Quantification of tumor fluorescence during intraoperative optical cancer imaging

Signal-to-Noise Ratio Imaging and Real-Time Sharpening of Tumor Boundaries for Image-Guided Cancer Surgery

Fluorescence-guided cancer surgery is of considerable current interest in bioanalytical chemistry, engineering, and medicine, but its clinical utility is still hampered by the diffusive (scattering) nature of human tissues and large variations among different patients. Here, we report a new method based on signal-to-noise (contrast-to-noise) ratio (SNR or CNR) imaging for real-time delineation and sharpening of tumor boundaries during image-guided cancer surgery. In particular, we show that in vivo tumor fluorescence signals (both intensity and standard deviation) are strongly correlated with those of the surrounding tissue of the same tissue type and that this relationship is maintained as a function of time for fluorescent tracers such as indocyanine green. This dynamic relationship permits a precise removal of nonspecific background fluorescence from tumor fluorescence. As a result, single-pixel SNR values have been calculated, mapped, and displayed across a large surgical field at 60 frames per second. Pathological validation studies indicate that these SNR values correspond to statistical confidence levels similar (but not identical) to those of normal distributions. When the tumor fluorescence has an SNR of 3, pathological data show a confidence level of approximately 95% in identifying the true tumor lesions. For clinical relevance, we have also carried out first-in-human clinical studies for both oral and esophageal tumors, achieving tumor margin precisions of 1-2 mm with 87.5% histological accuracy and no false positives.

Current Trends and Advances in Nanoplatforms-Based Imaging for Cancer Diagnosis

The intersection of nanotechnology and biomedical imaging has ushered in a new era in the early detection and diagnosis of cancer which has revolutionized biomedical imaging by enhancing sensitivity, resolution, and targeting capability. This review presents a comprehensive overview of the latest developments and innovations in nanoplatforms-based imaging for cancer diagnosis, a burgeoning field that holds significant potential in improving cancer detection and treatment. Recently multimodal imaging techniques utilizing the unique properties of different types of nanoparticles are providing comprehensive diagnostic information. This multi-pronged approach allows for more precise tumor localization, size estimation, and growth rate calculation, offering a holistic view of the tumor and its environment. The primary focus of this review is on the recent progress in various types of nanoparticle-based imaging modalities, including optical, magnetic resonance, ultrasound, and nuclear imaging. Specific advancements in nanomaterial design for targeted imaging are highlighted, showing the improvement of precision targeting as an impact on the detection of cancer cells, even in early-stage tumors. A keen examination on the integration of diagnostic and therapeutic capabilities into single nano-based platforms for theranostics, underscoring their potential in personalized medicine is provided. The current challenges in the field, such as issues related to toxicity, biodistribution, and clearance of nanoparticles, and it explores ongoing research aimed at overcoming these hurdles. The growing body of research in this field highlights the promising future of nanoplatforms in improving the early detection and treatment of cancer.

Tumor-Homing Phage Nanofibers for Nanozyme-Enhanced Targeted Breast Cancer Therapy

Photodynamic therapy (PDT) eliminates cancer cells by converting endogenous oxygen into reactive oxygen species (ROS). However, its efficacy is significantly hindered by hypoxia in solid tumors. Hence, to engineer filamentous fd phage, a human-friendly bacteria-specific virus is proposed, into a nanozyme-nucleating photosensitizer-loaded tumor-homing nanofiber for enhanced production of ROS in a hypoxic tumor. Specifically, Pt-binding and tumor-homing peptides are genetically displayed on the sidewall and tip of the fd phage, respectively. The Pt-binding peptides induced nucleation and orientation of Pt nanozymes (PtNEs) on the sidewall of the phage. The resultant PtNE-coated tumor-homing phage exhibits significantly enhanced sustained catalytic conversion of hydrogen peroxide in hypoxic tumors into O2 for producing ROS needed for PDT, compared to non-phage-templated PtNE. Density functional theory (DFT) calculations verify the catalytic mechanism of the phage-templated PtNE. After intravenous injection of the PtNE-coated indocyanine green (ICG)-loaded tumor-homing phages into breast tumor-bearing mice, the nanofibers home to the tumors and effectively inhibit tumor growth by the PtNE-enhanced PDT. The nanofibers can also serve as a tumor-homing imaging probe due to the fluorescence of ICG. This work demonstrates that filamentous phage, engineered to become tumor-homing nanozyme-nucleating tumor-hypoxia-relieving nanofibers, can act as cancer-targeting nanozymes with improved catalytic performance for effective targeted PDT.

Translocator Protein 18 kDa (TSPO): A Promising Molecular Target for Image-Guided Surgery of Solid Cancers

The translocator protein 18-kDa (TSPO) is a mitochondrial membrane protein that is previously identified as the peripheral benzodiazepine receptor (PBR). Furthermore, it plays a significant role in a diverse range of biochemical processes, including steroidogenesis, mitochondrial cholesterol transport, cell survival and death, cell proliferation, and carcinogenesis. Several investigations also reported its roles in various types of cancers, including colorectal, brain, breast, prostate, and lung cancers, as well as melanoma. According to a previous study, the expression of TSPO was upregulated in cancer cells, which corresponds to an aggressive phenotype and/or poor prognosis. Consequently, the potential for crafting diagnostic and prognostic tools with a focus on TSPO holds great potential. In this context, several radioligands designed to target this protein have been identified, and some of the candidates have advanced to clinical trials. In recent years, the use of hybrid probes with radioactive and fluorescence molecules for image-guided surgery has exhibited promising results in animal and human studies. This indicates that the approach can serve as a valuable surgical navigator during cancer surgery. The current hybrid probes are built from various molecular platforms, including small molecules, nanoparticles, and antibodies. Although several TSPO-targeted imaging probes have been developed, their development for image-guided surgery of cancers is still limited. Therefore, this review aims to highlight recent findings on the involvement of TSPO in carcinogenesis, as well as provide a new perspective on the potential application of TSPO-targeted hybrid probes for image-guided surgery.

[Intraoperative near-infrared fluorescence imaging of peripheral lung tumors]

The main objective of surgical intervention in lung cancer is the radical removal of the entire tumor with the maximum possible preservation of healthy tissue. Although the area of the tumor lesion is known by the results of preoperative studies, it can be difficult to use this information to establish the exact boundaries of resection during surgery, especially with small sizes of the lump and when using minimally invasive approaches. There are several techniques to solve this problem. One of the latter is intraoperative fluorescence imaging in the infrared range, which makes it possible to detect a tumor not only with greater contrast than it can be done in white light, but also with its deep location. This review is devoted to the discussion of various aspects of this approach related to molecular imaging methods. The current situation based on the use of green indocyanine green, available for clinical use as a fluorescent agent is considered, the issues of using new targeted drugs are examined, as well as the possibility of increasing the depth of probing and combining with related treatment methods, which should contribute to a more radical operation and reduce the likelihood of local relapses.

