Real-time Optical Imaging Research Articles

NI-44 * LIPOSOMAL NANOPARTICLES FOR TARGETING AND IMAGING OF PEDIATRIC BRAIN TUMORS

BACKGROUND: This study reports the targeting and real-time optical imaging of brainstem tumors using liposomal nanocarriers. Patients with infiltrating brainstem gliomas (BSG) known as diffuse intrinsic pontine gliomas (DIPGs) have one of the poorest survival rates. Blood brain barrier (BBB) is the main obstacle in the delivery of drugs and contrast agents to DIPGs. OBJECTIVE: Here, we demonstrate the specific delivery of liposomal nanoparticles containing Evans blue (nano-EB) to tumor in a murine model of BSG. METHODS/DESIGN: Mice with brainstem tumors were tail vein injected with nano-EB and in vivo tumor enhancement was monitored by optical fluorescence imaging. RESULTS/DISCUSSION: Necropsy analysis conducted 24 hr post injection showed site-specific delivery of nano-EB to the tumor but not adjacent normal tissue. Immunohistochemical assays confirmed high grade tumor at the site of nano-EB accumulation. These findings demonstrate the feasibility of nano-EB for drug delivery and real-time, sensitive optical imaging of BSGs in vivo. The study shows the specific accumulation of liposomal nano-EB nanocarriers in brainstem tumors in our murine model of brainstem glioma. Liposomes are an ideal drug delivery vehicle able to cross the BBB . Specific accumulation of nano-EB in tumor cells is explained by the enhanced permeability and retention (EPR) property of cancer cells which is believed to be due to the abnormal neovasculature with poorly-aligned defective endothelial cells and structure. This pilot study shows the efficacy of liposomes for targeted delivery and possibility of using nano-EB for in vivo imaging of tumors in a murine model of brain tumors.

Point-of-care and point-of-procedure optical imaging technologies for primary care and global health.

Leveraging advances in consumer electronics and wireless telecommunications, low-cost, portable optical imaging devices have the potential to improve screening and detection of disease at the point of care in primary health care settings in both low- and high-resource countries. Similarly, real-time optical imaging technologies can improve diagnosis and treatment at the point of procedure by circumventing the need for biopsy and analysis by expert pathologists, who are scarce in developing countries. Although many optical imaging technologies have been translated from bench to bedside, industry support is needed to commercialize and broadly disseminate these from the patient level to the population level to transform the standard of care. This review provides an overview of promising optical imaging technologies, the infrastructure needed to integrate them into widespread clinical use, and the challenges that must be addressed to harness the potential of these technologies to improve health care systems around the world.

FRI0362 Mineralized, Pegylated Hyaluronic Acid Nanoparticles for Ph-Responsive Delivery of Methotrexate in Inflammatory Arthritis

BackgroundTargeted delivery to inflamed joint and site specific drug release are the key factors for effective therapy against inflammatory arthritis. The critical dose-limiting factor for methotrexate, an anchor drug for...

Real-time 3D particle manipulation visualized using volume holographic gratings.

Holographic optical tweezers (HOTs) extend optical trapping into three dimensions. Volume imaging then becomes a concern as trapped objects are easily moved out of focus of the imaging objective lens. Here we demonstrate a three-dimensional real-time interactive optical trapping, manipulating, and imaging system based on HOTs incorporated with volume holographic microscope. Intensity information about the trapped objects at multiple depths can be captured in a single measurement. This method is compatible with most imaging modes such as bright-field and fluorescence.

Endoscopic Optical Coherence Tomography for Clinical Gastroenterology.

Optical coherence tomography (OCT) is a real-time optical imaging technique that is similar in principle to ultrasonography, but employs light instead of sound waves and allows depth-resolved images with near-microscopic resolution. Endoscopic OCT allows the evaluation of broad-field and subsurface areas and can be used ancillary to standard endoscopy, narrow band imaging, chromoendoscopy, magnification endoscopy, and confocal endomicroscopy. This review article will provide an overview of the clinical utility of endoscopic OCT in the gastrointestinal tract and of recent achievements using state-of-the-art endoscopic 3D-OCT imaging systems.

