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Sample records for quantitative tomography simulations

  1. Quantitative tomography simulations and reconstruction algorithms

    SciTech Connect

    Martz, H E; Aufderheide, M B; Goodman, D; Schach von Wittenau, A; Logan, C; Hall, J; Jackson, J; Slone, D

    2000-11-01

    X-ray, neutron and proton transmission radiography and computed tomography (CT) are important diagnostic tools that are at the heart of LLNLs effort to meet the goals of the DOE's Advanced Radiography Campaign. This campaign seeks to improve radiographic simulation and analysis so that radiography can be a useful quantitative diagnostic tool for stockpile stewardship. Current radiographic accuracy does not allow satisfactory separation of experimental effects from the true features of an object's tomographically reconstructed image. This can lead to difficult and sometimes incorrect interpretation of the results. By improving our ability to simulate the whole radiographic and CT system, it will be possible to examine the contribution of system components to various experimental effects, with the goal of removing or reducing them. In this project, we are merging this simulation capability with a maximum-likelihood (constrained-conjugate-gradient-CCG) reconstruction technique yielding a physics-based, forward-model image-reconstruction code. In addition, we seek to improve the accuracy of computed tomography from transmission radiographs by studying what physics is needed in the forward model. During FY 2000, an improved version of the LLNL ray-tracing code called HADES has been coupled with a recently developed LLNL CT algorithm known as CCG. The problem of image reconstruction is expressed as a large matrix equation relating a model for the object being reconstructed to its projections (radiographs). Using a constrained-conjugate-gradient search algorithm, a maximum likelihood solution is sought. This search continues until the difference between the input measured radiographs or projections and the simulated or calculated projections is satisfactorily small. We developed a 2D HADES-CCG CT code that uses full ray-tracing simulations from HADES as the projector. Often an object has axial symmetry and it is desirable to reconstruct into a 2D r-z mesh with a limited

  2. Concluding Report: Quantitative Tomography Simulations and Reconstruction Algorithms

    SciTech Connect

    Aufderheide, M B; Martz, H E; Slone, D M; Jackson, J A; Schach von Wittenau, A E; Goodman, D M; Logan, C M; Hall, J M

    2002-02-01

    In this report we describe the original goals and final achievements of this Laboratory Directed Research and Development project. The Quantitative was Tomography Simulations and Reconstruction Algorithms project (99-ERD-015) funded as a multi-directorate, three-year effort to advance the state of the art in radiographic simulation and tomographic reconstruction by improving simulation and including this simulation in the tomographic reconstruction process. Goals were to improve the accuracy of radiographic simulation, and to couple advanced radiographic simulation tools with a robust, many-variable optimization algorithm. In this project, we were able to demonstrate accuracy in X-Ray simulation at the 2% level, which is an improvement of roughly a factor of 5 in accuracy, and we have successfully coupled our simulation tools with the CCG (Constrained Conjugate Gradient) optimization algorithm, allowing reconstructions that include spectral effects and blurring in the reconstructions. Another result of the project was the assembly of a low-scatter X-Ray imaging facility for use in nondestructive evaluation applications. We conclude with a discussion of future work.

  3. Simulation-based evaluation of the resolution and quantitative accuracy of temperature-modulated fluorescence tomography

    PubMed Central

    Lin, Yuting; Nouizi, Farouk; Kwong, Tiffany C.; Gulsen, Gultekin

    2016-01-01

    Conventional fluorescence tomography (FT) can recover the distribution of fluorescent agents within a highly scattering medium. However, poor spatial resolution remains its foremost limitation. Previously, we introduced a new fluorescence imaging technique termed “temperature-modulated fluorescence tomography” (TM-FT), which provides high-resolution images of fluorophore distribution. TM-FT is a multimodality technique that combines fluorescence imaging with focused ultrasound to locate thermo-sensitive fluorescence probes using a priori spatial information to drastically improve the resolution of conventional FT. In this paper, we present an extensive simulation study to evaluate the performance of the TM-FT technique on complex phantoms with multiple fluorescent targets of various sizes located at different depths. In addition, the performance of the TM-FT is tested in the presence of background fluorescence. The results obtained using our new method are systematically compared with those obtained with the conventional FT. Overall, TM-FT provides higher resolution and superior quantitative accuracy, making it an ideal candidate for in vivo preclinical and clinical imaging. For example, a 4 mm diameter inclusion positioned in the middle of a synthetic slab geometry phantom (D:40 mm × W :100 mm) is recovered as an elongated object in the conventional FT (x = 4.5 mm; y = 10.4 mm), while TM-FT recovers it successfully in both directions (x = 3.8 mm; y = 4.6 mm). As a result, the quantitative accuracy of the TM-FT is superior because it recovers the concentration of the agent with a 22% error, which is in contrast with the 83% error of the conventional FT. PMID:26368884

  4. Quantitative photoacoustic tomography

    PubMed Central

    Yuan, Zhen; Jiang, Huabei

    2009-01-01

    In this paper, several algorithms that allow for quantitative photoacoustic reconstruction of tissue optical, acoustic and physiological properties are described in a finite-element method based framework. These quantitative reconstruction algorithms are compared, and the merits and limitations associated with these methods are discussed. In addition, a multispectral approach is presented for concurrent reconstructions of multiple parameters including deoxyhaemoglobin, oxyhaemoglobin and water concentrations as well as acoustic speed. Simulation and in vivo experiments are used to demonstrate the effectiveness of the reconstruction algorithms presented. PMID:19581254

  5. Quantitative assessment of photoacoustic tomography systems integrating clinical ultrasound transducers using novel tissue-simulating phantoms

    NASA Astrophysics Data System (ADS)

    Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Pfefer, Joshua

    2015-03-01

    Photoacoustic Tomography (PAT) systems based on commercial ultrasound instruments have the benefit of dualmodality imaging, which increases their appeal from a clinical standpoint. However, factors that influence PAT system performance have not been thoroughly investigated and standardized test methods have not been established for image quality evaluation. To address these issues we have adapted phantom-based approaches from ultrasound imaging standards and implemented them to assess a PAT system developed for vascular imaging. Our system comprises a tunable near-infrared pulsed laser and a commercial ultrasound imaging system, including four interchangeable linear array clinical ultrasound transducers with varying center frequencies, acoustic bandwidths and geometries. Phantoms consisted of a customized polyvinyl chloride (PVC) plastisol gel that simulates both optical and acoustic properties of breast tissue. One phantom incorporates a sub-resolution filament array suitable for bimodal ultrasound-photoacoustic imaging, while another contains an array of hemoglobin-filled cylindrical inclusions at various depths. Key performance characteristics were evaluated, including spatial resolution, signal uniformity, contrast, and penetration depth. These characteristics were evaluated at 750 nm at radiant exposures below ANSI safety limits. Effects of transducer properties on imaging performance were evaluated. Axial and lateral resolution ranged from 0.27-0.83 mm and 0.28-1.8 mm, respectively, and penetration depths from 1.9-4.2 cm were achieved. These results demonstrate variation in PAT system performance based on clinical transducer selection, as well as the utility of realistic phantom-based test methods in performing benchtop evaluations of system performance.

  6. Multigrid-based reconstruction algorithm for quantitative photoacoustic tomography

    PubMed Central

    Li, Shengfu; Montcel, Bruno; Yuan, Zhen; Liu, Wanyu; Vray, Didier

    2015-01-01

    This paper proposes a multigrid inversion framework for quantitative photoacoustic tomography reconstruction. The forward model of optical fluence distribution and the inverse problem are solved at multiple resolutions. A fixed-point iteration scheme is formulated for each resolution and used as a cost function. The simulated and experimental results for quantitative photoacoustic tomography reconstruction show that the proposed multigrid inversion can dramatically reduce the required number of iterations for the optimization process without loss of reliability in the results. PMID:26203371

  7. Quantitative microwave-induced thermoacoustic tomography.

    PubMed

    Yao, Lei; Guo, Gaofeng; Jiang, Huabei

    2010-07-01

    Microwave-induced thermoacoustic tomography (MI-TAT) is an imaging modality that exploits dielectric contrast while producing images with high ultrasound resolution. Existing reconstruction algorithms for MI-TAT are qualitative and can image only the distribution of the absorbed microwave energy or power loss density. Here the authors describe a method for quantitative MI-TAT and obtain the distribution of dielectric property which directly correlates with tissue structural and functional information. The authors implement the quantitative MI-TAT method based on the finite-element (FE) solution to the Helmholtz equation for electromagnetic field coupled with the thermoacoustic wave equation. Regularization techniques are also used in the FE-based reconstruction algorithm. Simulation results are obtained under various practical scenarios including different noise levels, different contrast levels between the heterogeneity and background region, and multiple targets with various sizes and shapes. The quantitative MI-TAT method described can provide accurate recovery of conductivity distribution in heterogeneous media and is insensitive to noise effect.

  8. Quantitative Simulation Games

    NASA Astrophysics Data System (ADS)

    Černý, Pavol; Henzinger, Thomas A.; Radhakrishna, Arjun

    While a boolean notion of correctness is given by a preorder on systems and properties, a quantitative notion of correctness is defined by a distance function on systems and properties, where the distance between a system and a property provides a measure of "fit" or "desirability." In this article, we explore several ways how the simulation preorder can be generalized to a distance function. This is done by equipping the classical simulation game between a system and a property with quantitative objectives. In particular, for systems that satisfy a property, a quantitative simulation game can measure the "robustness" of the satisfaction, that is, how much the system can deviate from its nominal behavior while still satisfying the property. For systems that violate a property, a quantitative simulation game can measure the "seriousness" of the violation, that is, how much the property has to be modified so that it is satisfied by the system. These distances can be computed in polynomial time, since the computation reduces to the value problem in limit average games with constant weights. Finally, we demonstrate how the robustness distance can be used to measure how many transmission errors are tolerated by error correcting codes.

  9. Quantitative positron emission tomography in brain research.

    PubMed

    Heurling, Kerstin; Leuzy, Antoine; Jonasson, My; Frick, Andreas; Zimmer, Eduardo R; Nordberg, Agneta; Lubberink, Mark

    2017-09-01

    The application of positron emission tomography (PET) in brain research has increased substantially during the past 20years, and is still growing. PET provides a unique insight into physiological and pathological processes in vivo. In this article we introduce the fundamentals of PET, and the methods available for acquiring quantitative estimates of the parameters of interest. A short introduction to different areas of application is also given, including basic research of brain function and in neurology, psychiatry, drug receptor occupancy studies, and its application in diagnostics of neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. Our aim is to inform the unfamiliar reader of the underlying basics and potential applications of PET, hoping to inspire the reader into considering how the technique could be of benefit for his or her own research. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Quantitative damage imaging using Lamb wave diffraction tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Yan; Ruan, Min; Zhu, Wen-Fa; Chai, Xiao-Dong

    2016-12-01

    In this paper, we investigate the diffraction tomography for quantitative imaging damages of partly through-thickness holes with various shapes in isotropic plates by using converted and non-converted scattered Lamb waves generated numerically. Finite element simulations are carried out to provide the scattered wave data. The validity of the finite element model is confirmed by the comparison of scattering directivity pattern (SDP) of circle blind hole damage between the finite element simulations and the analytical results. The imaging method is based on a theoretical relation between the one-dimensional (1D) Fourier transform of the scattered projection and two-dimensional (2D) spatial Fourier transform of the scattering object. A quantitative image of the damage is obtained by carrying out the 2D inverse Fourier transform of the scattering object. The proposed approach employs a circle transducer network containing forward and backward projections, which lead to so-called transmission mode (TMDT) and reflection mode diffraction tomography (RMDT), respectively. The reconstructed results of the two projections for a non-converted S0 scattered mode are investigated to illuminate the influence of the scattering field data. The results show that Lamb wave diffraction tomography using the combination of TMDT and RMDT improves the imaging effect compared with by using only the TMDT or RMDT. The scattered data of the converted A0 mode are also used to assess the performance of the diffraction tomography method. It is found that the circle and elliptical shaped damages can still be reasonably identified from the reconstructed images while the reconstructed results of other complex shaped damages like crisscross rectangles and racecourse are relatively poor. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474195, 11274226, 11674214, and 51478258).

  11. Weighted filtered backprojection for quantitative fluorescence optical projection tomography

    NASA Astrophysics Data System (ADS)

    Darrell, A.; Meyer, H.; Marias, K.; Brady, M.; Ripoll, J.

    2008-07-01

    Reconstructing images from a set of fluorescence optical projection tomography (OPT) projections is a relatively new problem. Several physical aspects of fluorescence OPT necessitate a different treatment of the inverse problem to that required for non-fluorescence tomography. Given a fluorophore within the depth of field of the imaging system, the power received by the optical system, and therefore the CCD detector, is related to the distance of the fluorophore from the objective entrance pupil. Additionally, due to the slight blurring of images of sources positioned off the focal plane, the CCD image of a fluorophore off the focal plane is lower in intensity than the CCD image of an identical fluorophore positioned on the focal plane. The filtered backprojection (FBP) algorithm does not take these effects into account and so cannot be expected to yield truly quantitative results. A full model of image formation is introduced which takes into account the effects of isotropic emission and defocus. The model is used to obtain a weighting function which is used in a variation of the FBP algorithm called weighted filtered backprojection (WFBP). This new algorithm is tested with simulated data and with experimental data from a phantom consisting of fluorescent microspheres embedded in an agarose gel.

