative systemic therapy, the median number of SLNs excised using the MIPS was 3 (range 2-6).

CONCLUSIONS

The MIPS is effective in detecting SLNs in patients with breast cancer, providing continuous and accurate projection of fluorescence signals in the surgical field, without need for operating lights, and could be useful in real-time navigation surgery for SLN biopsy.

Novel PET and Near Infrared Imaging Probes for the Specific Detection of Bacterial Infections Associated With Cardiac Devices

OBJECTIVES

The aim of this study was to develop imaging agents to detect early stage infections in implantable cardiac devices.

BACKGROUND

Bacteria ingest maltodextrins through the specific maltodextrin transporter. We developed probes conjugated with either a fluorescent dye (maltohexaose fluorescent dye probe [MDP]) or a F-18 (F18 fluoromaltohexaose) and determined their usefulness in a model of infections associated with implanted cardiac devices.

METHODS

Stainless steel mock-ups of medical devices were implanted subcutaneously in rats. On post-operative day 4, animals were injected with either Staphylococcus aureus around the mock-ups to induce a relatively mild infection or oil of turpentine to induce noninfectious inflammation. Animals with a sterile implant were used as control subjects. On post-operative day 6, either the MDP or F18 fluoromaltohexaose was injected intravenously, and the animals were scanned with the appropriate imaging device. Additional positron emission tomography imaging studies were performed with F18-fluorodeoxyglucose as a comparison of the specificity of our probes (n = 5 to 9 per group).

RESULTS

The accumulation of the MDP in the infected rats was significantly increased at 1 h after injection when compared with the control and noninfectious inflammation groups (intensity ratio 1.54 ± 0.07 vs. 1.26 ± 0.04 and 1.20 ± 0.05, respectively; p < 0.05) and persisted for more than 24 h. In positron emission tomography imaging, both F18 fluoromaltohexaose and F18 fluorodeoxyglucose significantly accumulated in the infected area 30 min after the injection (maximum standard uptake value ratio 4.43 ± 0.30 and 4.87 ± 0.28, respectively). In control rats, there was no accumulation of imaging probes near the device. In the noninfectious inflammation rats, no significant accumulation was observed with F18 fluoromaltohexaose, but F18 fluorodeoxyglucose accumulated in the mock-up area (maximum standard uptake value 2.53 ± 0.39 vs. 4.74 ± 0.46, respectively; p < 0.05).

CONCLUSIONS

Our results indicate that maltohexaose-based imaging probes are potentially useful for the specific and sensitive diagnosis of infections associated with implantable cardiac devices.

The inhibitory effect of gadoxetate disodium on hepatic transporters: a study using indocyanine green

OBJECTIVES

To assess the inhibitory effect of gadoxetate disodium on the transporter system using indocyanine green (ICG).

MATERIALS AND METHODS

Groups of six female B6 Albino mice were injected with the test agent (0.62 mmol/kg gadoxetate disodium) or phosphate-buffered saline (control) 10 min before injection of ICG. Identical fluorescence images were subsequently obtained to create time-efficiency curves of liver parenchymal uptake. The study was performed on hypothermic and normothermic mice. The logarithms of the absorption rate constants (logKa values) and of the elimination rate constants (logKe values) were calculated for each experimental condition, and between-group differences were compared using Student's t-test.

RESULTS

The logKe values of the test group were lower than those of the control group at both temperatures (-6.52 vs. -5.87 under hypothermic conditions and -4.54 vs. -4.14 under normothermic conditions), and both differences were statistically significant (p = 0.037, 0.015 respectively). In terms of the logKa values, although the difference did not reach statistical significance (p = 0.052), the test group had lower values than the control group under hypothermic conditions (-0.771 vs. -0.376). In normothermic mice, the logKa values for the test and control groups were 0.037 and 0.277 respectively, thus not significantly different (p = 0.404).

CONCLUSIONS

Gadoxetate disodium inhibited ICG excretion. Thus, gadoxetate disodium inhibited the ATP-binding cassette sub-family C member 2 transporter.

KEY POINTS

• Gadoxetate disodium inhibited ICG excretion. • Gadoxetate disodium tended to inhibit hepatic ICG uptake. • Drug-drug interactions of gadoxetate disodium need further investigation.

