Optical image-guided cancer surgery: challenges and limitations

Counter Anion Effect on the Photophysical Properties of Emissive Indolizine-Cyanine Dyes in Solution and Solid State

Near-infrared emissive materials with tunable Stokes shifts and solid-state emissions are needed for several active research areas and applications. To aid in addressing this need, a series of indolizine-cyanine compounds varying only the anions based on size, dipole, and hydrophilicity were prepared. The effect of the non-covalently bound anions on the absorption and emission properties of identical π-system indolizine-cyanine compounds were measured in solution and as thin films. Interestingly, the anion choice has a significant influence on the Stokes shift and molar absorptivities of the dyes in solution. In the solid-state, the anion choice was found to have an effect on the formation of aggregate states with higher energy absorptions than the parent monomer compound. The dyes were found to be emissive in the NIR region, with emissions peaking at near 900 nm for specific solvent and anion selections.

Elemental and optical imaging evaluation of zwitterionic gold nanoclusters in glioblastoma mouse models

We report in this study the in vivo biodistribution of ultra-small luminescent gold (Au) particles (∼1.5 nm core size; 17 kDa), so-called nanoclusters (NCs), stabilized by bidentate zwitterionic molecules in subcutaneous (s.c.) and orthotopic glioblastoma mice models. Particular investigations on renal clearance and tumor uptake were performed using highly sensitive advanced imaging techniques such as multi-elemental Laser-Induced Breakdown Spectroscopy (LIBS) imaging and in-line X-ray Synchrotron Phase Contrast Tomography (XSPCT). Results show a blood circulation time of 6.5 ± 1.3 min accompanied by an efficient and fast renal clearance through the cortex of the kidney with a 66% drop between 1 h and 5 h. With a similar size range, these Au NCs are 5 times more fluorescent than the well-described Au₂₅GSH₁₈ NCs in the near-infrared (NIR) region and present significantly stronger tumor uptake and retention illustrated by an in vivo s.c. tumor-to-skin ratio of 1.8 measured by non-invasive optical imaging and an ex vivo tumor-to-muscle of 6.1. This work highlights the pivotal role of surface coating in designing optimum Au NC candidates for cancer treatment.

Introducing fluorescence guided surgery into orthopedic oncology: A systematic review of candidate protein targets for Ewing sarcoma

Ewing sarcoma (ES), an aggressive bone and soft‐tissue tumor, is treated with chemotherapy, radiotherapy, and surgery. Intra‐operative distinction between healthy and tumorous tissue is of paramount importance but challenging, especially after chemotherapy and at complex anatomical locations. Near infrared (NIR) fluorescence‐guided surgery (FGS) is able to facilitate the determination of tumor boundaries intra‐operatively, improving complete resection and therefore survival. This review evaluates potential ES‐specific proteins from the literature as targets for NIR FGS.

Adjuvant anti-angiogenic therapy enhances chemotherapeutic uptake in a murine model of head and neck cancer

Intratumoural metabolic demands result in excessive angiogenic cytokine release leading to unorganised vasculature. Resultant fluid dynamics oppose blood flow and drug penetration due to a marked increase in interstitial fluid hydrostatic pressure. It is hypothesised that anti-angiogenic therapy may function to 'prune' vasculature and lead to improved chemotherapeutic penetration. Subcutaneous, OSC19 tumour bearing mice (n = 5/dose/agent) were administered varying doses of an anti-mouse VEGFR2 (DC101) or an anti-mouse VEGFR3 (31C1) -3 d, -1 d, 0 d, +1 d and +3 d prior to 200 µg of cetuximab fluorescently labelled with IRDye800CW. Fluorescence imaging of tumours was performed 10 d post cetuximab-IRDye800CW dose to monitor therapeutic uptake. Co-administration of dual anti-angiogenic agents at 50-50%, 75-25% and 25-75% using optimal dose and time (-1 d 10 mg/kg anti-VEGFR2 and -1 d 40 mg/kg anti-VEGFR3) was also evaluated. In order to establish vessel normalisation, NG2 (pericyte marker) and CD31 (endothelial cells) ratios were assessed during immunohistochemical staining of tumour sections. Twenty-mg/kg anti-VEGFR3 + 5 mg/kg anti-VEGFR2 significantly (p < .0005) reduced tumour size (-73%) compared to control (59%). The 20 mg/kg anti-VEGFR3 + 5 mg/kg anti-VEGFR2 and 30 mg/kg anti-VEGFR3 + 2.5 mg/kg anti-VEGFR2 significantly (p < .0004) improved percent-injected cetuximab-IRDye800CW dose/gram tumour tissue compared to other groups. Adjuvant, dual anti-angiogenic therapy targeting VEGFR2 and VEGFR3 significantly enhances tumour chemotherapeutic uptake compared to control.

[18F]fluoroethyltyrosine-induced Cerenkov Luminescence Improves Image-Guided Surgical Resection of Glioma

The extent of surgical resection is significantly correlated with outcome in glioma; however, current intraoperative navigational tools are useful only in a subset of patients. We show here that a new optical intraoperative technique, Cerenkov luminescence imaging (CLI) following intravenous injection of O‑(2-[18F]fluoroethyl)-L-tyrosine (FET), can be used to accurately delineate glioma margins, performing better than the current standard of fluorescence imaging with 5-aminolevulinic acid (5-ALA). Methods: Rats implanted orthotopically with U87, F98 and C6 glioblastoma cells were injected with FET and 5-aminolevulinic acid (5-ALA). Positive and negative tumor regions on histopathology were compared with CL and fluorescence images. The capability of FET CLI and 5-ALA fluorescence imaging to detect tumor was assessed using receptor operator characteristic curves and optimal thresholds (CLIOptROC and 5-ALAOptROC) separating tumor from healthy brain tissue were determined. These thresholds were used to guide prospective tumor resections, where the presence of tumor cells in the resected material and in the remaining brain were assessed by Ki-67 staining. Results: FET CLI signal was correlated with signal in preoperative PET images (y = 1.06x - 0.01; p < 0.0001) and with expression of the amino acid transporter SLC7A5 (LAT1). FET CLI (AUC = 97%) discriminated between glioblastoma and normal brain in human and rat orthografts more accurately than 5-ALA fluorescence (AUC = 91%), with a sensitivity >92% and specificity >91%, and resulted in a more complete tumor resection. Conclusion: FET CLI can be used to accurately delineate glioblastoma tumor margins, performing better than the current standard of fluorescence imaging following 5-ALA administration, and is therefore a promising technique for clinical translation.

Black-Phosphorus-Incorporated Hydrogel as a Sprayable and Biodegradable Photothermal Platform for Postsurgical Treatment of Cancer

Photothermal therapy (PTT) is a fledgling therapeutic strategy for cancer treatment with minimal invasiveness but clinical adoption has been stifled by concerns such as insufficient biodegradability of the PTT agents and lack of an efficient delivery system. Here, black phosphorus (BP) nanosheets are incorporated with a thermosensitive hydrogel [poly(d,l-lactide)-poly(ethylene glycol)-poly(d,l-lactide) (PDLLA-PEG-PDLLA: PLEL)] to produce a new PTT system for postoperative treatment of cancer. The BP@PLEL hydrogel exhibits excellent near infrared (NIR) photothermal performance and a rapid NIR-induced sol-gel transition as well as good biodegradability and biocompatibility in vitro and in vivo. Based on these merits, an in vivo PTT postoperative treatment strategy is established. Under NIR irradiation, the sprayed BP@PLEL hydrogel enables rapid gelation forming a gelled membrane on wounds and offers high PTT efficacy to eliminate residual tumor tissues after tumor removal surgery. Furthermore, the good photothermal antibacterial performance prevents infection and this efficient and biodegradable PTT system is very promising in postoperative treatment of cancer.

[Development of a near-infrared fluorescence imaging system based on fluorescence properties of methylene blue]

OBJECTIVE

To develop a near-infrared fluorescence imaging system based on the fluorescence properties of methylene blue.

