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Time-resolved diffuse optical tomography using a modified generalized pulse spectrum technique

IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2002年第1期E85D卷 133-142页

作者： Gao, F Zhao, HJ Tanikawa, Y Yamada, Y Natl Inst Adv Ind Sci & Technol Inst Human Sci & Biomed Engn Tsukuba Ibaraki 3058564 Japan Univ Electrocommun Dept Mech Engn & Intelligent Syst Chofu Tokyo 1828585 Japan

generalized pulse spectrum technique (GPST) is a method to solve the inverse problems of wave-propagation and diffusion-dominated phenomena, and therefore has been popularly applied in image reconstruction of time-resolved diffuse optical tomography. With a standard GPST for simultaneous re construction of absorption and scattering coefficients, the products of the gradients of the Green's function and the photon-density flux, based on the photon-diffusion equation, are required to calculate the diffusion-related Jacobian matrix. The adversities are of two-folds: time-consuming and singular in the field near the source. The latter causes a severe insensitivity of the algorithm to the scattering changes deep inside tissue. To cope with the above difficulties, we propose(,. in this paper a modified GPST algorithm that only involves the Green's function and the photon-density flux themselves in the scattering-related matrix. Our simulated and experimental reconstruct ions show that the modified algorithm can significantly improve the quality of scattering image and accelerate the reconstruction process, without an evident degradation in absorption image.

关键词： generalized pulse spectrum technique time-resolved diffuse optical tomography photon diffusion equation inverse problems

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Three-dimensional image reconstruction for time-domain fluorescence molecular tomography based on generalized pulse spectrum technique

Three-dimensional image reconstruction for time-domain fluor...

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Conference on Optics in Health Care and Biomedical Opticals III

作者： Zhang, Limin Gao, Feng He, Huiyuan Ma, Yiwen Ruan, Pingqiao Zhao, Huijuan Tianjin Univ Coll Precis Instrument & Optoelect Engn Tianjin 300072 Peoples R China

ISBN: (纸本)9780819470010

A linear generalized pulse spectrum technique for image reconstruction of fluorescence molecular tomography is proposed. The algorithm employs a finite element method solution to the Laplace-transformed coupled diffusion equations and can simultaneously reconstruct both fluorescent yield and lifetime images of fluorophores. The proposed algorithm was validated using simulated data for 3D phantoms. We investigated the ability of the algorithm to reconstruct the fluorescent yield and lifetime at different region, contrasted the imaging quality of different target lifetime and proved the noise-robustness by using noisy data with different signal-to-noise ratio. The results show that the approach accurately retrieves the position and shape of the target and prove the effectiveness of the methodology.

关键词： fluorescence molecular tomography time-domain mode generalized pulse spectrum technique diffuse optical tomography

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Data optimization for enhancing robustness of time-resolved reflectance diffuse optical tomography to optode position uncertainty

Data optimization for enhancing robustness of time-resolved ...

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Conference on Optical Tomography and Spectroscopy of Tissue VI

作者： Gao, F Zhao, HJ Tanikawa, Y Yamada, Y Tianjin Univ Coll Precis Instrument & Optoelect Engn Tianjin 300072 Peoples R China

ISBN: (纸本)0819456675

The absolute diffuse optical tomography (DOT) has been rather difficult to achieve due to the problems arising upon the robustness of the algorithm to uncertainties in measuring conditions. Alternatively, the differential imaging scheme was applied to reconstruct a difference image between a target and a baseline reference from the difference data. Nevertheless, the absolute imaging scheme is desirable for unavailability of the reference in many situations. The absolute imaging usually uses intensity-independent data-type, which has been popularly the mean time of flight (TOF) in time-resolved (TR) detection, to avoid absolute instrument scaling. A problem with the mean TOF is its is insufficient sensitivity to deep absorption change to cope with the measuring noises, such as uncertainty of the optode positions. Therefore seeking for more robust data-type has been a key task in the community. We have previously developed an image reconstruction algorithm for TR-DOT, based on the modified generalized pulse spectrum technique (GPST), where the ratio between the Laplace-transformed TR re-emissions at two real-domain frequencies is used as the data-type. It is computationally the same efficient as the mean TOF but offers a potentiality to enhance noise-robustness by optimizing the working frequencies. We demonstrate here that the robustness of this data-type to optode position uncertainty can be substantially increased by enlarge the difference between the two working frequencies. We optimize the working frequencies within the range of physical sense and numerically validate the method for brain-simulating two-layer geometry using the TR reflected light.