Polymeric nanotheranostics for real-time non-invasive optical imaging of breast cancer progression and drug release

Polymeric nanocarriers conjugated with low molecular weight drugs are designed in order to improve their efficacy and toxicity profile. This approach is particularly beneficial for anticancer drugs, where the polymer–drug conjugates selectively accumulate at the tumor site, due to the enhanced permeability and retention (EPR) effect. The conjugated drug is typically inactive, and upon its pH- or enzymatically-triggered release from the carrier, it regains its therapeutic activity. These settings lack information regarding drug-release time, kinetics and location. Thereby, real-time non-invasive intravital monitoring of drug release is required for theranostics (therapy and diagnostics). We present here the design, synthesis and characterization of a theranostic nanomedicine, based on N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer, owing its fluorescence-based monitoring of site-specific drug release to a self-quenched near-infrared fluorescence (NIRF) probe. We designed two HPMA copolymer-based systems that complement to a theranostic nanomedicine. The diagnostic system consists of self-quenched Cy5 (SQ-Cy5) as a reporter probe and the therapeutic system is based on the anticancer agent paclitaxel (PTX). HPMA copolymer–PTX/SQ-Cy5 systems enable site-specific release upon enzymatic degradation in cathepsin B-overexpressing breast cancer cells. The release of the drug occurs concomitantly with the activation of the fluorophore to its Turn-ON state. HPMA copolymer-SQ-Cy5 exhibits preferable body distribution and drug release compared with the free drug and probe when administered to cathepsin B-overexpressing 4T1 murine mammary adenocarcinoma-bearing mice. This approach of co-delivery of two complementary systems serves as a proof-of-concept for real-time deep tissue intravital orthotopic monitoring and may have the potential use in clinical utility as a theranostic nanomedicine.

High‐Resolution Microendoscope Images of Middle Ear Cholesteatoma and Surrounding Tissue: Evaluation of Interobserver Concordance

Investigate how accurately otolaryngologists could differentiate between images obtained with high-resolution microendoscopy (HRME) of ex vivo cholesteatoma specimens and surrounding middle ear epithelium. HRME images of surgically resected cholesteatoma and middle ear epithelium were obtained and otolaryngologists classified these images. Tertiary medical center. Resected cholesteatoma and middle ear epithelium were stained with a contrast agent, proflavine, and HRME images were captured. Specimens were sent for standard histopathology and compared with HRME images. Quality-controlled images were used to assemble a training set. After viewing training images, otolaryngologists without prior cholesteatoma HRME experience reviewed and classified test images. Ten cholesteatoma and 9 middle ear specimens were collected, of which 17 representative cholesteatoma and 19 middle ear epithelium images were extracted for a testing set. Qualitative analysis for concordance between HRME images and histological images yielded a strong correlation between modalities. The mean accuracy of all reviewers in correctly identifying images was 95% (95% confidence interval [CI], 92%-98%). The sensitivity to correctly detect cholesteatoma images was 98% (95% CI, 93%-100%), and the specificity was 92% (95% CI, 87%-97%). The Fleiss kappa interrater reliability score was 0.83, (95% CI, 0.77-0.89). Medical professionals can quickly be trained to accurately distinguish between HRME images of cholesteatoma and normal middle ear epithelium, both of which have distinct imaging characteristics. Real-time HRME optical imaging can potentially improve the results of otologic surgery by allowing for extirpation of cholesteatomas while eliminating residual disease.