New hybrid radio-fluorescent probes [131I]-BPF-01 and [131I]-BPF-02 for visualisation of cancer cells: Synthesis and preliminary in vitro and ex vivo evaluations

We synthesised and biologically evaluated two new hybrid probes [131I]BPF-01 and [131I]BPF-02 which were built from three structural entities: benzothiazole-phenyl, fluorescein isothiocyanate (FITC), and iodine-131. These probes were designed for potential applications in assisting surgical procedures of solid cancers. The cytotoxicity study demonstrated that fluorescent probes BPF-01 (31.23 μg/mL) and BPF-02 (250 μg/mL) were relatively not toxic to normal immortalized human keratinocytes (HaCaT) cells, as indicated by the percentage of cell survival above 50 %. Furthermore, both probes displayed low to moderate anticancer activity against the breast cancer cells (MDA-MB-231) and prostate cancer cells (LNCaP and DU-145). The probe BPF-01 apparently showed an accumulation in the tumour tissues, as suggested by ex vivo fluorescence examinations. In addition, the cellular uptake study suggests that hybrid probe [131I]-BPF-01 was potentially accumulated in the MCF-7 cell line with the highest uptake of 16.11 ± 1.52 % after 2 h of incubation, approximately 50-fold higher than the accumulation of iodine-131 (control). The magnetic bead assay suggests that [131I]-BPF-02 and [131I]-BPF-02 showed a promising capability to interact with translocator protein 18 kDa (TSPO). Moreover, the computational data showed that the binding scores for ligands 7-8, BPF-01 and BPF-02, and [131I]-BPF-01 and [131I]-BPF-02 in the TSPO were considerably high. Accordingly, fluorescent probes BPF-01 and BPF-02, and hybrid probes [131I]BPF-01 and [131I]BPF-02 can be further developed for targeting cancer cells during intraoperative tumour surgery.

Synthesis and Biological Evaluation of New Fluorescent Probe BPN-01: A Model Molecule for Fluorescence Image-guided Surgery

Fluorescence image-guided surgery (FIGS) can serve as a tool to achieve successful resection of tumour tissues during surgery, serving as a surgical navigator for surgeons. FIGS relies on the use of fluorescent molecules that can specifically interact with cancer cells. In this work, we developed a new model of fluorescent probe based on benzothiazole-phenylamide moiety featuring the visible fluorophore nitrobenzoxadiazole (NBD), namely BPN-01. This compound was designed and synthesised for potential applications in the tissue biopsy examination and ex-vivo imaging during FIGS of solid cancers. The probe BPN-01 exhibited favourable spectroscopic properties, particularly in nonpolar and alkaline solvents. Moreover, in vitro fluorescence imaging revealed that the probe appeared to recognise and be internalised in the prostate (DU-145) and melanoma (B16-F10) cancer cells, but not in the normal cells (myoblast C2C12). The cytotoxicity studies revealed that probe BPN-01 was not toxic to the B16 cells, suggesting excellent biocompatibility. Furthermore, the computational analysis showed that the calculated binding affinity of the probe to both translocator protein 18 kDa (TSPO) and human epidermal growth factor receptor 2 (HER2) was considerably high. Hence, probe BPN-01 displays promising properties and may be valuable for visualising cancer cells in vitro. Furthermore, ligand 5 can potentially be labelled with NIR fluorophore and radionuclide, and serves as a dual imaging agent for in vivo applications.

Desorption electrospray ionization mass spectrometry imaging (DESI-MSI) in disease diagnosis: an overview

Tissue analysis, which is essential to histology and is considered the benchmark for the diagnosis and prognosis of many illnesses, including cancer, is significant. During surgery, the surgical margin of the tumor is assessed using the labor-intensive, challenging, and commonly subjective technique known as frozen section histopathology. In the biopsy section, large numbers of molecules can now be visualized at once (ion images) following recent developments in [MSI] mass spectrometry imaging under atmospheric conditions. This is vastly superior to and different from the single optical tissue image processing used in traditional histopathology. This review article will focus on the advancement of desorption electrospray ionization mass spectrometry imaging [DESI-MSI] technique, which is label-free and requires little to no sample preparation. Since the proportion of molecular species in normal and abnormal tissues is different, DESI-MSI can capture ion images of the distributions of lipids and metabolites on biopsy sections, which can provide rich diagnostic information. This is not a systematic review but a summary of well-known, cutting-edge and recent DESI-MSI applications in cancer research between 2018 and 2023.

NIRDye 812: A molecular platform tailored for multimodal bioimaging applications of targeted fluorescence- and photoacoustic-guided surgery

The primary treatment for malignant tumors remains to be surgical removal of the diseased tissue. The presence or absence of residual diseased tissue at the tumor margin is the strongest predictor of postoperative prognosis and recurrence. Accordingly, reliance on the ability of surgeons to visually distinguish diseased tissue from healthy tissue unambiguously in real time is crucial. Near infrared-I (NIRI) fluorescence-emitting targeting biomolecular constructs such as anticancer antibody-fluorophore conjugates, namely cetuximab-IRDye® 800CW (CTB-IRDye® 800CW), are FDA-approved for clinical trial usage in the fluorescence-guided resection of diseased tissue due to affording improved direct visualization of tumor tissue when compared to the use of either the unaided eye under standard white light illumination (WLI) surgical techniques or non-targeting fluorophores. Unfortunately, though helpful, CTB-IRDye® 800CW affords limited (i) identification of diseased tissue and (ii) tumor margin delineation, because the immunoconjugate generates suboptimal tumor-to-background ratios (TBRs) as a result of its spectral/photophysical profiles poorly aligning with the fixed optical windows of pre-/clinical setups. As such, CTB-IRDye® 800CW is more prone to affording incomplete resection compared to if TBRs were higher due to otherwise. To aid in accurately identifying deep-seated diseased tissue, photoacoustic (PA) tomography has been implemented alongside CTB-IRDye® 800CW to achieve PA signals that could result in higher TBRs. However, in clinical trial practice, using IRDye® 800CW for PA imaging also yields subpar TBRs due to it affording low PA signals. To overcome such limitations, we developed NIRDye 812, a structurally-modified topological equivalent of IRDye® 800CW, to confer it the capability to yield both higher TBRs and superior PA signal than that of the equivalent CTB-conjugate and fluorophore IRDye® 800CW itself, respectively. To do so, we substituted the oxygen atom at its meso-position with a sulfur atom. CTB-NIRDye 812 demonstrated a red-shifted absorption wavelength at 796 nm and a peak NIR-I fluorescence emission wavelength at 820 nm, which better dovetails with the fixed windows of preinstalled fixed emission filters within commercial pre-/clinical NIR-I fluorescence imaging instruments. Overall, CTB-NIRDye 812 provided a ∼ 2-fold increase in TBRs compared to those of CTB-IRDye® 800CW in vivo. Also, NIRDye 812 displayed an ∼60% higher PA signal than that of IRDye® 800CW. Collectively, we achieved our goal of improving upon the spectral/photophysical and PA properties of IRDye® 800CW via introducing a subtle modification to its electronic core such that its CTB immunoconjugate could potentially allow for fast track or breakthrough designation by the FDA due to its near-identical structure displaying considerably improved efficacy.

Evaluation of Intraoperative Near-Infrared Fluorescence Visualization of the Lung Tumor Margin With Indocyanine Green Inhalation

Importance

Identification of the tumor margin during surgery is important for precise minimal resection of lung tumors. Intravenous injection of indocyanine green (ICG) has several limitations when used for intraoperative visualization of lung cancer.

Objectives

To describe a technique for intraoperative visualization of lung tumor margin using ICG inhalation and evaluate the clinical applicability of the technique in mouse and rabbit lung tumor models as well as lung specimens of patients with lung tumors.