  12. Quantitative photoacoustic tomography based on the radiative transfer equation.

    PubMed

    Yao, Lei; Sun, Yao; Jiang, Huabei

    2009-06-15

    We describe a method for quantitative photoacoustic tomography (PAT) based on the radiative transfer equation (RTE) coupled with the Helmholtz photoacoustic wave equation. This RTE-based quantitative PAT allows for accurate recovery of absolute absorption coefficient images of heterogeneous media and provides significantly improved image reconstruction for the cases where the photon diffusion approximation may fail. The method and associated finite element reconstruction algorithm are validated using a series of tissuelike phantom experiments.

  13. Quantitative comparison of analysis methods for spectroscopic optical coherence tomography: reply to comment

    PubMed Central

    Bosschaart, Nienke; van Leeuwen, Ton G.; Aalders, Maurice C.G.; Faber, Dirk J.

    2014-01-01

    We reply to the comment by Kraszewski et al on “Quantitative comparison of analysis methods for spectroscopic optical coherence tomography.” We present additional simulations evaluating the proposed window function. We conclude that our simulations show good qualitative agreement with the results of Kraszewski, in support of their conclusion that SOCT optimization should include window shape, next to choice of window size and analysis algorithm. PMID:25401016

  14. Quantitative contrast-enhanced optical coherence tomography

    PubMed Central

    Winetraub, Yonatan; SoRelle, Elliott D.; Liba, Orly; de la Zerda, Adam

    2016-01-01

    We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects. PMID:26869724

  15. Quantitative contrast-enhanced optical coherence tomography

    SciTech Connect

    Winetraub, Yonatan; SoRelle, Elliott D.; Liba, Orly; Zerda, Adam de la

    2016-01-11

    We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.

  16. Quantitative contrast-enhanced optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Winetraub, Yonatan; SoRelle, Elliott D.; Liba, Orly; de la Zerda, Adam

    2016-01-01

    We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.

  17. Quantitative analysis in medicine using photoacoustic tomography.

    PubMed

    Haisch, Christoph

    2009-01-01

    Photoacoustic imaging, or photoacoustic tomography, is a 2D or 3D optical imaging method based on localized optical absorption of pulsed laser radiation. By a spatially resolved detection of the following thermoelastic expansion, the local distribution of the absorption can be determined. The technique has been proven to have significant potential for the imaging of human and animal organs and single blood vessels, combining high contrast with good spatial resolution. The contrast is based on the specific optical absorption of certain components in the visible and near-infrared spectral range, for most applications of blood. Generally, the images represent the local distribution of blood in a qualitative or semiquantitative way. Although photoacoustic imaging is capable of revealing absolute and spatially resolved concentrations of endogenous (such as oxyhemoglobin and deoxyhemoglobin) or artificial (such as tumor markers) chromophores, only a very limited number of publications have dealt with this demanding task. In this report, the problems involved and possible solutions are reviewed and summarized.

  18. Quantitative Tomography of Organic Photovoltaic Blends at the Nanoscale.

    PubMed

    Pfannmöller, M; Heidari, H; Nanson, L; Lozman, O R; Chrapa, M; Offermans, T; Nisato, G; Bals, S

    2015-10-14

    The success of semiconducting organic materials has enabled green technologies for electronics, lighting, and photovoltaics. However, when blended together, these materials have also raised novel fundamental questions with respect to electronic, optical, and thermodynamic properties. This is particularly important for organic photovoltaic cells based on the bulk heterojunction. Here, the distribution of nanoscale domains plays a crucial role depending on the specific device structure. Hence, correlation of the aforementioned properties requires 3D nanoscale imaging of materials domains, which are embedded in a multilayer device. Such visualization has so far been elusive due to lack of contrast, insufficient signal, or resolution limits. In this Letter, we introduce spectral scanning transmission electron tomography for reconstruction of entire volume plasmon spectra from rod-shaped specimens. We provide 3D structural correlations and compositional mapping at a resolution of approximately 7 nm within advanced organic photovoltaic tandem cells. Novel insights that are obtained from quantitative 3D analyses reveal that efficiency loss upon thermal annealing can be attributed to subtle, fundamental blend properties. These results are invaluable in guiding the design and optimization of future devices in plastic electronics applications and provide an empirical basis for modeling and simulation of organic solar cells.

  19. Quantitative coherent-scatter-computed tomography

    NASA Astrophysics Data System (ADS)

    Batchelar, Deidre L.; Westmore, Michael S.; Lai, Hao; Cunningham, Ian A.

    1998-07-01

    Conventional means of diagnosiing and assessing the progression of osteoporosis, including radiographic absorptiometry and quantitative CT, are directly or indirectly dependent upon bone density. This is, how ever, not always a reliable indicator of fracture risk. Changes in the trabecular structure and bone mineral content (BMC) are thought to provide a better indication of the change of spontaneous fractures occurring. Coherent-scatter CT (CSCT) is a technique which produces images based on the low angle (0 - 10 degrees) x-ray diffraction properties of tissue. Diffraction patterns from an object are acquired using first-generation CT geometry with a diagnostic x-ray image intensifier based system. These patterns are used to reconstruct a series of maps of the angle dependent coherent scatter cross section in a tomographic slice which are dependent upon the molecular structure of the scatterer. Hydroxyapatite has a very different cross section to that of soft tissue, and the CSCT method may, therefore, form the basis for a more direct measure of BMC. Our original CSCT images suffered from a 'cupping' artifact, resulting in increased intensities for pixels at the periphery of the object. This artifact, which is due to self-attenuation of scattered x rays, caused a systematic error of up to 20% in cross-sections measured from a CT image. This effect has been removed by monitoring the transmitted intensity using a photodiode mounted on the primary beam stop, and normalizing the scatter intensity to that of the transmitted beam for each projection. Images reconstructed from data normalized in this way do not exhibit observable attenuation artifacts. Elimination of this artifact enables the determination of accurate quantitative measures of BMC at each pixel in a tomograph.

  20. HAADF-STEM atom counting in atom probe tomography specimens: Towards quantitative correlative microscopy.

    PubMed

    Lefebvre, W; Hernandez-Maldonado, D; Moyon, F; Cuvilly, F; Vaudolon, C; Shinde, D; Vurpillot, F

    2015-12-01

    The geometry of atom probe tomography tips strongly differs from standard scanning transmission electron microscopy foils. Whereas the later are rather flat and thin (<20 nm), tips display a curved surface and a significantly larger thickness. As far as a correlative approach aims at analysing the same specimen by both techniques, it is mandatory to explore the limits and advantages imposed by the particular geometry of atom probe tomography specimens. Based on simulations (electron probe propagation and image simulations), the possibility to apply quantitative high angle annular dark field scanning transmission electron microscopy to of atom probe tomography specimens has been tested. The influence of electron probe convergence and the benefice of deconvolution of electron probe point spread function electron have been established. Atom counting in atom probe tomography specimens is for the first time reported in this present work. It is demonstrated that, based on single projections of high angle annular dark field imaging, significant quantitative information can be used as additional input for refining the data obtained by correlative analysis of the specimen in APT, therefore opening new perspectives in the field of atomic scale tomography.

  1. [Quantitative computerized tomography in the study of osteoporosis. Our experience].

    PubMed

    Mecozzi, B; Anselmetti, G C

    1992-01-01

    In the diagnosis of osteoporosis there are, today, several techniques for investigating bone mineral density. In this work the authors evaluate the sensitivity of Computed Tomography in the diagnosis of this metabolic disease, because of the built-in competence of this method in determining the density of the anatomical tissues. In a randomised study the Authors performed Single Energy Quantitative Computed Tomography (SEQCT) in estimating the bone mineral density of lumbar vertebrae in 44 female patients. The data obtained were correlated, using the Student "t" test, to the measurements acquired, in the same group of patients, employing Dual Energy X-ray Absorptiometry (DEXA), 27 patients, and Total Body DEXA, 17 patients. Results revealed a good correlation between SEQCT and DEXA (R = 0.89) and statistical significance (p < 0.001). On the contrary there is not a good correlation (R = 0.58) if SEQCT is compared to Total Body DEXA. According to our experience Quantitative Computed Tomography is useful in diagnosis osteoporosis and it should be performed in all post-menopausal patients. This method, which has a high level of precision, is cheap and easily adaptable to every Computed Tomography. Because of the high X-ray dose rate, only DEXA should be performed in monitoring patients undergoing therapy.

  2. In vivo validation of quantitative frequency domain fluorescence tomography

    NASA Astrophysics Data System (ADS)

    Lin, Yuting; Ghijsen, Michael; Nalcioglu, Orhan; Gulsen, Gultekin

    2012-12-01

    We have developed a hybrid frequency domain fluorescence tomography and magnetic resonance imaging system (MRI) for small animal imaging. The main purpose of this system is to obtain quantitatively accurate fluorescence concentration and lifetime images using a multi-modality approach. In vivo experiments are undertaken to evaluate the system. We compare the recovered fluorescence parameters with and without MRI structural a priori information. In addition, we compare two optical background heterogeneity correction methods: Born normalization and utilizing diffuse optical tomography (DOT) functional a priori information. The results show that the concentration and lifetime of a 4.2-mm diameter indocyanine green inclusion located 15 mm deep inside a rat can be recovered with less than a 5% error when functional a priori information from DOT and structural a priori information from MRI are utilized.

  3. Quantitative cone beam X-ray luminescence tomography/X-ray computed tomography imaging

    SciTech Connect

    Chen, Dongmei; Zhu, Shouping Chen, Xueli; Chao, Tiantian; Cao, Xu; Zhao, Fengjun; Huang, Liyu; Liang, Jimin

    2014-11-10

    X-ray luminescence tomography (XLT) is an imaging technology based on X-ray-excitable materials. The main purpose of this paper is to obtain quantitative luminescence concentration using the structural information of the X-ray computed tomography (XCT) in the hybrid cone beam XLT/XCT system. A multi-wavelength luminescence cone beam XLT method with the structural a priori information is presented to relieve the severe ill-posedness problem in the cone beam XLT. The nanophosphors and phantom experiments were undertaken to access the linear relationship of the system response. Then, an in vivo mouse experiment was conducted. The in vivo experimental results show that the recovered concentration error as low as 6.67% with the location error of 0.85 mm can be achieved. The results demonstrate that the proposed method can accurately recover the nanophosphor inclusion and realize the quantitative imaging.

  4. Seismic traveltime tomography: a simulated annealing approach

    NASA Astrophysics Data System (ADS)

    Wéber, Zoltán

    2000-04-01

    Seismic traveltime tomography involves finding a velocity model that minimizes the error energy between the measured and the theoretical traveltimes. When solving this nonlinear inverse problem, a local optimization technique can easily produce a solution for which the gradient of the error energy function vanishes, but the energy function itself does not take its global minimum. Other methods such as simulated annealing can be applied to such global optimization problems. The simulated annealing approach to seismic traveltime tomography described in this paper has been tested on synthetic as well as real seismic data. It is shown that unlike local methods, the convergence of the simulated annealing algorithm is independent of the initial model: even in cases of virtually no prior information, it is capable of producing reliable results. The method can provide a number of acceptable solutions. When prior information is sparse, the solution of the global optimization can be used as an input to a local optimization procedure, such as, e.g., simultaneous iterative reconstruction technique (SIRT), producing an even more accurate result.

  5. Shifted helical computed tomography to optimize cardiac positron emission tomography-computed tomography coregistration: quantitative improvement and limitations.

    PubMed

    Johnson, Nils P; Pan, Tinsu; Gould, K Lance

    2010-10-01

    Positron emission tomography-computed tomography (PET-CT) uses CT attenuation correction but suffers from misregistration artifacts. However, the quantitative accuracy of helical versus cine CT in the same patient after optimized coregistration by shifting both CT data as needed for each patient is unknown. We studied 293 patients undergoing cardiac perfusion PET-CT using helical CT attenuation correction for comparison to cine CT. Objective, quantitative criteria identified perfusion abnormalities that were associated visually with PET-CT misregistration. Custom software shifted CT data to optimize coregistration with quantitative artifact improvement. The majority (58.1%) of cases with both helical and shifted helical CT data (n  = 93) had artifacts that improved or resolved by software shifting helical CT data. Translation of shifted helical CT was greatest in the x-direction (8.8 ± 3.3 mm) and less in the y- and z-directions (approximately 3.5 mm). The magnitude of differences in quantitative end points was greatest for helical (p  =  .0001, n  =  177 studies), less for shifted helical but significant (p  =  .0001, n  =  93 studies), and least for cine (not significant, n  =  161 studies) CT compared to optimal attenuation correction for each patient. Frequent artifacts owing to attenuation-emission misregistration are substantially corrected by software shifting helical CT scans to achieve proper coregistration that, however, remains on average significantly inferior to cine CT attenuation quantitatively.