The Usefulness of Photodynamic Eye for Sentinel Lymph Node Identification in Patients with Cervical Cancer

Aims and background

We studied the potential use of sentinel lymph node identification using a near-infrared fluorescence imaging technique in the treatment of cervical cancer.

Methods and study design

Directly before the start of the operation, 0.2 ml of 5 mg/ml indocyanine green was prepared and injected into 4 sites in the cervix using a 26-gauge standard needle, at 3, 6, 9 and 12 o'clock positions. When the operation was advanced to the pelvis, near-infrared fluorescence imaging was performed using photodynamic eye (Hamamatsu Photonics Co., Japan). The sentinel lymph nodes and other dissected lymph nodes were histologically examined to find any metastases.

Results

Twelve patients were examined. Their ages ranged from 36 to 68 years (median, 58). Sentinel lymph nodes were identified in 10 patients (83%), and all were bi-laterally identified. The median maximum tumor diameter of dissected cervical tumors was 35 mm (22–65); histology was squamous cell carcinoma in 8 patients and adenocarcinoma in 2 patients. Capillary lymphatic space involvement was found in 8 of the 10 patients. The site of the sentinel lymph node was the right external iliac node in 8 patients, the right obturator node in 8, the left external iliac node in 9, and the left obturator node in 8. Lymph node metastasis was found in 2 of the 12 patients, and all were sentinel lymph nodes. No metastasis from lymph nodes other than sentinel lymph nodes was observed.

Conclusions

Photodynamic eye achieved a detection rate similar to that obtained with the blue dye and radioisotope method. It is also easier to use than the other two methods. Free full text available at www.tumorionline.it

Multifunctional Photonic Nanomaterials for Diagnostic, Therapeutic, and Theranostic Applications

The last decade has seen dramatic progress in the principle, design, and fabrication of photonic nanomaterials with various optical properties and functionalities. Light-emitting and light-responsive nanomaterials, such as semiconductor quantum dots, plasmonic metal nanoparticles, organic carbon, and polymeric nanomaterials, offer promising approaches to low-cost and effective diagnostic, therapeutic, and theranostic applications. Reasonable endeavors have begun to translate some of the promising photonic nanomaterials to the clinic. Here, current research on the state-of-the-art and emerging photonic nanomaterials for diverse biomedical applications is reviewed, and the remaining challenges and future perspectives are discussed.

Evolution in sentinel lymph node biopsy in breast cancer

Sentinel lymph node biopsy (SLNB) is the standard of care for axillary staging in clinically node-negative (cN0) breast cancer patients without neoadjuvant chemotherapy (NAC). The application of SLNB in patients receiving NAC has also been explored. Evidence supports its use after NAC in pretreatment cN0 patients. Nonetheless, its routine use in all the pretreatment node-positive patients who become cN0 after NAC is unjustified due to the unacceptably high false-negative rate, which can be improved in a subset of patients. Axillary surgery omission in selected patients with a low risk of ALN metastasis has gained more and more research interest because the SLNs are tumor-free in more than 70% of all patients. To avoid drawbacks of conventional mapping methods, novel techniques for SLN detection have been developed and shown to be highly accurate in patients with early breast cancer. This article reviews the progress in SLNB in patients with breast cancer.

Gap-enhanced Raman tags for high-contrast sentinel lymph node imaging

The sentinel lymph node (SLN) biopsy is gaining in popularity as a procedure to investigate the lymphatic metastasis of malignant tumors. The commonly used techniques to identify the SLNs in clinical practice are blue dyes-guided visualization, radioisotope-based detection and near-infrared fluorescence imaging. However, all these methods have not been found to perfectly fit the clinical criteria with issues such as short retention time in SLN, poor spatial resolution, autofluorescence, low photostability and high cost. In this study, we have reported a new type of nanoprobes, named, gap-enhanced Raman tags (GERTs) for the SLN Raman imaging. With the advantageous features including unique "fingerprint" Raman signal, strong Raman enhancement, high photostability, good biocompatibility and extra-long retention time, we have demonstrated that GERTs are greatly favorable for high-contrast and deep SLN Raman imaging, which meanwhile reveals the dynamic migration behavior of the probes entering the SLN. In addition, a quantitative volumetric Raman imaging (qVRI) data-processing method is employed to acquire a high-resolution 3-dimensional (3D) margin of SLN as well as the content variation of GERTs in the SLN. Moreover, SLN detection could be realized via a cost-effective commercial portable Raman scanner. Therefore, GERTs hold the great potential to be translated in clinical application for accurate and intraoperative location of the SLN.

