This PDF file contains the front matter associated with SPIE Proceedings Volume 9155, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.

In this presentation we will discuss the development of a point-of-care optofluidic device that uses gold nanoparticlebased surface enhanced Raman spectroscopy (SERS) for detection of blood biomarkers. SERS approaches have been successfully used for detection of analytes due to the large enhancements provided by the interaction between the light, gold particles, and analyte. However, SERS approaches developed for use to accurately quantify an analyte have suffered from a lack of repeatability. We will describe our SERS optofluidic device with functionalized nanoparticles that helps to overcome these problems and will show results with a focus on blood cardiac biomarkers.

Suspension assay using optically color-encoded microbeads is a novel way to increase the reaction speed and multiplex of biomolecular detection and analysis. To boost the detection speed, a hyperspectral imaging (HSI) system is of great interest for quickly decoding the color codes of the microcarriers. Imaging Fourier transform spectrometer (IFTS) is a potential candidate for this task due to its advantages in HSI measurement. However, conventional IFTS is only popular in IR spectral bands because it is easier to track its scanning mirror position in longer wavelengths so that the fundamental Nyquist criterion can be satisfied when sampling the interferograms; the sampling mechanism for shorter wavelengths IFTS used to be very sophisticated, high-cost and bulky. In order to overcome this handicap and take better usage of its advantages for HSI applications, a new wide spectral range IFTS platform is proposed based on an optical beam-folding position-tracking technique. This simple technique has successfully extended the spectral range of an IFTS to cover 350-1000nm. Test results prove that the system has achieved good spectral and spatial resolving performances with instrumentation flexibilities. Accurate and fast measurement results on novel colloidal photonic crystal microbeads also demonstrate its practical potential for high-throughput and multiplex suspension molecular assays.

Identifying depth-dependent alterations associated with epithelial cancerous lesions can be challenging in the oral cavity where variable epithelial thicknesses and troublesome keratin growths are prominent. Spectroscopic methods with enhanced depth resolution would immensely aid in isolating optical properties associated with malignant transformation. Combining multiple beveled fibers, oblique collection geometry, and polarization gating, oblique polarized reflectance spectroscopy (OPRS) achieves depth sensitive detection. We report promising results from a clinical trial of patients with oral lesions suspected of dysplasia or carcinoma demonstrating the potential of OPRS for the analysis of morphological and architectural changes in the context of multilayer, epithelial oral tissue.

In this proof-of-concept study we seek to demonstrate the delivery of fluorescent contrast agent to the tumor-draining lymph node basin following intraparenchymal breast injections and intradermal arm injection of micrograms of indocyanine green in 20 breast cancer patients undergoing complete axillary lymph node dissection. Individual lymph nodes were assessed ex vivo for presence of fluorescent signal. In all, 88% of tumor-negative lymph nodes and 81% of tumor-positive lymph nodes were fluorescent. These results indicate that future studies utilizing targeted fluorescent contrast agents may demonstrate improved surgical and therapeutic intervention.

The lack of functional information and targeted imaging in conventional white-light endoscopy leads to a high miss-rate of gastrointestinal tumor. The combination of near-infrared fluorescence imaging and endoscopy presents a promising approach. Here we introduce a new endoscopy method employing a home-made flexible wide-field epi-fluorescence endoscope, that can be inserted through the biopsy channel of a gastrointestinal endoscope, with the glucose analogue 2- DeoxyGlucosone as the near-infrared fluorescent probe. System characterization indicates a good sensitivity and linearity over a large field of view. Its capability of tumor identification and location is demonstrated with in-vivo imaging of xenografted tumor model.

We are developing a miniature fiber-optic spectral-detection device and topical-staining protocol to rapidly detect multiplexed surface-enhanced Raman scattering (SERS) nanoparticles (NPs) targeted to cell-surface biomarkers in fresh tissues. Ex vivo and in vivo experiments were performed to optimize our strategy for the rapid detection of multiple cell-surface biomarkers following a brief (5 min) topical application of SERS NPs on tissues. The simultaneous detection and ratiometric quantification of targeted and nontargeted NPs allows for an unambiguous assessment of molecular expression that is insensitive to nonspecific variations in NP concentrations, potentially enabling point-of-care surgical guidance or early disease detection.

A strategy is presented to enable optical-sectioning microscopy with improved contrast and imaging depth using low-power (0.5 mW) diode laser illumination. While the DAC architecture’s intersecting illumination and collection beams significantly improves the spatial-filtering and opticalsectioning performance of confocal microscopy, we propose that modulating the spatial alignment of the dual-axis beams at a frequency f, such the focal volume signal of the microscope is modulated at 2f, further provides nearly an order-of-magnitude improvement in optical-sectioning contrast. Lock-in detection is used to remove the unmodulated background light, thereby enhancing our ability to image deeply within highly scattering tissues.

We have developed a line-scanned dual-axis confocal (LS-DAC) microscope with subcellular resolution suitable for real time diagnostic imaging at shallow depths. This design serves as a benchtop prototype for a handheld version of the LS-DAC intended for rapid point-of-care pathology. We have assessed the performance trade-offs between the LS-DAC and a point-scanned dual-axis confocal (PS-DAC) microscope via diffraction-theory analysis, Monte-Carlo simulations, and characterization experiments with phantoms and fresh tissues. In addition, we are exploring the use of a sCMOS detector array and rapid 3D deconvolution to improve the sensitivity and resolution of our LS-DAC microscope.