The behaviour of magnesium during free corrosion and potentiodynamic polarization investigated by real-time hydrogen measurement and optical imaging

The behaviour of magnesium electrodes has been investigated in 3.5% NaCl during free corrosion and potentiodynamic polarizations. The usual electrochemical measurements were complemented with real-time direct measurement of the amount of hydrogen evolved and real-time optical imaging of the electrode surface. It was found that the anodic reaction of magnesium oxidation results in the generation of dark regions on the surface of the electrode and such regions are efficient in supporting the cathodic reaction (hydrogen evolution). Further, compared to the behaviour observed at the free corrosion potential, the dark regions propagated significantly faster during anodic potentiodynamic polarization and did not propagate significantly during cathodic potentiodynamic polarization. The findings indicate that the negative difference effect is due to an increase in cathodic current during anodic polarization resulting from the modification of the electrode surface after the anodic reaction has occurred. Additionally, the real-time measurement of the amount of hydrogen evolved enabled a direct estimation of the corrosion current. Thus, the actual value of the corrosion current could be compared to the values of corrosion current estimated by potentiodynamic polarization. It was found that anodic polarization provides little information on the corrosion rate, whereas cathodic polarization provides a more accurate estimation. Finally, it is suggested that the corrosion rate on magnesium is controlled by the rate of the cathodic reaction. Such reaction is self-limiting on magnesium since it produces alkalinity and alkalinity promotes passivity.

不同波长光源照明的水下成像及光学图像实时处理

不同波长光源照明的水下成像及光学图像实时处理

Angiogenesis following Cell Injection is Induced by an Excess Inflammatory Response Coordinated by Bone Marrow Cells

The aim of this study was to identify novel angiogenic mechanisms underlying the regenerative process. To that end, interactions between adipose tissue-derived stromal cells (ASCs) and bone marrow cells (BMCs) were initially investigated using real-time fluorescence optical imaging. To monitor cell behavior in mice, we injected green fluorescent protein-positive (GFP(+)) BMCs into the tail vein and injected PKH26-labeled ASCs behind the ears. Angiogenesis and inflammation were observed at these sites via an optical imaging probe. Injected GFP(+) BMCs migrated from the blood vessels into the tissues surrounding the ASC injection sites. Many of the migrating GFP(+) BMCs discovered at the ASC injection sites were inflammatory cells, including Gr-1(+), CD11b(+), and F4/80(+) cells. ASCs cocultured with inflammatory cells secreted increased levels of chemokines such as macrophage inflammatory protein (MIP)-1α, MIP-1β, keratinocyte-derived chemokines, and monocyte chemotactic protein 1. Similarly, these ASCs secreted increased levels of angiogenic growth factors such as hepatocyte growth factor and vascular endothelial growth factor. However, when anti-CXC chemokine receptor type 4 antibody was injected at regular intervals, the migration of GFP(+) BMCs (especially Gr-1(+) and CD11b(+) cells) to ASC injection sites was inhibited, as was angiogenesis. The collective influence of the injected ASCs and BMC-derived inflammatory cells promoted acute inflammation and angiogenesis. Together, the results suggest that the outcome of cell-based angiogenic therapy is influenced not only by the injected cells but also by the effect of intrinsic inflammatory cells.

High-throughput optical imaging and spectroscopy of individual carbon nanotubes in devices

Single-walled carbon nanotubes are uniquely identified by a pair of chirality indices (n,m), which dictate the physical structures and electronic properties of each species. Carbon nanotube research is currently facing two outstanding challenges: achieving chirality-controlled growth and understanding chirality-dependent device physics. Addressing these challenges requires, respectively, high-throughput determination of the nanotube chirality distribution on growth substrates and in situ characterization of the nanotube electronic structure in operating devices. Direct optical imaging and spectroscopy techniques are well suited for both goals, but their implementation at the single nanotube level has remained a challenge due to the small nanotube signal and unavoidable environment background. Here, we report high-throughput real-time optical imaging and broadband in situ spectroscopy of individual carbon nanotubes on various substrates and in field-effect transistor devices using polarization-based microscopy combined with supercontinuum laser illumination. Our technique enables the complete chirality profiling of hundreds of individual carbon nanotubes, both semiconducting and metallic, on a growth substrate. In devices, we observe that high-order nanotube optical resonances are dramatically broadened by electrostatic doping, an unexpected behaviour that points to strong interband electron-electron scattering processes that could dominate ultrafast dynamics of excited states in carbon nanotubes.