关键词： diffuse optical tomography data type time-resolved detection image reconstruction algorithm generalized pulse spectrum technique

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Fluorescence diffuse optical tomography by full time-resolved scheme

Fluorescence diffuse optical tomography by full time-resolve...

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Conference on Optical Tomography and Spectroscopy of Tissue VII

作者： Gao, Feng Miao, Hui Zhao, Huijuan Tanikawa, Yukari Yamada, Yukio Tianjin Univ Coll Precis Instrument & Optoelect Engn Tianjin 300072 Peoples R China Natl Inst Adv Ind Sci & Technol Inst Human Sci & Biomed Engn Tsukuba Ibaraki 3058564 Japan Univ Electrocommun Dept Mech Engn & Intelligent Syst Tokyo 1828585 Japan

ISBN: (纸本)9780819465474

A full time-resolved (TR) scheme that has been previously developed for diffuse optical tomography is extended to time-domain fluorescence diffuse optical tomography regime, based on the finite-element-finite-time-difference diffusion modeling and the Newtown-Raphson inversion method. We validate the proposed methodology using simulated data and demonstrate its capability of simultaneously recovering the fluorescent yield and lifetime, as well as its superiority of improving quantitative accuracy and spatial resolution of reconstruction to the featured-data one. The full time-resolved scheme helps set up the 'gold standard' for evaluating the performance of the other featured-data ones, and is more practically feasible in molecular imaging than in generic diffuse optical tomography due to availability of the difference measuring.

关键词： diffuse optical tomography data type time-resolved detection image reconstruction algorithm generalized pulse spectrum technique

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An analytic scheme for time-domain diffuse fluorescence tomography in circular geometry: methodology and validation

An analytic scheme for time-domain diffuse fluorescence tomo...

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Conference on Optics in Health Care and Biomedical Optics IV

作者： Li, Jiao Gao, Feng Wang, Xin Zhang, Limin Zhao, Huijuan Tianjin Univ Coll Precis Instruments & Optoelect Engn Tianjin 300072 Peoples R China

ISBN: (纸本)9780819483751

Near-infrared fluorescence diffuse optical tomography has proven to be an efficient tool for visualizing the bio-distributions of fluorescent markers in tissue. We present a two-dimensional image reconstruction method for time-domain fluorescence diffuse optical tomography on a turbid medium of circular domain. The methodology is based on a linear generalized pulse spectrum technique that employs the analytical solution to the Laplace-transformed time-domain photon-diffusion equation to construct a Born normalized inverse model. A pair of real domain transform-factors is introduced to simultaneously reconstruct the fluorescent yield and lifetime images and the resultant linear inversions are solved using an algebraic reconstruction technique. The algorithm is validated using simulated data, and the spatial resolution, noise-robustness and so on are assessed. The experimental validation is performed using a multi-channel time-correlated single-photon-counting system and a cylinder phantom that embeds a fluorescent target made from 1%-Intralipid solution and Cy5.5 agent. The results show that the approach retrieves the position and shape of the target with a reasonable accuracy.

关键词： Fluorescence Diffuse Optical Tomography Analytic Solution to the Diffuse Equation Algebraic Reconstruction technique generalized pulse spectrum technique Time-Correlated Single Photon Counting

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PH-sensitive fluorescence detection by diffuse fluorescence tomography

PH-sensitive fluorescence detection by diffuse fluorescence ...

