A5051116835- Optical Coherence Tomography Applications
- Advanced Fluorescence Microscopy Techniques
- Photoacoustic and Ultrasonic Imaging
- Cell Image Analysis Techniques
- Optical Imaging and Spectroscopy Techniques
- Advanced Neuroimaging Techniques and Applications
- Advanced MRI Techniques and Applications
- Glaucoma and retinal disorders
- Functional Brain Connectivity Studies
- Cultural Heritage Materials Analysis
- Robotics and Sensor-Based Localization
- Retinal Imaging and Analysis
- Medical Image Segmentation Techniques
- Cerebrovascular and Carotid Artery Diseases
- Thermoregulation and physiological responses
- Advanced Image and Video Retrieval Techniques
- Color perception and design
- Image and Signal Denoising Methods
- Aesthetic Perception and Analysis
- Neurological Disease Mechanisms and Treatments
- Neonatal and fetal brain pathology
- Spectroscopy Techniques in Biomedical and Chemical Research
- Advanced Vision and Imaging
- Neuroinflammation and Neurodegeneration Mechanisms
- Alzheimer's disease research and treatments
Athinoula A. Martinos Center for Biomedical Imaging
2015-2025
Massachusetts General Hospital
2015-2025
Harvard University
2014-2025
MGH Institute of Health Professions
2024
Boston University
2021
Inserm
2014
Seoul National University
2013
Magna International (Germany)
2013
Sorbonne Université
2008-2010
Centre National de la Recherche Scientifique
2009-2010
Optical coherence tomography (OCT) and optical microscopy (OCM) have demonstrated the ability to investigate cyto- myelo-architecture in brain. Polarization-sensitive OCT provides sensitivity additional contrast mechanisms, specifically birefringence of myelination and, therefore, is advantageous for investigating white matter fiber tracts. In this Letter, we developed a polarization-sensitive microscope (PS-OCM) with 3.5 μm axial 1.3 transverse resolution organization orientation at finer...
Aging is one of the major risk factors for white matter injury in cerebrovascular disease. However, effects age on mechanisms injury/repair remain to be fully elucidated. Here, we ask whether, compared with young brains, regions older brains may more vulnerable part because decreased rates compensatory oligodendrogenesis after injury.A mouse model prolonged cerebral hypoperfusion was prepared by bilateral common carotid artery stenosis 2-month and 8-month-old mice. Matching vitro studies...
In the first study comparing high angular resolution diffusion MRI (dMRI) in human brain to axonal orientation measurements from polarization-sensitive optical coherence tomography (PSOCT), we compare accuracy of estimates various dMRI sampling schemes and reconstruction methods. We find that, if approach is chosen carefully, single-shell data can yield same as multi-shell data, only moderately lower than a full Cartesian-grid scheme. Our results suggest that current approaches do not...
The cytoarchitecture of the human brain is great interest in diverse fields: neuroanatomy, neurology, neuroscience, and neuropathology. Traditional histology a method that has been historically used to assess cell fiber content ex vivo brain. However, this technique suffers from significant distortions. We previously demonstrated optical coherence microscopy image individual neurons several square millimeters en-face tissue blocks layer II entorhinal cortex, over 50 µm depth. same slices...
Brain cells are arranged in laminar, nuclear, or columnar structures, spanning a range of scales. Here, we construct reliable cell census the frontal lobe human cerebral cortex at micrometer resolution magnetic resonance imaging (MRI)-referenced system using innovative and analysis methodologies. MRI establishes macroscopic reference coordinate laminar cytoarchitectural boundaries. Cell counting is obtained with digital stereological approach on 3D reconstruction cellular from custom-made...
Quantification of tissue optical properties with coherence tomography (OCT) has proven to be useful in evaluating structural characteristics and pathological changes. Previous studies primarily used an exponential model analyze low numerical aperture (NA) OCT measurements obtain the total attenuation coefficient for biological tissue. In this study, we develop a systematic method that includes confocal parameter modeling depth profiles high NA OCT, when cannot ignored. This approach enables...
As scientists interested in fetal, infant, and toddler (FIT) neurodevelopment, our research questions often focus on how individual children differ their neurodevelopment the predictive value of those differences for long-term neural behavioral outcomes. Measuring interpreting can present challenges: Is there a "standard" way human brain to develop? How do semantic, practical, or theoretical constraints that we place studying "development" influence measure interpret differences? While it is...