Comparison of sentinel lymph node detection performances using blue dye in conjunction with indocyanine green or radioisotope in breast cancer patients: a prospective single-center randomized study

Objective:

This randomized study aimed to compare the clinical efficacy between the novel dual tracer composed of indocyanine green (ICG) and blue dye (BD) and the conventional dual tracer composed of radioisotope and BD for sentinel lymph node (SLN) mapping in patients with breast cancer.

Methods:

This study enrolled 471 clinically lymph node-negative patients with primary breast cancer. All patients underwent mastectomy, and those undergoing sentinel lymph node biopsy (SLNB) were randomized to receive blue dye plus radioisotope (RB group) or BD plus ICG (IB group). The detection performances on SLN identification rate, positive SLN counts, detection sensitivity, and false-negative rate were compared between the two groups.

Results:

In the IB group, 97% (194/200) of the patients who underwent the ICG and BD dual tracer injection showed fluorescent-positive lymphatic vessels within 2–5 min. The identification rate of SLNs was comparable between the IB group (99.0%, 198/200) and the RB group (99.6%, 270/271) (P = 0.79). No significant differences were observed in the identification rate of metastatic SLNs (22.5% vs. 22.9%, P > 0.05, RB group vs. IB group, the same below), positive SLN counts (3.72 ± 2.28 vs. 3.91 ± 2.13, P > 0.05), positive metastatic SLN counts (0.38 ± 0.84 vs. 0.34 ± 0.78, P > 0.05), SLNB detection sensitivity (94.4% vs. 92.5%, P > 0.05), or false-negative rate (5.6% vs. 7.5%, P > 0.05) between the two groups.

Conclusions:

ICG can be used as a promising alternative tracer for radioisotope in SLN mapping, and when it is combined with BD in lymphangiography, it offers comparable detection sensitivity compared to the conventional lymphatic mapping strategies that are widely used in clinical practice.

Role of Indocyanine Green in Fluorescence Imaging with Near-Infrared Light to Identify Sentinel Lymph Nodes, Lymphatic Vessels and Pathways Prior to Surgery - A Critical Evaluation of Options

Modern surgical strategies aim to reduce trauma by using functional imaging to improve surgical outcomes. This reviews considers and evaluates the importance of the fluorescent dye indocyanine green (ICG) to visualize lymph nodes, lymphatic pathways and vessels and tissue borders in an interdisciplinary setting. The work is based on a selective search of the literature in PubMed, Scopus, and Google Scholar and the authors' own clinical experience. Because of its simple, radiation-free and uncomplicated application, ICG has become an important clinical indicator in recent years. In oncologic surgery ICG is used extensively to identify sentinel lymph nodes with promising results. In some studies, the detection rates with ICG have been better than the rates obtained with established procedures. When ICG is used for visualization and the quantification of tissue perfusion, it can lead to fewer cases of anastomotic insufficiency or transplant necrosis. The use of ICG for the imaging of organ borders, flap plasty borders and postoperative vascularization has also been scientifically evaluated. Combining the easily applied ICG dye with technical options for intraoperative and interventional visualization has the potential to create new functional imaging procedures which, in future, could expand or even replace existing established surgical techniques, particularly the techniques used for sentinel lymph node and anastomosis imaging.

Fluorescence-Guided Surgery

Surgical resection of cancer remains an important treatment modality. Despite advances in preoperative imaging, surgery itself is primarily guided by the surgeon’s ability to locate pathology with conventional white light imaging. Fluorescence-guided surgery (FGS) can be used to define tumor location and margins during the procedure. Intraoperative visualization of tumors may not only allow more complete resections but also improve safety by avoiding unnecessary damage to normal tissue which can also reduce operative time and decrease the need for second-look surgeries. A number of new FGS imaging probes have recently been developed, complementing a small but useful number of existing probes. In this review, we describe current and new fluorescent probes that may assist FGS.

Lymphatic Territories (Lymphosomes) in the Rat: An Anatomical Study for Future Lymphatic Research

BACKGROUND

Understanding the precise anatomy in experimental animals is crucial for correct design of research projects. Rats are commonly used for scientific research in plastic surgery because of their availability in academic institutions, moderate cost, and sizable vessels for microsurgical procedures. In past publications about rat anatomy, lymphatic mapping has been limited and incomplete. The aim of this study was to comprehensively map the superficial lymphatic system in the rat.