  6. The APOSTEL recommendations for reporting quantitative optical coherence tomography studies.

    PubMed

    Cruz-Herranz, Andrés; Balk, Lisanne J; Oberwahrenbrock, Timm; Saidha, Shiv; Martinez-Lapiscina, Elena H; Lagreze, Wolf A; Schuman, Joel S; Villoslada, Pablo; Calabresi, Peter; Balcer, Laura; Petzold, Axel; Green, Ari J; Paul, Friedemann; Brandt, Alexander U; Albrecht, Philipp

    2016-06-14

    To develop consensus recommendations for reporting of quantitative optical coherence tomography (OCT) study results. A panel of experienced OCT researchers (including 11 neurologists, 2 ophthalmologists, and 2 neuroscientists) discussed requirements for performing and reporting quantitative analyses of retinal morphology and developed a list of initial recommendations based on experience and previous studies. The list of recommendations was subsequently revised during several meetings of the coordinating group. We provide a 9-point checklist encompassing aspects deemed relevant when reporting quantitative OCT studies. The areas covered are study protocol, acquisition device, acquisition settings, scanning protocol, funduscopic imaging, postacquisition data selection, postacquisition data analysis, recommended nomenclature, and statistical analysis. The Advised Protocol for OCT Study Terminology and Elements recommendations include core items to standardize and improve quality of reporting in quantitative OCT studies. The recommendations will make reporting of quantitative OCT studies more consistent and in line with existing standards for reporting research in other biomedical areas. The recommendations originated from expert consensus and thus represent Class IV evidence. They will need to be regularly adjusted according to new insights and practices. © 2016 American Academy of Neurology.

  7. The APOSTEL recommendations for reporting quantitative optical coherence tomography studies

    PubMed Central

    Cruz-Herranz, Andrés; Balk, Lisanne J.; Oberwahrenbrock, Timm; Saidha, Shiv; Martinez-Lapiscina, Elena H.; Lagreze, Wolf A.; Schuman, Joel S.; Villoslada, Pablo; Calabresi, Peter; Balcer, Laura; Petzold, Axel; Green, Ari J.; Paul, Friedemann; Brandt, Alexander U.

    2016-01-01

    Objective: To develop consensus recommendations for reporting of quantitative optical coherence tomography (OCT) study results. Methods: A panel of experienced OCT researchers (including 11 neurologists, 2 ophthalmologists, and 2 neuroscientists) discussed requirements for performing and reporting quantitative analyses of retinal morphology and developed a list of initial recommendations based on experience and previous studies. The list of recommendations was subsequently revised during several meetings of the coordinating group. Results: We provide a 9-point checklist encompassing aspects deemed relevant when reporting quantitative OCT studies. The areas covered are study protocol, acquisition device, acquisition settings, scanning protocol, funduscopic imaging, postacquisition data selection, postacquisition data analysis, recommended nomenclature, and statistical analysis. Conclusions: The Advised Protocol for OCT Study Terminology and Elements recommendations include core items to standardize and improve quality of reporting in quantitative OCT studies. The recommendations will make reporting of quantitative OCT studies more consistent and in line with existing standards for reporting research in other biomedical areas. The recommendations originated from expert consensus and thus represent Class IV evidence. They will need to be regularly adjusted according to new insights and practices. PMID:27225223

  8. Quantitative fluorescence tomography using a trimodality system: in vivo validation

    NASA Astrophysics Data System (ADS)

    Lin, Yuting; Barber, William C.; Iwanczyk, Jan S.; Roeck, Werner W.; Nalcioglu, Orhan; Gulsen, Gultekin

    2010-07-01

    A fully integrated trimodality fluorescence, diffuse optical, and x-ray computed tomography (FT/DOT/XCT) system for small animal imaging is reported in this work. The main purpose of this system is to obtain quantitatively accurate fluorescence concentration images using a multimodality approach. XCT offers anatomical information, while DOT provides the necessary background optical property map to improve FT image accuracy. The quantitative accuracy of this trimodality system is demonstrated in vivo. In particular, we show that a 2-mm-diam fluorescence inclusion located 8 mm deep in a nude mouse can only be localized when functional a priori information from DOT is available. However, the error in the recovered fluorophore concentration is nearly 87%. On the other hand, the fluorophore concentration can be accurately recovered within 2% error when both DOT functional and XCT structural a priori information are utilized together to guide and constrain the FT reconstruction algorithm.

  9. Assessment of metabolic bone diseases by quantitative computed tomography

    SciTech Connect

    Richardson, M.L.; Genant, H.K.; Cann, C.E.; Ettinger, B.; Gordan, G.S.; Kolb, F.O.; Reiser, U.J.

    1985-05-01

    Advances in the radiologic sciences have permitted the development of numerous noninvasive techniques for measuring the mineral content of bone, with varying degrees of precision, accuracy, and sensitivity. The techniques of standard radiography, radiogrammetry, photodensitometry, Compton scattering, neutron activation analysis, single and dual photon absorptiometry, and quantitative computed tomography (QCT) are described and reviewed in depth. Results from previous cross-sectional and longitudinal QCT investigations are given. They then describe a current investigation in which they studied 269 subjects, including 173 normal women, 34 patients with hyperparathyroidism, 24 patients with steroid- induced osteoporosis, and 38 men with idiopathic osteoporosis. Spinal quantitative computed tomography, radiogrammetry, and single photon absorptiometry were performed, and a spinal fracture index was calculated on all patients. The authors found a disproportionate loss of spinal trabecular mineral compared to appendicular mineral in the men with idiopathic osteoporosis and the patients with steroid-induced osteoporosis. They observed roughly equivalent mineral loss in both the appendicular and axial regions in the hyperparathyroid patients. The appendicular cortical measurements correlated moderately well with each other but less well with spinal trabecular QCT. The spinal fracture index correlated well with QCT and less well with the appendicular measurements.

  10. Quantitative 3-dimensional computed tomography analysis of olecranon fractures.

    PubMed

    Lubberts, Bart; Janssen, Stein; Mellema, Jos; Ring, David

    2016-05-01

    Olecranon fractures have variable size of the proximal fragment, patterns of fragmentation, and subluxation of the ulnohumeral joint that might be better understood and categorized on the basis of quantitative 3-dimensional computed tomography analysis. Mayo type I fractures are undisplaced, Mayo type II are displaced and stable, and Mayo type III are displaced and unstable. The last is categorized into anterior and posterior dislocations. The purpose of this study was to further clarify fracture morphology between Mayo type I, II, and III fractures. Three-dimensional models were created for a consecutive series of 78 patients with olecranon fractures that were evaluated with computed tomography. We determined the total number of fracture fragments, the volume and articular surface area of each fracture fragment, and the degree of displacement of the most proximal olecranon fracture fragment. Displaced olecranon fractures were more comminuted than nondisplaced fractures (P = .02). Displaced fractures without ulnohumeral subluxation were smallest in terms of both volume (P < .001) and articular surface involvement (P < .001) of the most proximal olecranon fracture fragment. There was no difference in average displacement of the proximal fragment between displaced fractures with and without ulnohumeral subluxation (P = .74). Anterior olecranon fracture-dislocations created more displaced (P = .04) and smaller proximal fragments than posterior fracture-dislocations (P = .005), with comparable fragmentation on average (P = .60). The ability to quantify volume, articular surface area, displacement, and fragmentation using quantitative 3-dimensional computed tomography should be considered when increased knowledge of fracture morphology and fracture patterns might be useful. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  11. Quantitative computed tomography imaging of airway remodeling in severe asthma.

    PubMed

    Grenier, Philippe A; Fetita, Catalin I; Brillet, Pierre-Yves

    2016-02-01

    Asthma is a heterogeneous condition and approximately 5-10% of asthmatic subjects have severe disease associated with structure changes of the airways (airway remodeling) that may develop over time or shortly after onset of disease. Quantitative computed tomography (QCT) imaging of the tracheobronchial tree and lung parenchyma has improved during the last 10 years, and has enabled investigators to study the large airway architecture in detail and assess indirectly the small airway structure. In severe asthmatics, morphologic changes in large airways, quantitatively assessed using 2D-3D airway registration and recent algorithms, are characterized by airway wall thickening, luminal narrowing and bronchial stenoses. Extent of expiratory gas trapping, quantitatively assessed using lung densitometry, may be used to assess indirectly small airway remodeling. Investigators have used these quantitative imaging techniques in order to attempt severity grading of asthma, and to identify clusters of asthmatic patients that differ in morphologic and functional characteristics. Although standardization of image analysis procedures needs to be improved, the identification of remodeling pattern in various phenotypes of severe asthma and the ability to relate airway structures to important clinical outcomes should help target treatment more effectively.

  12. Quantitative computed tomography imaging of airway remodeling in severe asthma

    PubMed Central

    Fetita, Catalin I.; Brillet, Pierre-Yves

    2016-01-01

    Asthma is a heterogeneous condition and approximately 5–10% of asthmatic subjects have severe disease associated with structure changes of the airways (airway remodeling) that may develop over time or shortly after onset of disease. Quantitative computed tomography (QCT) imaging of the tracheobronchial tree and lung parenchyma has improved during the last 10 years, and has enabled investigators to study the large airway architecture in detail and assess indirectly the small airway structure. In severe asthmatics, morphologic changes in large airways, quantitatively assessed using 2D-3D airway registration and recent algorithms, are characterized by airway wall thickening, luminal narrowing and bronchial stenoses. Extent of expiratory gas trapping, quantitatively assessed using lung densitometry, may be used to assess indirectly small airway remodeling. Investigators have used these quantitative imaging techniques in order to attempt severity grading of asthma, and to identify clusters of asthmatic patients that differ in morphologic and functional characteristics. Although standardization of image analysis procedures needs to be improved, the identification of remodeling pattern in various phenotypes of severe asthma and the ability to relate airway structures to important clinical outcomes should help target treatment more effectively. PMID:26981458

  13. Assessment of metabolic bone diseases by quantitative computed tomography

    NASA Technical Reports Server (NTRS)

    Richardson, M. L.; Genant, H. K.; Cann, C. E.; Ettinger, B.; Gordan, G. S.; Kolb, F. O.; Reiser, U. J.

    1985-01-01

    Advances in the radiologic sciences have permitted the development of numerous noninvasive techniques for measuring the mineral content of bone, with varying degrees of precision, accuracy, and sensitivity. The techniques of standard radiography, radiogrammetry, photodensitometry, Compton scattering, neutron activation analysis, single and dual photon absorptiometry, and quantitative computed tomography (QCT) are described and reviewed in depth. Results from previous cross-sectional and longitudinal QCT investigations are given. They then describe a current investigation in which they studied 269 subjects, including 173 normal women, 34 patients with hyperparathyroidism, 24 patients with steroid-induced osteoporosis, and 38 men with idiopathic osteoporosis. Spinal quantitative computed tomography, radiogrammetry, and single photon absorptiometry were performed, and a spinal fracture index was calculated on all patients. The authors found a disproportionate loss of spinal trabecular mineral compared to appendicular mineral in the men with idiopathic osteoporosis and the patients with steroid-induced osteoporosis. They observed roughly equivalent mineral loss in both the appendicular and axial regions in the hyperparathyroid patients. The appendicular cortical measurements correlated moderately well with each other but less well with spinal trabecular QCT. The spinal fracture index correlated well with QCT and less well with the appendicular measurements. Knowledge of appendicular cortical mineral status is important in its own right but is not a valid predictor of axial trabecular mineral status, which may be disproportionately decreased in certain diseases. Quantitative CT provides a reliable means of assessing the latter region of the skeleton, correlates well with the spinal fracture index (a semiquantitative measurement of end-organ failure), and offers the clinician a sensitive means of following the effects of therapy.

  14. Assessment of metabolic bone diseases by quantitative computed tomography

    NASA Technical Reports Server (NTRS)

    Richardson, M. L.; Genant, H. K.; Cann, C. E.; Ettinger, B.; Gordan, G. S.; Kolb, F. O.; Reiser, U. J.

    1985-01-01

    Advances in the radiologic sciences have permitted the development of numerous noninvasive techniques for measuring the mineral content of bone, with varying degrees of precision, accuracy, and sensitivity. The techniques of standard radiography, radiogrammetry, photodensitometry, Compton scattering, neutron activation analysis, single and dual photon absorptiometry, and quantitative computed tomography (QCT) are described and reviewed in depth. Results from previous cross-sectional and longitudinal QCT investigations are given. They then describe a current investigation in which they studied 269 subjects, including 173 normal women, 34 patients with hyperparathyroidism, 24 patients with steroid-induced osteoporosis, and 38 men with idiopathic osteoporosis. Spinal quantitative computed tomography, radiogrammetry, and single photon absorptiometry were performed, and a spinal fracture index was calculated on all patients. The authors found a disproportionate loss of spinal trabecular mineral compared to appendicular mineral in the men with idiopathic osteoporosis and the patients with steroid-induced osteoporosis. They observed roughly equivalent mineral loss in both the appendicular and axial regions in the hyperparathyroid patients. The appendicular cortical measurements correlated moderately well with each other but less well with spinal trabecular QCT. The spinal fracture index correlated well with QCT and less well with the appendicular measurements. Knowledge of appendicular cortical mineral status is important in its own right but is not a valid predictor of axial trabecular mineral status, which may be disproportionately decreased in certain diseases. Quantitative CT provides a reliable means of assessing the latter region of the skeleton, correlates well with the spinal fracture index (a semiquantitative measurement of end-organ failure), and offers the clinician a sensitive means of following the effects of therapy.

  15. Quantitative single-photon emission computed tomography/computed tomography for technetium pertechnetate thyroid uptake measurement.