Design, Setting, and Participants

In lung tumor models of both mice and rabbits, the distribution of inhaled ICG in the lung tumor margin was investigated in vivo and ex vivo using a near-infrared imaging system. Lung tumor margin detection via inhalation of ICG was evaluated by comparing the results obtained with those of the intravenous injection method (n = 32, each time point for 4 mice). Based on preclinical data, use of ICG inhalation to help detect the tumor margin in patients with lung cancer was also evaluated (n = 6). This diagnostic study was conducted from May 31, 2017, to March 30, 2019.

Main Outcomes and Measures

The use of tumor margin detection by inhaled ICG was evaluated by comparing the inhaled formulation with intravenous administration of ICG.

Results

From 10 minutes after inhalation of ICG to 24 hours, the distribution of ICG in the lungs was significantly higher than that in other organs (signal to noise ratio in the lungs: 39 486.4; interquartile range [IQR], 36 983.74-43 592.5). Ex vivo and histologic analysis showed that, in both lung tumor models, inhaled ICG was observed throughout the healthy lung tissue but was rarely found in tumor tissue. The difference in the fluorescent signal between healthy and tumor lung tissues was associated with the mechanical airway obstruction caused by the tumor and with alveolar macrophage uptake of the inhaled ICG in healthy tissues. Inhalation at a 20-fold lower dose of ICG had a 2-fold higher efficiency for tumor margin detection than did the intravenous injection (2.9; IQR, 2.7-3.2; P < .001).

Conclusions and Relevance

The results of this study suggest that lung-specific inhalation delivery of ICG is feasible and may be useful for the intraoperative visualization of lung tumor margin in clinical practice.

Prospective Non-Randomized Study of Intraoperative Assessment of Surgical Resection Margin of Colo-Rectal Liver Metastases

Introduction: More than 50% of patients with colorectal cancer (CRC) develop liver metastases during the natural course of disease. Surgical resection is currently the most potentially curative method in the treatment of colorectal liver metastases (CRLM). The goal of surgery is to achieve a negative resection margin (RM) of at least 1 mm, which provides the best prognosis for patients. The RM can be assessed by the pathologist of the resected liver specimen (RLS) and by the surgeon intraoperatively. The aim of this research paper is to determine the degree of agreement on intraoperative assessment of the RM by the surgeon and histopathological RM assessment by the pathologist.

Material and methods: This prospective non-randomized double-blind study was approved by the Ethics Committee of the Oncology Institute of Vojvodina and registered on ClinicalTrials.gov #NCT04634526. The study was conducted at the Oncology Institute of Vojvodina, Sremska Kamenica, Serbia. An experienced hepatobiliary surgeon assessed RM for every specimen intra-operatively, immediately after CRLM resection. Resected CRLM lesions were analyzed by two experienced pathologists. These data were compared with pathological RM assessment as a “gold standard”. RM of 1 mm or more was rated as negative RM (RM-). Disease-free survival (DFS) and recurrence rate was calculated by RM status defined by surgeon and by pathologist.

Results: From 01 January 2015 to 31 August 2019, 98 patients were enrolled in the study. There were 219 RLS with 245 CRLM. The surgeon registered positive RM (RM+) of <1mm in 41 (18.7%) RLS. Taking the result of the histopathological assessment (HPA) as the “gold standard”, it was determined that RM was true positive in 32 (14.6%) cases. False positive RM was found in 9 (4.1%) cases. False negative RM was found in 20 (9.1%) cases. True negative RM was found in 158 (72.2%) cases. Sensitivity of surgical assessment (SA) of RM+ was 61.5% (32/52). Specificity of SA of RM+ was 94.6% (158/167). The positive predictive value (PPV) was 78.0% (32/41), while the negative predictive value (NPV) was 88.8% (158/178). The overall accuracy of the RM+ SA was 86.8% (190/219). There was no statistically significant difference in the assessment of RM+ per RLS by surgeon and pathologists (p=0.061), but it was significant when analyses per patients was performed (p=0.017). Recurrence rate for RM+ patients was 48.1% (13/27, p=0.05) for SA and 35.0% (14/40, p=0.17) for HPA. Three year DFS for RM- and RM+ was 66.5% and 27.9% (p=0.04), respectively, by SA, and 64.8% and 42.1% (p=0.106), respectively, by HPA.

Conclusion: Intraoperative assessment of RM- by surgeon of RLS is clinically meaningful. There is not a statistically significant difference in the assessment of RM+ by surgeon and pathologists per RLS, but it was statically significant on a per patient basis. RM determined by surgeon has better prognostic impact on recurrence rate and 1- and 3-year DFS than standard histopathological assessment.

Rapid and Accurate Visualization of Breast Tumors with a Fluorescent Probe Targeting α-Mannosidase 2C1

Accurate detection of breast tumors and discrimination of tumor from normal tissues during breast-conserving surgery are essential to reduce the risk of misdiagnosis or recurrence. However, existing probes show substantial background signals in normal breast tissues. In this study, we focus on glycosidase activities in breast tumors. We synthesized a series of 12 fluorescent probes and performed imaging-based evaluation on surgically resected human breast specimens. Among them, the α-mannosidase-reactive fluorescent probe HMRef-αMan detected breast cancer with 90% sensitivity and 100% specificity. We identified α-mannosidase 2C1 as the target enzyme and confirmed its overexpression in various breast tumors. We found that fibroadenoma, the most common benign breast lesion in young woman, tends to have higher α-mannosidase 2C1 activity than malignant cancer. Combined application of green-emitting HMRef-αMan and a red-emitting γ-glutamyltranspeptidase probe enabled efficient dual-color, dual-target optical discrimination of malignant and benign tumors.

Off-Peak Near-Infrared-II (NIR-II) Bioimaging of an Immunoconjugate Having Peak Fluorescence Emission in the NIR-I Spectral Region for Improving Tumor Margin Delineation

The primary treatment for malignant tumors remains to be resection. The strongest predictor of recurrence and postoperative prognosis is whether diseased tissue/cells remain(s) at the surgical margin. Cancer surgery entails surgeons having the capability to visually distinguish between subtle shades of color in attempts of differentiating between diseased tissue and healthy tissue under standard white-light illumination, as such tissue states appear identical at the meso-/macroscopic level. Accordingly, enhancing the capability of surgeons to do so such that they can accurately delineate the tumor margin is of paramount importance. Fluorescence-guided surgery facilitates in enhancing such capability by color-coding the surgical field with overlaid contrasting pseudo-colors from real-time intraoperative fluorescence emission via utilizing fluorescent constructs in tandem. Constructs undergoing clinical trials or that are FDA-approved provide peak fluorescence emission in the visible (405 - 700 nm) or near-infrared-I (NIR-I) spectral region (700-900 nm), whereby differentiation between tissue states progressively improves in sync with using constructs that emit longer wavelengths of light. Here, we repurpose the usage of such fluorescent constructs by establishing feasibility of a tumor-targeting immunoconjugate (cetuximab-IRDye800) having peak fluorescence emission at the NIR-I spectral region to provide improved tumor margin delineation by affording higher tumor-to-background ratios (TBRs) when measuring its off-peak fluorescence emission at the near-infrared-II (NIR-II) spectral region (1000-1700 nm) in in vivo applications. We prepared murine tumor models, administered such immunoconjugate, and imaged such models pre-/post-administration via utilizing imaging systems that separately afforded acquisition of fluorescence emission in the NIR-I or NIR-II spectral region. On doing so, we determined in vivo TBRs, ex vivo TBRs with/-out skin, and ex vivo biodistribution, all via measuring the fluorescence emission of the immunoconjugate at tumor site(s) at both spectral regions. Collectively, we established feasibility of using the immunoconjugate to afford improved tumor margin delineation by providing 2-fold higher TBRs via utilizing the NIR-II spectral region to capture off-peak fluorescence emission from a fluorescent construct having NIR-I peak fluorescence emission.