METHODS

According to the optical properties of methylene blue, we used a custom-made specific LED light source and an interference filter, a CCD camera and other relevant components to construct the near-infrared fluorescence imaging system. We tested the signal-to-background ratio (SBR) of this imaging system for detecting methylene blue under different experimental conditions and analyzed the SBR in urine samples collected from 15 Wistar rats with intravenous injection of methylene blue at the doses of 0, 1.4, 1.6, 1.8, or 2.0 0 mg/kg methylene blue.

RESULTS

The SBR of this imaging system for detecting methylene blue was affected by the concentration of methylene blue and the distance from the sample (P<0.05). In the urine samples from Wistar rats, the SBR varied with the the injection dose, and the rats injected with 1.6 mg/kg methylene blue showed the highest SBR (8.71∓0.20) in the urine (P<0.05).

CONCLUSION

This near-infrared fluorescence imaging system is useful for fluorescence detection of methylene blue and can be used for real-time recognition of ureters during abdominal surgery.

John MA. Detection of surgical margins in oral cavity cancer: the role of dynamic optical contrast imaging

PURPOSE OF REVIEW

The quantity of tissue removed during an oncologic surgical procedure is not standardized and there are numerous reports of local recurrence despite histologically adequate resection margins. The oral cavity is one of the sites in the head and neck with high chances of recurrence following negative margins. To address this need, this article reviews the recent applications of Dynamic Optical Contrast Imaging (DOCI) towards both oral screening and the intraoperative evaluation of tumor margins in head and neck surgery.

RECENT FINDINGS

Human ex-vivo and in-vivo trials suggest DOCI is well tolerated, low-cost, and sensitive for differentiating cancerous from normal tissues throughout the head and neck, in addition to the oral cavity. Ex-vivo imaging of OSCC specimens generated histologically verified image contrast. Furthermore, in-vivo intraoperative results demonstrate significant potential for image-guided detection and resection of oral cavity squamous cell carcinoma (OSCC).

SUMMARY

DOCI augments tissue contrast and may enable surgeons to clinically screen patients for oral cancer, make histologic evaluations in vivo with fewer unnecessary biopsies, delineate clinical margins for tumor resection, provide guidance in the choice of biopsy sites, and preserve healthy tissue to increase the postoperative functionality and quality of life of the patient.

In-vivo optical imaging in head and neck oncology: basic principles, clinical applications and future directions

Head and neck cancers become a severe threat to human's health nowadays and represent the sixth most common cancer worldwide. Surgery remains the first-line choice for head and neck cancer patients. Limited resectable tissue mass and complicated anatomy structures in the head and neck region put the surgeons in a dilemma between the extensive resection and a better quality of life for the patients. Early diagnosis and treatment of the pre-malignancies, as well as real-time in vivo detection of surgical margins during en bloc resection, could be leveraged to minimize the resection of normal tissues. With the understanding of the head and neck oncology, recent advances in optical hardware and reagents have provided unique opportunities for real-time pre-malignancies and cancer imaging in the clinic or operating room. Optical imaging in the head and neck has been reported using autofluorescence imaging, targeted fluorescence imaging, high-resolution microendoscopy, narrow band imaging and the Raman spectroscopy. In this study, we reviewed the basic theories and clinical applications of optical imaging for the diagnosis and treatment in the field of head and neck oncology with the goal of identifying limitations and facilitating future advancements in the field.

Intraoperative imaging during minimally invasive transoral robotic surgery using near-infrared light

PURPOSE

The purpose of this study was to determine if the use of the FIREFLY imaging system could be an asset in transoral robotic surgery (TORS) for oropharyngeal squamous cell carcinoma (OPSCC). The system uses indocyanine green dye (ICG), which fluoresces when illuminated by near-infrared light from the Da Vinci robot. The system may improve visualization of tumor margins, highlight important vascular structures, and help identify the location of tumors and unknown primary head and neck cancers.

METHODS

Six patients with OPSCC were enrolled in the study. Two of these cases were unknown primaries, one was base of tongue, and three were palatine tonsils. Each patient was given two 3ml doses of ICG, one at the beginning of the surgical case and one during resection of the tumor. The oropharynx was then visualized using the near-infrared light of the Da Vinci robot for a minute after injection.

RESULTS

The FIREFLY system was unable to detect gross tumors, positive margins, unknown primaries, or vascular structures in any of the six subjects in the study. In addition, there were no adverse events or side effects in any of the subjects.

CONCLUSION

The use of the FIREFLY system with indocyanine green fluorescence did not identify tumor boundaries, unknown primary head and neck cancers, or vascular structures in the oropharynx.

A Novel Tumor-Specific Agent for Intraoperative Near-Infrared Fluorescence Imaging: A Translational Study in Healthy Volunteers and Patients with Ovarian Cancer

PURPOSE

Completeness of cytoreductive surgery is a key prognostic factor for survival in patients with ovarian cancer. The ability to differentiate clearly between malignant and healthy tissue is essential for achieving complete cytoreduction. Using current approaches, this differentiation is often difficult and can lead to incomplete tumor removal. Near-infrared fluorescence imaging has the potential to improve the detection of malignant tissue during surgery, significantly improving outcome. Here, we report the use of OTL38, a near-infrared (796 nm) fluorescent agent, that binds folate receptor alpha, which is expressed in >90% of epithelial ovarian cancers.

EXPERIMENTAL DESIGN

We first performed a randomized, placebo-controlled study in 30 healthy volunteers. Four single increasing doses of OTL38 were delivered intravenously. At fixed times following drug delivery, tolerability and blood/skin pharmacokinetics were assessed. Next, using the results of the first study, three doses were selected and administered to 12 patients who had epithelial ovarian cancer and were scheduled for cytoreductive surgery. We measured tolerability and blood pharmacokinetics, as well as the ability to detect the tumor using intraoperative fluorescence imaging.

RESULTS

Intravenous infusion of OTL38 in 30 healthy volunteers yielded an optimal dosage range and time window for intraoperative imaging. In 12 patients with ovarian cancer, OTL38 accumulated in folate receptor alpha-positive tumors and metastases, enabling the surgeon to resect an additional 29% of malignant lesions that were not identified previously using inspection and/or palpation.

CONCLUSIONS

This study demonstrates that performing real-time intraoperative near-infrared fluorescence imaging using a tumor-specific agent is feasible and potentially clinically beneficial. Clin Cancer Res; 22(12); 2929-38. ©2016 AACR.

Detecting tumour-positive resection margins after oral cancer surgery by spraying a fluorescent tracer activated by gamma-glutamyltranspeptidase

OBJECTIVES

Tumour-positive resection margins are a major problem during oral cancer surgery. gGlu-HMRG is a tracer that becomes fluorescent upon activation by gamma-glutamyltranspeptidase (GGT). This study aims to investigate the combination of gGlu-HMRG and a clinical fluorescence imaging system for the detection of tumour-positive resection margins.

MATERIALS AND METHODS

The preclinical Maestro and clinical Artemis imaging systems were compared in vitro and ex vivo with cultured human head and neck cancer cells (OSC19, GGT-positive; and FaDu, GGT negative) and tumour-bearing nude mice. Subsequently, frozen sections of normal and oral cancer tissues were ex vivo sprayed with gGlu-HMRG to determine the sensitivity and specificity. Finally, resection margins of patients with suspected oral cancer were ex vivo sprayed with gGlu-HMRG to detect tumour-positive resection margins.

RESULTS

Both systems could be used to detect gGlu-HMRG activation in vitro and ex vivo in GGT positive cancer cells. Sensitivity and specificity of gGlu-HMRG and the Artemis on frozen tissue samples was 80% and 87%, respectively. Seven patients undergoing surgery for suspected oral cancer were included. In three patients fluorescence was observed at the resection margin. Those margins were either tumour-positive or within 1 mm of tumour. The margins of the other patients were clear (≥8 mm).