The importance of polarization-sensitive optical coherence tomography (PS-OCT) has been increasingly recognized in human brain imaging. Despite the recent progress PS-OCT revealing white matter architecture and orientation, quantification fine-scale fiber tracts cortex a challenging problem, due to low birefringence gray matter. In this study, we investigated effect refractive index matching by 2,2’-thiodiethanol (TDE) immersion on improvement measurements ex vivo tissue. We show that can...
Abstract Optical coherence tomography (OCT) is an emerging 3D imaging technique that allows quantification of intrinsic optical properties such as scattering coefficient and back-scattering coefficient, has proved useful in distinguishing delicate microstructures the human brain. The origins brain tissues are contributed by myelin content, neuron size density primarily; however, no quantitative relationships between them have been reported, which hampers use OCT fundamental studies...
We report on local superficial blood flow monitoring in biological tissue from laser Doppler holographic imaging. In time averaging recording conditions, holography acts as a narrowband bandpass filter, which, combined with frequency shifted reference beam, permits selective imaging the radiofrequency range. These images are acquired an off axis Mach Zehnder interferometer. Microvascular hemodynamic components mapping is performed cerebral cortex of mouse and eye fundus rat near-infrared...
Significance: The optical properties of biological samples provide information about the structural characteristics tissue and any changes arising from pathological conditions. Optical coherence tomography (OCT) has proven to be capable extracting tissue's using a model that combines exponential decay due scattering axial point spread function arises confocal nature detection system, particularly for higher numerical aperture (NA) measurements. A weakness in estimating is inter-parameter...
Serial sectioning optical coherence tomography (OCT) enables accurate volumetric reconstruction of several cubic centimeters human brain samples. We aimed to identify anatomical features the ex vivo brain, such as intraparenchymal blood vessels and axonal fiber bundles, from OCT data in 3D, using intrinsic contrast.We developed an automatic processing pipeline enable characterization microvascular network samples.We demonstrated extraction down a 20 μm diameter filtering strategy followed by...
We report the use of frequency compounding to significantly reduce speckle noise in optical coherence microscopy, more specifically on en face images. This method relies fact that patterns recorded from different wavelengths simultaneously are independent; hence their summation yields significant reduction noise, with only a single acquisition. The results our experiments microbeads show narrow confocal parameter, due high numerical aperture objective, restricts axial resolution loss would...
Optical coherence tomography (OCT) images of ex vivo human brain tissue are corrupted by multiplicative speckle noise that degrades the contrast to ratio (CNR) microstructural compartments. This work proposes a novel algorithm reduce corruption in OCT minimizes penalized negative log likelihood gamma distributed noise. The proposed method is formulated as majorize-minimize problem reduces solving an iterative regularized least squares optimization. We demonstrate usefulness removing...
The auxiliary function method is an efficient technique for solving the radiative tranfer equation without adding any assumption and was applied until now only theoretical stratified media. first application (to our knowledge) of to a real case, human skin, presented. This makes it possible validate by comparing model results with experimental reflectance spectra skin. An excellent agreement obtained multilayer skin made 22 sublayers taking into account anisotropic phase scatterers. Thus...
We report laser Doppler ophthalmoscopic fundus imaging in the rat eye with near-IR heterodyne holography. Sequential sampling of beat reflected radiation against a frequency-shifted optical local oscillator is made onto an array detector. Wide-field maps fluctuation spectra 10 Hz to 25 kHz band exhibit angiographic contrasts retinal vascular tree without requirement exogenous marker.
In a previous article [J. Opt. Soc. Am. A 24, 2196 (2007)] we have modeled skin color using the radiative transfer equation, solved by auxiliary function method. Three main parameters been determined as being predominant in diversity of color: concentrations melanosomes and red blood cells oxygen saturation blood. From reflectance spectrum measured on real Caucasian skin, these are now evaluated minimizing standard deviation adjusted wavelength range between experimental simulated spectra...
Neuroimaging studies have routinely used hippocampal volume as a measure of Alzheimer's disease severity, but changes occur too late in the process for potential therapies to be effective. The entorhinal cortex is one first cortical areas affected by disease; its neurons are especially vulnerable neurofibrillary tangles. Entorhinal atrophy also relates conversion from non-clinical clinical disease. In neuroimaging, human has so far mostly been considered entirety or divided into medial and...
Abstract The study of aging and neurodegenerative processes in the human brain requires a comprehensive understanding cytoarchitectonic, myeloarchitectonic, vascular structures. Recent computational advances have enabled volumetric reconstruction using thousands stained slices, however, tissue distortions loss resulting from standard histological processing hindered deformation‐free reconstruction. Here, authors describe an integrated serial sectioning polarization‐sensitive optical...