METHODS

Twenty-seven Sprague-Dawley rats were used for this study. Indocyanine green fluorescence lymphography was used to identify the lymphatic vessels and lymph nodes. Under general anaesthesia, indocyanine green was injected intradermally at multiple spots along the dorsal and medial midlines, front and hind paws, ears, and tail. The course of the lymphatic vessels was traced on the skin with a marker pen and photographed. The superficial lymphatic vessels in each rat were sketched on a graphic template and all of the templates were superimposed using graphics software to define the relationship between the lymphatic vessel and sentinel node.

RESULTS

Indocyanine green fluorescence lymphography was able to demonstrate the superficial lymphatic vessels in the rat. Six groups of regional lymph node/s were identified and lymphatic pathways to those nodes delineated. The authors' lymphosome concept was successfully applied to the rat, with six lymphosomes identified.

CONCLUSIONS

The authors succeeded in performing superficial lymphatic mapping in the rat. The authors' anatomical findings can provide further information about the lymphatic system in the normal state and promote understanding of pathologic changes generated by surgical manipulation for future studies.

Comparison of sentinel lymph node biopsy guided by indocyanine green, blue dye, and their combination in breast cancer patients: a prospective cohort study

BACKGROUND

Recent studies show that near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) has the potential to improve the performance of sentinel lymph node (SLN) mapping. The current cohort study was designed to assess the value of the combination of ICG and methylene blue (MB) dye in patients undergoing SLN biopsy.

METHODS

A prospective self-controlled trial was designed to detect the difference in the detection efficacies of ICG, MB, and combined ICG and MB (ICG + MB) navigation methods. Between 2010 and 2013, 198 consecutive early breast cancer patients eligible for sentinel lymph node biopsy were enrolled and 200 biopsy procedures were performed by injection of both ICG and MB. SLNs were searched and removed under the guidance of fluorescence and/or blue dye. The mapping characteristics, the detection rate of SLNs and positive SLNs, and the number of SLNs of ICG, MB, and ICG + MB were compared. Injection safety of ICG and MB was evaluated.

RESULTS

Fluorescence imaging of lymphatic flow, which is helpful to locate the incision site, could be seen in 184 of 200 procedures. The nodal detection rate of ICG, MB, and ICG + MB samples was 97, 89, and 99.5% (χ 2 = 26.2, p < 0.001), respectively, with the combination method yielding a superior identification result. The addition of ICG to the MB method resulted in the identification of more lymph nodes (median 3 versus 2) and more positive axillas (22.7% involved axillas were discovered by fluorescence only) than either method alone. No acute or chronic allergic reaction was observed in this study. However, 23 patients (23/82) who received breast-conserving therapy reported temporary skin staining, and 5 patients had permanent tattooing. Palpable subcutaneous nodules at the injection sites were reported in nine patients. There were no reports of skin necrosis.

CONCLUSIONS

The lymphatic navigation by ICG fluorescence detects SLNs at a high detection rate and improves the mapping performance when added to the MB method. The novel ICG + MB dual tracing modality, without involvement of radioactive isotopes, exhibits great potential as an alternative to traditional standard mapping methods.

TRIAL REGISTRATION

ACTRN12612000109808 . Retrospectively registered on 23 January 2012.

[Imaging diagnostic methods for identification of sentinel lymph nodes in patients with early squamous cell carcinoma of the oral cavity mucosa: a literature review]

The paper describes properties of clinical visualization approaches which are applied for detection of sentinel lymph nodes in patients suffering from oral cavity squamous cell cancer. Diagnostic efficiency results and technological features of different imaging techniques are discussed.