High‐Resolution Microendoscope Images of Middle Ear Cholesteatoma and Surrounding Tissue: Evaluation of Interobserver Concordance

Objectives: High-resolution microendoscopy (HRME) has great potential to detect residual cholesteatoma in patients. This study investigated how accurately otolaryngologists could differentiate between images obtained with HRME of ex vivo cholesteatoma specimens and surrounding middle ear epithelium. Methods: Cholesteatoma and surrounding middle ear epithelium were resected from patients. Tissues were stained with a contrast agent, proflavine. The HRME was placed directly on each specimen, and images were captured. Specimens were sent for standard histopathology and were subsequently compared with HRME images. Images were evaluated for quality control, and a training set was assembled. After viewing training images, 8 otolaryngologists without prior cholesteatoma HRME experience reviewed and classified test images. Results: Ten cholesteatoma and 9 middle ear specimens were collected, of which 17 representative cholesteatoma and 19 middle ear epithelium images were extracted for a testing set. Qualitative analysis for concordance between HRME images and histological images yielded a strong correlation between modalities. The mean accuracy of all reviewers in correctly identifying images was 95% [95% confidence interval [CI]: 92, 98]. The sensitivity to correctly detect cholesteatoma images was 98% [95% CI: 93, 100], and the specificity was 92% [95% CI: 87, 97]. The Fleiss kappa inter-rater reliability score was 0.83 [95% CI: 0.77, 0.89]. Conclusions: Medical professionals can quickly be trained to accurately distinguish between HRME images of cholesteatoma and normal middle ear epithelium, both of which have distinct imaging characteristics. Real-time HRME optical imaging can potentially improve the results of otologic surgery by allowing for extirpation of cholesteatomas while eliminating residual disease.

In vivo lung microvasculature visualized in three dimensions using fiber-optic color Doppler optical coherence tomography

For the first time, the use of fiber-optic color Doppler optical coherence tomography (CDOCT) to map in vivo the three-dimensional (3-D) vascular network of airway segments in human lungs is demonstrated. Visualizing the 3-D vascular network in the lungs may provide new opportunities for detecting and monitoring lung diseases such as asthma, chronic obstructive pulmonary disease, and lung cancer. Our CDOCT instrument employs a rotary fiber-optic probe that provides simultaneous two-dimensional (2-D) real-time structural optical coherence tomography (OCT) and CDOCT imaging at frame rates up to 12.5 frames per second. Controlled pullback of the probe allows 3-D vascular mapping in airway segments up to 50 mm in length in a single acquisition. We demonstrate the ability of CDOCT to map both small and large vessels. In one example, CDOCT imaging allows assignment of a feature in the structural OCT image as a large (∼1 mm diameter) blood vessel. In a second example, a smaller vessel (∼80 μm diameter) that is indistinguishable in the structural OCT image is fully visualized in 3-D using CDOCT.

Fluorescently labeled therapeutic antibodies for detection of microscopic melanoma.