Targeting intracranial patient-derived glioblastoma (GBM) with a NIR-I fluorescent immunoconjugate for facilitating its image-guided resection

Glioblastoma multiforme (GBM) is the most aggressive form of primary brain tumor type and is associated with a high mortality rate borne out of such affording a survival rate of only 15 months. GBM aggressiveness is associated with the overexpression of epidermal growth factor receptor (EGFR) and its mutants. Targeting GBM with therapeutics is challenging because the blood-brain barrier (BBB) permits primarily select small-molecule entities across its semipermeable blockade. However, recent preclinical data suggest that large biomolecules, such as the anti-EGFR antibody therapeutic, cetuximab, could be capable of bypassing the BBB despite the relative enormity of its size. As such, we set forth to establish the feasibility of utilizing an EGFR-targeting near-infrared-I (NIR-I) fluorescent construct in the form of an immunoconjugate (cetuxmimab-IRDye800) to achieve visual differentiation between diseased brain tissue arising from a low-passage patient-derived GBM cell line (GBM39) and healthy brain tissue via utilizing orthotopic intracranial murine GBM39 tumor models for in vivo and ex vivo evaluation such that by doing so would establish proof of concept for ultimately facilitating its in vivo fluorescence-guided resection and ex vivo surgical back-table pathological confirmation in the clinic. As anticipated, we were not capable of distinguishing between malignant tumor tissue and healthy tissue in resected intact and slices of whole brain ex vivo under white-light illumination (WLI) due to both the diseased tissue and healthy tissue appearing virtually identical to the unaided eye. However, we readily observed over an average 6-fold enhancement in the fluorescence emission in the resected intact whole brain ex vivo when performing NIR-I fluorescence imaging (FLI) on the cohort of GBM39 tumor models that were administered the immunoconjugate compared to controls. In all, we laid the initial groundwork for establishing that NIR-I fluorescent immunoconjugates (theranostics) such as cetuximab–IRDye800 can bypass the BBB to visually afford GBM39 tumor tissue differentiation for its image-guided surgical removal.

Fluorescent immunoconjugate cetuximab-IRDye800 bypasses the blood-brain-barrier to afford visualization of patient-derived GBM39 brain tumor tissue for facilitating its fluorescence-guided resection.

Real-time surgical margin assessment using ICG-fluorescence during laparoscopic and robot-assisted resections of colorectal liver metastases

Background

Almost a third of the resections in patients with colorectal liver metastases (CRLM) undergoing curative surgery, end up being tumor-margin positive (≤1 mm margin). Near-infrared fluorescent (NIRF) imaging using the fluorescent contrast agent indocyanine green (ICG) has been studied for many different applications. When administered in a relatively low dose (10 mg) 24 hours prior to surgery, ICG accumulated in hepatocytes surrounding the CRLM. This results in the formation of a characteristic fluorescent 'rim' surrounding CRLM when located at the periphery of the liver. By resecting the metastasis with the entire surrounding fluorescent rim, in real-time guided by NIRF imaging, the surgeon can effectively acquire margin-negative (>1 mm) resections. This pilot study aims to describe the surgical technique for using near-infrared fluorescence imaging to assess tumor-margins in vivo in patients with CRLM undergoing laparoscopic or robot-assisted resections.

Methods

Out of our institutional database we selected 16 CRLM based on margin-status (R0; n=8, R1; n=8), which were resected by a minimally-invasive approach using ICG-fluorescence. NIRF images acquired during surgery, from both the resection specimen and the wound bed, were analysed for fluorescent signal. We hypothesized that a protruding fluorescent rim at the parenchymal side of the resection specimen could indicate a too close proximity to the tumor and could be predictive for a tumor-positive surgical margin. NIRF images were correlated to final histopathological assessment of the resection margin.

Results

All lesions with a NIRF positive resection plane in vivo were reported as having a tumor-positive margin. Lesions that showcased no protruding rim in the wound bed in vivo were diagnosed as having a tumor-negative margin in 88% of cases. A 5-step surgical workflow is described to document the NIRF signal was used assess the resection margin in vivo for future clinical studies.

Conclusions

The pilot study shows that image-guided surgery using real-time ICG-fluorescence has the potential to aid surgeons in achieving a tumor-negative margin in minimally invasive liver metastasectomies. The national multi-centre MIMIC-Trial will prospectively study the effect of this technique on surgical tumor-margins (Dutch Trial Register number NL7674).

Real-time surveillance of surgical margins via ICG-based near-infrared fluorescence imaging in patients with OSCC

Background

Local recurrence is the main cause of death among patients with oral squamous cell carcinoma (OSCC). This study assessed near-infrared fluorescence (NIF) imaging and spectroscopy to monitor surgical margins intraoperatively for OSCC.

Methods

Cytological and animal experiments were first performed to confirm the feasibility of monitoring surgical margins with NIF imaging and spectroscopy. Then, 20 patients with OSCC were included in the clinical trials. At 6–8 h after 0.75 mg/kg indocyanine green (ICG) injection, all patients underwent surgery with NIF imaging. During the surgery, both NIF images and quantified fluorescence intensity were acquired to monitor the surgical margins.

Results

In cytological and animal experiments, the results showed it was feasible to monitor surgical margins with NIF imaging and spectroscopy. Fluorescence was detected in primary tumors in all patients. The fluorescence intensities of the tumor, peritumoral, and normal tissues were 398.863 ± 151.47, 278.52 ± 84.89, and 274.5 ± 100.93 arbitrary units (AUs), respectively (P < 0.05). The SBR of tumor to peritumoral tissue and normal tissues was computed to be 1.45 ± 0.36 and 1.56 ± 0.41, respectively. After primary tumor excision, the wounds showed abnormal fluorescence in four patients (4/20), and residual cancer cells were confirmed by pathological examination in two patients (2/20).

Conclusion

These findings confirmed the complementary value of NIF imaging during radical tumor resection of OSCC. Before tumor resection, we could utilize the fluorescence margin produced by ICG NIF imaging to determine the surgical margin. Moreover, after tumor blocks were removed, the status of surgical margin could also be evaluated rapidly by ICG NIF imaging of tumor bed and in vitro specimens.