Multifunctional Liposomes for Image-Guided Intratumoral Chemo-Phototherapy

Intratumoral (IT) drug injections reduce systemic toxicity, but delivered volumes and distribution can be inconsistent. To improve IT delivery paradigms, porphyrin-phospholipid (PoP) liposomes are passively loaded with three hydrophilic cargos: sulforhodamine B, a fluorophore; gadolinium-gadopentetic acid, a magnetic resonance (MR) agent; and oxaliplatin, a colorectal cancer chemotherapeutic. Liposome composition is optimized so that cargo is retained in serum and storage, but is released in less than 1 min with exposure to near infrared light. Light-triggered release occurs with PoP-induced photooxidation of unsaturated lipids and all cargos release concurrently. In subcutaneous murine colorectal tumors, drainage of released cargo is delayed when laser treatment occurs 24 h after IT injection, at doses orders of magnitude lower than systemic ones. Delayed light-triggering results in substantial tumor shrinkage relative to controls a week following treatment, although regrowth occurs subsequently. MR imaging reveals that over this time frame, pools of liposomes within the tumor migrate to adjacent regions, possibly leading to altered spatial distribution during triggered drug release. Although further characterization of cargo loading and release is required, this proof-of-principle study suggests that multimodal theranostic IT delivery approaches hold potential to both guide injections and interpret outcomes, in particular when combined with chemo-phototherapy.

Optical Characteristics and Tumor Imaging Capabilities of Near Infrared Dyes in Free and Nano-Encapsulated Formulations Comprised of Viral Capsids

Near infrared (NIR) fluorescent molecules and nanosized structures can serve as potential optical probes for image-guided removal of small tumor nodules (≲ 1 mm diameter). Although indocyanine green (ICG) remains as the only FDA-approved NIR dye, other organic dyes are under extensive development for enhanced imaging capabilities. One such dye is BrCy106-NHS where bromine is substituted for aromatic structures in cyanine dyes. Herein, we investigate the absorption and fluorescence characteristics of ICG and BrCy106-NHS, and quantitatively assess their tumor imaging capabilities in free (non-encapsulated) and a nano-encapsulated form that utilizes the capsid protein (CP) from genome-depleted plant-infecting brome mosaic virus as the encapsulating shell. We refer to these nanoconstructs as optical viral ghosts (OVGs). For example, when fabricated at CP to dye concentration ratio of 200, value of the spectrally integrated fluorescence emission for BrCy106-NHS-doped OVGs is ∼60 times higher than that of ICG-doped OVGs. Our analysis of homogenized mice intraperitoneal tumors indicate that the averaged total fluorescence emission associated with the use of BrCy106-NHS-doped can be at least about 44 times greater than that of ICG-doped OVGs. Our results suggest that OVGs containing BrCy106-NHS may potentially serve as effective optical probes for tumor imaging.

A Conjugate of Pentamethine Cyanine and 18F as a Positron Emission Tomography/Near-Infrared Fluorescence Probe for Multimodality Tumor Imaging

The novel synthesis of a dual-modality, pentamethine cyanine (Cy5) fluorescent, ¹⁸F positron emission tomography (PET) imaging probe is reported. The probe shows a large extinction coefficient and large quantum yield in the biologically transparent, near-infrared window (650–900 nm) for in vivo fluorescent imaging. This fluorophore bears the isotope, ¹⁸F, giving a ¹⁸F-PET/near-infrared fluorescent (NIRF), bi-modal imaging probe, that combines the long-term stability of NIRF and the unlimited penetration depth of PET imaging. The bi-modal probe is labeled with ¹⁸F in a quick, one-step reaction, which is important in working with the rapid decay of ¹⁸F. The bi-modal probe bears a free carboxyl group, highlighting a PET/NIRF synthon that can be conjugated onto many advanced biomolecules for biomarker-specific in vivo dual-modal PET/NIR tumor imaging, confocal histology, and utility in multi-fluorophore, fluorescence-guided surgery. Its potential in vivo biocompatibility is explored in a quick proof-of-principal in vivo study. The dye is delivered to A549 xenograft flank-tumors to generate PET and NIRF signals at the tumor site. The tumor distribution is confirmed in ex vivo gamma counting and imaging. Pentamethine cyanine (Cy5) has the ability to preferentially accumulate in tumor xenografts. We substitute the PET/NIRF probe for Cy5, and explore this phenomenon.

Indocyanine green fluorescence-guided surgery after IV injection in metastatic colorectal cancer: A systematic review

OBJECTIVE

Indocyanine green fluorescence-guided surgery (ICG-FGS) has emerged as a potential new imaging modality for improving the detection of hepatic, lymph node (LN), and peritoneal metastases in colorectal cancer (CRC) patients. The aim of this paper is to review the available literature in the clinical setting of ICG-FGS for tumoral detection in various fields of metastatic colorectal disease.