Detection of microscopic disease during surgical resection of melanoma remains a significant challenge. To assess real-time optical imaging for visualization of microscopic cancer, we evaluated three US Food and Drug Administration (FDA)-approved therapeutic monoclonal antibodies. Prospective, basic science. Melanoma cell lines (A375 and SKMEL5) were xenografted into the ears of immunodeficient mice. Bevacizumab, panitumumab, tocilizumab, or a nonspecific immunoglobin G (IgG) were covalently linked to a near-infrared (NIR) fluorescent probe (IRDye800CW) and systemically injected. Primary tumors were imaged and then resected under fluorescent guidance using the SPY (Novadaq, Toronto, Ontario, Canada), an NIR imaging system used in plastic and reconstructive surgeries to evaluate perfusion. Mice were also imaged with the Pearl Impulse small animal imager (LI-COR Biosciences, Lincoln, NE), an NIR imaging system designed for use with IRDye800CW. Postresection, small tissue fragments were fluorescently imaged and the presence of tumor subsequently confirmed by correlation with histology. All fluorescently labeled therapeutic monoclonal antibodies could adequately delineate tumor from normal tissue based on tumor-to-background ratios (TBR) compared to IgG-IRDye800CW. On serial imaging, panitumumab achieved the highest TBRs with both SPY and Pearl (3.8 and 6.6, respectively). When used to guide resections, the antibody-dye conjugates generated TBRs in the range of 1.3 to 2.2 (average, 1.6) using the SPY and 1.9 to 6.3 (average, 2.7) using the Pearl. There was no significant difference among the antibodies with either imaging modality or cell line (one-way analysis of variance). Our data suggest that FDA-approved antibodies may be suitable targeting agents for the intraoperative fluorescent detection of melanoma.

Distorted Dammann grating

We introduce the Dammann phase-encoding method into original distorted gratings and propose a modified distorted grating, called a distorted Dammann grating (DDG), to realize multiplane imaging of several tens of layers within the object field onto a single image plane. This property implies that the DDG makes it possible to achieve simultaneously high axial resolving power and large axial imaging range without scanning. This DDG should be of high interest for its potential applications in real-time three-dimensional optical imaging and tracking. Multiplane imaging of 7×7 object layers onto a single camera plane is experimentally demonstrated using a 7×7 DDG for an objective of NA=0.127.

Real-Time Dynamic Optical Imaging of ACC-M Tumor Cells Killed by HSV-tk/ACV System

HSV-tk/ACV induced and killed human adenoid cystic carcinoma cell (ACC-M) in vivo and in vitro, which were observed through optical imaging and green fluorescence protein (GFP) tagging technique. ACC-M was transfected with TK-GFP, and the single clone cell ACC-M-TK-GFP was selected by G418. With fluorescent stereomicroscope, whole-body fluorescent imaging system and fluorescent microscope, we could observe ACV treated ACC-M-TK-GFP cells in cell level and nude mice. The therapies of tumor were visualized clearly with optical imaging. This study proves that optical imaging is a very good approach for studying the effect of HSV-tk/ACV on the ACC-M tumor cells and decreasing the amount of vessel about tumors cell. Optical imaging will become a visual groundwork for monitoring tumor growth and evaluating in vivo curative effect of antitumor drugs.

Optical Image Compression Using a Real Fourier Plane

Hastening transmission by efficiently providing compression is our goal in this work. Image compression consists in reducing information size representing an image. Elimination of redundancies and non-pertinent information enables memory space minimization and thus fast data transmission. Optics can offer an alternative choice to overcome the limitation of numerical compression algorithms. In this paper, we propose real-time optical image compression using a real Fourier plane to save time required for compression by using the principles of coherent optics. Digital and optical simulation results are presented and analyzed. An optical compression decompression setup is demonstrated using two different SLMs (SEIKO and DisplayTech). The purpose of this method is to simplify our earlier method, improve the quality of reconstructed image, and avoid the disadvantages of numerical algorithms.