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Conference on Multimodal Biomedical Imaging VII

作者： Li, Jiao Gao, Feng Duan, Linjing Wang, Xin Zhang, Limin Zhao, Huijuan Tianjin Univ Coll Precis Instruments & Optoelect Engn Tianjin 300072 Peoples R China

ISBN: (纸本)9780819488596

The importance of cellular pH has been shown clearly in the study of cell activity, pathological feature, drug metabolism, etc. Monitoring pH changes of living cells and imaging the regions with abnormal pH values in vivo could provide the physiologic and pathologic information for the research of the cell biology, pharmacokinetics, diagnostics and therapeutics of certain diseases such as cancer. Thus, pH-sensitive fluorescence imaging of bulk tissues has been attracting great attention in the regime of near-infrared diffuse fluorescence tomography (DFT), an efficient small-animal imaging tool. In this paper, the feasibility of quantifying pH-sensitive fluorescence targets in turbid medium is investigated using both time-domain and steady-state DFT methods. By use of the specifically designed time-domain and continuous-wave systems and the previously proposed image reconstruction scheme, we validate the method through 2-dimensional imaging experiments on a small-animal-sized phantom with multiply targets of distinct pH values. The results show that the approach can localize the targets with reasonable accuracy and achieve quantitative reconstruction of the pH-sensitive fluorescent yield.

关键词： Diffuse Fluorescence Tomography pH-sensitive detection Quantitative Reconstruction generalized pulse spectrum technique Photon Counting

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A pilot characterization of quantitative time-domain fluorescence diffuse optical tomography

A pilot characterization of quantitative time-domain fluores...

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Conference on Optical Tomography and Spectroscopy of Tissue IX

作者： Li, Jiao Gao, Feng Yi, Xi Wang, Xin Wu, Linhui Zhu, Pingping Zhang, Limin Zhao, Huijuan Tianjin Univ Coll Precis Instruments & Optoelect Engn Tianjin 300072 Peoples R China Tianjin Univ Key Lab Biomed Detecting Technique & Instrument Tianjin 300072 Peoples R China

ISBN: (纸本)9780819484338

Quantitative measurements of fluorescent parameters have merited great interest lately for near-infrared fluorescence diffuse optical tomography - the efficient small animal imaging tool. We present a two-dimensional image reconstruction method for time-domain fluorescence diffuse optical tomography, which employs the analytical solution to the Laplace-transformed time-domain photon-diffusion equation to construct the inverse model and introduces a pair of real-domain transform-factors to effectively separate the fluorescent yield and lifetime parameters from the algebraic reconstruction technique solutions to the resultant linear inversions. By use of a specifically designed a multi-channel time-correlated single photon counting system and a normalized Born formulation for the inversion, the proposed scheme in a circular domain is experimentally validated using small-animal-sized cylindrical phantoms that embed several fluorescent targets made from 1%-Intralipid solution and differently contrasting fluorescent agents, where the time-resolved excitation and fluorescence signals are measured on the boundary. The results show that the approach retrieves the positions and shapes of the targets with a reasonable accuracy and simultaneously achieve quantitative reconstruction of the fluorescent yield and lifetime.

关键词： Fluorescence Diffuse Optical Tomography Analytic Solution to the Diffuse Equation Quantitative Reconstruction generalized pulse spectrum technique Time-Correlated Single Photon Counting

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In-vivo experimental validation for a featured-data time-domain diffuse fluorescence tomography based on the radiative transfer equation 11

In-vivo experimental validation for a featured-data time-dom...

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Conference on Optical Tomography and Spectroscopy of Tissue XI

作者： Zhang, Yan Zhang, Limin Jin, Meng Zhao, Huijuan Gao, Feng Li, Jiao Tianjin Univ Coll Precis Instruments & Optoelect Engn Tianjin 300072 Peoples R China Tianjin Key Lab Biomed Detecting Tech & Instrumen Tianjin 300072 Peoples R China

ISBN: (纸本)9781628414097

In diffuse florescence tomography (DFT), the radiative transfer equation (RTE) and its P1 approximation, i.e. the diffuse equation (DE), have been used as the forward models. Since the assumptions of the diffusion approximation are not valid in particular regions of biological tissue which are close to the collimated light sources and boundaries, not scattering dominated or having void-like sub-domains, the RTE-based DFT methodology has become a focus of investigation. Therefore, we present a RTE-based featured-data scheme for time-domain DFT, which combines the discrete solid-angle-element method and the finite element method to obtain numerical solutions of the Laplace-transformed 2D time-domain RTE, with the natural boundary condition and collimating light source model. The scheme is validated using the measurement data from phantom and in-vivo small-animal experiments compared to the DE-based scheme.