METHODS

PubMed and Medline literature databases were searched for original articles on the use of ICG in the setting of clinical studies on colorectal cancer. The search terms used were "near-infrared fluorescence", "intraoperative imaging", "indocyanine green", "human" and "colorectal cancer".

RESULTS

ICG fluorescence imaging (ICG-FI) is clearly supported as an intraoperative technique that allows the detection of additional superficial hepatic metastases of CRC. Data on the role of ICG-FI in the intraoperative detection of peritoneal metastases and LN metastases are scarce but encouraging and ICG-FI could potentially improve the staging and treatment of these patients.

CONCLUSION

ICG-FI is a promising imaging technique in the detection of small infraclinic LN, hepatic, and peritoneal metastatic deposits that may allow better staging and more complete surgical resection with a potential prognostic benefit for patients.

Applications of fusion-fluorescence imaging using indocyanine green in laparoscopic hepatectomy

BACKGROUND

Indocyanine green (ICG)-fluorescence imaging has been developed for real-time identification of hepatic tumors and segmental boundaries during hepatectomy. Fusion ICG-fluorescence imaging (real-time visualization of pseudocolor-fluorescence signals on white-light color images) may serve as a reliable navigation tool especially in laparoscopic hepatectomy, in which gross inspection and palpation are limited.

METHODS

The study population consisted of 41 patients undergoing laparoscopic hepatectomy. Hepatic tumors were identified by fluorescence imaging following the preoperative intravenous administration of ICG (0.5 mg/kg body weight). To visualize hepatic perfusion and segmental boundaries, ICG (1.25 mg) was injected intravenously during surgery, following closure of the proximal portal pedicle. A laparoscopic imaging system, which enabled superimposition of the pseudocolor-fluorescence images on white color images, was used for the fusion ICG-fluorescence imaging.

RESULTS

Among the 53 malignant tumors resected, fusion ICG-fluorescence imaging revealed 45 nodules (85%), including three nodules of colorectal liver metastasis unidentifiable by white-light color images or intraoperative ultrasonography. It also delineated the segmental boundaries on the hepatic raw surfaces as well as on the phrenic/visceral surfaces in all 12 patients evaluated using this technique.

CONCLUSIONS

Fusion imaging enhances the feasibility of intraoperative ICG-fluorescence imaging in the identification of hepatic tumors and segmental boundaries. It may therefore help surgeons in the safe and accurate completion of laparoscopic hepatectomies.

Clinical utility of the additional use of blue dye for indocyanine green for sentinel node biopsy in breast cancer

BACKGROUND

Indocyanine green (ICG) is widely used as a tracer in sentinel lymph node biopsy (SLNB) of patients with breast cancer. Whether SLNB performance can be improved by supplementing ICG with methylene blue dye remains controversial. This study compared the performance of SLNB when ICG was used alone or with blue dye.

MATERIALS AND METHODS

Consecutive patients with T1-3 primary breast cancer at our hospital were recruited into our study and randomized to undergo SLNB with ICG alone (n = 62) or with the combination of ICG and blue dye (n = 65). We compared the two methods in terms of identification rate, number and detection time of sentinel lymph nodes (SLNs) removed.

RESULTS

SLN identification rate were similar in the absence (95.2%) or presence of blue dye (98.5%, P = 0.578) but significantly, more average nodes were removed when blue dye was used (3.8 ± 1.5 versus 2.7 ± 1.2, P = 0.000), and the average time for detecting each SLN was significantly shorter (3.91 ± 1.87 versus 5.65 ± 2.95 min; P = 0.000). No patient in the study experienced severe adverse reactions or complications. Recurrence of axillary node was detected in one patient (1.6%) using ICG alone but not in any patients using ICG and blue dye.

CONCLUSIONS

The efficiency and sensitivity of SLNB can be improved by combining ICG with blue dye.

Use of indocyanine green for detecting sentinel lymph nodes in breast cancer: letter to the editor

In a previous issue of the journal, Oldřich Coufal and Vuk Fait reported a pilot study that specifically addressed the use of indocyanine green for detecting sentinel lymph nodes in breast cancer within a European population. They concluded that fluorescence method cannot currently be considered a method fully comparable with using radioisotopes in this setting. We consider that the absence of a learning curve, the low mean of retrieved sentinel nodes, and the possibility that migration of indocyanine green occurred after the initial biopsy limit the strength of their conclusion.