A dual-functional Embolization-Visualization System for Fluorescence image-guided Tumor Resection

Rationale: Intraoperative bleeding impairs physicians' ability to visualize the surgical field, leading to increased risk of surgical complications and reduced outcomes. Bleeding is particularly challenging during endoscopic-assisted surgical resection of hypervascular tumors in the head and neck. A tool that controls bleeding while marking tumor margins has the potential to improve gross tumor resection, reduce surgical morbidity, decrease blood loss, shorten procedure time, prevent damage to surrounding tissues, and limit postoperative pain. Herein, we develop and characterize a new system that combines pre-surgical embolization with improved visualization for endoscopic fluorescence image-guided tumor resection. Methods: Silk-elastinlike protein (SELP) polymers were employed as liquid embolic vehicles for delivery of a clinically used near-infrared dye, indocyanine green (ICG). The biophysical properties of SELP, including gelation kinetics, modulus of elasticity, and viscosity, in response to ICG incorporation using rheology, were characterized. ICG release from embolic SELP was modeled in tissue phantoms and via fluorescence imaging. The embolic capability of the SELP-ICG system was then tested in a microfluidic model of tumor vasculature. Lastly, the cytotoxicity of the SELP-ICG system in L-929 fibroblasts and human umbilical vein endothelial cells (HUVEC) was assessed. Results: ICG incorporation into SELP accelerated gelation and increased its modulus of elasticity. The SELP embolic system released 83 ± 8% of the total ICG within 24 hours, matching clinical practice for pre-surgical embolization procedures. Adding ICG to SELP did not reduce injectability, but did improve the gelation kinetics. After simulated embolization, ICG released from SELP in tissue phantoms diffused a sufficient distance to deliver dye throughout a tumor. ICG-loaded SELP was injectable through a clinical 2.3 Fr microcatheter and demonstrated deep penetration into 50-µm microfluidic-simulated blood vessels with durable occlusion. Incorporation of ICG into SELP improved biocompatibility with HUVECs, but had no effect on L-929 cell viability. Principle Conclusions: We report the development and characterization of a new, dual-functional embolization-visualization system for improving fluorescence-imaged endoscopic surgical resection of hypervascular tumors.

Tuned near infrared fluorescent hyaluronic acid conjugates for delivery to pancreatic cancer for intraoperative imaging

The prognosis of pancreatic cancer remains poor. Intraoperative fluorescence imaging of tumors could improve staging and surgical resection, thereby improving prognosis. However, imaging pancreatic cancer with macromolecular delivery systems, is often hampered by nonspecific organ accumulation.

Methods: We describe the rational development of hyaluronic acid (HA) conjugates that vary in molecular weight and are conjugated to near infrared fluorescent (NIRF) dyes that have differences in hydrophilicity, serum protein binding affinity, and clearance mechanism. We systematically investigated the roles of each of these properties on tumor accumulation, relative biodistribution, and the impact of intraoperative imaging of orthotopic, syngeneic pancreatic cancer.

Results: Each HA-NIRF conjugate displayed intrapancreatic tumor enhancement. Regardless of HA molecular weight, Cy7.5 conjugation directed biodistribution to the liver, spleen, and bowels. Conjugation of IRDye800 to 5 and 20 kDa HA resulted in low liver and spleen signal while enhancing the tumor up to 14-fold compared to healthy pancreas, while 100 kDa HA conjugated to IRDye800 resulting in liver and spleen accumulation.

Conclusion: These studies demonstrate that by tuning HA molecular weight and the physicochemical properties of the conjugated moiety, in this case a NIRF probe, peritoneal biodistribution can be substantially altered to achieve optimized delivery to tumors intraoperative abdominal imaging.

Nanodrug Delivery Systems for the Treatment of Ovarian Cancer

Despite advances achieved in medicine, chemotherapeutics still has detrimental side effects with ovarian cancer (OC), accounting for numerous deaths among females. The provision of safe, early detection and active treatment of OC remains a challenge, in spite of improvements in new antineoplastic discovery. Nanosystems have shown remarkable progress with impact in diagnosis and chemotherapy of various cancers, due to their ideal size; improved drug encapsulation within its interior core; potential to minimize drug degradation; improve in vivo drug release kinetics; and prolong blood circulation times. However, nanodrug delivery systems have few limitations regarding its accuracy of tumour targeting and the ability to provide sustained drug release. Hence, a cogent and strategic approach has focused on nanosystem functionalization with antibody-based ligands to selectively enhance cellular uptake of antineoplastics. Antibody functionalized nanosystems are (advanced) synthetic candidates, with a broad range of efficiency in specific tumour targeting, whilst leaving normal cells unaffected. This article comprehensively reviews the present status of nanosystems, with particular emphasis on nanomicelles for molecular diagnosis and treatment of OC. In addition, biomarkers of nanosystems provide important prospects as chemotherapeutic strategies to upsurge the survival rate of patients with OC.

Acid specific dark quencher QC1 pHLIP for multi-spectral optoacoustic diagnoses of breast cancer

Breast cancer is the most common type of malignant growth in women. Early detection of breast cancer, as well as the identification of possible metastatic spread poses a significant challenge because of the structural and genetic heterogeneity that occurs during the progression of the disease. Currently, mammographies, biopsies and MRI scans are the standard of care techniques used for breast cancer diagnosis, all of which have their individual shortfalls, especially when it comes to discriminating tumors and benign growths. With this in mind, we have developed a non-invasive optoacoustic imaging strategy that targets the acidic environment of breast cancer. A pH low insertion peptide (pHLIP) was conjugated to the dark quencher QC1, yielding a non-fluorescent sonophore with high extinction coefficient in the near infrared that increases signal as a function of increasing amounts of membrane insertion. In an orthotopic murine breast cancer model, pHLIP-targeted optoacoustic imaging allowed us to differentiate between healthy and breast cancer tissues with high signal/noise ratios. In vivo, the sonophore QC1-pHLIP could detect malignancies at higher contrast than its fluorescent analog ICG-pHLIP, which was developed for fluorescence-guided surgical applications. PHLIP-type optoacoustic imaging agents in clinical settings are attractive due to their ability to target breast cancer and a wide variety of other malignant growths for diagnostic purposes. Intuitively, these agents could also be used for visualization during surgery.

Detection and Differentiation of Breast Cancer Sub-Types using a cPLA2α Activatable Fluorophore

Cytosolic phospholipase A2α (cPLA2α) has been shown to be elevated in breast cancer and is a potential biomarker in the differentiation of molecular sub-types. Using a cPLA2α activatable fluorophore, DDAO arachidonate, we explore its ability to function as a contrast agent in fluorescence-guided surgery. In cell lines ranging in cPLA2α expression and representing varying breast cancer sub-types, we show DDAO arachidonate activates with a high correlation to cPLA2α expression level. Using a control probe, DDAO palmitate, in addition to cPLA2α inhibition and genetic knockdown, we show that this activation is a result of cPLA2α activity. In mouse models, using an ex vivo tumor painting technique, we show that DDAO arachidonate activates to a high degree in basal-like versus luminal-like breast tumors and healthy mammary tissue. Finally, we show that using an in vivo model, orthotopic basal-like tumors give significantly high probe activation compared to healthy mammary fat pads and surrounding tissue. Together we conclude that cPLA2α activatable fluorophores such as DDAO arachidonate may serve as a useful contrast agent for the visualization of tumor margins in the fluorescence-guided surgery of basal-like breast cancer.

Hybrid single-port laparoscopic cisterna chyli ablation for the adjunct treatment of chylothorax disease in dogs

OBJECTIVE

To describe a hybrid, single-port, minimally invasive cisterna chyli ablation (CCA) technique in clinical cases of canine idiopathic chylothorax and evaluate this technique as a method for mesenteric lymphangiography (ML) in canine cadavers and clinical cases of idiopathic chylothorax.

STUDY DESIGN

Cadaveric and retrospective study.

ANIMALS

Six canine cadavers and 14 client-owned dogs with naturally occurring idiopathic chylothorax.

METHODS

Both cadaveric and clinically affected dogs were placed in sternal recumbency. A wound retractor device (WRD) and a single-port device were placed in the abdominal flank 2-3 cm caudal to the 13th rib. Mesenteric lymphangiography was evaluated by using indocyanine green (ICG) in 6 canine cadavers. Single-port laparoscopic CCA was performed in all clinical cases with idiopathic chylothorax.