    PubMed

    Lee, Hyunjong; Kim, Ji Hyun; Kang, Yeon-Koo; Moon, Jae Hoon; So, Young; Lee, Won Woo

    2016-07-01

    Technetium pertechnetate (TcO4) is a radioactive tracer used to assess thyroid function by thyroid uptake system (TUS). However, the TUS often fails to deliver accurate measurements of the percent of thyroid uptake (%thyroid uptake) of TcO4. Here, we investigated the usefulness of quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) after injection of TcO4 in detecting thyroid function abnormalities. We retrospectively reviewed data from 50 patients (male:female = 15:35; age, 46.2 ± 16.3 years; 17 Graves disease, 13 thyroiditis, and 20 euthyroid). All patients underwent TcO4 quantitative SPECT/CT (185 MBq = 5 mCi), which yielded %thyroid uptake and standardized uptake value (SUV). Twenty-one (10 Graves disease and 11 thyroiditis) of the 50 patients also underwent conventional %thyroid uptake measurements using a TUS. Quantitative SPECT/CT parameters (%thyroid uptake, SUVmean, and SUVmax) were the highest in Graves disease, second highest in euthyroid, and lowest in thyroiditis (P < 0.0001, Kruskal-Wallis test). TUS significantly overestimated the %thyroid uptake compared with SPECT/CT (P < 0.0001, paired t test) because other TcO4 sources in addition to thyroid, such as salivary glands and saliva, contributed to the %thyroid uptake result by TUS, whereas %thyroid uptake, SUVmean and SUVmax from the SPECT/CT were associated with the functional status of thyroid. Quantitative SPECT/CT is more accurate than conventional TUS for measuring TcO4 %thyroid uptake. Quantitative measurements using SPECT/CT may facilitate more accurate assessment of thyroid tracer uptake.

  16. Quantitative single-photon emission computed tomography/computed tomography for technetium pertechnetate thyroid uptake measurement

    PubMed Central

    Lee, Hyunjong; Kim, Ji Hyun; Kang, Yeon-koo; Moon, Jae Hoon; So, Young; Lee, Won Woo

    2016-01-01

    Abstract Objectives: Technetium pertechnetate (99mTcO4) is a radioactive tracer used to assess thyroid function by thyroid uptake system (TUS). However, the TUS often fails to deliver accurate measurements of the percent of thyroid uptake (%thyroid uptake) of 99mTcO4. Here, we investigated the usefulness of quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) after injection of 99mTcO4 in detecting thyroid function abnormalities. Materials and methods: We retrospectively reviewed data from 50 patients (male:female = 15:35; age, 46.2 ± 16.3 years; 17 Graves disease, 13 thyroiditis, and 20 euthyroid). All patients underwent 99mTcO4 quantitative SPECT/CT (185 MBq = 5 mCi), which yielded %thyroid uptake and standardized uptake value (SUV). Twenty-one (10 Graves disease and 11 thyroiditis) of the 50 patients also underwent conventional %thyroid uptake measurements using a TUS. Results: Quantitative SPECT/CT parameters (%thyroid uptake, SUVmean, and SUVmax) were the highest in Graves disease, second highest in euthyroid, and lowest in thyroiditis (P < 0.0001, Kruskal–Wallis test). TUS significantly overestimated the %thyroid uptake compared with SPECT/CT (P < 0.0001, paired t test) because other 99mTcO4 sources in addition to thyroid, such as salivary glands and saliva, contributed to the %thyroid uptake result by TUS, whereas %thyroid uptake, SUVmean and SUVmax from the SPECT/CT were associated with the functional status of thyroid. Conclusions: Quantitative SPECT/CT is more accurate than conventional TUS for measuring 99mTcO4 %thyroid uptake. Quantitative measurements using SPECT/CT may facilitate more accurate assessment of thyroid tracer uptake. PMID:27399139

  17. Quantitative Cardiac Positron Emission Tomography: The Time Is Coming!

    PubMed Central

    Sciagrà, Roberto

    2012-01-01

    In the last 20 years, the use of positron emission tomography (PET) has grown dramatically because of its oncological applications, and PET facilities are now easily accessible. At the same time, various groups have explored the specific advantages of PET in heart disease and demonstrated the major diagnostic and prognostic role of quantitation in cardiac PET. Nowadays, different approaches for the measurement of myocardial blood flow (MBF) have been developed and implemented in user-friendly programs. There is large evidence that MBF at rest and under stress together with the calculation of coronary flow reserve are able to improve the detection and prognostication of coronary artery disease. Moreover, quantitative PET makes possible to assess the presence of microvascular dysfunction, which is involved in various cardiac diseases, including the early stages of coronary atherosclerosis, hypertrophic and dilated cardiomyopathy, and hypertensive heart disease. Therefore, it is probably time to consider the routine use of quantitative cardiac PET and to work for defining its place in the clinical scenario of modern cardiology. PMID:24278760

  18. Bayesian parameter estimation in spectral quantitative photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Pulkkinen, Aki; Cox, Ben T.; Arridge, Simon R.; Kaipio, Jari P.; Tarvainen, Tanja

    2016-03-01

    Photoacoustic tomography (PAT) is an imaging technique combining strong contrast of optical imaging to high spatial resolution of ultrasound imaging. These strengths are achieved via photoacoustic effect, where a spatial absorption of light pulse is converted into a measurable propagating ultrasound wave. The method is seen as a potential tool for small animal imaging, pre-clinical investigations, study of blood vessels and vasculature, as well as for cancer imaging. The goal in PAT is to form an image of the absorbed optical energy density field via acoustic inverse problem approaches from the measured ultrasound data. Quantitative PAT (QPAT) proceeds from these images and forms quantitative estimates of the optical properties of the target. This optical inverse problem of QPAT is illposed. To alleviate the issue, spectral QPAT (SQPAT) utilizes PAT data formed at multiple optical wavelengths simultaneously with optical parameter models of tissue to form quantitative estimates of the parameters of interest. In this work, the inverse problem of SQPAT is investigated. Light propagation is modelled using the diffusion equation. Optical absorption is described with chromophore concentration weighted sum of known chromophore absorption spectra. Scattering is described by Mie scattering theory with an exponential power law. In the inverse problem, the spatially varying unknown parameters of interest are the chromophore concentrations, the Mie scattering parameters (power law factor and the exponent), and Gruneisen parameter. The inverse problem is approached with a Bayesian method. It is numerically demonstrated, that estimation of all parameters of interest is possible with the approach.

  19. Single-stage reconstruction algorithm for quantitative photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Haltmeier, Markus; Neumann, Lukas; Rabanser, Simon

    2015-06-01

    The development of efficient and accurate image reconstruction algorithms is one of the cornerstones of computed tomography. Existing algorithms for quantitative photoacoustic tomography (qPAT) currently operate in a two-stage procedure: first an inverse source problem for the acoustic wave propagation is solved, whereas in a second step the optical parameters are estimated from the result of the first step. Such an approach has several drawbacks. In this paper we therefore propose the use of single-stage reconstruction algorithms for qPAT, where the optical parameters are directly reconstructed from the observed acoustical data. In that context we formulate the image reconstruction problem of qPAT as a single nonlinear inverse problem by coupling the radiative transfer equation with the acoustic wave equation. The inverse problem is approached by Tikhonov regularization with a convex penalty in combination with the proximal gradient iteration for minimizing the Tikhonov functional. We present numerical results, where the proposed single-stage algorithm shows an improved reconstruction quality at a similar computational cost.

  20. Quantitative computed tomography imaging in chronic obstructive pulmonary disease

    PubMed Central

    Fernandes, Lalita; Fernandes, Yasmin; Mesquita, Anthony Menezes

    2016-01-01

    Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease having small airway inflammation, emphysema, and pulmonary hypertension. It is now clear that spirometry alone cannot differentiate each component. Quantitative computed tomography (QCT) is increasingly used to quantify the amount of emphysema and small airway involvement in COPD. Inspiratory CT guides in assessing emphysema while expiratory CT identifies areas of air trapping which is a surrogate of small airway inflammation. By constructing a three-dimensional model of airways, we can also measure the airway wall thickness of segmental and subsegmental airways. The aim of this review is to present the current knowledge and methodologies in QCT of the lung that aid in identifying discrete COPD phenotypes. PMID:27890994

  1. Optical coherence Doppler tomography for quantitative cerebral blood flow imaging

    PubMed Central

    You, Jiang; Du, Congwu; Volkow, Nora D.; Pan, Yingtian

    2014-01-01

    Optical coherence Doppler tomography (ODT) is a promising neurotechnique that permits 3D imaging of the cerebral blood flow (CBF) network; however, quantitative CBF velocity (CBFv) imaging remains challenging. Here we present a simple phase summation method to enhance slow capillary flow detection sensitivity without sacrificing dynamic range for fast flow and vessel tracking to improve angle correction for absolute CBFv quantification. Flow phantom validation indicated that the CBFv quantification accuracy increased from 15% to 91% and the coefficient of variation (CV) decreased 9.3-fold; in vivo mouse brain validation showed that CV decreased 4.4-/10.8- fold for venular/arteriolar flows. ODT was able to identify cocaine-elicited microischemia and quantify CBFv disruption in branch vessels and capillaries that otherwise would have not been possible. PMID:25401033

  2. Quantitative 3-dimensional computed tomography measurements of coronoid fractures.

    PubMed

    Mellema, Jos J; Janssen, Stein J; Guitton, Thierry G; Ring, David

    2015-03-01

    Using quantitative 3-dimensional computed tomography (Q3DCT) modeling, we tested the null hypothesis that there was no difference in fracture fragment volume, articular surface involvement, and number of fracture fragments between coronoid fracture types and patterns of traumatic elbow instability. We studied 82 patients with a computed tomography scan of a coronoid fracture using Q3DCT modeling. Fracture fragments were identified and fragment volume and articular surface involvement were measured within fracture types and injury patterns. Kruskal-Wallis test was used to evaluate the Q3DCT data of the coronoid fractures. Fractures of the coronoid tip (n = 45) were less fragmented and had the smallest fragment volume and articular surface area involvement compared with anteromedial facet fractures (n = 20) and base fractures (n = 17). Anteromedial facet and base fractures were more fragmented than tip fractures, and base fractures had the largest fragment volume and articular surface area involvement compared with tip and anteromedial facet fractures. We found similar differences between fracture types described by Regan and Morrey. Furthermore, fractures associated with terrible triad fracture dislocation (n = 42) had the smallest fragment volume, and fractures associated with olecranon fracture dislocations (n = 17) had the largest fragment volume and articular surface area involvement compared with the other injury patterns. Analyzing fractures of the coronoid using Q3DCT modeling demonstrated that fracture fragment characteristics differ significantly between fracture types and injury patterns. Detailed knowledge of fracture characteristics and their association with specific patterns of traumatic elbow instability may assist decision making and preoperative planning. Quantitative 3DCT modeling can provide a more detailed understanding of fracture morphology, which might guide decision making and implant development. Copyright © 2015 American Society for

  3. Quantitative computed tomography for measuring bone mineral density in athletes.

    PubMed

    Dinç, H; Savci, G; Demirci, A; Sadikoğlu, M Y; Tuncel, E; Yavuz, H

    1996-06-01

    We studied the effect of different training patterns on vertebral trabecular and cortical bone mineral density (BMD) in male athletes using quantitative computed tomography. Vertebral trabecular (t) and cortical (c) BMDs of the first three lumbar vertebrae were measured using single energy quantitative computed tomography in 51 athletes including 10 weight lifters (mean age 20 years), 13 soccer players (mean age 27 years), 28 wrestlers (mean age 17 years), and 45 age-matched volunteers (mean age 21 years). Measured BMDs were correlated with age, body height and weight, training hours per week, sports years, and type of physical activity. Vertebral tBMDs were found to be 44%, 23%, and 24% higher in the weight lifters, soccer players, and wrestlers, respectively, compared with the volunteers. The corresponding cBMDs were 18%, 6%, and 11% higher than that of volunteers. There was significant correlation between the trabecular and cBMD, and height of the athletes, sports years, training hours per week, and physical activity. The most significant correlation with BMD was the type of physical activity. Both the height of the subjects and physical activity variables showed variations of 47% and 32% in trabecular and cBMD, respectively. According to the multiple analysis of variance (MANOVA) only the physical activity factor was effective, with a significance level of P < 0.01; the other factors and interactions were not effective (P > 0.05) on trabecular and cBMD. Different training patterns have a different anabolic effect on both trabecular and cBMDs of the vertebrae, and this effect is more pronounced on the trabecular compartment. Weight lifting showed the highest anabolic effect on both trabecular and cBMDs compared with soccer playing and wrestling. Of the independent variables, physical activity showed the highest anabolic effect on the vertebrae. These results may have implications for devising exercise strategies to reduce the possibility of fracture in old age.

  4. Quantitation of microcomputed tomography-imaged ocular microvasculature.

    PubMed

    Atwood, Robert C; Lee, Peter D; Konerding, Moritz A; Rockett, Peter; Mitchell, Christopher A

    2010-01-01

    To quantitatively assess microvascular dimensions in the eyes of neonatal wild-type and VEGF(120)-tg mice, using a novel combination of techniques which permit three-dimensional (3D) image reconstruction. A novel combination of techniques was developed for the accurate 3D imaging of the microvasculature and demonstrated on the hyaloid vasculature of the neonatal mouse eye. Vascular corrosion casting is used to create a stable replica of the vascular network and X-ray microcomputed tomography (muCT) to obtain the 3D images. In-house computer-aided image analysis techniques were then used to perform a quantitative morphological analysis of the images. With the use of these methods, differences in the numbers of vessel segments, their diameter, and volume of vessels in the vitreous compartment were quantitated in wild-type neonatal mice or littermates over-expressing a labile (nonheparin binding) isoform of vascular endothelial growth factor (VEGF(120)) from the developing lens. This methodology was instructive in demonstrating that hyaloid vascular networks in VEGFA(120) over-expressing mice have a 10-fold increase in blind-ended, a six-fold increase in connected vessel segments, in addition to a sixfold increase (0.0314 versus 0.0051 mm(3)) in total vitreous vessel volume compared with wild type. These parameters are not readily quantified via histological, ultrastructural, or stereological analysis. The combination of techniques described here provides the first 3D quantitative characterization of vasculature in an organ system; i.e., the neonatal murine intra-ocular vasculature in both wild-type mice and a transgenic model of lens-specific over-expression of VEGF.