Liposomal Indocyanine Green for Enhanced Photothermal Therapy

In this study, we engineered liposomal indocyanine green (ICG) to maximize its photothermal effects while maintaining the fluorescence intensity. Various liposomal formulations of ICG were prepared by varying the lipid composition and the molar ratio between total lipid and ICG, and their photothermal characteristics were evaluated under near-infrared irradiation. We showed that the ICG dispersity in the liposomal membrane and its physical interaction with phospholipids were the main factors determining the photothermal conversion efficiency. In phototherapeutic studies, the optimized formulation of liposomal ICG showed greater anticancer effects in a mouse tumor model compared with other liposomal formulations and the free form of ICG. Furthermore, we utilized liposomal ICG to visualize the metastatic lymph node around the primary tumor under fluorescence imaging guidance and ablate the lymph node with the enhanced photothermal effect, indicating the potential for selective treatment of metastatic lymph node.

Optical See-Through Cancer Vision Goggles Enable Direct Patient Visualization and Real-Time Fluorescence-Guided Oncologic Surgery

BACKGROUND

The inability to visualize the patient and surgical site directly, limits the use of current near infrared fluorescence-guided surgery systems for real-time sentinel lymph node biopsy and tumor margin assessment.

METHODS

We evaluated an optical see-through goggle augmented imaging and navigation system (GAINS) for near-infrared, fluorescence-guided surgery. Tumor-bearing mice injected with a near infrared cancer-targeting agent underwent fluorescence-guided, tumor resection. Female Yorkshire pigs received hind leg intradermal indocyanine green injection and underwent fluorescence-guided, popliteal lymph node resection. Four breast cancer patients received ^99mTc-sulfur colloid and indocyanine green retroareolarly before undergoing sentinel lymph node biopsy using radioactive tracking and fluorescence imaging. Three other breast cancer patients received indocyanine green retroareolarly before undergoing standard-of-care partial mastectomy, followed by fluorescence imaging of resected tumor and tumor cavity for margin assessment.

RESULTS

Using near-infrared fluorescence from the dyes, the optical see-through GAINS accurately identified all mouse tumors, pig lymphatics, and four pig popliteal lymph nodes with high signal-to-background ratio. In 4 human breast cancer patients, 11 sentinel lymph nodes were identified with a detection sensitivity of 86.67 ± 0.27% for radioactive tracking and 100% for GAINS. Tumor margin status was accurately predicted by GAINS in all three patients, including clear margins in patients 1 and 2 and positive margins in patient 3 as confirmed by paraffin-embedded section histopathology.

CONCLUSIONS

The optical see-through GAINS prototype enhances near infrared fluorescence-guided surgery for sentinel lymph node biopsy and tumor margin assessment in breast cancer patients without disrupting the surgical workflow in the operating room.

Influence of Indocyanine Green on Hepatic Gd-EOB-DTPA Uptake: A Proof-of-Concept Study in Mice

OBJECTIVES

The aim of this study was to explore the influence of indocyanine green (ICG) on hepatic uptake of gadolinium ethoxybenzyldiethylenetriaminepenta-acetic acid (Gd-EOB-DTPA).

MATERIALS AND METHODS

Groups of 6 female C57BL6 mice were injected with 5 mg/kg ICG, 20 mg/kg ICG, or phosphate-buffered saline (control group) 10 minutes before the injection of Gd-EOB-DTPA; identical 3-dimensional gradient echo T1-weighted images were subsequently obtained to create time-intensity curves and to measure the peak contrast ratios (CRs) of liver parenchyma. We studied both hypothermic and normothermic mice. Peak CRs for all experimental conditions were evaluated, and among-group differences were assessed using 2-way factorial analysis of variance with Bonferroni post hoc testing.

RESULTS

In hypothermic mice, the time-intensity curves of the 3 groups gradually increased from 5 to 30 minutes and almost plateaued after 30 minutes. The peak CR decreased as the amount of injected ICG increased (control group, 5 mg/kg ICG, 20 mg/kg ICG: 1.66 ± 0.09, 1.37 ± 0.18, 1.25 ± 0.24, respectively). In normothermic animals, the time-intensity curves of the control and ICG 5 mg/kg groups peaked 10 to 15 minutes after injection, the peak CRs were very similar (control group, 5 mg/kg ICG: 2.01 ± 0.16, 1.95 ± 0.14, respectively), and the intensities thereof then gradually fell until 60 minutes. Compared with these groups, the ICG 20 mg/kg group exhibited lower peak CR (1.48 ± 0.14) and a weaker decrease in intensity to 60 minutes. Both the amount of ICG injected (P < 0.001) and the experimental temperature (P < 0.001) significantly affected the measurements.

