scholarly journals Functional Imaging of the Ocular Fundus Using an 8-Band Retinal Multispectral Imaging System

Instruments ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 12
Author(s):  
Emanuel R. de Carvalho ◽  
Richelle J. M. Hoveling ◽  
Cornelis J. F. van Noorden ◽  
Reinier O. Schlingemann ◽  
Maurice C. G. Aalders
Keyword(s):  
Oxygen Saturation ◽  
Functional Imaging ◽  
Multispectral Imaging ◽  
Imaging System ◽  
Imaging Techniques ◽  
Incident Light ◽  
Contrast Imaging ◽  
Blood Oxygen Saturation ◽  
Full Scan

Application of functional imaging in ophthalmology requires efficient imaging techniques that can detect and quantify chromophores to visualise processes in vivo. The aim of the present study was to develop and evaluate a fast and affordable imaging system. We describe an eight-band retinal multispectral imaging (MSI) system and compare it with a hyperspectral imaging (HSI) device. Determination of blood oxygen saturation was studied as proof of principle. Reflectance of incident light is measured as 1/absorbance at different wavelengths between 440 nm and 580 nm. Both devices have incorporated optical bandpass filters in a mydriatic fundus camera. The MSI system scans the retina at eight pre-defined wavelengths specific for the spectrum of haemoglobin. The HSI system acquires a full scan from 480 to 720 nm in 5 nm steps. A simple assessment of the ratio between the absorbance peaks of oxygenated haemoglobin (HbO2) and reduced haemoglobin (HbR) was not suitable for generating validated oxygenation maps of the retina. However, a correction algorithm that compares the measured reflectance with reflectance spectra of fully oxygenated and fully deoxygenated blood allowed our MSI setup to estimate relative oxygen saturation at higher levels, but underestimated relative oxygen saturation at lower levels. The MSI device generated better quality images than the HSI device. It allows customisation with filter sets optimised for other chromophores of interest, and augmented with extrinsic contrast imaging agents, it has the potential for a wider range of ophthalmic molecular imaging applications.

MULTISPECTRAL IMAGING SYSTEM FOR QUANTITATIVE ASSESSMENT OF TRANSCUTANEOUS BLOOD OXYGEN SATURATION

2015 ◽  
Vol 77 (7) ◽  
Author(s):  
Sheena P. Philimon ◽  
Audrey K. C. Huong ◽  
Xavier T. I. Ngu
Keyword(s):  
Oxygen Saturation ◽  
Multispectral Imaging ◽  
Continuous Wave ◽  
Imaging System ◽  
Left Index Finger ◽  
Blood Oxygen ◽  
Blood Oxygen Saturation ◽  
Fitting Algorithm ◽  
Alternative Means ◽  
Spectroscopy System

This paper presents the use of Extended Modified Lambert Beer (EMLB) model for quantification of transcutaneous blood oxygen saturation (StO2) via a noninvasive approach. Continuous wave (CW) reflectance spectroscopy system is employed for measurement of intensity reflected from left index finger of an Asian nonsmoking volunteer at resting condition. Multispectral images captured in the wavelength range of 520 − 600 nm at an interval of 10 nm are mathematically analyzed and fitted using the developed fitting algorithm to give the best estimation of StO2. The result from this preliminary study revealed a mean StO2 value of 75 ± 5% for the participating individual, which value agreed considerably well with that presented in previous works. This work concluded that the developed spectroscopy system and quantification technique can potentially be used as an alternative means to clinical assessment of wound healing progress

scholarly journals Optical Measurement of Blood Oxygen Saturation of Dental Pulp

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Satoko Kakino ◽  
Shinya Kushibiki ◽  
Azusa Yamada ◽  
Zenzo Miwa ◽  
Yuzo Takagi ◽  
...  
Keyword(s):  
Light Intensity ◽  
Oxygen Saturation ◽  
Dental Pulp ◽  
Optical Measurement ◽  
Blood Oxygen ◽  
Arterial Pulse ◽  
Blood Oxygen Saturation ◽  
Visible Wavelengths

The applicability of arterial pulse oximetry to dental pulp was demonstrated using in vitro and in vivo measurements. First, porcine blood of known oxygen saturation (SO2) was circulated through extracted human upper incisors, while transmitted-light plethysmography was performed using three different visible wavelengths. From the light intensity waveforms measured in vitro, a parameter that is statistically correlated to SO2 was calculated using the pulsatile/nonpulsatile component ratios of two wavelengths for different SO2. Then, values were measured in vivo for living incisors, and the corresponding SO2 values were calculated using the results of in vitro measurements. The estimated SO2 values of the upper central incisors measured in vivo were from 71.0 to 92.7%. This study showed the potential to measure the oxygen saturation changes to identify the sign of pulpal inflammation.

scholarly journals Multimodal Functional Imaging for Cancer/Tumor Microenvironments Based on MRI, EPRI, and PET

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1614
Author(s):  
Ken-ichiro Matsumoto ◽  
James B. Mitchell ◽  
Murali C. Krishna
Keyword(s):  
Radiation Therapy ◽  
Functional Imaging ◽  
Imaging Techniques ◽  
Biological Effects ◽  
Tumor Hypoxia ◽  
Redox Status ◽  
Blood Oxygen Level Dependent ◽  
Oxygen Level ◽  
Cancer Tumor