CONCLUSION

This study demonstrates the feasibility to detect tumour-positive resection margins with gGlu-HMRG and a clinical fluorescence imaging system. Applying this technique would enable intraoperative screening of the entire resection margin and allow direct re-resection in case of tumour-positivity.

A Tumor-Activatable Theranostic Nanomedicine Platform for NIR Fluorescence-Guided Surgery and Combinatorial Phototherapy

Fluorescence image-guided surgery combined with intraoperative therapeutic modalities has great potential for intraoperative detection of oncologic targets and eradication of unresectable cancer residues. Therefore, we have developed an activatable theranostic nanoplatform that can be used concurrently for two purposes: (1) tumor delineation with real-time near infrared (NIR) fluorescence signal during surgery, and (2) intraoperative targeted treatment to further eliminate unresected disease sites by non-toxic phototherapy.

Methods: The developed nanoplatform is based on a single agent, silicon naphthalocyanine (SiNc), encapsulated in biodegradable PEG-PCL (poly (ethylene glycol)-b-poly(ɛ-caprolactone)) nanoparticles. It is engineered to be non-fluorescent initially via dense SiNc packing within the nanoparticle's hydrophobic core, with NIR fluorescence activation after accumulation at the tumor site. The activatable nanoplatform was evaluated in vitro and in two different murine cancer models, including an ovarian intraperitoneal metastasis-mimicking model. Furthermore, fluorescence image-guided surgery mediated by this nanoplatform was performed on the employed animal models using a Fluobeam^® 800 imaging system. Finally, the phototherapeutic efficacy of the developed nanoplatform was demonstrated in vivo.

Results: Our in vitro data suggest that the intracellular environment of cancer cells is capable of compromising the integrity of self-assembled nanoparticles and thus causes disruption of the tight dye packing inside the hydrophobic cores and activation of the NIR fluorescence. Animal studies demonstrated accumulation of activatable nanoparticles at the tumor site following systemic administration, as well as release and fluorescence recovery of SiNc from the polymeric carrier. It was also validated that the developed nanoparticles are compatible with the intraoperative imaging system Fluobeam® 800, and nanoparticle-mediated image-guided surgery provides successful resection of cancer tumors. Finally, in vivo studies revealed that combinatorial phototherapy mediated by the nanoparticles could efficiently eradicate chemoresistant ovarian cancer tumors.

Conclusion: The revealed properties of the activatable nanoplatform make it highly promising for further application in clinical image-guided surgery and combined phototherapy, facilitating a potential translation to clinical studies.

Evaluation of fluorescence-guided surgery agents in a murine model of soft tissue fibrosarcoma

BACKGROUND AND OBJECTIVES

Soft tissue sarcomas (STS) are mesenchymal malignancies. Treatment mainstay is surgical resection with negative margins ± adjuvant treatment. Fluorescence-guided surgical (FGS) resection can delineate intraoperative margins; FGS has improved oncologic outcomes in other malignancies. This novel strategy may minimize resection-associated morbidity while improving local tumor control.

METHODS

We evaluate the tumor-targeting specificity and utility of fluorescence-imaging agents to provide disease-specific contrast. Mice with HT1080 fibrosarcoma tumors received one of five probes: cetuximab-IRDye800CW (anti-EGFR), DC101-IRDye800CW (anti-VEGFR-2), IgG-IRDye800CW, the cathepsin-activated probe Prosense750EX, or the small molecule probe IntegriSense750. Tumors were imaged daily using open- and closed-field fluorescence imaging systems. Tumor-to-background ratios (TBR) were evaluated. On peak TBR days, probe sensitivity was evaluated. Tumors were stained and imaged microscopically.

RESULTS

At peak, closed-field imaging TBR of cetuximab-IRDye800CW (16.8) was significantly greater (P < 0.0001) than Integrisense750 (7.0), Prosense750EX (5.8), and DC101-IRDye800CW (3.7). All agents successfully localized as little as 1.0 mg of tumor tissue in the post-resection bed; cetuximab-IRDye800CW generated the greatest contrast (2.5). Cetuximab-IRDye800CW revealed strong tumor affinity microscopically; tumor fluorescence intensity was significantly greater (P < 0.0004) than 0.2 mm away from tumor border.

CONCLUSION

This study demonstrates cetuximab-IRDye800CW superiority. FGS has the potential to improve post-resection morbidity and mortality by improving disease detection.

Synthesis, Characterization, and Biomedical Applications of a Targeted Dual-Modal Near-Infrared-II Fluorescence and Photoacoustic Imaging Nanoprobe

Our development of multifunctional dual-modal imaging probes aims to integrate the benefits from both second near-infrared (NIR-II) fluorescence (1000-1700 nm) and photoacoustic imaging with an ultimate goal of improving overall cancer diagnosis efficacy. Herein we designed a donor-acceptor chromophore based nanoparticle (DAP) as a dual-modal image contrast agent has strong absorption in the NIR-I window and a strong fluorescence emission peak in the NIR-II region. The dual-modal DAPs composed of D-π-A-π-D-type chromophores were PEGylated through nanoprecipitation. The multifunctional DAP surface was thus available for subsequent bioconjugation of EGFR Affibody (Ac-Cys-Z_EGFR:1907) to target EGFR-positive cancers. The Affibody-conjugated DAPs appeared as highly monodisperse nanoparticles (∼30 nm) with strong absorption in the NIR-I window (at ca. 680 nm) and an extremely high fluorescence in the NIR-II region (maximum peak at 1000 nm). Consequently, the Affibody-DAPs show significantly enhanced photoacoustic and NIR-II fluorescence contrast effects in both in vitro and in vivo experiments. Moreover, the Affibody-DAPs have the capability to selectively target EGFR-positive tumors in an FTC-133 subcutaneous mouse model with relatively high photoacoustic and fluorescent signals. By taking advantage of high spatial resolution and excellent temporal resolution, photoacoustic/NIR-II fluorescence imaging with targeted dual-modal contrast agents allows us to specifically image and detect various cancers and diseases in an accurate manner.

Developments in optical imaging for gastrointestinal surgery

To improve outcomes for patients with cancer, in terms of both survival and a reduction in the morbidity and mortality that results from surgical resection and treatment, there are two main areas that require improvement. Accurate early diagnosis of the cancer, at a stage where curative and, ideally, minimally invasive treatment is achievable, is desired as well as identification of tumor margins, lymphatic and distant disease, enabling complete, but not unnecessarily extensive, resection. Optical imaging is making progress in achieving these aims. This review discusses the principles of optical imaging, focusing on fluorescence and spectroscopy, and the current research that is underway in GI tract carcinomas.

Pre-clinical Evaluation of a Cyanine-Based SPECT Probe for Multimodal Tumor Necrosis Imaging

PURPOSE

Recently we showed that a number of carboxylated near-infrared fluorescent (NIRF) cyanine dyes possess strong necrosis avid properties in vitro as well as in different mouse models of spontaneous and therapy-induced tumor necrosis, indicating their potential use for cancer diagnostic- and prognostic purposes. In the previous study, the detection of the cyanines was achieved by whole body optical imaging, a technique that, due to the limited penetration of near-infrared light, is not suitable for investigations deeper than 1 cm within the human body. Therefore, in order to facilitate clinical translation, the purpose of the present study was to generate a necrosis avid cyanine-based NIRF probe that could also be used for single photon emission computed tomography (SPECT). For this, the necrosis avid NIRF cyanine HQ4 was radiolabeled with ¹¹¹indium, via the chelate diethylene triamine pentaacetic acid (DTPA).

PROCEDURES

The necrosis avid properties of the radiotracer [¹¹¹In]DTPA-HQ4 were examined in vitro and in vivo in different breast tumor models in mice using SPECT and optical imaging. Moreover, biodistribution studies were performed to examine the pharmacokinetics of the probe in vivo.

RESULTS

Using optical imaging and radioactivity measurements, in vitro, we showed selective accumulation of [¹¹¹In]DTPA-HQ4 in dead cells. Using SPECT and in biodistribution studies, the necrosis avidity of the radiotracer was confirmed in a 4T1 mouse breast cancer model of spontaneous tumor necrosis and in a MCF-7 human breast cancer model of chemotherapy-induced tumor necrosis.