  5. Numerical Simulation for Generalized Aurora Computed Tomography

    NASA Astrophysics Data System (ADS)

    Tanaka, Y.; Aso, T.; Gustavsson, B.; Tanabe, K.; Kadokura, A.; Ogawa, Y.

    2007-12-01

    The conventional method of aurora tomographic inversion is extended to a more generalized aurora computed tomography (CT). The generalized aurora CT is the method to reconstruct energy distribution of auroral precipitating electrons from multimodal data, such as electron density enhancement from the EISCAT radar and cosmic noise absorption (CNA) from imaging riometer, as well as auroral images. In this study, we evaluate the feasibility of the generalized aurora CT by numerical simulation. The forward problem is based on model calculation of auroral emission and electron density enhancement for incident electrons and the mapping of the results to the instruments. Assuming the energy and spatial distributions of the incident electrons, the three-dimensional (3D) distributions of volume emission rate and electron density are calculated. The data observed with the ALIS (Auroral Large Imaging System) cameras, the EISCAT radar, and the imaging riometer are obtained by mapping the volume emission rate and electron density to each instrument. We attempt to retrieve the initial distribution of precipitating electrons from the simulated observational data. The inversion analysis is based on the Bayesian inference, in which the problem is formulated as the maximization problem of posterior probability. The results are compared between the reconstruction from only auroral images and that from multimodal data.

  6. Role of computed tomography in quantitative assessment of emphysema

    PubMed Central

    Choromańska, Agnieszka; Macura, Katarzyna J.

    2012-01-01

    Summary Pulmonary emphysema, together with chronic bronchitis is a part of chronic obstructive pulmonary disease (COPD), which is one of the leading causes of death in the United States and worldwide. There are many methods to diagnose emphysema. Unfortunately many of them, for example pulmonary function tests (PFTs), clinical signs and conventional radiology are able to detect emphysema usually in its late stages when a great portion of lung parenchyma has been already destroyed by the disease. Computed tomography (CT) allows for early detection of emphysema. CT also makes it possible to quantify the total amount of emphysema in the lungs which is important in order to precisely estimate the severity of the disease. Those abilities of CT are important in monitoring the course of the disease and in attempts to prevent its further progression. In this review we discuss currently available methods for imaging emphysema with emphasis on the quantitative assessment of emphysema. To date, quantitative methods have not been widely used clinically, however, the initial results of several research studies regarding this subject are very encouraging. PMID:22802863

  7. Towards quantitative analysis of retinal features in optical coherence tomography.

    PubMed

    Baroni, Maurizio; Fortunato, Pina; La Torre, Agostino

    2007-05-01

    The purpose of this paper was to propose a new computer method for quantitative evaluation of representative features of the retina using optical coherence tomography (OCT). A multi-step approach was devised and positively tested for segmentation of the three main retinal layers: the vitreo-retinal interface and the inner and outer retina. Following a preprocessing step, three regions of interest were delimited. Significant peaks corresponding to high and low intensity strips were located along the OCT A-scan lines and accurate boundaries between different layers were obtained by maximizing an edge likelihood function. For a quantitative description, thickness measurement, densitometry, texture and curvature analyses were performed. As a first application, the effect of intravitreal injection of triamcinolone acetonide (IVTA) for the treatment of vitreo-retinal interface syndrome was evaluated. Almost all the parameters, measured on a set of 16 pathologic OCT images, were statistically different before and after IVTA injection (p<0.05). Shape analysis of the internal limiting membrane confirmed the reduction of the pathological traction state. Other significant parameters, such as reflectivity and texture contrast, exhibited relevant changes both at the vitreo-retinal interface and in the inner retinal layers. Texture parameters in the inner and outer retinal layers significantly correlated with the visual acuity restoration. According to these findings an IVTA injection might be considered a possible alternative to surgery for selected patients. In conclusion, the proposed approach appeared to be a promising tool for the investigation of tissue changes produced by pathology and/or therapy.

  8. Monte Carlo Simulation Of Emission Tomography And Other Medical Imaging Techniques.

    PubMed

    Harrison, Robert L

    2010-01-05

    An introduction to Monte Carlo simulation of emission tomography. This paper reviews the history and principles of Monte Carlo simulation, then applies these principles to emission tomography using the public domain simulation package SimSET (a Simulation System for Emission Tomography) as an example. Finally, the paper discusses how the methods are modified for X-ray computed tomography and radiotherapy simulations.

  9. Morphological analysis of the proximal femur using quantitative computed tomography

    PubMed Central

    Jacobson, Donald; Carrera, Guilermo

    2006-01-01

    The anatomy of the proximal femur was studied in 35 specimens using quantitative computed tomography (QCT) and compared with anatomical sections studied by plane radiography and gross dissection. We found the primary supporting structure of the femoral head to be the primary compressive strut, which is a dense column of trabecular bone projecting from the pressure buttress of the medial femoral neck to the epiphyseal scar. Trabecular bone mushroomed from the epiphyseal scar and terminated at right angles to the cortex of the femoral head. We believe the primary compressive strut is the predominant load-bearing structure connecting the femoral head to the femoral neck, as many specimens lacked continuity of the head cortex to the femoral neck. Based on the CT number, the primary compressive strut had similar bone density to cortical structures such as the lesser trochanter, calcar femorale and posterior lateral femoral cortex. Ward’s triangle lacked structural integrity in many cases, and we doubt the significance of tensile trabculae for sharing load. Surgical techniques such as femoral fracture fixation, resurfacing hip arthroplasty and allograft transplantation may benefit from this knowledge. PMID:16896872

  10. Quantitative characterization of developing collagen gels using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Levitz, David; Hinds, Monica T.; Choudhury, Niloy; Tran, Noi T.; Hanson, Stephen R.; Jacques, Steven L.

    2010-03-01

    Nondestructive optical imaging methods such as optical coherence tomography (OCT) have been proposed for characterizing engineered tissues such as collagen gels. In our study, OCT was used to image collagen gels with different seeding densities of smooth muscle cells (SMCs), including acellular gels, over a five-day period during which the gels contracted and became turbid with increased optical scattering. The gels were characterized quantitatively by their optical properties, specified by analysis of OCT data using a theoretical model. At 6 h, seeded cell density and scattering coefficient (μs) were correlated, with μs equal to 10.8 cm-1/(106 cells/mL). Seeded cell density and the scattering anisotropy (g) were uncorrelated. Over five days, the reflectivity in SMC gels gradually doubled with little change in optical attenuation, which indicated a decrease in g that increased backscatter, but only a small drop in μs. At five days, a subpopulation of sites on the gel showed substantially higher reflectivity (approximately a tenfold increase from the first 24 h). In summary, the increased turbidity of SMC gels that develops over time is due to a change in the structure of collagen, which affects g, and not simply due to a change in number density of collagen fibers due to contraction.

  11. Deterministic simulation of thermal neutron radiography and tomography

    NASA Astrophysics Data System (ADS)

    Pal Chowdhury, Rajarshi; Liu, Xin

    2016-05-01

    In recent years, thermal neutron radiography and tomography have gained much attention as one of the nondestructive testing methods. However, the application of thermal neutron radiography and tomography is hindered by their technical complexity, radiation shielding, and time-consuming data collection processes. Monte Carlo simulations have been developed in the past to improve the neutron imaging facility's ability. In this paper, a new deterministic simulation approach has been proposed and demonstrated to simulate neutron radiographs numerically using a ray tracing algorithm. This approach has made the simulation of neutron radiographs much faster than by previously used stochastic methods (i.e., Monte Carlo methods). The major problem with neutron radiography and tomography simulation is finding a suitable scatter model. In this paper, an analytic scatter model has been proposed that is validated by a Monte Carlo simulation.

  12. Quantitative ultrasonic computed tomography using phase-insensitive pyroelectric detectors

    NASA Astrophysics Data System (ADS)

    Zeqiri, Bajram; Baker, Christian; Alosa, Giuseppe; Wells, Peter N. T.; Liang, Hai-Dong

    2013-08-01

    The principle of using ultrasonic computed tomography (UCT) clinically for mapping tissue acoustic properties was suggested almost 40 years ago. Despite strong research activity, UCT been unable to rival its x-ray counterpart in terms of the ability to distinguish tissue pathologies. Conventional piezoelectric detectors deployed in UCT are termed phase-sensitive (PS) and it is well established that this property can lead to artefacts related to refraction and phase-cancellation that mask true tissue structure, particularly for reconstructions involving attenuation. Equally, it has long been known that phase-insensitive (PI) detectors are more immune to this effect, although sufficiently sensitive devices for clinical use have not been available. This paper explores the application of novel PI detectors to UCT. Their operating principle is based on exploiting the pyroelectric properties of the piezoelectric polymer polyvinylidene difluoride. An important detector performance characteristic which makes it particularly suited to UCT, is the lack of directionality of the PI response, relative to the PS detector mode of operation. The performance of the detectors is compared to conventional PS detection methods, for quantitatively assessing the attenuation distribution within various test objects, including a two-phase polyurethane phantom. UCT images are presented for a range of single detector apertures; tomographic reconstruction images being compared with the known structure of phantoms containing inserts as small as 3 mm, which were readily imaged. For larger diameter inserts (>10 mm), the transmitter-detector combination was able to establish the attenuation coefficient of the insert to within ±10% of values determined separately from plane-wave measurements on representative material plaques. The research has demonstrated that the new PI detectors are significantly less susceptible to refraction and phase-cancellation artefacts, generating realistic images in

  13. Bone morphometry and mineral density measurement using quantitative computed tomography

    SciTech Connect

    Jacobson, D.R.

    1991-01-01

    Application of computed tomography (CT) to the study of bone structure and density was explored and developed. A review of bone mineral densitometry (BMD) methodology and general principles of quantitative CT (QCT) are presented. A method for QCT of the spine was developed using a flexible tissue equivalent reference placed adjacent to the patient. A methodology for the development and production of tissue equivalent materials is also presented. Patient equivalent phantoms were used to characterize the method, and phantom studies were performed at five clinical sites. A protocol is defined for measuring the inside diameter of the lumbar pedicular canal. Data generated from this study has proven invaluable in the planning for lumbar fusion surgery when screws are to be used for immobilization. Pedicular canal data from 33 patients is presented. QCT was also used to quantify several parameters of the femoral shaft for use in hip replacement surgical planning. Parameters studied include inside diameter, BMD, endosteal BMD and proximal shaft morphology. The structure and trabecular BMD of the proximal femur was extensively studied using QCT. A large variation was found in the fat content of marrow within the proximal femur, and phantom studies were performed to quantify the effect of fat on trabecular QCT BMD. Cadaveric trabecular bone samples with marrow were analyzed physically to determine water, fat, non-fat soft tissue, and ash content. Multiple thin-slice CT studies were performed on cadaveric femurs. A structural model of the proximal femur was developed in which the structural support is provided primarily by trabecular bone. This model may have profound implications in the study of femoral fractures and prosthetic hardware design.

  14. Simulation Study of Single Photon Emission Computed Tomography for Industrial Applications

    SciTech Connect

    Roy, Tushar; Sarkar, P. S.; Sinha, Amar

    2008-09-26

    SPECT (Single Photon Emission Computed Tomography) provides for an invaluable non-invasive technique for the characterization and activity distribution of the gamma-emitting source. For many applications of radioisotopes for medical and industrial application, not only the positional information of the distribution of radioisotopes is needed but also its strength. The well-established X-ray radiography or transmission tomography techniques do not yield sufficient quantitative information about these objects. Emission tomography is one of the important methods for such characterization. Application of parallel beam, fan beam and 3D cone beam emission tomography methods have been discussed in this paper. Simulation studies to test these algorithms have been carried out to validate the technique.

  15. Accounting for filter bandwidth improves the quantitative accuracy of bioluminescence tomography

    NASA Astrophysics Data System (ADS)

    Taylor, Shelley L.; Mason, Suzannah K. G.; Glinton, Sophie L.; Cobbold, Mark; Dehghani, Hamid

    2015-09-01

    Bioluminescence imaging is a noninvasive technique whereby surface weighted images of luminescent probes within animals are used to characterize cell count and function. Traditionally, data are collected over the entire emission spectrum of the source using no filters and are used to evaluate cell count/function over the entire spectrum. Alternatively, multispectral data over several wavelengths can be incorporated to perform tomographic reconstruction of source location and intensity. However, bandpass filters used for multispectral data acquisition have a specific bandwidth, which is ignored in the reconstruction. In this work, ignoring the bandwidth is shown to introduce a dependence of the recovered source intensity on the bandwidth of the filters. A method of accounting for the bandwidth of filters used during multispectral data acquisition is presented and its efficacy in increasing the quantitative accuracy of bioluminescence tomography is demonstrated through simulation and experiment. It is demonstrated that while using filters with a large bandwidth can dramatically decrease the data acquisition time, if not accounted for, errors of up to 200% in quantitative accuracy are introduced in two-dimensional planar imaging, even after normalization. For tomographic imaging, the use of this method to account for filter bandwidth dramatically improves the quantitative accuracy.

