The Experts below are selected from a list of 96453 Experts worldwide ranked by ideXlab platform

Simon R Arridge - One of the best experts on this subject based on the ideXlab platform.

Tanja Tarvainen - One of the best experts on this subject based on the ideXlab platform.

David A. Boas - One of the best experts on this subject based on the ideXlab platform.

  • impact of experimental parameter errors on reconstructed breast images using diffuse Optical Tomography
    Biomedical optics, 2016
    Co-Authors: Bin Deng, David A. Boas, Qianqian Fang, Stefan A Carp
    Abstract:

    Mesh based Monte Carlo simulations are used to generate transmission breast diffuse Optical Tomography data. Controlled instrumental errors are then added to test the impact of data degradation on finite element diffusion based image reconstructions.

  • monte carlo simulations of realistic transmission breast Optical Tomography data to estimate the impact of errors in experimental parameters on reconstructed images
    IEEE Transactions on Biomedical Engineering, 2014
    Co-Authors: Amir Y Sajjadi, David A. Boas, Qianqian Fang, Mark Martino, Stefan A Carp
    Abstract:

    We use mesh based Monte Carlo simulations to generate realistic transmission breast diffuse Optical Tomography data. We use these controlled conditions to test the impact of data degradation on finite element diffusion based image reconstructions.

  • Anatomical atlas-guided diffuse Optical Tomography of brain activation
    NeuroImage, 2009
    Co-Authors: Anna Custo, David A. Boas, Daisuke Tsuzuki, Ippeita Dan, Rickson C. Mesquita, Bruce Fischl, W. Eric L. Grimson, William M. Wells
    Abstract:

    We describe a neuroimaging protocol that utilizes an anatomical atlas of the human head to guide diffuse Optical Tomography of human brain activation. The protocol is demonstrated by imaging the hemodynamic response to median-nerve stimulation in three healthy subjects, and comparing the images obtained using a head atlas with the images obtained using the subject-specific head anatomy. The results indicate that using the head atlas anatomy it is possible to reconstruct the location of the brain activation to the expected gyrus of the brain, in agreement with the results obtained with the subject-specific head anatomy. The benefits of this novel method derive from eliminating the need for subject-specific head anatomy and thus obviating the need for a subject-specific MRI to improve the anatomical interpretation of diffuse Optical Tomography images of brain activation.

  • optimal linear inverse solution with multiple priors in diffuse Optical Tomography
    Applied Optics, 2005
    Co-Authors: Greg Boverman, Dana H Brooks, Yiheng Zhang, Eric L Miller, Misha E Kilmer, Quan Zhang, Elizabeth M C Hillman, David A. Boas
    Abstract:

    A general framework for incorporating single and multiple priors in diffuse Optical Tomography is described. We explore the use of this framework for simultaneously utilizing spatial and spectral priors in the context of imaging breast cancer. The utilization of magnetic resonance images of water and lipid content as a statistical spatial prior for the diffuse Optical image reconstructions is also discussed. Simulations are performed to demonstrate the significant improvement in image quality afforded by combining spatial and spectral priors.

  • volumetric diffuse Optical Tomography of brain activity
    Optics Letters, 2003
    Co-Authors: Joseph P Culver, Jonathan J Stott, Andrew M Siegel, David A. Boas
    Abstract:

    We present three-dimensional diffuse Optical Tomography of the hemodynamic response to somatosensory stimulation in a rat. These images show the feasibility of volumetrically imaging the functional response to brain activity with diffuse light. A combination of positional optode calibration and contrast-to-noise ratio weighting was found to improve imaging performance.

Britton Chance - One of the best experts on this subject based on the ideXlab platform.

  • diffuse Optical Tomography with a priori anatomical information
    Physics in Medicine and Biology, 2005
    Co-Authors: Murat Guven, Birsen Yazici, Xavier Intes, Britton Chance
    Abstract:

    Diffuse Optical Tomography (DOT) poses a typical ill-posed inverse problem with a limited number of measurements and inherently low spatial resolution. In this paper, we propose a hierarchical Bayesian approach to improve spatial resolution and quantitative accuracy by using a priori information provided by a secondary high resolution anatomical imaging modality, such as magnetic resonance (MR) or x-ray. In such a dual imaging approach, while the correlation between Optical and anatomical images may be high, it is not perfect. For example, a tumour may be present in the Optical image, but may not be discernable in the anatomical image. The proposed hierarchical Bayesian approach allows incorporation of partial a priori knowledge about the noise and unknown Optical image models, thereby capturing the function-anatomy correlation effectively. We present a computationally efficient iterative algorithm to simultaneously estimate the Optical image and the unknown a priori model parameters. Extensive numerical simulations demonstrate that the proposed method avoids undesirable bias towards anatomical prior information and leads to significantly improved spatial resolution and quantitative accuracy.