CONCLUSIONS

The radiotracer [¹¹¹In]DTPA-HQ4 possessed strong and selective necrosis avidity in vitro and in various mouse models of tumor necrosis in vivo, indicating its potential to be clinically applied for diagnostic purposes and to monitor anti-cancer treatment efficacy.

Firearm Projectile in the Maxillary Tuberosity Located by Adjunctive Examination of Wide-Field Optical Fluorescence

OBJECTIVE

Demonstrate the use of wide-field optical fluorescence as an adjunctive examination in a clinical routine to oral diagnosis.

BACKGROUND DATA

Use of wide-field optical fluorescence in the oral cavity has been restricted to topics related to the detection and diagnosis of oral cancer.

MATERIALS AND METHODS

In a regular medical appointment, a 58-year-old female patient, without any complaint or oral symptom, underwent the complementary examination by wide-field optical fluorescence. A device with high-power light-emitting diode emitting light centered at a wavelength of (400 ± 10) nm and maximum irradiance of (0.040 ± 0.008) W/cm² was used for fluorescence visualization.

RESULTS

We report the location of a firearm projectile, intraosseous, in the maxillary tuberosity using wide-field optical fluorescence.

CONCLUSIONS

It is evidenced that wide-field optical fluorescence, within a clinical routine, can provide relevant images and data, with an immediate result, without the use of ionizing radiation, enabling an efficient oral diagnosis.

Comparative Study of Tumor Targeting and Biodistribution of pH (Low) Insertion Peptides (pHLIP(®) Peptides) Conjugated with Different Fluorescent Dyes

PURPOSE

Acidification of extracellular space promotes tumor development, progression, and invasiveness. pH (low) insertion peptides (pHLIP(®) peptides) belong to the class of pH-sensitive membrane peptides, which target acidic tumors and deliver imaging and/or therapeutic agents to cancer cells within tumors.

PROCEDURES

Ex vivo fluorescent imaging of tissue and organs collected at various time points after administration of different pHLIP(®) variants conjugated with fluorescent dyes of various polarity was performed. Methods of multivariate statistical analyses were employed to establish classification between fluorescently labeled pHLIP(®) variants in multidimensional space of spectral parameters.

RESULTS

The fluorescently labeled pHLIP(®) variants were classified based on their biodistribution profile and ability of targeting of primary tumors. Also, submillimeter-sized metastatic lesions in lungs were identified by ex vivo imaging after intravenous administration of fluorescent pHLIP(®) peptide.

CONCLUSIONS

Different cargo molecules conjugated with pHLIP(®) peptides can alter biodistribution and tumor targeting. The obtained knowledge is essential for the design of novel pHLIP(®)-based diagnostic and therapeutic agents targeting primary tumors and metastatic lesions.

Multispectral open-air intraoperative fluorescence imaging

Intraoperative fluorescence imaging informs decisions regarding surgical margins by detecting and localizing signals from fluorescent reporters, labeling targets such as malignant tissues. This guidance reduces the likelihood of undetected malignant tissue remaining after resection, eliminating the need for additional treatment or surgery. The primary challenges in performing open-air intraoperative fluorescence imaging come from the weak intensity of the fluorescence signal in the presence of strong surgical and ambient illumination, and the auto-fluorescence of non-target components, such as tissue, especially in the visible spectral window (400-650 nm). In this work, a multispectral open-air fluorescence imaging system is presented for translational image-guided intraoperative applications, which overcomes these challenges. The system is capable of imaging weak fluorescence signals with nanomolar sensitivity in the presence of surgical illumination. This is done using synchronized fluorescence excitation and image acquisition with real-time background subtraction. Additionally, the system uses a liquid crystal tunable filter for acquisition of multispectral images that are used to spectrally unmix target fluorescence from non-target auto-fluorescence. Results are validated by preclinical studies on murine models and translational canine oncology models.

Biofunctionalized Hybrid Magnetic Gold Nanoparticles as Catalysts for Photothermal Ablation of Colorectal Liver Metastases

Purpose To demonstrate that anti-MG1 conjugated hybrid magnetic gold nanoparticles (HNPs) act as a catalyst during photothermal ablation (PTA) of colorectal liver metastases, and thus increase ablation zones. Materials and Methods All experiments were performed with approval of the institutional animal care and use committee. Therapeutic and diagnostic multifunctional HNPs conjugated with anti-MG1 monoclonal antibodies were synthesized, and the coupling efficiency was determined. Livers of 19 Wistar rats were implanted with 5 × 10⁶ rat colorectal liver metastasis cell line cells. The rats were divided into three groups according to injection: anti-MG1-coupled HNPs (n = 6), HNPs only (n = 6), and cells only (control group, n = 7). Voxel-wise R2 and R2* magnetic resonance (MR) imaging measurements were obtained before, immediately after, and 24 hours after injection. PTA was then performed with a fiber-coupled near-infrared (808 nm) diode laser with laser power of 0.56 W/cm² for 3 minutes, while temperature changes were measured. Tumors were assessed for necrosis with hematoxylin-eosin staining. Organs were analyzed with inductively coupled plasma mass spectrometry to assess biodistribution. Therapeutic efficacy and tumor necrosis area were compared by using a one-way analysis of variance with post hoc analysis for statistically significant differences. Results The coupling efficiency was 22 μg/mg (55%). Significant differences were found between preinfusion and 24-hour postinfusion measurements of both T2 (repeated measures analysis of variance, P = .025) and T2* (P < .001). Significant differences also existed for T2* measurements between the anti-MG1 HNP and HNP-only groups (P = .034). Mean temperature ± standard deviation with PTA in the anti-MG1-coated HNP, HNP, and control groups was 50.2°C ± 7.8, 51°C ± 4.4, and 39.5°C ± 2.0, respectively. Inductively coupled plasma mass spectrometry revealed significant tumor targeting and splenic sequestration. Mean percentages of tumor necrosis in the anti-MG1-coated HNP, HNP, and control groups were 38% ± 29, 14% ± 17, and 7% ± 8, respectively (P = .043). Conclusion Targeted monoclonal antibody-conjugated HNPs can serve as a catalyst for photothermal ablation of colorectal liver metastases by increasing ablation zones. ^© RSNA, 2017.

Characterizing the detection threshold for optical imaging in surgical oncology

BACKGROUND AND OBJECTIVES

Optical imaging to guide cancer resections is rapidly transitioning into the operating room. However, the sensitivity of this technique to detect subclinical disease is yet characterized. The purpose of this study was to determine the minimum range of cancer cells that can be detected by antibody-based fluorescence imaging.

METHODS

2LMP (breast), COLO-205 (colon), MiaPaca-2 (pancreas), and SCC-1 (head and neck) cells incubated in vitro with cetuximab-IRDye800CW (dose range 8.6-86 nM) were implanted subcutaneously in mice (n = 3 mice, 5 tumors/mouse). Following incubation with 8.6 × 10^-2  µM of cetuximab-IRDye800CW in vitro, serial dilutions of each cell type (1 × 10³ -1 × 10⁶ ) were implanted subcutaneously (n = 3, 5 tumors/mouse). Tumors were imaged with Pearl Impulse and Xenogen IVIS 100 imaging systems. Scatchard analysis was performed to determine receptor density and kinetics for each cell line.

RESULTS

Under conditions of minimal cetuximab-IRDye800CW exposure to low cellular quantity, closed-field fluorescence imaging theoretically detected a minimum of 4.2 × 10⁴ -9.5 × 10⁴ 2LMP cells, 1.9 × 10⁵ -4.5 × 10⁵ MiaPaca-2 cells, and 2.4 × 10⁴ -6.7 × 10⁴ SCC-1 cells; COLO-205 cells could not be identified. Higher EGFR-mediated uptake of cetuximab correlated with sensitivity of detection.