CONCLUSIONS

Indocyanine green inhibits the hepatic uptake of Gd-EOB-DTPA and affects the signal intensity upon Gd-EOB-DTPA-enhanced magnetic resonance imaging. Such inhibition was more obvious in hypothermic mice.

Contrast-enhanced dual mode imaging: photoacoustic imaging plus more

Conventional biomedical imaging modalities in wide clinical use, such as ultrasound imaging, X-ray computed tomography, magnetic resonance imaging, and positron emission tomography, can provide morphological, anatomical, and functional information about biological tissues. However, single mode imaging in conventional medicine provides only limited information for definitive diagnoses. Thus, combinational diagnosis using multiple imaging modalities has become increasingly important. Recently, photoacoustic imaging (PAI) has gained significant attention, and several PAI prototypes have been used in clinical trials. At the same time, PAI has been tested in combination with conventional imaging modalities. For all these imaging modalities, various contrast-enhancing agents have been developed for various purposes. In this review article, we will focus on recent progress in developing dual mode contrast agents for PAI in combination with other conventional imaging modalities.

Indocyanine green detects sentinel lymph nodes in early breast cancer

Objective

To explore the clinical value of indocyanine green (ICG) for the fluorescence-guided detection of sentinel lymph nodes (SLNs) during sentinel lymph node biopsy (SLNB) in patients with early breast cancer.

Methods

This retrospective study included female patients with breast cancer. Patients were administered methylene blue and ICG using standard techniques. All SLNs that were collected during surgery were submitted for pathological examination. SLNs were defined as those that were either fluorescent, blue, fluorescent and blue or palpably suspicious. Surgical complications, axillary recurrence, distant metastasis and overall survival rates were observed postoperatively.

Results

A total of 60 patients were enrolled in the study. The fluorescence detection rate of SLNs was 100% (n = 177), with a mean of 2.95 SLNs per patient. The methylene blue staining rate was 88.3% (n = 106), with a mean of 1.77 SLNs per patient. Pathological assessment of intraoperative frozen specimens revealed SLN metastases in 10 patients, who immediately underwent axillary lymph node dissection. No patient had axillary recurrence or distant metastases, with a survival rate of 100%. Patients who underwent SLNB showed good appearance in the axillary wound, with no limited shoulder joint abduction and upper limb oedema.

Conclusion

Fluorescence-guided SLNB has several advantages and is suitable for clinical application.

Fluorescent Versus Radioguided Lymph Node Mapping in Bladder Cancer

INTRODUCTION

The aim of the study was to compare 2 methods of the sentinel lymph node biopsy (SLNB) procedure in bladder cancer: we applied technetium radiocolloid (RadCol) detected by a gamma ray detection probe, and indocyanine green (ICG) detected by a near-infrared fluorescent (NIRF) camera.

MATERIAL AND METHODS

The SLNB was performed on 50 patients using the RadCol and the ICG, followed by a lymphadenectomy and a pathologic examination.

RESULTS

In the analyzed group of 47 patients (3 patients were excluded owing to the lack of lymphatic drainage from the tumor), the SLNB was performed using the 2 methods. The ICG with a NIRF-guided camera detected all sentinel lymph nodes (SLNs) in 46 cases, whereas RadCol detected them in 45 cases. In 12 (25.6%) of 47 patients, the ICG-fluorescent method revealed more SLNs than the RadCol method. In 8 (17%) patients, the SLNs revealed in the ICG fluorescence were metastatic. In 3 (6.4%) patients, we found SLNs outside the standard lymphadenectomy template, but a histopathologic examination showed they were negative for cancer. In 3 (6.4%) patients, the SLNs detected by both methods were negative for cancer, but other resected lymph nodes revealed metastases.

CONCLUSION

Our study shows that SLNB procedure with the RadCol or the ICG method is useful for the evaluation of lymph nodes in bladder cancer. The new ICG fluorescent technique with a NIRF camera system is safe, enables live view of the results of the procedure, and does not create additional costs. However, it highlights more lymph nodes than the radioactive method.