  16. Evaluation of static and dynamic perfusion cardiac computed tomography for quantitation and classification tasks.

    PubMed

    Bindschadler, Michael; Modgil, Dimple; Branch, Kelley R; La Riviere, Patrick J; Alessio, Adam M

    2016-04-01

    Cardiac computed tomography (CT) acquisitions for perfusion assessment can be performed in a dynamic or static mode. Either method may be used for a variety of clinical tasks, including (1) stratifying patients into categories of ischemia and (2) using a quantitative myocardial blood flow (MBF) estimate to evaluate disease severity. In this simulation study, we compare method performance on these classification and quantification tasks for matched radiation dose levels and for different flow states, patient sizes, and injected contrast levels. Under conditions simulated, the dynamic method has low bias in MBF estimates (0 to [Formula: see text]) compared to linearly interpreted static assessment (0.45 to [Formula: see text]), making it more suitable for quantitative estimation. At matched radiation dose levels, receiver operating characteristic analysis demonstrated that the static method, with its high bias but generally lower variance, had superior performance ([Formula: see text]) in stratifying patients, especially for larger patients and lower contrast doses [area under the curve [Formula: see text] to 96 versus 0.86]. We also demonstrate that static assessment with a correctly tuned exponential relationship between the apparent CT number and MBF has superior quantification performance to static assessment with a linear relationship and to dynamic assessment. However, tuning the exponential relationship to the patient and scan characteristics will likely prove challenging. This study demonstrates that the selection and optimization of static or dynamic acquisition modes should depend on the specific clinical task.

  17. Quantitative simultaneous positron emission tomography and magnetic resonance imaging

    PubMed Central

    Ouyang, Jinsong; Petibon, Yoann; Huang, Chuan; Reese, Timothy G.; Kolnick, Aleksandra L.; El Fakhri, Georges

    2014-01-01

    Abstract. Simultaneous positron emission tomography and magnetic resonance imaging (PET-MR) is an innovative and promising imaging modality that is generating substantial interest in the medical imaging community, while offering many challenges and opportunities. In this study, we investigated whether MR surface coils need to be accounted for in PET attenuation correction. Furthermore, we integrated motion correction, attenuation correction, and point spread function modeling into a single PET reconstruction framework. We applied our reconstruction framework to in vivo animal and patient PET-MR studies. We have demonstrated that our approach greatly improved PET image quality. PMID:26158055

  18. Cell death monitoring using quantitative optical coherence tomography methods

    NASA Astrophysics Data System (ADS)

    Farhat, Golnaz; Yang, Victor X. D.; Kolios, Michael C.; Czarnota, Gregory J.

    2011-03-01

    Cell death is characterized by a series of predictable morphological changes, which modify the light scattering properties of cells. We present a multi-parametric approach to detecting changes in subcellular morphology related to cell death using optical coherence tomography (OCT). Optical coherence tomography data were acquired from acute myeloid leukemia (AML) cells undergoing apoptosis over a period of 48 hours. Integrated backscatter (IB) and spectral slope (SS) were computed from OCT backscatter spectra and statistical parameters were extracted from a generalized gamma (GG) distribution fit to OCT signal intensity histograms. The IB increased by 2-fold over 48 hours with significant increases observed as early as 4 hours. The SS increased in steepness by 2.5-fold with significant changes at 12 hours, while the GG parameters were sensitive to apoptotic changes at 24 to 48 hours. Histology slides indicated nuclear condensation and fragmentation at 24 hours, suggesting the late scattering changes could be related to nuclear structure. A second series of measurements from AML cells treated with cisplatin, colchicine or ionizing radiation suggested that the GG parameters could potentially differentiate between modes of cell death. Distinct cellular morphology was observed in histology slides obtained from cells treated under each condition.

  19. Quantitative assessment of lesion detection accuracy, resolution, and reconstruction algorithms in neutron stimulated emission computed tomography.

    PubMed

    Lakshmanan, Manu N; Kapadia, Anuj J

    2012-07-01

    We present a quantitative analysis of the image quality obtained using filtered back-projection (FBP) with Ram-Lak filtering and maximum likelihood-expectation maximization (ML-EM)-with no post-reconstruction filtering in either case-in neutron stimulated emission computed tomography (NSECT) imaging using Monte Carlo simulations in the context of clinically relevant models of liver iron overload. The ratios of pixel intensities for several regions of interest and lesion shape detection using an active-contours segmentation algorithm are assessed for accuracy across different scanning configurations and reconstruction algorithms. The modulation transfer functions (MTFs) are also computed for the cases under study and are applied to determine a minimum detectable lesion spacing as a form of sensitivity analysis. The accuracy of NSECT imaging in measuring relative tissue concentration is presented for simulated clinical liver cases. When using the 15th iteration, ML-EM provides at least 25% better resolution than FBP and proves to be highly robust under low-signal high-noise conditions prevalent in NSECT. However, FBP gives more accurate lesion pixel intensity ratios and size estimates in some cases; due to advantages provided by both reconstruction algorithms, it is worth exploring the development of an algorithm that is a hybrid of the two. We also show that NSECT imaging can be used to accurately detect 3-cm lesions in backgrounds that are a significant fraction (one-quarter) of the concentration of the lesion, down to a 4-cm spacing between lesions.

  20. Serial Quantitative Computed Tomography Perfusion in Aneurysmal Subarachnoid Hemorrhage.

    PubMed

    Lum, Cheemun; Hogan, Matthew J; Sinclair, John; English, Shane; Lesiuk, Howard; Shankar, Jai; Ayoub, Hala

    2016-05-01

    Computed tomography perfusion (CTP) has been performed to predict which patients with aneurysmal subarachnoid hemorrhage are at risk of developing delayed cerebral ischemia (DCI). Patients with severe arterial narrowing may have significant reduction in perfusion. However, many patients have less severe arterial narrowing. There is a paucity of literature evaluating perfusion changes which occur with mild to moderate narrowing. The purpose of our study was to investigate serial whole-brain CTP/computed tomography angiography in aneurysm-related subarachnoid hemorrhage (aSAH) patients with mild to moderate angiographic narrowing. We retrospectively studied 18 aSAH patients who had baseline and follow-up whole-brain CTP/computed tomography angiography. Thirty-one regions of interest/hemisphere at six levels were grouped by vascular territory. Arterial diameters were measured at the circle of Willis. The correlation between arterial diameter and change in CTP values, change in CTP in with and without DCI, and response to intra-arterial vasodilator therapy in DCI patients was evaluated. There was correlation among the overall average cerebral blood flow (CBF; R=0.49, p<0.04), mean transit time (R=-0.48, p=0.04), and angiographic narrowing. In individual arterial territories, there was correlation between changes in CBF and arterial diameter in the middle cerebral artery (R=0.53, p=0.03), posterior cerebral artery (R=0.5, p=0.03), and anterior cerebral artery (R=0.54, p=0.02) territories. Prolonged mean transit time was correlated with arterial diameter narrowing in the middle cerebral artery territory (R=0.52, p=0.03). Patients with DCI tended to have serial worsening of CBF compared with those without DCI (p=0.055). Our preliminary study demonstrates there is a correlation between mild to moderate angiographic narrowing and serial changes in perfusion in patients with aSAH. Patients developing DCI tended to have progressively worsening CBF compared with those not

  1. Quantitative photo-acoustic tomography with partial data

    NASA Astrophysics Data System (ADS)

    Chen, Jie; Yang, Yang

    2012-11-01

    Photo-acoustic tomography is a newly developed hybrid imaging modality that combines a high-resolution modality with a high-contrast modality. We analyze the reconstruction of diffusion and absorption parameters in an elliptic equation and extend an earlier result of Bal and Uhlmann (2010 Inverse Problems 26 085010) to the partial data case. We show that the reconstruction can be uniquely determined by the knowledge of four internal data based on well-chosen partial boundary conditions. Stability of this reconstruction is ensured if a convexity condition is satisfied. A similar stability result is obtained without this geometric constraint if 4n well chosen partial boundary conditions are available, where n is the spatial dimension. The set of well chosen boundary measurements is characterized by some complex geometric optics solutions vanishing on a part of the boundary.

  2. Quantitative Pulmonary Imaging Using Computed Tomography and Magnetic Resonance Imaging

    PubMed Central

    Washko, George R.; Parraga, Grace; Coxson, Harvey O.

    2011-01-01

    Measurements of lung function, including spirometry and body plethesmography, are easy to perform and are the current clinical standard for assessing disease severity. However, these lung functional techniques do not adequately explain the observed variability in clinical manifestations of disease and offer little insight into the relationship of lung structure and function. Lung imaging and the image based assessment of lung disease has matured to the extent that it is common for clinical, epidemiologic, and genetic investigation to have a component dedicated to image analysis. There are several exciting imaging modalities currently being used for the non-invasive study of lung anatomy and function. In this review we will focus on two of them, x-ray computed tomography and magnetic resonance imaging. Following a brief introduction of each method we detail some of the most recent work being done to characterize smoking-related lung disease and the clinical applications of such knowledge. PMID:22142490

  3. Quantitative assessment of impedance tomography for temperature measurements in hyperthermia.

    PubMed

    Blad, B; Persson, B; Lindström, K

    1992-01-01

    The objective of this study is a non-invasive assessment of the thermal dose in hyperthermia. Electrical impedance tomography (EIT) has previously been given a first trial as a temperature monitoring method together with microwave-induced hyperthermia treatment, but it has not been thoroughly investigated. In the present work we have examined this method in order to investigate the correlation in vitro between the true spatial temperature distribution and the corresponding measured relative resistivity changes. Different hyperthermia techniques, such as interstitial water tubings, microwave-induced, laser-induced and ferromagnetic seeds have been used. The results show that it is possible to find a correlation between the measured temperature values and the tomographically measured relative resistivity changes in tissue-equivalent phantoms. But the uncertainty of the temperature coefficients, which has been observed, shows that the method has to be improved before it can be applied to clinical in vivo applications.

  4. Evaluation of static and dynamic perfusion cardiac computed tomography for quantitation and classification tasks

    PubMed Central

    Bindschadler, Michael; Modgil, Dimple; Branch, Kelley R.; La Riviere, Patrick J.; Alessio, Adam M.

    2016-01-01

    Abstract. Cardiac computed tomography (CT) acquisitions for perfusion assessment can be performed in a dynamic or static mode. Either method may be used for a variety of clinical tasks, including (1) stratifying patients into categories of ischemia and (2) using a quantitative myocardial blood flow (MBF) estimate to evaluate disease severity. In this simulation study, we compare method performance on these classification and quantification tasks for matched radiation dose levels and for different flow states, patient sizes, and injected contrast levels. Under conditions simulated, the dynamic method has low bias in MBF estimates (0 to 0.1  ml/min/g) compared to linearly interpreted static assessment (0.45 to 0.48  ml/min/g), making it more suitable for quantitative estimation. At matched radiation dose levels, receiver operating characteristic analysis demonstrated that the static method, with its high bias but generally lower variance, had superior performance (p<0.05) in stratifying patients, especially for larger patients and lower contrast doses [area under the curve (AUC)=0.95 to 96 versus 0.86]. We also demonstrate that static assessment with a correctly tuned exponential relationship between the apparent CT number and MBF has superior quantification performance to static assessment with a linear relationship and to dynamic assessment. However, tuning the exponential relationship to the patient and scan characteristics will likely prove challenging. This study demonstrates that the selection and optimization of static or dynamic acquisition modes should depend on the specific clinical task. PMID:27175377

  5. Quantitative phase tomography by using x-ray microscope with Foucault knife-edge scanning filter

    SciTech Connect

    Watanabe, Norio; Tsuburaya, Yuji; Shimada, Akihiro; Aoki, Sadao

    2016-01-28

    Quantitative phase tomography was evaluated by using a differential phase microscope with a Foucault knife-edge scanning filter. A 3D x-ray phase image of polystyrene beads was obtained at 5.4 keV. The reconstructed refractive index was fairly good agreement with the Henke’s tabulated data.

  6. Quantitative phase tomography by using x-ray microscope with Foucault knife-edge scanning filter

    NASA Astrophysics Data System (ADS)

    Watanabe, Norio; Tsuburaya, Yuji; Shimada, Akihiro; Aoki, Sadao

    2016-01-01

    Quantitative phase tomography was evaluated by using a differential phase microscope with a Foucault knife-edge scanning filter. A 3D x-ray phase image of polystyrene beads was obtained at 5.4 keV. The reconstructed refractive index was fairly good agreement with the Henke's tabulated data.