CONCLUSION

This study supports the clinical utility of cetuximab-IRDye800CW to sensitively localize subclinical disease in the surgical setting.

Detection of Head and Neck Cancer in Surgical Specimens Using Quantitative Hyperspectral Imaging

Purpose: This study intends to investigate the feasibility of using hyperspectral imaging (HSI) to detect and delineate cancers in fresh, surgical specimens of patients with head and neck cancers.Experimental Design: A clinical study was conducted in order to collect and image fresh, surgical specimens from patients (N = 36) with head and neck cancers undergoing surgical resection. A set of machine-learning tools were developed to quantify hyperspectral images of the resected tissue in order to detect and delineate cancerous regions which were validated by histopathologic diagnosis. More than two million reflectance spectral signatures were obtained by HSI and analyzed using machine-learning methods. The detection results of HSI were compared with autofluorescence imaging and fluorescence imaging of two vital-dyes of the same specimens.Results: Quantitative HSI differentiated cancerous tissue from normal tissue in ex vivo surgical specimens with a sensitivity and specificity of 91% and 91%, respectively, and which was more accurate than autofluorescence imaging (P < 0.05) or fluorescence imaging of 2-NBDG (P < 0.05) and proflavine (P < 0.05). The proposed quantification tools also generated cancer probability maps with the tumor border demarcated and which could provide real-time guidance for surgeons regarding optimal tumor resection.Conclusions: This study highlights the feasibility of using quantitative HSI as a diagnostic tool to delineate the cancer boundaries in surgical specimens, and which could be translated into the clinic application with the hope of improving clinical outcomes in the future. Clin Cancer Res; 23(18); 5426-36. ©2017 AACR.

Development and application of the near-infrared and white-light thoracoscope system for minimally invasive lung cancer surgery

In minimally invasive surgery, the white-light thoracoscope as a standard imaging tool is facing challenges of the low contrast between important anatomical or pathological regions and surrounding tissues. Recently, the near-infrared (NIR) fluorescence imaging shows superior advantages over the conventional white-light observation, which inspires researchers to develop imaging systems to improve overall outcomes of endoscopic imaging. We developed an NIR and white-light dual-channel thoracoscope system, which achieved high-fluorescent signal acquisition efficiency and the simultaneously optimal visualization of the NIR and color dual-channel signals. The system was designed to have fast and accurate image registration and high signal-to-background ratio by optimizing both software algorithms and optical hardware components for better performance in the NIR spectrum band. The system evaluation demonstrated that the minimally detectable concentration of indocyanine green (ICG) was 0.01 ?? ? M , and the spatial resolution was 35 ?? ? m . The in vivo feasibility of our system was verified by the preclinical experiments using six porcine models with the intravenous injection of ICG. Furthermore, the system was successfully applied for guiding the minimally invasive segmentectomy in three lung cancer patients, which revealed that our system held great promise for the clinical translation in lung cancer surgeries.

A Near-Infrared, Wavelength-Shiftable, Turn-on Fluorescent Probe for the Detection and Imaging of Cancer Tumor Cells

Fast, selective, and noninvasive reporting of intracellular cancer-associated events and species will lead to a better understanding of tumorigenesis at the molecular level and development of precision medicine approaches in oncology. Overexpressed reductase presence in solid tumor cells is key to cancer progression and protection of those diseased cells from the oxidative effects of therapeutics meant to kill them. Human NAD(P)H:quinone oxidoreductase isozyme I (hNQO1), a cytoprotective 2-electron-specific reductase found at unusually high activity levels in cancer cells of multiple origins, has attracted significant attention due to its major role in metastatic pathways and its link to low survival rates in patients, as well as its ability to effectively activate quinone-based, anticancer drugs. Accurate assessment of hNQO1 activities in living tumor models and ready differentiation of metastases from healthy tissue by fluorescent light-based protocols requires creation of hNQO1-responsive, near-infrared probes that offer deep tissue penetration and low background fluorescence. Herein, we disclose a quinone-trigger-based, near-infrared probe whose fluorescence is effectively turned on several hundred-fold through highly selective reduction of the quinone trigger group by hNQO1, with unprecedented, catalytically efficient formation of a fluorescent reporter. hNQO1 activity-specific production of a fluorescence signal in two-dimensional cultures of respiring human cancer cells that harbor the reductase enzyme allows for their quick (30 min) high-integrity recognition. The characteristics of the near-infrared probe make possible the imaging of clinically relevant three-dimensional colorectal tumor models possessing spatially heterogeneous hNQO1 activities and provide for fluorescence-assisted identification of submillimeter dimension metastases in a preclinical mouse model of human ovarian serous adenocarcinoma.

One-pot synthesis of silicon based nanoparticles with incorporated phthalocyanine for long-term bioimaging and photo-dynamic therapy of tumors

Combining the merits of delivery vectors with drug molecules is one of the key directions for development of efficient cancer monitoring and treatment techniques. In this work, a novel type of silicon based composite nanoparticles (NPs) with incorporated hydrophobic phthalocyanine molecules (Pc) was synthesized via a facile one-pot method. The as-synthesized Pc@Si NPs, with a small size of 4.2 ± 0.8 nm, have excellent dispersibility in water and good biocompatibility with cells, in addition to favorable photoluminescence and robust photostability even in cells. Moreover, the Pc@Si NPs show significant in vitro cancer cell killing and in vivo tumor inhibiting abilities upon near-infrared light exposure, due to the photodynamic therapy (PDT) effect of Pc. This work develops an efficient fluorescent PDT drug carrier; moreover, the facile one-pot synthesis strategy may be used generally to prepare silicon-based composite NPs incorporated with diverse hydrophobic drugs/diagnostic molecules for a wide range of biomedical applications.

Characterizing the Utility and Limitations of Repurposing an Open-Field Optical Imaging Device for Fluorescence-Guided Surgery in Head and Neck Cancer Patients

The purpose of this study was to assess the potential of U.S. Food and Drug Administration-cleared devices designed for indocyanine green-based perfusion imaging to identify cancer-specific bioconjugates with overlapping excitation and emission wavelengths. Recent clinical trials have demonstrated potential for fluorescence-guided surgery, but the time and cost of the approval process may impede clinical translation. To expedite this translation, we explored the feasibility of repurposing existing optical imaging devices for fluorescence-guided surgery.

METHODS

Consenting patients (n = 15) scheduled for curative resection were enrolled in a clinical trial evaluating the safety and specificity of cetuximab-IRDye800 (NCT01987375). Open-field fluorescence imaging was performed preoperatively and during the surgical resection. Fluorescence intensity was quantified using integrated instrument software, and the tumor-to-background ratio characterized fluorescence contrast.

RESULTS

In the preoperative clinic, the open-field device demonstrated potential to guide preoperative mapping of tumor borders, optimize the day of surgery, and identify occult lesions. Intraoperatively, the device demonstrated robust potential to guide surgical resections, as all peak tumor-to-background ratios were greater than 2 (range, 2.2-14.1). Postresection wound bed fluorescence was significantly less than preresection tumor fluorescence (P < 0.001). The repurposed device also successfully identified positive margins.

CONCLUSION

The open-field imaging device was successfully repurposed to distinguish cancer from normal tissue in the preoperative clinic and throughout surgical resection. This study illuminated the potential for existing open-field optical imaging devices with overlapping excitation and emission spectra to be used for fluorescence-guided surgery.

Nanoparticle-mediated radiopharmaceutical-excited fluorescence molecular imaging allows precise image-guided tumor-removal surgery

Fluorescent molecular imaging technique has been actively explored for optical image-guided cancer surgery in pre-clinical and clinical research and has attracted many attentions. However, the efficacy of the fluorescent image-guided cancer surgery can be compromised by the low signal-to-noise ratio caused by the external light excitation. This study presents a novel nanoparticle-mediated radiopharmaceutical-excited fluorescent (REF) image-guided cancer surgery strategy, which employs the internal dual-excitation of europium oxide nanoparticles through both gamma rays and Cerenkov luminescence emitted from radiopharmaceuticals. The performance of the novel image-guided surgery technique was systematically evaluated using subcutaneous breast cancer 4 T1 tumor models, orthotropic and orthotropic-ectopic hepatocellular carcinoma tumor-bearing mice. The results reveal that the novel REF image-guided cancer surgery technique exhibits high performance of detecting invisible ultra-small size tumor (even less than 1 mm) and residual tumor tissue. Our study demonstrates the high potential of the novel image-guided cancer surgery for precise tumor resection.

