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Fr-040-A transportable hyperspectral imaging setup based on fast, high-density spectral scanning for in situ quantitative biochemical mapping of fresh tissue biopsies
We present here a transportable, high-density, hyperspectral imaging setup, named HyperProbe1, to provide in situ, fast biochemical analysis of fresh surgical samples, within 1 hour after excision. The system is applied on ex vivo biopsies of glioma from routine patients, including different tumour gradings. Quantitative analysis of the composition of the tissue is performed via fast spectral unmixing to map biomarkers, such as oxy- and deoxyhaemoglobin, cytochrome-c-oxidase and lipid content. The versatility of HyperProbe1 can enable its utilisation as investigative tool to provide tailored HSI technology, that could be translated into the clinics as compact, cost-effective prototypes for intraoperative neuronavigation. Continue reading
Vi-025-Imaging static absorbing properties using wavelength modulated near-infrared spectroscopy
A method called wavelength-modulated near-infrared spectroscopy is used to estimate the absolute concentrations of absorbers in highly scattering media using measurements of the rate of change of optical attenuation with wavelength. The method is demonstrated using three experimental systems based on a wavelength-modulated source, a spectrometer, and discrete sources at adjacent wavelengths. Measurements are independent of absolute intensity and thus less influenced by changes in coupling (to which hair is a significant contributor) which cause artefacts in conventional NIRS data. Images of a tissue equivalent phantom clearly reveal internal absorbers despite a random layer of dark hair on the surface. Continue reading
Fr-075-Hyperspectral time-resolved near-infrared spectroscopy technique for adult neuromonitoring
Hyperspectral time-resolved near-infrared spectrometers have the potential to monitor adult cerebral blood oxygenation and metabolism with minimal extracerebral contamination; however, they are typically limited by trade-offs between spectral range, spectral resolution, and sampling rate. This work presents a hyperspectral time-resolved near-infrared spectrometer that uses compressive sensing to enable fast data acquisition while maintaining spectral range and resolution. The sensitivity of the device to changes in blood oxygenation and metabolism in deep tissue was confirmed in phantom experiments with comparison to gold standard measures. Future work will validate the sensitivity of the device to adult cerebral blood oxygenation and metabolism. Continue reading
Sa-041-A high-density hyperspectral imaging system for real-time quantitative biochemical monitoring of ex vivo and in vivo brain tissue
We present here HyperProbe1.1; a hyperspectral imaging setup based on fast spectral scanning up to 127 spectral bands (385 to 1015 nm). It utilises a plasma laser source coupled to a flexible wavelength selector to access any wavelength with adjustable bandwidth (3 to 15 nm). HyperProbe1.1 captures images of a 1x1-cm2 field of view with 15.63-μm resolution. The setup has been fully characterised: enhanced image contrast, signal-to-noise ratio and stability ensure clearer and more interpretable imagery for quantitative biochemical analysis of the exposed cerebral tissue. HyperProbe1.1 will be applied to image fresh tumour biopsies and in preclinical models of glioma. Continue reading
Su-025-Fiber-less speckle contrast optical spectroscopy system using a multi-hole aperture method
A multi-hole aperture fiber-less SCOS system is proposed. In conventional SCOS systems, there exists an upper limit on the aperture size, since the minimum speckle size must be greater than the Nyquist pixel rate. Consequently, obtaining high light intensity under long source-detector distance is a challenge. In the solid phantom experiment, the proposed multi-hole aperture SCOS system exhibits higher intensity and contrast compared to conventional single-hole aperture SCOS system. In both two-layer liquid phantom and in-vivo arm-cuff extension experiments, the proposed system exhibits higher sensitivity with respect to the blood flow. Continue reading
Fr-014-Comparison of Commercially Available LEDs for Broadband NIRS
This study presents an experimental evaluation aiming to assess the feasibility of using commercially available broadband Light Emitting Diodes (LEDs) as potential substitutes for the traditional tungsten halogen (TH) light sources in broadband Near-Infrared Spectroscopy (bNIRS) applications with demonstration in arm occlusion experiments. Results indicated similar chromophore concentration changes and area under curve metrics across all light sources. The findings suggest that LEDs can replace halogen sources in bNIRS applications. Continue reading
Fr-048-Illumind: An Accessible, Flexible Graphical User Interface for Hemodynamic and Fluorescent Widefield Imaging
In order to make widefield optical imaging (WOI) accessible to a wide range of neuroscience laboratories, acquisition software must become user-friendly. We have replaced vendor-specific interfaces and the MATLAB command line with an integrated graphical user interface, termed Illumind. This program integrates with hardware to automatically determine system capabilities. Hemodynamic and fluorescence imaging are easily performed with automated calibration and error handling. Illumind reduces the training needed prior to performing WOI imaging. Modularity allows for integration of new camera hardware and fluorophores. Standardized metadata with JSON files enables streamlined integration with flexible processing. Continue reading
Sa-061-Low-cost, portable, multi-purpose, versatile module for speckle contrast optical spectroscopy/tomography
Speckle contrast optical spectroscopy/tomography (SCOS/SCOT) is emerging as a low-cost, compact technology for non-invasive blood flow monitoring. To match the growing number of its potential applications and the different project needs, we have designed a configurable SCOS/SCOT hardware module that can readily be stacked for multi-channel use and hybridized with other modalities. An internal computation unit and a software suite are provided for the processing, transfer, and display of the data, cloud computing is utilized for data storage, and redundant smart systems are deployed for laser safety. Continue reading
Sa-090-A modular TD-fNIRS system for many applications
Kernel has developed a new and modular system for time-domain functional near-infrared spectroscopy (TD-fNIRS). We have previously demonstrated the ability of the system to accurately measure absolute optical properties and tissue oxygen saturation. Here, we will present a highly configurable form factor that we’ve made to enable additional applications using our core modular TD-NIRS technology. We will share results that demonstrate the ability of our system to resolve functional brain activation along with physiological signals. In summary, these technological innovations allow for the development of new applications of TD-fNIRS that use a modular, scalable system for measuring multimodal brain signals. Continue reading
Sa-093-Optimizing Short Distance Diffuse Correlation Spectroscopy
Diffuse correlation spectroscopy (DCS) is a promising method for non-invasively monitoring cerebral blood flow (CBF). Its accuracy requires accounting for signal contamination from scalp blood flow, typically performed by recording DCS signals at a short source-detector separation (SDS), in addition to a longer SDS that provides sensitivity to CBF. However, balancing the signal-to-noise ratio (SNR) at the two distances is challenging. Our study investigates the potential impact of emitter light intensity on short separation DCS measurements. Continue reading