关键词： Diffuse Fluorescence Tomography Radiative Transfer Equation Natural Boundary Condition generalized pulse spectrum technique Time Domain

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Influences from relative size and absorption contrast of an inhomogeneity on NIR diffuse optical image reconstruction

Influences from relative size and absorption contrast of an ...

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Conference on Optical Tomography and Spectroscopy of Tissue VI

作者： Zhao, HJ Gao, F Tanikawa, Y Homma, K Yamada, Y Tianjin Univ Coll Precis Instrument & Optoelect Engn Tianjin 300072 Peoples R China

ISBN: (纸本)0819456675

Near infrared (NIR) diffused optical tomography (DOT) is emerging as a potential tool of non-invasively diagnosing woman breast cancers, neonatal brain hypoxia, and other human organ diseases. The intensive and worldwide investigations in theory and experiment have revealed the possibility of NIR DOT in providing both anatomical and functional information of biological tissue simultaneously, which is important for distinguishing between healthy and diseased tissues, such as benign and malignant tumors. In this paper, our recent DOT experiments on human lower legs and forearms are presented using our time-resolved measuring system and image reconstruction algorithm based on the modified generalized pulse spectrum technique. It was found that the image quality in the experiments, including both the spatial resolution and the quantitativeness of the targets, was rather poor, and the interior blood vessels undisclosed in the absorption images. To clarify this issue, the influences of target contrast and size on the image reconstruction were investigated with simulated data. We have accordingly obtained the following observations: the quantitativeness of the reconstructed optical properties was prone to be spoiled by the small size ratio and high contrast of the interior targets (such as blood vessels) to the background, and the incompleteness of information embedded in the featured data-types, in addition to the experimental noise, evidently answers for the degradation of the spatial resolution and quantitativeness. It was shown in a further simulative investigation that the image quality could be substantially improved by making full use of the time-resolved data.

关键词： diffuse optical tomography image reconstruction full time-resolved data generalized pulse spectrum technique in vivo validation

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A linear GPST-based scheme for time-domain fluorescence molecular tomography

A linear GPST-based scheme for time-domain fluorescence mole...

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Conference on Optical Tomography and Spectroscopy of Tissue VII

作者： Gao, Feng Xue, Yuan Zhao, Huijuan Tanikawa, Yukari Yamada, Yukio Tianjin Univ Coll Precis Instrument & Optoelect Engn Tianjin 300072 Peoples R China Natl Inst Adv Ind Sci & Technol Inst Human Sci & Biol Engn Tsukuba 3058564 Japan Univ Electrocommun Dept Mech Engn & Intelligent Syst Tokyo Japan

ISBN: (纸本)9780819465474

Fluorescence diffuse optical tomography (DOT) has attracted many attentions from the community of biomedical imaging, since it provides effective enhancement in imaging contrast. This modality is now rapidly evolving as a potential means of monitoring molecular events in small living organisms with help of molecule-specific contrast agents, referred to as fluorescence molecular tomography (FMT). FMT could greatly promote pathogenesis research, drug development, and therapeutic intervention. Although FMT in steady-state and frequency-domain modes have been promisingly demonstrated, the extension to time-domain scheme is imminent for its several unique advantages over the others. By extending the previously developed generalized pulse spectrum technique (GPST) for time-domain DOT, we propose a linear, featured-data image reconstruction algorithm for time-domain FMT that can simultaneously reconstruct both fluorescent yield and lifetime images, and validate the methodology with simulated data.

关键词： light propagation in tissues fluorescence molecular tomography image reconstruction techniques time-resolved detection generalized pulse spectrum technique

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