  • diffuse Optical Tomography with a priori anatomical information
    Biomedical optics, 2003
    Co-Authors: Murat Guven, Birsen Yazici, Xavier Intes, Britton Chance
    Abstract:

    Diffuse Optical imaging is an emerging modality that uses Near Infrared (NIR) light to reveal structural and functional information of deep biological tissue. It provides contrast mechanisms for molecular, chemical, and anatomical imaging that is not available from other imaging modalities. Diffuse Optical Tomography (DOT) deals with 3D reconstruction of Optical properties of tissue given the measurements and a forward model of photon propagation. DOT has inherently low spatial resolution due to diffuse nature of photons. In this work, we focus to improve the spatial resolution and the quantitative accuracy of DOT by using a priori anatomical information specific to unknown image. Such specific a priori information can be obtained from a secondary high-resolution imaging modality such as Magnetic Resonance (MR) or X-ray. Image reconstruction is formulated within a Bayesian framework to determine the spatial distribution of the absorption coefficients of the medium. A spatially varying a priori probability density function is designed based on the segmented anatomical information. Conjugate gradient method is utilized to solve the resulting optimization problem. Proposed method is evaluated using simulation and phantom measurements collected with a novel time-resolved Optical imaging system. Results demonstrate that the proposed method leads to improved spatial resolution, quantitative accuracy and faster convergence than standard least squares approach.

  • projection access order in algebraic reconstruction technique for diffuse Optical Tomography
    Physics in Medicine and Biology, 2002
    Co-Authors: Xavier Intes, Vasilis Ntziachristos, Joseph P Culver, Arjun G Yodh, Britton Chance
    Abstract:

    Algebraic reconstruction technique (ART) is one of the popular image reconstruction techniques used in diffuse Optical Tomography (DOT). We investigate in this note the influence of the order in which data are accessed in ART. Simulations mimicking breast tissues in transmission geometry with contrast agent tumour enhancement were used to evaluate the image quality of the diverse projection access investigated. We show that by selecting proper projection access order, the convergence speed can be significantly improved when ART is used to perform DOT. Moreover, low-contrast detection is improved.

  • concurrent mri and diffuse Optical Tomography of breast after indocyanine green enhancement
    Proceedings of the National Academy of Sciences of the United States of America, 2000
    Co-Authors: Vasilis Ntziachristos, Arjun G Yodh, Mitchell D Schnall, Britton Chance
    Abstract:

    We present quantitative Optical images of human breast in vivo. The images were obtained by using near-infrared diffuse Optical Tomography (DOT) after the administration of indocyanine green (ICG) for contrast enhancement. The Optical examination was performed concurrently with a magnetic resonance imaging (MRI) exam on patients scheduled for excisional biopsy or surgery so that accurate image coregistration and histopathological information of the suspicious lesions was available. The ICG-enhanced Optical images coregistered accurately with Gadolinium-enhanced magnetic resonance images validating the ability of DOT to image breast tissue. In contrast to simple transillumination, we found that DOT provides for localization and quantification of exogenous tissue chromophore concentrations. Additionally our use of ICG, an albumin bound absorbing dye in plasma, demonstrates the potential to differentiate disease based on the quantified enhancement of suspicious lesions.

Lihong V Wang - One of the best experts on this subject based on the ideXlab platform.

  • slow light for cancer detection ultrasound modulated Optical Tomography using slow light in spectral hole burning materials
    Advanced Photonics (2011) paper SLMB1, 2011
    Co-Authors: P R Hemmer, Huiliang Zhang, Lihong V Wang, Stefan Kroll, Lars Rippe, Mahmood Sabooni, Chulhong Kim
    Abstract:

    Ultrasound modulated Optical Tomography allows Optical imaging with ultrasound resolution in highly scattering tissue, with application to early tumor detection. Slow light provides additional time domain filtering to enhance detection sensitivity.