Radiation therapy is one of the main modalities to treat cancer/tumor. The response to radiation therapy, however, can be influenced by physiological and/or pathological conditions in the target tissues, especially by the low partial oxygen pressure and altered redox status in cancer/tumor tissues. Visualizing such cancer/tumor patho-physiological microenvironment would be a useful not only for planning radiotherapy but also to detect cancer/tumor in an earlier stage. Tumor hypoxia could be sensed by positron emission tomography (PET), electron paramagnetic resonance (EPR) oxygen mapping, and in vivo dynamic nuclear polarization (DNP) MRI. Tissue oxygenation could be visualized on a real-time basis by blood oxygen level dependent (BOLD) and/or tissue oxygen level dependent (TOLD) MRI signal. EPR imaging (EPRI) and/or T1-weighted MRI techniques can visualize tissue redox status non-invasively based on paramagnetic and diamagnetic conversions of nitroxyl radical contrast agent. 13C-DNP MRI can visualize glycometabolism of tumor/cancer tissues. Accurate co-registration of those multimodal images could make mechanisms of drug and/or relation of resulted biological effects clear. A multimodal instrument, such as PET-MRI, may have another possibility to link multiple functions. Functional imaging techniques individually developed to date have been converged on the concept of theranostics.

scholarly journals In vivo imaging of swimming micromotors using hybrid high-frequency ultrasound and photoacoustic imaging

2020 ◽  
Author(s):  
Azaam Aziz ◽  
Joost Holthof ◽  
Sandra Meyer ◽  
Oliver G. Schmidt ◽  
Mariana Medina-Sánchez
Keyword(s):  
High Frequency ◽  
Imaging System ◽  
Ex Vivo ◽  
Photoacoustic Imaging ◽  
Imaging Techniques ◽  
High Frequency Ultrasound ◽  
Living Organisms ◽  
And Function ◽  
Frequency Ultrasound

AbstractThe fast evolution of medical micro- and nanorobots in the endeavor to perform non-invasive medical operations in living organisms boosted the use of diverse medical imaging techniques in the last years. Among those techniques, photoacoustic (PA) tomography has shown to be promising for the imaging of microrobots in deep-tissue (ex vivo and in vivo), as it possesses the molecular specificity of optical techniques and the penetration depth of ultrasound imaging. However, the precise maneuvering and function control of microrobots, in particular in living organisms, demand the combination of both anatomical and functional imaging methods. Therefore, herein, we report the use of a hybrid High-Frequency Ultrasound (HFUS) and PA imaging system for the real-time tracking of magnetically driven micromotors (single and swarms) in phantoms, ex vivo, and in vivo (in mice bladder and uterus), envisioning their application for targeted drug-delivery.

scholarly journals Fundus Autofluorescence and Clinical Applications

2021 ◽  
Author(s):  
Cameron Pole ◽  
Hossein Ameri
Keyword(s):  
Structural Changes ◽  
Clinical Evidence ◽  
Imaging Techniques ◽  
Incident Light ◽  
Fundus Autofluorescence ◽  
Clinical Applications ◽  
Retinal Degenerations ◽  
Clinical Scenarios ◽  
Before And After

Fundus autofluorescence (FAF) has allowed in vivo mapping of retinal metabolic derangements and structural changes not possible with conventional color imaging. Incident light is absorbed by molecules in the fundus, which are excited and in turn emit photons of specific wavelengths that are captured and processed by a sensor to create a metabolic map of the fundus. Studies on the growing number of FAF platforms has shown each may be suited to certain clinical scenarios. Scanning laser ophthalmoscopes, fundus cameras, and modifications of these each have benefits and drawbacks that must be considered before and after imaging to properly interpret the images. Emerging clinical evidence has demonstrated the usefulness of FAF in diagnosis and management of an increasing number of chorioretinal conditions, such as agerelated macular degeneration, central serous chorioretinopathy, retinal drug toxicities, and inherited retinal degenerations such as retinitis pigmentosa and Stargardt disease. This article reviews commercial imaging platforms, imaging techniques, and clinical applications of FAF.

scholarly journals A practical method for multimodal registration and assessment of whole-brain disease burden using PET, MRI, and optical imaging

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Matthew L. Scarpelli ◽  
Debbie R. Healey ◽  
Shwetal Mehta ◽  
Vikram D. Kodibagkar ◽  
Christopher C. Quarles
Keyword(s):  
Optical Imaging ◽  
Imaging System ◽  
Ex Vivo ◽  
Imaging Techniques ◽  
Neurological Diseases ◽  
Spatial Scales ◽  
Phenotypic Heterogeneity ◽  
Tissue Slices ◽  
Rodent Brain

Abstract Many neurological diseases present with substantial genetic and phenotypic heterogeneity, making assessment of these diseases challenging. This has led to ineffective treatments, significant morbidity, and high mortality rates for patients with neurological diseases, including brain cancers and neurodegenerative disorders. Improved understanding of this heterogeneity is necessary if more effective treatments are to be developed. We describe a new method to measure phenotypic heterogeneity across the whole rodent brain at multiple spatial scales. The method involves co-registration and localized comparison of in vivo radiologic images (e.g. MRI, PET) with ex vivo optical reporter images (e.g. labeled cells, molecular targets, microvasculature) of optically cleared tissue slices. Ex vivo fluorescent images of optically cleared pathology slices are acquired with a preclinical in vivo optical imaging system across the entire rodent brain in under five minutes, making this methodology practical and feasible for most preclinical imaging labs. The methodology is applied in various examples demonstrating how it might be used to cross-validate and compare in vivo radiologic imaging with ex vivo optical imaging techniques for assessing hypoxia, microvasculature, and tumor growth.

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