Care for head and neck (HN) cancer could be improved with better mapping of lymphatic drainage pathways in HN region as well as understanding the effect of the cancer treatments on lymphatics. In this study, near-infrared fluorescence imaging is being used to visualize the lymphatics in human subjects diagnosed with HN cancer before and after treatments. Imaging results show the lymphatic architecture and contractile function in HN. Reformation of lymphatics during the course of cancer care was also seen in the longitudinal imaging. This allows us to better understand the lymphatics in HN cancer patients.

Current technologies for cell surface marker screening such as flow cytometry and florescence microscopy, though indispensable, are not well suited for deployment in low resource or point-ofcare settings. Recently, node-pore sensing (NPS) has emerged as a microfluidic platform for labelfree cell surface marker screening. In NPS the transit time of individual cells being flowed through an antibody-functionalized microchannel are measured. Cells that express surface markers corresponding to a functionalized region are delayed due to specific, transient interactions with the surface. In this manner, the presence or absence of a particular surface marker is determined with single cell resolution. Here we show that by measuring the transit time optically as opposed to electrically, the abilities of NPS can be extended. We demonstrate this approach through measurements on human breast cancer cells. The technology presented here could potentially be deployed in low-resource settings as a diagnostic tool.

Herein we present recent improvements in system design and performance evaluation of near-infrared fluorescence (NIRF) frequency-domain photon migration (FDPM) system developed for small animal fluorescence tomography and installed within a commercial micro-CT/PET scanner. We improved system performance by increasing signal-to-noise ratio (SNR) through use of high powered rf modulation, novel data collection scheme, and data discrimination based on the associated noise levels. Noise characteristics show improvement with these techniques and are currently being employed to improve 3-D fluorescence for tomographic reconstructions in phantoms before incorporating into hybrid scanner.

Although there has been a plethora of devices advanced for clinical translation, there has been no standards to compare and determine the optical device for fluorescence molecular imaging. In this work, we compare different CCD configurations using a solid phantom developed to mimic pM - fM concentrations of near-infrared fluorescent dyes in tissues. Our results show that intensified CCD systems (ICCDs) offer greater contrast at larger signal-tonoise ratios (SNRs) in comparison to their un-intensified CCD systems operated at clinically reasonable, sub-second acquisition times. Furthermore, we compared our investigational ICCD device to the commercial NOVADAQ SPY system, demonstrating different performance in both SNR and contrast.

A tri-modal (PET/CT/Optical) small animal tomographic imaging system was developed by integrating our advanced non-contact intensified CCD (ICCD) frequency-domain fluorescence imaging components into a Siemens Inveon scanner. We performed a performance evaluation of the developed imaging system by using the developed regularization-free high-order radiative-transfer-based reconstruction algorithm and custom solid phantoms. Our results show that frequency-domain photon migration (FDPM) fluorescence tomography can achieve better tomographic images with less artifacts and more precise fluorescent source localization compared to the continuous-wave counterpart. The developed multimodal tomographic imaging system provides a powerful tool for translational biomedical research.

Osteoporosis is a common side effect of spinal cord injuries. Blood perfusion in the bone provides an indication of bone health and may help to evaluate therapies addressing bone loss. Current methods for measuring blood perfusion of bone use dyes and ionizing radiation, and yield qualitative results. We present a device capable of measuring blood oxygenation in the tibia. The device illuminates the skin directly over the tibia with a white light source and measures the diffusely reflected light in the near infrared spectrum. Multiple source-detector distances are utilized so that the blood perfusion in skin and bone may be differentiated.

We developed an automated frame selection algorithm for high resolution microendoscope images. The algorithm rapidly selects a representative frame with minimal motion artifact from a short video sequence, enabling fully automated image analysis at the point-of-care. The performance of the algorithm was evaluated by comparing automatically selected frames to manually selected frames using quantitative image parameters. The implementation of fully automated high-resolution microendoscopy at the point-of-care has the potential to reduce the number of biopsies needed for accurate diagnosis of precancer and cancer in low-resource settings, where there may be limited infrastructure and personnel for standard histologic analysis.

Spectral Domain Optical Coherence Tomography (SD-OCT) is a valuable diagnostic tool in both clinical and research settings. The depth-resolved intensity profiles generated by light backscattered from discrete layers of the retina provide a non-invasive method of investigating progressive diseases and injury within the eye. This study demonstrates the application of steerable convolution filters capable of automatically separating gradient orientations to identify edges and delineate tissue boundaries. The edge maps were recombined to measure thickness of individual retinal layers. This technique was successfully applied to longitudinally monitor changes in retinal morphology in a mouse model of laser-induced choroidal neovascularization (CNV) and human data from age-related macular degeneration patients. The steerable filters allow for direct segmentation of noisy images, while novel recombination of weaker segmentations allow for denoising post-segmentation. The segmentation before denoising strategy allows the rapid detection of thin retinal layers even under suboptimal imaging conditions.