In vivo real‐time lymphatic draining using quantum‐dot optical imaging in mice

The lymphatic system is essential for fluid regulation and for the maintenance of host immunity. However, in vivo lymph flow is difficult to track in real time, because of the lack of an appropriate imaging method. In this study, we combined macro-zoom fluorescence microscopy with quantum-dot (Qdot) optical lymphatic imaging to develop an in vivo real-time optical lymphatic imaging method that allows the tracking of lymph through lymphatic channels and into lymph nodes. After interstitial injection of Qdots in a mouse, rapid visualization of the cervical lymphatics and cervical lymph nodes was achieved. Real-time monitoring of the injected Qdots revealed that the cortex of the node enhanced first followed by a net-like pattern in the central portion of the node. Histology revealed that the rim and net-like enhancing regions corresponded to the subcapsular sinuses and medullary sinuses respectively. Additionally, multiplexed two-color real-time lymphatic tracking was performed with two different Qdots. With this real-time imaging system, we successfully tracked microscopic lymphatic flow in vivo. This method could have a potential impact for lymphatic research in visualizing normal or abnormal functional lymphatic flows.

Investigation of 3-dimensional Optical Image Guided Frameless Stereotactic Radiosurgery Using Homegrown Volumetric Modulated Arc Therapy

Recently, powerful on-board imaging technologies have propelled SRS into the frameless era. Yet, all the mainstream on-board imaging systems resort to ionizing X-rays as imaging sources. Moreover, most SRS procedures are planned with IMRT, a modality that suffers from an elevated MU, a reduced MU-to-cGy coefficient, and a prolonged treatment time. To tackle these issues, we commissioned a novel frameless stereotactic system for intracranial SRS immobilization, a 3D optical surface imaging system for target localization and real-time patient monitoring, and a homegrown VMAT system for SRS planning. Here, we present our initial results of a feasibility study. The frameless stereotactic system includes carbon fiber base boards, a cranial stereotactic localizer frame, a support bridge, patient-specific mouthpiece assemblies, and a portable vacuum pump. The portable vacuum pump applies a negative pressure to the patient mouthpiece. The resulting vacuum suction seals the mouthpiece precisely into the palate of the mouth. VMAT-SRS plans were computed with a single 360° arc containing 180 equally-spaced beams, optimized incrementally using a differentiated optimization scheme. The target localization was accomplished with a video-based 3D optical surface imaging system, consisting of three 3D camera units and fast 3D image registration software. After the patient had been initially setup, the 3D optical surface imaging system acquired a verification skin surface of the patient. This verification image was registered to a reference skin surface created from the planning 3DCT in a user-defined region of interest. The registration software calculated three translational shifts (ΔVRT, ΔLNG, and ΔLAT), and three rotational shifts (ΔPITCH, ΔROLL, and ΔYAW) for patient re-positioning. The frameless system was found to be able to secure a sustained immobilization accuracy of ∼ ±1.0 mm and 1.0° for intracranial SRS as measured by CBCT and 3D real-time optical surface imaging. With this system, the patient could be simulated, planned, and treated on different days. VMAT-SRS plan optimization converged in 10 minutes for a PTV of ∼ 35 cm3 and 6 other critical structures. VMAT-SRS plans exhibited superior dose distribution to IMRT-SRS plans as measured by conformality and homogeneity indices. The target dose inhomogeneity was less than 17% compared to about 30% for conventional SRS plans. The doses to the critical structures for VMAT-SRS plans were less than or comparable to those for conventional SRS plans. With this new approach, the treatment time was reduced by more than one hour. Our initial data revealed that the synergistic combination of the frameless system, VMAT-SRS, and the 3D real-time optical surface imaging could be an optimal intracranial SRS sub-modality.

A Comparison of FPGA and GPU for Real-Time Phase-Based Optical Flow, Stereo, and Local Image Features

Low-level computer vision algorithms have extreme computational requirements. In this work, we compare two real-time architectures developed using FPGA and GPU devices for the computation of phase-based optical flow, stereo, and local image features (energy, orientation, and phase). The presented approach requires a massive degree of parallelism to achieve real-time performance and allows us to compare FPGA and GPU design strategies and trade-offs in a much more complex scenario than previous contributions. Based on this analysis, we provide suggestions to real-time system designers for selecting the most suitable technology, and for optimizing system development on this platform, for a number of diverse applications.