RESULTS

Successful ML was completed by using ICG in all 6 canine cadavers. A right- or left-sided single-port laparoscopic CCA was successfully performed in 14 dogs with naturally occurring idiopathic chylothorax. Mesenteric lymphangiography was successfully performed through the WRD in 11 of these cases. No intraoperative complications were reported. Three dogs developed severe chyloabdomen postoperatively, with 1 dog requiring multiple abdominocenteses.

CONCLUSION

Direct ML and single-port laparoscopic CCA was performed through a WRD in dogs positioned in sternal recumbency. Although minimal operative complications were noted, postoperative chyloabdomen was reported.

CLINICAL SIGNIFICANCE

This hybrid single-port laparoscopic technique performed in sternal recumbency allows both a CCA and an intraoperative ML through the same incision. This procedure may be combined with thoracoscopic thoracic duct ligation and pericardectomy for the treatment of idiopathic chylothorax in dogs.

Multimodal imaging platform for optical virtual skin biopsy enabled by a fiber-based two-color ultrafast laser source

We demonstrate multimodal label-free nonlinear optical microscopy in human skin enabled by a fiber-based two-color ultrafast source. Energetic femtosecond pulses at 775 nm and 1250 nm are simultaneously generated by an Er-fiber laser source employing frequency doubling and self-phase modulation enabled spectral selection. The integrated nonlinear optical microscope driven by such a two-color femtosecond source enables the excitation of endogenous two-photon excitation fluorescence, second-harmonic generation, and third-harmonic generation in human skin. Such a 3-channel imaging platform constitutes a powerful tool for clinical application and optical virtual skin biopsy.

Kinetics of indocyanine green: Optimizing tumor to normal tissue fluorescence in image-guided oral cancer surgery applications

BACKGROUND

The study aimed to define indocyanine green (ICG) kinetics to determine the optimal ICG dose and surgical time for near-infrared fluorescence-guided oral cancer surgery.

METHODS

Spectrometer and grayscale digital imaging were used to quantify the ICG kinetics in 12 patients with oral cancer. The fluorescence intensity and signal-to-background ratio (SBR) of tumor and normal tissue were tested at 1, 6, and 24 hours after ICG injection.

RESULTS

The greatest contrast in the fluorescence intensity between tumor and normal tissue was observed at 6 hours (P < .01), and of three dose groups (0.5, 0.75, and 1.0 mg/kg), 0.75 mg/kg showed the highest SBR (2.06 ± 0.23) after ICG injection.

CONCLUSIONS

Fluorescence quantification based on spectrometry and grayscale imaging could be effective in determining the optimal ICG dose and surgical time after ICG injection in this cohort of patients with oral cancer.

Standardization and Optimization of Intraoperative Molecular Imaging for Identifying Primary Pulmonary Adenocarcinomas

PURPOSE

Intraoperative molecular imaging (IMI) is an emerging technology used to locate pulmonary adenocarcinomas and identify positive margins during surgery. Background noise and tissue autofluorescence have been major obstacles. The goal of this study is to optimize the image quality of folate receptor alpha (FRα) targeted IMI for pulmonary adenocarcinomas by modifying emission data.

PROCEDURES

A total of 15 lung cancer patients were enrolled in a pilot study. In the first cohort, FRα upregulation within pulmonary adenocarcinoma tumors was confirmed by analyzing specimens from five pulmonary adenocarcinoma patients with flow cytometry and immunohistochemistry. Next, in a cohort of five additional patients, autofluorescence of intrathoracic structures and tissues was quantified. Lastly, five patients with tumors at various depths from the pleural surface were enrolled and received the FRα-targeted optical contrast agent, EC17. In this final cohort, resected pulmonary adenocarcinomas were imaged at a wide range of fluorescence exposure times (0 to 200 ms), various laser powers, and with unique filter configurations. Tumor-to-noise ratio (TNR) for images was generated using region of interest software.

RESULTS

Pulmonary adenocarcinomas highly express FRα. Significant autofluorescence from native thoracic tissues was found with the highest fluorescent signals at the bronchial stump (547 ± 98, range 423-699), the pulmonary artery (267 ± 64, range 200-374), and cortical bone (266 ± 17, range 243-287). High levels of autofluorescence were appreciated after systemic administration of EC17; however, TNR was improved by altering exposure settings at the time of the imaging. Optimal fluorescent exposure time occurs at 40 ms (25 frames/s).

CONCLUSIONS

Exposure properties can be manipulated to maximize TNR thus allowing for successful intraoperative detection of pulmonary adenocarcinomas during surgery. Optimization of the conditions for intraoperative molecular imaging sets the stage for future clinical trials utilizing targeted IMI techniques which can aid the surgeon at the time of cancer resection.

Ambient ionization mass spectrometry imaging for disease diagnosis: Excitements and challenges

Tissue analysis in histology is extremely important and also considered to be a gold standard to diagnose and prognosticate several diseases including cancer. Intraoperative evaluation of surgical margin of tumor also relies on frozen section histopathology, which is time consuming, challenging and often subjective. Recent development in the ambient ionization mass spectrometry imaging (MSI) technique has enabled us to simultaneously visualize hundreds to thousands of molecules (ion images) in the biopsy specimen, which are strikingly different and more powerful than the single optical tissue image analysis in conventional histopathology. This paper will highlight the emergence of the desorption electrospray ionization MSI (DESI-MSI) technique, which is label-free, requires minimal or no sample preparation and operates under ambient conditions. DESI-MSI can record ion images of lipid/metabolite distributions on biopsy specimens, providing a wealth of diagnostic information based on differential distributions of these molecular species in healthy and unhealthy tissues. Remarkable success of this technology in rapidly evaluating the cancer margin intraoperatively with very high accuracy also promises to bring this imaging technique from bench to bedside.

Fluorescence-guided surgery of cancer: applications, tools and perspectives

Thousands of patients die each year from residual cancer that remains following cytoreductive surgery. Use of tumor-targeted fluorescent dyes (TTFDs) to illuminate undetected malignant tissue and thereby facilitate its surgical resection shows promise for reducing morbidity and mortality associated with unresected malignant disease. TTFDs can also improve i) detection of recurrent malignant lesions, ii) differentiation of normal from malignant lymph nodes, iii) accurate staging of cancer patients, iv) detection of tumors during robotic/endoscopic surgery (where tumor palpation is no longer possible), and v) preservation of healthy tissue during resection of cancer tissue. Although TTFDs that passively accumulate in a tumor mass provide some tumor contrast, the most encouraging TTFDs in human clinical trials are either enzyme-activated or ligand-targeted to tumor-specific receptors.

Quantitative Primary Tumor Indocyanine Green Measurements Predict Osteosarcoma Metastatic Lung Burden in a Mouse Model

BACKGROUND

Current preclinical osteosarcoma (OS) models largely focus on quantifying primary tumor burden. However, most fatalities from OS are caused by metastatic disease. The quantification of metastatic OS currently relies on CT, which is limited by motion artifact, requires intravenous contrast, and can be technically demanding in the preclinical setting. We describe the ability for indocyanine green (ICG) fluorescence angiography to quantify primary and metastatic OS in a previously validated orthotopic, immunocompetent mouse model.

QUESTIONS/PURPOSES

(1) Can near-infrared ICG fluorescence be used to attach a comparable, quantitative value to the primary OS tumor in our experimental mouse model? (2) Will primary tumor fluorescence differ in mice that go on to develop metastatic lung disease? (3) Does primary tumor fluorescence correlate with tumor volume measured with CT?