  7. Quantitative pulmonary single photon emission computed tomography (SPECT) with radiotherapy applications

    NASA Astrophysics Data System (ADS)

    Scarfone, Christopher

    1998-09-01

    The potential benefits of single photon emission computed tomography (SPECT) lung perfusion imaging for 3- dimensional radiation treatment planning and dose- response analysis, are currently being investigated. Accurate and precise SPECT quantification may facilitate the development of models to predict radiation-induced pulmonary dysfunction prior to treatment. The purpose of this research was to quantitatively evaluate the accuracy and precision of SPECT filtered backprojection (FBP) and maximum likelihood-expectation maximization (ML-EM) image reconstruction methods for measuring absolute and relative activity concentration estimates in the lungs. The investigation is conducted using Monte Carlo simulation and validation, experimental phantom studies and applications to patient data. The scatter response function and scatter fraction (SF) for the lung is measured using Monte Carlo simulation and experimental imaging of point and line sources surrounded by lung density media. The Monte Carlo (experimental) SF value for lung density material is determined to be 14.86% (14.01%) for the line source and 18.88% (20.32%) for the point source. Quantitative experimental evaluation of FBP and ML-EM reconstruction techniques is performed using an anthropomorphic torso phantom containing spherical defects (simulating areas of reduced perfusion) of inner diameters 1.4 cm, 3.4 cm, and 5.6 cm at sphere:background concentration ratios of 0:1, 0.38:1, 0.47:1, 0.51:1, 0.70:1. Quantification is examined as a function of attenuation, scatter constant (k, range = 0.45 to 2.00), total iteration number (5 → 500) and deconvolution (Metz) filter power (X, range = 2.0 to 10.0). Relative (to lung background) and absolute quantification is performed using region of interest (ROI) analysis. A dependence of quantitative accuracy on both defect diameter and density is observed. In general, percent bias increases as defect diameter and density decrease. Also, negative bias in the lung

  8. Quantitative analyses of maxillary sinus using computed tomography.

    PubMed

    Perella, Andréia; Rocha, Sara Dos Santos; Cavalcanti, Marcelo de Gusmão Paraiso

    2003-09-01

    The aim of this study was to evaluate the precision and accuracy of linear measurements of maxillary sinus made in tomographic films, by comparing with 3D reconstructed images. Linear measurements of both maxillary sinus in computed tomography CT of 17 patients, with or without lesion by two calibrated examiners independently, on two occasions, with a single manual caliper. A third examiner has done the same measurements electronically in 3D-CT reconstruction. The statistical analysis was performed using ANOVA (analyses of variance). Intra-observer percentage error was little in both cases, with and without lesion; it ranged from 1.14% to 1.82%. The inter-observer error was a little higher reaching a 2.08% value. The accuracy presented a higher value. The perceptual accuracy error was higher in samples, which had lesion compared to that which had not. CT had provided adequate precision and accuracy for maxillary sinus analyses. The precision in cases with lesion was considered inferior when compared to that without lesion, but it can't affect the method efficacy.

  9. Quantitative Computed Tomography and Image Analysis for Advanced Muscle Assessment

    PubMed Central

    Edmunds, Kyle Joseph; Gíslason, Magnus K.; Arnadottir, Iris D.; Marcante, Andrea; Piccione, Francesco; Gargiulo, Paolo

    2016-01-01

    Medical imaging is of particular interest in the field of translational myology, as extant literature describes the utilization of a wide variety of techniques to non-invasively recapitulate and quantity various internal and external tissue morphologies. In the clinical context, medical imaging remains a vital tool for diagnostics and investigative assessment. This review outlines the results from several investigations on the use of computed tomography (CT) and image analysis techniques to assess muscle conditions and degenerative process due to aging or pathological conditions. Herein, we detail the acquisition of spiral CT images and the use of advanced image analysis tools to characterize muscles in 2D and 3D. Results from these studies recapitulate changes in tissue composition within muscles, as visualized by the association of tissue types to specified Hounsfield Unit (HU) values for fat, loose connective tissue or atrophic muscle, and normal muscle, including fascia and tendon. We show how results from these analyses can be presented as both average HU values and compositions with respect to total muscle volumes, demonstrating the reliability of these tools to monitor, assess and characterize muscle degeneration. PMID:27478562

  10. Understanding Cellulose Through Molecular Simulation and Electron Tomography

    SciTech Connect

    Matthews, J.

    2013-01-01

    High-resolution cellulose crystal structures have been determined from diffraction experiments using large diameter microfibrils as the sample material. However, cellulose microfibrils in plants are much smaller in diameter, and are more difficult to directly examine experimentally. Molecular dynamics simulation combined with quantum chemical calculations can help to elucidate the structure and dynamics of small diameter cellulose microfibrils. These simulation techniques also aid in the interpretation of electron tomography volumetric structural data from maize cell walls, where pretreatment with dilute acid or ammonia reveals microfibril geometry.

  11. Geographic and demographic variabilities of quantitative parameters in stress myocardial computed tomography perfusion.

    PubMed

    Park, Jinoh; Kim, Hyun-Sook; Hwang, Hye Jeon; Yang, Dong Hyun; Koo, Hyun Jung; Kang, Joon-Won; Kim, Young-Hak

    2017-09-01

    To evaluate the geographic and demographic variabilities of the quantitative parameters of computed tomography perfusion (CTP) of the left ventricular (LV) myocardium in patients with normal coronary artery on computed tomography angiography (CTA). From a multicenter CTP registry of stress and static computed tomography, we retrospectively recruited 113 patients (mean age, 60 years; 57 men) without perfusion defect on visual assessment and minimal (< 20% of diameter stenosis) or no coronary artery disease on CTA. Using semiautomatic analysis software, quantitative parameters of the LV myocardium, including the myocardial attenuation in stress and rest phases, transmural perfusion ratio (TPR), and myocardial perfusion reserve index (MPRI), were evaluated in 16 myocardial segments. In the lateral wall of the LV myocardium, all quantitative parameters except for MPRI were significantly higher compared with those in the other walls. The MPRI showed consistent values in all myocardial walls (anterior to lateral wall: range, 25% to 27%; p = 0.401). At the basal level of the myocardium, all quantitative parameters were significantly lower than those at the mid- and apical levels. Compared with men, women had significantly higher values of myocardial attenuation and TPR. Age, body mass index, and Framingham risk score were significantly associated with the difference in myocardial attenuation. Geographic and demographic variabilities of quantitative parameters in stress myocardial CTP exist in healthy subjects without significant coronary artery disease. This information may be helpful when assessing myocardial perfusion defects in CTP.

  12. Objective breast tissue image classification using Quantitative Transmission ultrasound tomography

    PubMed Central

    Malik, Bilal; Klock, John; Wiskin, James; Lenox, Mark

    2016-01-01

    Quantitative Transmission Ultrasound (QT) is a powerful and emerging imaging paradigm which has the potential to perform true three-dimensional image reconstruction of biological tissue. Breast imaging is an important application of QT and allows non-invasive, non-ionizing imaging of whole breasts in vivo. Here, we report the first demonstration of breast tissue image classification in QT imaging. We systematically assess the ability of the QT images’ features to differentiate between normal breast tissue types. The three QT features were used in Support Vector Machines (SVM) classifiers, and classification of breast tissue as either skin, fat, glands, ducts or connective tissue was demonstrated with an overall accuracy of greater than 90%. Finally, the classifier was validated on whole breast image volumes to provide a color-coded breast tissue volume. This study serves as a first step towards a computer-aided detection/diagnosis platform for QT. PMID:27934955

  13. Objective breast tissue image classification using Quantitative Transmission ultrasound tomography

    NASA Astrophysics Data System (ADS)

    Malik, Bilal; Klock, John; Wiskin, James; Lenox, Mark

    2016-12-01

    Quantitative Transmission Ultrasound (QT) is a powerful and emerging imaging paradigm which has the potential to perform true three-dimensional image reconstruction of biological tissue. Breast imaging is an important application of QT and allows non-invasive, non-ionizing imaging of whole breasts in vivo. Here, we report the first demonstration of breast tissue image classification in QT imaging. We systematically assess the ability of the QT images’ features to differentiate between normal breast tissue types. The three QT features were used in Support Vector Machines (SVM) classifiers, and classification of breast tissue as either skin, fat, glands, ducts or connective tissue was demonstrated with an overall accuracy of greater than 90%. Finally, the classifier was validated on whole breast image volumes to provide a color-coded breast tissue volume. This study serves as a first step towards a computer-aided detection/diagnosis platform for QT.

  14. Quantitative imaging of tumor vasculature using multispectral optoacoustic tomography (MSOT)

    NASA Astrophysics Data System (ADS)

    Tomaszewski, Michal R.; Quiros-Gonzalez, Isabel; Joseph, James; Bohndiek, Sarah E.

    2017-03-01

    The ability to evaluate tumor oxygenation in the clinic could indicate prognosis and enable treatment monitoring, since oxygen deficient cancer cells are often more resistant to chemotherapy and radiotherapy. MultiSpectral Optoacoustic Tomography (MSOT) is a hybrid technique combining the high contrast of optical imaging with spatial resolution and penetration depth similar to ultrasound. We hypothesized that MSOT could reveal both tumor vascular density and function based on modulation of blood oxygenation. We performed MSOT on nude mice (n=8) bearing subcutaneous xenograft PC3 tumors using an inVision 256 (iThera Medical). The mice were maintained under inhalation anesthesia during imaging and respired oxygen content was modified from 21% to 100% and back. After imaging, Hoechst 33348 was injected to indicate vascular perfusion and permeability. Tumors were then extracted for histopathological analysis and fluorescence microscopy. The acquired data was analyzed to extract a bulk measurement of blood oxygenation (SO2MSOT) from the whole tumor using different approaches. The tumors were also automatically segmented into 5 regions to investigate the effect of depth on SO2MSOT. Baseline SO2MSOT values at 21% and 100% oxygen breathing showed no relationship with ex vivo measures of vascular density or function, while the change in SO2MSOT showed a strong negative correlation to Hoechst intensity (r=- 0.92, p=0.0016). Tumor voxels responding to oxygen challenge were spatially heterogeneous. We observed a significant drop in SO2 MSOT value with tumor depth following a switch of respiratory gas from air to oxygen (0.323+/-0.017 vs. 0.11+/-0.05, p=0.009 between 0 and 1.5mm depth), but no such effect for air breathing (0.265+/-0.013 vs. 0.19+/-0.04, p=0.14 between 0 and 1.5mm depth). Our results indicate that in subcutaneous prostate tumors, baseline SO2MSOT levels do not correlate to tumor vascular density or function while the magnitude of the response to oxygen

  15. SU-D-210-03: Limited-View Multi-Source Quantitative Photoacoustic Tomography

    SciTech Connect

    Feng, J; Gao, H

    2015-06-15

    Purpose: This work is to investigate a novel limited-view multi-source acquisition scheme for the direct and simultaneous reconstruction of optical coefficients in quantitative photoacoustic tomography (QPAT), which has potentially improved signal-to-noise ratio and reduced data acquisition time. Methods: Conventional QPAT is often considered in two steps: first to reconstruct the initial acoustic pressure from the full-view ultrasonic data after each optical illumination, and then to quantitatively reconstruct optical coefficients (e.g., absorption and scattering coefficients) from the initial acoustic pressure, using multi-source or multi-wavelength scheme.Based on a novel limited-view multi-source scheme here, We have to consider the direct reconstruction of optical coefficients from the ultrasonic data, since the initial acoustic pressure can no longer be reconstructed as an intermediate variable due to the incomplete acoustic data in the proposed limited-view scheme. In this work, based on a coupled photo-acoustic forward model combining diffusion approximation and wave equation, we develop a limited-memory Quasi-Newton method (LBFGS) for image reconstruction that utilizes the adjoint forward problem for fast computation of gradients. Furthermore, the tensor framelet sparsity is utilized to improve the image reconstruction which is solved by Alternative Direction Method of Multipliers (ADMM). Results: The simulation was performed on a modified Shepp-Logan phantom to validate the feasibility of the proposed limited-view scheme and its corresponding image reconstruction algorithms. Conclusion: A limited-view multi-source QPAT scheme is proposed, i.e., the partial-view acoustic data acquisition accompanying each optical illumination, and then the simultaneous rotations of both optical sources and ultrasonic detectors for next optical illumination. Moreover, LBFGS and ADMM algorithms are developed for the direct reconstruction of optical coefficients from the

  16. Treatment modification of yttrium-90 radioembolization based on quantitative positron emission tomography/CT imaging.

    PubMed

    Chang, Ted T; Bourgeois, Austin C; Balius, Anastasia M; Pasciak, Alexander S

    2013-03-01

    Treatment activity for yttrium-90 ((90)Y) radioembolization when calculated by using the manufacturer-recommended technique is only partially patient-specific and may result in a subtumoricidal dose in some patients. The authors describe the use of quantitative (90)Y positron emission tomography/computed tomography as a tool to provide patient-specific optimization of treatment activity and evaluate this new method in a patient who previously received traditional (90)Y radioembolization. The modified treatment resulted in a 40-Gy increase in absorbed dose to tumor and complete resolution of disease in the treated area within 3 months.

  17. The potential optical coherence tomography in tooth bleaching quantitative assessment

    NASA Astrophysics Data System (ADS)

    Ni, Y. R.; Guo, Z. Y.; Shu, S. Y.; Zeng, C. C.; Zhong, H. Q.; Chen, B. L.; Liu, Z. M.; Bao, Y.

    2011-12-01

    In this paper, we report the outcomes from a pilot study on using OCT functional imaging method to evaluate and quantify color alteration in the human teeth in vitro. The image formations of the dental tissues without and with treatment 35% hydrogen peroxide were obtained by an OCT system at a 1310 nm central wavelength. One parameter for the quantification of optical properties from OCT measurements is introduced in our study: attenuate coefficient (μ). And the attenuate coefficient have significant decrease ( p < 0.001) in dentine as well as a significant increase ( p < 0.001) in enamel was observed during tooth bleaching process. From the experimental results, it is found that attenuate coefficient could be useful to assess color alteration of the human tooth samples. OCT has a potential to become an effective tool for the assessment tooth bleaching. And our experiment offer a now method to evaluate color change in visible region by quantitative analysis of the infrared region information from OCT.

  18. Quantitation of the human basal ganglia with Positron Emission Tomography

    SciTech Connect

    Bendriem, B.; Dewey, S.L.; Schlyer, D.J.; Wolf, A.P.; Volkow, N.D.