Preclinical uPAR-targeted multimodal imaging of locoregional oral cancer

OBJECTIVES

Establishing adequate resection margins and lymphatic mapping are crucial for the prognosis of oral cancer patients. Novel targeted imaging modalities are needed, enabling pre- and intraoperative detection of tumour cells, in combination with improved post-surgical examination by the pathologist. The urokinase-receptor (uPAR) is overexpressed in head and neck cancer, where it is associated with tumour progression and metastasis.

MATERIAL AND METHODS

To determine suitability of uPAR for molecular imaging of oral cancer surgery, human head and neck tumours were sectioned and stained for uPAR to evaluate the expression pattern compared to normal mucosa. Furthermore, metastatic oral squamous carcinoma cell line OSC-19 was used for targeting uPAR in in vivo mouse models. Using anti-uPAR antibody ATN-658, equipped with a multimodal label, the in vivo specificity was investigated and the optimal dose and time-window were evaluated.

RESULTS

All human oral cancer tissues expressed uPAR in epithelial and stromal cells. Hybrid ATN-658 clearly visualized tongue tumours in mice using either NIRF or SPECT imaging. Mean fluorescent TBRs over time were 4.3±0.7 with the specific tracer versus 1.7±0.1 with a control antibody. A significant difference in TBRs could be seen between 1nmol (150μg) and 0.34nmol (50μg) dose groups (n=4, p<0.05). Co-expression between BLI, GFP and the NIR fluorescent signals were seen in the tongue tumour, whereas human cytokeratin staining confirmed presence of malignant cells in the positive cervical lymph nodes.

CONCLUSION

This study shows the applicability of an uPAR specific multimodal tracer in an oral cancer model, combining SPECT with intraoperative guidance.

Synthesis of Near-Infrared Fluorescent Two-Photon-Absorbing Fluorenyl Benzothiadiazole and Benzoselenadiazole Derivatives

A series of dyes 2-5 based on 5-thienyl-2,1,3-benzothiadiazole and 5-thienyl-2,1,3-benzoselenadiazole cores were synthesized as near-infrared-emitting two-photon-absorbing fluorophores. Fluorescence maxima wavelengths as long as 714 nm and quantum yields as high as 0.67 were realized. The fluorescence quantum yields of dyes 2-4 were nearly constant, regardless of solvent polarity. These diazoles exhibited large Stokes shifts (>110 nm) and high two-photon figure of merit. Cells incubated on a 3D scaffold with probe 4 (encapsulated in Pluronic micelles) exhibited bright fluorescence, enabling 3D two-photon fluorescence imaging to a depth of 100 μm.

Necrosis avid near infrared fluorescent cyanines for imaging cell death and their use to monitor therapeutic efficacy in mouse tumor models

Quantification of tumor necrosis in cancer patients is of diagnostic value as the amount of necrosis is correlated with disease prognosis and it could also be used to predict early efficacy of anti-cancer treatments. In the present study, we identified two near infrared fluorescent (NIRF) carboxylated cyanines, HQ5 and IRDye 800CW (800CW), which possess strong necrosis avidity. In vitro studies showed that both dyes selectively bind to cytoplasmic proteins of dead cells that have lost membrane integrity. Affinity for cytoplasmic proteins was confirmed using quantitative structure activity relations modeling. In vivo results, using NIRF and optoacoustic imaging, confirmed the necrosis avid properties of HQ5 and 800CW in a mouse 4T1 breast cancer tumor model of spontaneous necrosis. Finally, in a mouse EL4 lymphoma tumor model, already 24 h post chemotherapy, a significant increase in 800CW fluorescence intensity was observed in treated compared to untreated tumors. In conclusion, we show, for the first time, that the NIRF carboxylated cyanines HQ5 and 800CW possess strong necrosis avid properties in vitro and in vivo. When translated to the clinic, these dyes may be used for diagnostic or prognostic purposes and for monitoring in vivo tumor response early after the start of treatment.

EpCAM as multi-tumour target for near-infrared fluorescence guided surgery

Background

Evaluation of resection margins during cancer surgery can be challenging, often resulting in incomplete tumour removal. Fluorescence-guided surgery (FGS) aims to aid the surgeon to visualize tumours and resection margins during surgery. FGS relies on a clinically applicable imaging system in combination with a specific tumour-targeting contrast agent. In this study EpCAM (epithelial cell adhesion molecule) is evaluated as target for FGS in combination with the novel Artemis imaging system.

Methods

The NIR fluorophore IRDye800CW was conjugated to the well-established EpCAM specific monoclonal antibody 323/A3 and an isotype IgG1 as control. The anti-EpCAM/800CW conjugate was stable in serum and showed preserved binding capacity as evaluated on EpCAM positive and negative cell lines, using flow cytometry and cell-based plate assays. Four clinically relevant orthotopic tumour models, i.e. colorectal cancer, breast cancer, head and neck cancer, and peritonitis carcinomatosa, were used to evaluate the performance of the anti-EpCAM agent with the clinically validated Artemis imaging system. The Pearl Impulse small animal imaging system was used as reference. The specificity of the NIRF signal was confirmed using bioluminescence imaging and green-fluorescent protein.

Results

All tumour types could clearly be delineated and resected 72 h after injection of the imaging agent. Using NIRF imaging millimetre sized tumour nodules were detected that were invisible for the naked eye. Fluorescence microscopy demonstrated the distribution and tumour specificity of the anti-EpCAM agent.

Conclusions

This study shows the potential of an EpCAM specific NIR-fluorescent agent in combination with a clinically validated intraoperative imaging system to visualize various tumours during surgery.

Feasibility of real-time near-infrared indocyanine green fluorescence endoscopy for the evaluation of mucosal head and neck lesions

Background

The purpose of this study was to explore the feasibility and potential drawbacks of near‐infrared (NIR) endoscopy with indocyanine green (ICG) to examine mucosal head and neck lesions.

Methods

NIR ICG endoscopy was applied to image head and neck cancer epithelium in vivo. The evaluation of the ICG videos was performed off‐line independently by 2 evaluators and blinded with respect to final histopathological results from biopsies taken as the gold standard.

Results

Forty percent of the lesions from 55 patients were histologically malignant. ICG positivity showed a sensitivity, specificity, and accuracy to be related to a malignant tumor of 90.5%, 90.9%, and 89.1%, respectively. The kappa index for the interobserver assessment showed a 94.4% agreement for the assessment of the ICG positivity. Side effects of the NIR ICG endoscopy did not arise.

Conclusion

NIR ICG endoscopy in patients with mucosal head and neck lesions was feasible and safe. It might help intraoperatively to differentiate benign from malignant lesions. © 2016 Wiley Periodicals, Inc. Head Neck39: 234–240, 2017

Bright and Stable Near-Infrared Pluronic-Silica Nanoparticles as a Contrast Agent for in vivo Optical Imaging

Near-infrared (NIR) fluorescent nanostructured materials have emerged as novel contrast agents for non-invasive bioimaging. Here we report a class of polymer-silica nanoparticles doped with a NIR fluorescent dye prepared through a facile one-pot strategy. Hydrophobic NIR fluorescent dyes such as IR 780 iodide could be easily encapsulated into the micellar core by self-assembly of amphiphilic triblock copolymer Pluronic F127. When subsequently adding silane in aqueous solution, nanoparticles with a cross-linked core and a hydrophilic PEG shell were formed. The structure of the as-obtained nanoparticles was confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The nanoparticles exhibited a well-defined spherical structure with a mean diameter of approximately 30 nm, and excellent monodispersity and stability in aqueous solution. In addition, the photo-stability of IR 780 was significantly improved by encapsulation into the nanoparticles. In vitro MTT assay with cell lines HEK293 and A431 demonstrated that the IR 780 loaded nanoparticles (termed as IR780@NPs) were biocompatible. In vivo sentinel lymph node imaging revealed that the fluorescent intensity and retention time of the IR780@NPs were clearly superior to its constituent free dye, making it amenable to in vivo bioimaging. Further in vivo tumor imaging indicated that IR780@NPs have a longer retention time and much higher accumulation on the tumor site compared to free dye after intravenous administration. Overall this hydrophilic NIR fluorescent contrast agent exhibits excellent photophysical characteristics and low cytotoxicity, and holds a strong promise for a variety of applications including bioimaging and therapy.