METHODS

Six groups of 4- to 6-week-old immunocompetent Balb/c mice (n = 6 per group) received paraphyseal injections into their left hindlimb proximal tibia consisting of variable numbers of K7M2 mouse OS cells. A hindlimb transfemoral amputation was performed 4 weeks after injection with euthanasia and lung extraction performed 10 weeks after injection. Histologic examination of lung and primary tumor specimens confirmed ICG localization only within the tumor bed.

RESULTS

Mice with visible or palpable tumor growth had greater hindlimb fluorescence (3.5 ± 2.3 arbitrary perfusion units [APU], defined as the fluorescence pixel return normalized by the detector) compared with those with a negative examination (0.71 ± 0.38 APU, -2.7 ± 0.5 mean difference, 95% confidence interval -3.7 to -1.8, p < 0.001). A strong linear trend (r = 0.81, p < 0.01) was observed between primary tumor and lung fluorescence, suggesting that quantitative ICG tumor fluorescence is directly related to eventual metastatic burden. We did not find a correlation (r = 0.04, p = 0.45) between normalized primary tumor fluorescence and CT volumetric measurements.

CONCLUSIONS

We demonstrate a novel methodology for quantifying primary and metastatic OS in a previously validated, immunocompetent, orthotopic mouse model. Quantitative fluorescence of the primary tumor with ICG angiography is linearly related to metastatic burden, a relationship that does not exist with respect to clinical tumor size. This highlights the potential utility of ICG near-infrared fluorescence imaging as a valuable preclinical proof-of-concept modality. Future experimental work will use this model to evaluate the efficacy of novel OS small molecule inhibitors.

CLINICAL RELEVANCE

Given the histologic localization of ICG to only the tumor bed, we envision the clinical use of ICG angiography as an intraoperative margin and tumor detector. Such a tool may be used as an alternative to intraoperative histology to confirm negative primary tumor margins or as a valuable tool for debulking surgeries in vulnerable anatomic locations. Because we have demonstrated the successful preservation of ICG in frozen tumor samples, future work will focus on blinded validation of this modality in observational human trials, comparing the ICG fluorescence of harvested tissue samples with fresh frozen pathology.

Organic anion-transporting polypeptide 1B3 as a dual reporter gene for fluorescence and magnetic resonance imaging

Reporter proteins have broad applications in visualizing molecular events at the cellular, tissue and whole-body levels. Transmembrane transporters recognizing specific molecular domains are of particular interest because they enable the migration of signal-source molecules from the extracellular space to the cytoplasm for subsequent application in multimodality imaging. Organic anion-transporting polypeptides (OATPs) have demonstrated their MRI reporter efficacy. We further expanded their use as a dual-modality reporter in MRI and noninvasive in vivo imaging system (IVIS). We overexpressed OATP1B3 in the HT-1080 sarcoma cell line. Both Gd-EOB-DTPA, an MRI contrast agent, and indocyanine green (ICG), a near-infrared fluorescent dye that provides better deep-tissue detection because of its long wavelength, could be delivered to the intracellular space and imaged in a tumor-bearing nude mouse model. Our in vivo dual-imaging reporter system achieved high sensitivity in MRI and observation periods lasting as long as 96 h in IVIS. Because of the superior temporal and spatial resolutions and the clinical availability of both ICG and Gd-EOB-DTPA, this dual-imaging OATP1B3 system will find biomedical use in tumor biology, stem cell trafficking, and tissue engineering.—Wu, M.-R., Liu, H.-M., Lu, C.-W., Shen, W.-H., Lin, I.-J., Liao, L.-W., Huang, Y.-Y., Shieh, M.-J., Hsiao, J.-K. Organic anion-transporting polypeptide 1B3 as a dual reporter gene for fluorescence and magnetic resonance imaging.

Near-infrared Intraoperative Imaging of Thoracic Sympathetic Nerves: From Preclinical Study to Clinical Trial

The sympathetic nervous system controls and regulates the activities of the heart and other organs. Sympathetic nervous system dysfunction leads to disease. Therefore, intraoperative real-time imaging of thoracic sympathetic nerves (ITSN) would be of great clinical significance for diagnosis and therapy. The aim of this experimental study was to evaluate the feasibility and validity of intraoperative ITSN using indocyanine green (ICG).

METHODS

ITSN using ICG was performed on 10 rabbits to determine its feasibility. Animals were allocated to two groups. The rabbits in one group received the same dose of ICG, but were observed at different times. The rabbits in the other group were administered different doses of ICG, but were observed at the same time. Signal to background ratio (SBR) was measured in regions of interest in all rabbits. Furthermore, fifteen consecutive patients with pulmonary nodules were intravenously injected with ICG 24 h preoperatively and underwent near-infrared (NIR) fluorescence imaging (FI) thoracoscopic surgeries between July 2015 and June 2016. A novel self-developed NIR and white-light dual-channel thoracoscope system was used. SBRs of thoracic sympathetic nerves were calculated in all patients.

RESULTS

In the preclinical study, we were able to precisely recognize each rabbit's second (T2) to fifth (T5) thoracic ganglia on both sides of the spine using ITSN with ICG. In addition, we explored the relationship between SBR and the injection time of ICG and that between SBR and the dose of ICG. Using the novel dual-channel thoracoscope system, we were able to locate the ganglia from the stellate ganglion (SG) to the sixth thoracic ganglion (T6), as well as the chains between these ganglia in all patients with a high SBR value of 3.26 (standard deviation: 0.57). The pathological results confirmed our findings.

CONCLUSION

We were able to use ICG FI to distinguish thoracic sympathetic nerves during NIR thoracoscopic surgery. The technique may replace the rib-oriented method as standard practice for mapping the thoracic sympathetic nerves.

Individual Susceptibility Analysis Using Patient-derived Slice Cultures of Colorectal Carcinoma

BACKGROUND

Nonresponse to chemotherapy in colorectal carcinoma (CRC) is still a clinical problem. For most established treatment regimens, no predictive biomarkers are available. Patient-derived tumor slice culture may be a promising ex vivo technology to assess the drug susceptibility in individual tumors.

METHODS

Patient-derived slice cultures of CRC specimens were prepared according to a standardized protocol and treated with different concentrations of 5-fluorouracil (5-FU) and an adapted FOLFOX regimen (5-FU and oxaliplatin) to investigate histologic response. Additionally, a semi-automatized readout using fluorescent stain-specific segmentation algorithms for Image J was established to quantify changes in tumor proliferation. Nonresponse to chemotherapy was defined as persisting tumor cell proliferation.

RESULTS

Slices treated with 5-FU showed lower tumor cell fractions and dose-dependent alterations of proliferating tumor cells compared with controls (1 μM, Δ +3%; 10 μM, Δ -9%; 100 μM, Δ -15%). Individual tumor samples were examined and differences in chemotherapy susceptibility could be observed. Untreated slice cultures contained an average tumor cell fraction of 31% ± 7%. For all samples, the histopathologic characteristics exhibited some degree of intratumoral heterogeneity with regard to tumor cell morphology and distribution. The original tumor matched the features found in slices at baseline and after 3 days of cultivation.

CONCLUSIONS

Patient-derived slice cultures may help to predict response to clinical treatment in individual patients with CRC. Future studies need to address the problem of tumor heterogeneity and evolution. Prospective correlation of ex vivo results with the clinical course of treated patients is warranted.