  • pulsed ultrasound modulated Optical Tomography using spectral hole burning as a narrowband spectral filter
    Applied Physics Letters, 2008
    Co-Authors: Huiliang Zhang, P R Hemmer, Kelvin H Wagner, Chulhong Kim, Lihong V Wang
    Abstract:

    We applied a submegahertz nonlinear Optical filter afforded by a cryogenically cooled spectral-hole burning crystal to ultrasound-modulated Optical Tomography. Our experimental results show that this technique, having the largest etendue among all available ultrasound-modulated Optical Tomography techniques and being immune to speckle decorrelation, offers potential for imaging in vivo and forming high resolution Optical tomograms in real time. It opens an opportunity for the development of a clinically applicable high resolution Optical imaging modality.

  • ultrasound modulated Optical Tomography with intense acoustic bursts
    Applied Optics, 2007
    Co-Authors: Roger J Zemp, Lihong V Wang
    Abstract:

    Ultrasound-modulated Optical Tomography (UOT) detects ultrasonically modulated light to spatially localize multiply scattered photons in turbid media with the ultimate goal of imaging the Optical properties in living subjects. A principal challenge of the technique is weak modulated signal strength. We discuss ways to push the limits of signal enhancement with intense acoustic bursts while conforming to Optical and ultrasonic safety standards. A CCD-based speckle-contrast detection scheme is used to detect acoustically modulated light by measuring changes in speckle statistics between ultrasound-on and ultrasound-off states. The CCD image capture is synchronized with the ultrasound burst pulse sequence. Transient acoustic radiation force, a consequence of bursts, is seen to produce slight signal enhancement over pure ultrasonic-modulation mechanisms for bursts and CCD exposure times of the order of milliseconds. However, acoustic radiation-force-induced shear waves are launched away from the acoustic sample volume, which degrade UOT spatial resolution. By time gating the CCD camera to capture modulated light before radiation force has an opportunity to accumulate significant tissue displacement, we reduce the effects of shear-wave image degradation, while enabling very high signal-to-noise ratios. Additionally, we maintain high-resolution images representative of Optical and not mechanical contrast. Signal-to-noise levels are sufficiently high so as to enable acquisition of 2D images of phantoms with one acoustic burst per pixel.

  • Optical and mechanical properties in photorefractive crystal based ultrasound modulated Optical Tomography
    Biomedical optics, 2006
    Co-Authors: Huiliang Zhang, P R Hemmer, Dekui Qing, Lihong V Wang
    Abstract:

    Ultrasound-modulated Optical Tomography (UOT) is a new technique that combines laser light and ultrasound to provide images with good Optical contrast and good ultrasound resolution in soft biological tissue. We improve the method proposed by Murray et al to obtain UOT images in thick biological tissues with the use of photorefractive crystal based interferometers. It is found that a long ultrasound burst (on the order of a millisecond) can improve the signal-to-noise ratio dramatically. Also with a long ultrasound burst, the response of the acoustic radiation force impulses can be clearly observed in the UOT signal, which will help to acquire images that record both the Optical and mechanical properties of biological soft tissues.

  • ultrasound mediated biophotonic imaging a review of acousto Optical Tomography and photo acoustic Tomography
    Disease Markers, 2004
    Co-Authors: Lihong V Wang
    Abstract:

    This article reviews two types of ultrasound-mediated biophotonic imaging–acousto-Optical Tomography (AOT, also called ultrasound-modulated Optical Tomography) and photo-acoustic Tomography (PAT, also called opto-acoustic or thermo-acoustic Tomography)–both of which are based on non-ionizing Optical and ultrasonic waves. The goal of these technologies is to combine the contrast advantage of the Optical properties and the resolution advantage of ultrasound. In these two technologies, the imaging contrast is based primarily on the Optical properties of biological tissues, and the imaging resolution is based primarily on the ultrasonic waves that either are provided externally or produced internally, within the biological tissues. In fact, ultrasonic mediation overcomes both the resolution disadvantage of pure Optical imaging in thick tissues and the contrast and speckle disadvantages of pure ultrasonic imaging. In our discussion of AOT, the relationship between modulation depth and acoustic amplitude is clarified. Potential clinical applications of ultrasound-mediated biophotonic imaging include early cancer detection, functional imaging, and molecular imaging.