Optical Imaging of Tumor Response to Hyperbaric Oxygen Treatment and Irradiation in an Orthotopic Mouse Model of Head and Neck Squamous Cell Carcinoma

Purpose

Hyperbaric oxygen therapy (HBOT) is used in the treatment of radiation-induced tissue injury but its effect on (residual) tumor tissue is indistinct and therefore investigated in this study.

Procedures

Orthotopic FaDu tumors were established in mice, and the response of the (irradiated) tumors to HBOT was monitored by bioluminescence imaging. Near infrared fluorescence imaging using AngioSense750 and Hypoxisense680 was applied to detect tumor vascular permeability and hypoxia.

Results

HBOT treatment resulted in accelerated growth of non-irradiated tumors, but mouse survival was improved. Tumor vascular leakiness and hypoxia were enhanced after HBOT, whereas histological characteristics, epithelial-to-mesenchymal transition markers, and metastatic incidence were not influenced.

Conclusions

Squamous cell carcinoma responds to HBOT with respect to tumor growth, vascular permeability, and hypoxia, which may have implications for its use in cancer patients. The ability to longitudinally analyze tumor characteristics highlights the versatility and potential of optical imaging methods in oncological research.

Electronic supplementary material

The online version of this article (doi:10.1007/s11307-015-0834-8) contains supplementary material, which is available to authorized users.

Cerenkov luminescence imaging (CLI) for image-guided cancer surgery

Cerenkov luminescence imaging (CLI) is a novel molecular optical imaging technique based on the detection of optical Cerenkov photons emitted by positron emission tomography (PET) imaging agents. The ability to use clinically approved tumour-targeted tracers in combination with small-sized imaging equipment makes CLI a particularly interesting technique for image-guided cancer surgery. The past few years have witnessed a rapid increase in proof-of-concept preclinical studies in this field, and several clinical trials are currently underway. This article provides an overview of the basic principles of Cerenkov radiation and outlines the challenges of CLI-guided surgery for clinical use. The preclinical and clinical trial literature is examined including applications focussed on image-guided lymph node detection and Cerenkov luminescence endoscopy, and the ongoing clinical studies and technological developments are highlighted. By intraoperatively guiding the oncosurgeon towards more accurate and complete resections, CLI has the potential to transform current surgical practice, and improve oncological and cosmetic outcomes for patients.

Optical imaging of bacterial infections

The rise in multidrug resistant (MDR) bacteria has become a global crisis. Rapid and accurate diagnosis of infection will facilitate antibiotic stewardship and preserve our ability to treat and cure patients from bacterial infection. Direct in situ imaging of bacteria offers the prospect of accurately diagnosing disease and monitoring patient outcomes and response to treatment in real-time. There have been many recent advances in the field of optical imaging of infection; namely in specific probe and fluorophore design. This combined with the advances in imaging device technology render direct optical imaging of infection a feasible approach for accurate diagnosis in the clinic. Despite this, there are currently no licensed molecular probes for clinical optical imaging of infection. Here we report some of the most promising and interesting probes and approaches under development for this purpose, which have been evaluated in in vivo models within the laboratory setting.

Evaluation of a Fluorescent and Radiolabeled Hybrid Somatostatin Analog In Vitro and in Mice Bearing H69 Neuroendocrine Xenografts

In the treatment of neuroendocrine tumors (NETs), complete surgical removal of malignancy is generally desirable, because it offers curative results. Preoperative guidance with radiolabeled somatostatin analogs, commonly used for NET diagnosis and preoperative planning, is limited by its low resolution, with the risk that tumor margins and small metastases will be incompletely resected with subsequent recurrence. A single hybrid probe combining radiotracer and optical dye would enable high-resolution optical guidance, also during surgery. In the current study, the hybrid labeled somatostatin analog Cy5-DTPA-Tyr(3)-octreotate (DTPA is diethylene triamine pentaacetic acid) was synthesized and evaluated for its ability to specifically trace NET cells in vitro and in an animal model. The performance of the hybrid tracer was compared with that of octreotate with only radiolabel or only optical label.

METHODS

The binding affinity and internalization capacity of Cy5-DTPA-Tyr(3)-octreotate were assessed in vitro. Biodistribution profiles and both nuclear and optical in vivo imaging of Cy5-(111)In -DTPA-Tyr(3)-octreotate were performed in NET-bearing mice and compared with the performance of (111)In-DTPA-Tyr(3)-octreotate.

RESULTS

In vitro studies showed a low receptor affinity and internalization rate for Cy5-DTPA-Tyr(3)-octreotate. The dissociation constant value was 387.7 ± 97.9 nM for Cy5-DTPA-Tyr(3)-octreotate, whereas it was 120.5 ± 18.1 nM for DTPA-Tyr(3)-octreotate. Similarly, receptor-mediated internalization reduced from 33.76% ± 1.22% applied dose for DTPA-Tyr(3)-octreotate to 1.32% ± 0.02% applied dose for Cy5-DTPA-Tyr(3)-octreotate. In contrast, in vivo and ex vivo studies revealed similar tumor uptake values of Cy5-(111)In-DTPA-Tyr(3)-octreotate and (111)In -DTPA-Tyr(3)-octreotate (6.93 ± 2.08 and 5.16 ± 1.27, respectively). All organs except the kidneys showed low background radioactivity, with especially low activities in the liver, and high tumor-to-tissue ratios were achieved-both favorable for the tracer's toxicity profile. Hybrid imaging in mice confirmed that the nuclear and fluorescence signals colocalized.

CONCLUSION

The correlation between findings with the optical and the nuclear probes underlines the potential of combining SPECT imaging with fluorescence guidance and shows the promise of this novel hybrid peptide for preoperative and intraoperative imaging of NET.

Dual-modality imaging demonstrates the enhanced antitumoral effect of herpes simplex virus-thymidine kinase/ganciclovir plus gemcitabine combination therapy on cholangiocarcinoma

Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) therapy is one of the most promising therapeutic strategies for the treatment of cholangiocarcinoma, which is the second most common hepatobiliary cancer. The aim of the present study was to evaluate the enhanced therapeutic effects of HSV-TK/GCV with gemcitabine on cholangiocarcinoma. QBC939 cholangiocarcinoma cells and mouse models of cholangiocarcinoma (established via tumor xenografts) received one of the following treatments: i) Gemcitabine therapy (3 µg/ml); ii) HSV-TK/GCV monotherapy; iii) HSV-TK/GCV + gemcitabine; and iv) control group, treated with phosphate-buffered saline. Cell proliferation was quantified using MTT assay and post-treatment tumor alterations were monitored using ultrasound imaging and optical imaging. For the in vitro experiments, the MTT assays demonstrated that the relative cell viabilities in the gene therapy, gemcitabine and gemcitabine + gene groups were 70.37±9.07, 52.64±8.28 and 34.21±6.63%, respectively. For the in vivo experiments, optical imaging indicated significantly decreased optical signals in the combination therapy group, as compared with the gemcitabine and gemcitabine + gene groups (1.68±0.74 vs. 2.27±0.58 and 2.87±0.82, respectively; Р<0.05). As demonstrated by ultrasound imaging, reduced tumor volumes were detected in the combination therapy group, as compared with the three control groups (114.32±17.17 vs. 159±23.74, 201.63±19.26 and 298.23±36.1 mm3, respectively; P<0.05). The results of the present study demonstrated that gemcitabine enhances the antitumoral effects of HSV-TK/GCV on cholangiocarcinoma, which may provide a novel therapeutic strategy for the management and treatment of cholangiocarcinoma using gemcitabine and gene therapy.