Near infrared fluorescent imaging of choline kinase alpha expression and inhibition in breast tumors

Choline kinase alpha (ChoKα) overexpression is associated with an aggressive tumor phenotype. ChoKα inhibitors induce apoptosis in tumors, however validation of their specificity is difficult in vivo. We report the use of optical imaging to assess ChoKα status in cells and in vivo using JAS239, a carbocyanine-based ChoKα inhibitor with inherent near infrared fluorescence. JAS239 attenuated choline phosphorylation and viability in a panel of human breast cancer cell lines. Antibody blockade prevented cellular retention of JAS239 indicating direct interaction with ChoKα independent of the choline transporters and catabolic choline pathways. In mice bearing orthotopic MCF7 breast xenografts, optical imaging with JAS239 distinguished tumors overexpressing ChoKα from their empty vector counterparts and delineated tumor margins. Pharmacological inhibition of ChoK by the established inhibitor MN58b led to a growth inhibition in 4175-Luc+ tumors that was accompanied by concomitant reduction in JAS239 uptake and decreased total choline metabolite levels as measured using magnetic resonance spectroscopy. At higher therapeutic doses, JAS239 was as effective as MN58b at arresting tumor growth and inducing apoptosis in MDA-MB-231 tumors, significantly reducing tumor choline below baseline levels without observable systemic toxicity. These data introduce a new method to monitor therapeutically effective inhibitors of choline metabolism in breast cancer using a small molecule companion diagnostic.

Diagnosis of prostate cancer by desorption electrospray ionization mass spectrometric imaging of small metabolites and lipids

Accurate identification of prostate cancer in frozen sections at the time of surgery can be challenging, limiting the surgeon's ability to best determine resection margins during prostatectomy. We performed desorption electrospray ionization mass spectrometry imaging (DESI-MSI) on 54 banked human cancerous and normal prostate tissue specimens to investigate the spatial distribution of a wide variety of small metabolites, carbohydrates, and lipids. In contrast to several previous studies, our method included Krebs cycle intermediates (m/z <200), which we found to be highly informative in distinguishing cancer from benign tissue. Malignant prostate cells showed marked metabolic derangements compared with their benign counterparts. Using the "Least absolute shrinkage and selection operator" (Lasso), we analyzed all metabolites from the DESI-MS data and identified parsimonious sets of metabolic profiles for distinguishing between cancer and normal tissue. In an independent set of samples, we could use these models to classify prostate cancer from benign specimens with nearly 90% accuracy per patient. Based on previous work in prostate cancer showing that glucose levels are high while citrate is low, we found that measurement of the glucose/citrate ion signal ratio accurately predicted cancer when this ratio exceeds 1.0 and normal prostate when the ratio is less than 0.5. After brief tissue preparation, the glucose/citrate ratio can be recorded on a tissue sample in 1 min or less, which is in sharp contrast to the 20 min or more required by histopathological examination of frozen tissue specimens.

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.

Near-Infrared Intraoperative Molecular Imaging Can Locate Metastases to the Lung

BACKGROUND

Pulmonary metastasectomy is widely accepted for many tumor types because it may prolong survival and potentially cure some patients. However, intraoperative localization of pulmonary metastases can be technically challenging. We propose that intraoperative near-infrared (NIR) molecular imaging can be used as an adjunct during disease localization.

METHODS

We inoculated 50 C57BL/6 mice with Lewis lung carcinoma (LLC) flank tumors. After flank tumor growth, mice were injected through the tail vein with indocyanine green (ICG) before operation, and intraoperative imaging was used to detect pulmonary metastases. On the basis of these experiments, we enrolled 8 patients undergoing pulmonary metastasectomy into a pilot and feasibility clinical trial. Each patient received intravenous ICG 1 day before operation, followed by wedge or segmental resection. Samples were imaged on the back table with an NIR camera to confirm disease presence and margins. All murine and human tumors and margins were confirmed by pathologic examination.

RESULTS

Mice had an average of 4 ± 2 metastatic tumors on both lungs, with an average size of 5.1 mm (interquartile range [IQR] 2.2 mm to 7.6 mm). Overall, 200 of 211 (95%) metastatic deposits were markedly fluorescent, with a mean tumor-to-background ratio (TBR) of 3.4 (IQR 3.1 to 4.1). The remaining tumors had a TBR below 1.5. In the human study, intraoperative NIR imaging identified six of the eight preoperatively localized lesions. Intraoperative back table NIR imaging identified all metastatic lesions, which were confirmed by pathologic examination. The average tumor size was 1.75 ± 1.4 cm, and the mean ex vivo TBR was 3.3 (IQR 3.1 to 3.7). Pathologic examination demonstrated melanoma (n = 4), osteogenic sarcoma (n = 2), renal cell carcinoma (n = 2), chondrosarcoma (n = 1), leiomyosarcoma (n = 1), and colorectal carcinoma (n = 1).

CONCLUSIONS

Systemic ICG identifies subcentimeter tumor metastases to the lung in murine models, and this work provides proof of principle in humans. Future research is focused on improving depth of penetration into the lung parenchyma.

Longitudinal monitoring of skin accumulation of nanocarriers and biologicals with fiber optic near infrared fluorescence spectroscopy (FONIRS)

Systemically injected drug delivery systems distribute into various organs and tissues, including liver, spleen and kidneys. Recent reports pointed out a significant accumulation of systemically injected nanoparticles in the skin. Skin constitutes the largest organ in the body with important immune functions, and accumulation of drug delivery systems could have significant implications for skin toxicity in living subjects. Fiber optic-based near-infrared spectroscopy (FONIRS) setup was developed and tested for measuring of NIR (760nm excitation) emission spectra in the skin. Ex vivo spectral measurements of NIR fluorescence through the skin showed linear response down to 34 femtomole of dye DiR. Following systemic injection of IRDye 800 labeled 500kDa dextran, FONIRS detected an immediate and stable accumulation of fluorescence in the skin. Longitudinal monitoring of skin accumulation and elimination of IRDye 800-labeled therapeutic anti-epidermal growth factor antibody (cetuximab) showed significant signal in the skin after the antibody cleared from circulation. Comparison of skin accumulation of DiR labeled, long-circulating PEGylated liposomes with short-circulating non-PEGylated liposomes showed much higher accumulation of PEGylated liposomes that persisted several days after the liposomes cleared from blood. Measurements with FONIRS enabled to estimate skin concentration of liposomes (percent of injected dose per gram). This simple and practical approach can be used to monitor accumulation of drug delivery systems in preclinical and clinical studies.

Lasing in blood

Indocyanine green (ICG) is the only near-infrared dye approved by the U.S. Food and Drug Administration for clinical use. When injected in blood, ICG binds primarily to plasma proteins and lipoproteins, resulting in enhanced fluorescence. Recently, the optofluidic laser has emerged as a novel tool in bio-analysis. Laser emission has advantages over fluorescence in signal amplification, narrow linewidth, and strong intensity, leading to orders of magnitude increase in detection sensitivity and imaging contrast. Here we successfully demonstrate, to the best of our knowledge, the first ICG lasing in human serum and whole blood with the clinical ICG concentrations and the pump intensity far below the clinically permissible level. Furthermore, we systematically study ICG laser emission within each major serological component (albumins, globulins, and lipoproteins) and reveal the critical elements and conditions responsible for lasing. Our work marks a critical step toward eventual clinical and biomedical applications of optofluidic lasers using FDA approved fluorophores, which may complement or even supersede conventional fluorescence-based sensing and imaging.

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.