Characterization and evaluation of the artemis camera for fluorescence-guided cancer surgery

Purpose

Near-infrared (NIR) fluorescence imaging can provide the surgeon with real-time visualization of, e.g., tumor margins and lymph nodes. We describe and evaluate the Artemis, a novel, handheld NIR fluorescence camera.

Procedures

We evaluated minimal detectable cell numbers (FaDu-luc2, 7D12-IRDye 800CW), preclinical intraoperative detection of sentinel lymph nodes (SLN) using indocyanine green (ICG), and of orthotopic tongue tumors using 7D12-800CW. Results were compared with the Pearl imager. Clinically, three patients with liver metastases were imaged using ICG.

Results

Minimum detectable cell counts for Artemis and Pearl were 2 × 10⁵ and 4 × 10⁴ cells, respectively. In vivo, seven SLNs were detected in four mice with both cameras. Orthotopic OSC-19-luc2-cGFP tongue tumors were clearly identifiable, and a minimum FaDu-luc2 tumor size of 1 mm³ could be identified. Six human malignant lesions were identified during three liver surgery procedures.

Conclusions

Based on this study, the Artemis system has demonstrated its utility in fluorescence-guided cancer surgery.

Electronic supplementary material

The online version of this article (doi:10.1007/s11307-014-0799-z) contains supplementary material, which is available to authorized users.

Gold Nanorods Based Air Scanning Electron Microscopy and Diffusion Reflection Imaging for Mapping Tumor Margins in Squamous Cell Carcinoma

A critical challenge arising during a surgical procedure for tumor removal is the determination of tumor margins. Gold nanorods (GNRs) conjugated to epidermal growth factor receptors (EGFR) (GNRs-EGFR) have long been used in the detection of cancerous cells as the expression of EGFR dramatically increases once the tissue becomes cancerous. Optical techniques for the identification of these GNRs-EGFR in tumor are intensively developed based on the unique scattering and absorption properties of the GNRs. In this study, we investigate the distribution of the GNRs in tissue sections presenting squamous cell carcinoma (SCC) to evaluate the SCC margins. Air scanning electron microscopy (airSEM), a novel, high resolution microscopy is used, enabling to localize and actually visualize nanoparticles on the tissue. The airSEM pictures presented a gradient of GNRs from the tumor to normal epithelium, spread in an area of 1 mm, suggesting tumor margins of 1 mm. Diffusion reflection (DR) measurements, performed in a resolution of 1 mm, of human oral SCC have shown a clear difference between the DR profiles of the healthy epithelium and the tumor itself.

Preclinical Validation of the Utility of BLZ-100 in Providing Fluorescence Contrast for Imaging Spontaneous Solid Tumors

There is a need in surgical oncology for contrast agents that can enable real-time intraoperative visualization of solid tumors that can enable complete resections while sparing normal surrounding tissues. The Tumor Paint agent BLZ-100 is a peptide-fluorophore conjugate that can specifically bind solid tumors and fluoresce in the near-infrared range, minimizing light scatter and signal attenuation. In this study, we provide a preclinical proof of concept for use of this imaging contrast agent as administered before surgery to dogs with a variety of naturally occurring spontaneous tumors. Imaging was performed on excised tissues as well as intraoperatively in a subset of cases. Actionable contrast was achieved between tumor tissue and surrounding normal tissues in adenocarcinomas, squamous cell carcinomas, mast cell tumors, and soft tissue sarcomas. Subcutaneous soft tissue sarcomas were labeled with the highest fluorescence intensity and greatest tumor-to-background signal ratio. Our results establish a foundation that rationalizes clinical studies in humans with soft tissue sarcoma, an indication with a notably high unmet need.

Peptide-Based Optical uPAR Imaging for Surgery: In Vivo Testing of ICG-Glu-Glu-AE105

Near infrared intra-operative optical imaging is an emerging technique with clear implications for improved cancer surgery by enabling a more distinct delineation of the tumor margins during resection. This modality has the potential to increase the number of patients having a curative radical tumor resection. In the present study, a new uPAR-targeted fluorescent probe was developed and the in vivo applicability was evaluated in a human xenograft mouse model. Most human carcinomas express high level of uPAR in the tumor-stromal interface of invasive lesions and uPAR is therefore considered an ideal target for intra-operative imaging. Conjugation of the flourophor indocyanine green (ICG) to the uPAR agonist (AE105) provides an optical imaging ligand with sufficiently high receptor affinity to allow for a specific receptor targeting in vivo. For in vivo testing, human glioblastoma xenograft mice were subjected to optical imaging after i.v. injection of ICG-AE105, which provided an optimal contrast in the time window 6–24 h post injection. Specificity of the uPAR-targeting probe ICG-AE105 was demonstrated in vivo by 1) no uptake of unconjugated ICG after 15 hours, 2) inhibition of ICG-AE105 tumor uptake by a bolus injection of the natural uPAR ligand pro-uPA, and finally 3) the histological colocalization of ICG-AE105 fluorescence and immunohistochemical detected human uPAR on resected tumor slides. Taken together, our data supports the potential use of this probe for intra-operative optical guidance in cancer surgery to ensure complete removal of tumors while preserving adjacent, healthy tissue.

Functional biomedical hydrogels for in vivo imaging

In vivo imaging of biomedical hydrogels enables real-time and non-invasive visualization of the status of structure and function of hydrogels.

Innovations in Intraoperative Tumor Visualization

In the surgical management of solid tumors, adequacy of tumor resection has implications for local recurrence and survival. The standard method of intraoperative identification of tumor margin is frozen section pathologic analysis, which is time-consuming with potential for sampling error. Intraoperative tumor visualization has the potential to significantly improve surgical cancer care across disciplines, by guiding accuracy of biopsies, increasing adequacy of resections, directing adjuvant therapy, and even providing diagnostic information. We provide an outline of various methods of intraoperative tumor visualization developed to aid in the real-time assessment of tumor extent and adequacy of resection.

Intraoperative mapping of sentinel lymph node metastases using a clinically translated ultrasmall silica nanoparticle

The management of regional lymph nodes in patients with melanoma has undergone a significant paradigm shift over the past several decades, transitioning from the use of more aggressive surgical approaches, such as lymph node basin dissection, to the application of minimally invasive sentinel lymph node (SLN) biopsy methods to detect the presence of nodal micrometastases. SLN biopsy has enabled reliable, highly accurate, and low-morbidity staging of regional lymph nodes in early stage melanoma as a means of guiding treatment decisions and improving patient outcomes. The accurate identification and staging of lymph nodes is an important prognostic factor, identifying those patients for whom the expected benefits of nodal resection outweigh attendant surgical risks. However, currently used standard-of-care technologies for SLN detection are associated with significant limitations. This has fueled the development of clinically promising platforms that can serve as intraoperative visualization tools to aid accurate and specific determination of tumor-bearing lymph nodes, map cancer-promoting biological properties at the cellular/molecular levels, and delineate nodes from adjacent critical structures. Among a number of promising cancer-imaging probes that might facilitate achievement of these ends is a first-in-kind ultrasmall tumor-targeting inorganic (silica) nanoparticle, designed to overcome translational challenges. The rationale driving these considerations and the application of this platform as an intraoperative treatment tool for guiding resection of cancerous lymph nodes is discussed and presented within the context of alternative imaging technologies. WIREs Nanomed Nanobiotechnol 2016, 8:535-553. doi: 10.1002/wnan.1380 For further resources related to this article, please visit the WIREs website.