    1990-01-01

    The accurate measurement of the concentration of a radioisotope in small structures with PET requires a correction for quantitation loss due to the partial volume effect and the effect of scattered radiation. To evaluate errors associated with measures in the human basal ganglia (BG) we have built a unilateral model of the BG that we have inserted in a 20 cm cylinder. The recovery coefficient (RC = measured activity/true activity) for our BG phantom has been measured on a CTI tomograph (model 931-08/12) with different background concentrations (contrast) and at different axial locations in the gantry. The BG was visualized on 4 or 5 slices depending on its position in the gantry and on the contrast used. The RC was 0.75 with no background (contrast equal to 1.0). Increasing the relative radioactivity concentration in the background increased the RC from 0.75 to 2.00 when the contrast was {minus}0.7 (BG < Background). The RC was also affected by the size and the shape of the region of interest (ROI) used (RC from 0.75 to 0.67 with ROI size from 0.12 to 1.41 cm{sup 2}). These results show that accurate RC correction depends not only on the volume of the structure but also on its contrast with its surroundings as well as on the selection of the ROI. They also demonstrate that the higher the contrast the more sensitive to axial positioning PET measurements in the BG are. These data provide us with some information about the variability of PET measurements in small structure like the BG and we have proposed some strategies to improve the reproducibility. 18 refs., 3 figs., 5 tabs.

  19. The transesophageal echocardiography simulator based on computed tomography images.

    PubMed

    Piórkowski, Adam; Kempny, Aleksander

    2013-02-01

    Simulators are a new tool in education in many fields, including medicine, where they greatly improve familiarity with medical procedures, reduce costs, and, importantly, cause no harm to patients. This is so in the case of transesophageal echocardiography (TEE), in which the use of a simulator facilitates spatial orientation and helps in case studies. The aim of the project described in this paper is to simulate an examination by TEE. This research makes use of available computed tomography data to simulate the corresponding echocardiographic view. This paper describes the essential characteristics that distinguish these two modalities and the key principles of the wave phenomena that should be considered in the simulation process, taking into account the conditions specific to the echocardiography. The construction of the CT2TEE (Web-based TEE simulator) is also presented. The considerations include ray-tracing and ray-casting techniques in the context of ultrasound beam and artifact simulation. An important aspect of the interaction with the user is raised.

  20. Simulation of computed tomography dose based on voxel phantom

    NASA Astrophysics Data System (ADS)

    Liu, Chunyu; Lv, Xiangbo; Li, Zhaojun

    2017-01-01

    Computed Tomography (CT) is one of the preferred and the most valuable imaging tool used in diagnostic radiology, which provides a high-quality cross-sectional image of the body. It still causes higher doses of radiation to patients comparing to the other radiological procedures. The Monte-Carlo method is appropriate for estimation of the radiation dose during the CT examinations. The simulation of the Computed Tomography Dose Index (CTDI) phantom was developed in this paper. Under a similar conditions used in physical measurements, dose profiles were calculated and compared against the measured values that were reported. The results demonstrate a good agreement between the calculated and the measured doses. From different CT exam simulations using the voxel phantom, the highest absorbed dose was recorded for the lung, the brain, the bone surface. A comparison between the different scan type shows that the effective dose for a chest scan is the highest one, whereas the effective dose values during abdomen and pelvis scan are very close, respectively. The lowest effective dose resulted from the head scan. Although, the dose in CT is related to various parameters, such as the tube current, exposure time, beam energy, slice thickness and patient size, this study demonstrates that the MC simulation is a useful tool to accurately estimate the dose delivered to any specific organs for patients undergoing the CT exams and can be also a valuable technique for the design and the optimization of the CT x-ray source.

  1. Macropore Flow in Soil Columns: Investigations with Computer Tomography and Lattice Boltzmann Simulations

    NASA Astrophysics Data System (ADS)

    Schaap, M. G.; Tuller, M.; Guber, A.; Martin, M. A.; Martinez, F. S.; Pachepsky, Y.

    2007-12-01

    Soil structure greatly affects the ability of soil to transmit and to retain water, chemicals, and colloidal particles that can carry contaminants or be contaminants themselves, e.g. pathogenic microorganisms. No theory or empirical relationships have been developed to date to quantitatively relate parameters of soil structure and parameters of the contaminant transport in soils. The absence of theoretical advances in this area seriously hampers the ability to address issues of public concern, e.g. spread of contaminants introduced in the environment by agricultural activities. Recently, computer tomography of soils has become available to generate detailed images of soil pore space with high resolution and density. Successful applications of computer tomography in medical and material sciences show the great potential of this technique to create an exhaustive characterization of soil structure heterogeneity. In this presentation we investigate saturated flow through twelve undisturbed macroporous soil columns (7.62- cm sample diameter and 18-cm length) with lattice Boltzmann simulations. Saturated flow was measured for the complete columns, as well as on 2 cm sections for selected columns. Computed X-Ray tomography was performed on each of the columns, using the 420 kV X-ray source of a HYTEC FlashCT high-speed industrial CT scanner. The resolution was 116 microns per voxel, yielding a final tomography image of 656x656x1482 (~ 6.3 10E8) voxels. X-Ray CT observations typically provide "gray-scale" representations of the imaged object that must be segmented to yield discrete pore and particle geometry. Many segmentation algorithms are available, each yielding different final pore geometries thus potentially creating uncertainties in subsequent flow analyses. Lattice Boltzmann (LB) simulations will be presented only for some of the columns as the simulations are extremely computationally intensive (each simulation requires ~ 60 GB of computer RAM at the observed

  2. Quantitative assessment of the retinal microvasculature using optical coherence tomography angiography

    NASA Astrophysics Data System (ADS)

    Chu, Zhongdi; Lin, Jason; Gao, Chen; Xin, Chen; Zhang, Qinqin; Chen, Chieh-Li; Roisman, Luis; Gregori, Giovanni; Rosenfeld, Philip J.; Wang, Ruikang K.

    2016-06-01

    Optical coherence tomography angiography (OCTA) is clinically useful for the qualitative assessment of the macular microvasculature. However, there is a need for comprehensive quantitative tools to help objectively analyze the OCT angiograms. Few studies have reported the use of a single quantitative index to describe vessel density in OCT angiograms. In this study, we introduce a five-index quantitative analysis of OCT angiograms in an attempt to detect and assess vascular abnormalities from multiple perspectives. The indices include vessel area density, vessel skeleton density, vessel diameter index, vessel perimeter index, and vessel complexity index. We show the usefulness of the proposed indices with five illustrative cases. Repeatability is tested on both a healthy case and a stable diseased case, giving interclass coefficients smaller than 0.031. The results demonstrate that our proposed quantitative analysis may be useful as a complement to conventional OCTA for the diagnosis of disease and monitoring of treatment.

  3. Quantitative assessment of the retinal microvasculature using optical coherence tomography angiography

    PubMed Central

    Chu, Zhongdi; Lin, Jason; Gao, Chen; Xin, Chen; Zhang, Qinqin; Chen, Chieh-Li; Roisman, Luis; Gregori, Giovanni; Rosenfeld, Philip J.; Wang, Ruikang K.

    2016-01-01

    Abstract. Optical coherence tomography angiography (OCTA) is clinically useful for the qualitative assessment of the macular microvasculature. However, there is a need for comprehensive quantitative tools to help objectively analyze the OCT angiograms. Few studies have reported the use of a single quantitative index to describe vessel density in OCT angiograms. In this study, we introduce a five-index quantitative analysis of OCT angiograms in an attempt to detect and assess vascular abnormalities from multiple perspectives. The indices include vessel area density, vessel skeleton density, vessel diameter index, vessel perimeter index, and vessel complexity index. We show the usefulness of the proposed indices with five illustrative cases. Repeatability is tested on both a healthy case and a stable diseased case, giving interclass coefficients smaller than 0.031. The results demonstrate that our proposed quantitative analysis may be useful as a complement to conventional OCTA for the diagnosis of disease and monitoring of treatment. PMID:27286188

  4. Simulation study of respiratory-induced errors in cardiac positron emission tomography/computed tomography

    SciTech Connect

    Fitzpatrick, Gianna M.; Wells, R. Glenn

    2006-08-15

    Heart disease is a leading killer in Canada and positron emission tomography (PET) provides clinicians with in vivo metabolic information for diagnosing heart disease. Transmission data are usually acquired with {sup 68}Ge, although the advent of PET/CT scanners has made computed tomography (CT) an alternative option. The fast data acquisition of CT compared to PET may cause potential misregistration problems, leading to inaccurate attenuation correction (AC). Using Monte Carlo simulations and an anthropomorphic dynamic computer phantom, this study determines the magnitude and location of respiratory-induced errors in radioactivity uptake measured in cardiac PET/CT. A homogeneous tracer distribution in the heart was considered. The AC was based on (1) a time-averaged attenuation map (2) CT maps from a single phase of the respiratory cycle, and (3) CT maps phase matched to the emission data. Circumferential profiles of the heart uptake were compared and differences of up to 24% were found between the single-phase CT-AC method and the true phantom values. Simulation results were supported by a PET/CT canine study which showed differences of up to 10% in the heart uptake in the lung-heart boundary region when comparing {sup 68}Ge- to CT-based AC with the CT map acquired at end inhalation.

  5. A framework of modeling detector systems for computed tomography simulations

    NASA Astrophysics Data System (ADS)

    Youn, H.; Kim, D.; Kim, S. H.; Kam, S.; Jeon, H.; Nam, J.; Kim, H. K.

    2016-01-01

    Ultimate development in computed tomography (CT) technology may be a system that can provide images with excellent lesion conspicuity with the patient dose as low as possible. Imaging simulation tools have been cost-effectively used for these developments and will continue. For a more accurate and realistic imaging simulation, the signal and noise propagation through a CT detector system has been modeled in this study using the cascaded linear-systems theory. The simulation results are validated in comparisons with the measured results using a laboratory flat-panel micro-CT system. Although the image noise obtained from the simulations at higher exposures is slightly smaller than that obtained from the measurements, the difference between them is reasonably acceptable. According to the simulation results for various exposure levels and additive electronic noise levels, x-ray quantum noise is more dominant than the additive electronic noise. The framework of modeling a CT detector system suggested in this study will be helpful for the development of an accurate and realistic projection simulation model.

  6. Corrected coronary opacification decrease from coronary computed tomography angiography: Validation with quantitative 13N-ammonia positron emission tomography.

    PubMed

    Benz, Dominik C; Gräni, Christoph; Ferro, Paola; Neumeier, Luis; Messerli, Michael; Possner, Mathias; Clerc, Olivier F; Gebhard, Catherine; Gaemperli, Oliver; Pazhenkottil, Aju P; Kaufmann, Philipp A; Buechel, Ronny R

    2017-07-06

    To assess the functional relevance of a coronary artery stenosis, corrected coronary opacification (CCO) decrease derived from coronary computed tomography angiography (CCTA) has been proposed. The present study aims at validating CCO decrease with quantitative 13N-ammonia positron emission tomography (PET) myocardial perfusion imaging (MPI). This retrospective study consists of 39 patients who underwent hybrid CCTA/PET-MPI. From CCTA, attenuation in the coronary lumen was measured before and after a stenosis and corrected to the aorta to calculate CCO and its decrease. Relative flow reserve (RFR) was calculated by dividing the stress myocardial blood flow (MBF) of a vessel territory subtended by a stenotic coronary by the stress MBF of the reference territories without stenoses. RFR was abnormal in 11 vessel territories (27%). CCO decrease yielded a sensitivity, specificity, negative predictive value, positive predictive value, and accuracy for prediction of an abnormal RFR of 73%, 70%, 88%, 47%, and 70%, respectively. CCTA-derived CCO decrease has moderate diagnostic accuracy to predict an abnormal RFR in PET-MPI. However, its high negative predictive value to rule out functional relevance of a given lesion may confer clinical implications in the diagnostic work-up of patients with a coronary stenosis.

  7. Qualitative, semi-quantitative, and quantitative simulation of the osmoregulation system in yeast.

    PubMed

    Pang, Wei; Coghill, George M

    2015-05-01

    In this paper we demonstrate how Morven, a computational framework which can perform qualitative, semi-quantitative, and quantitative simulation of dynamical systems using the same model formalism, is applied to study the osmotic stress response pathway in yeast. First the Morven framework itself is briefly introduced in terms of the model formalism employed and output format. We then built a qualitative model for the biophysical process of the osmoregulation in yeast, and a global qualitative-level picture was obtained through qualitative simulation of this model. Furthermore, we constructed a Morven model based on existing quantitative model of the osmoregulation system. This model was then simulated qualitatively, semi-quantitatively, and quantitatively. The obtained simulation results are presented with an analysis. Finally the future development of the Morven framework for modelling the dynamic biological systems is discussed.

  8. Qualitative, semi-quantitative, and quantitative simulation of the osmoregulation system in yeast

    PubMed Central

    Pang, Wei; Coghill, George M.

    2015-01-01

    In this paper we demonstrate how Morven, a computational framework which can perform qualitative, semi-quantitative, and quantitative simulation of dynamical systems using the same model formalism, is applied to study the osmotic stress response pathway in yeast. First the Morven framework itself is briefly introduced in terms of the model formalism employed and output format. We then built a qualitative model for the biophysical process of the osmoregulation in yeast, and a global qualitative-level picture was obtained through qualitative simulation of this model. Furthermore, we constructed a Morven model based on existing quantitative model of the osmoregulation system. This model was then simulated qualitatively, semi-quantitatively, and quantitatively. The obtained simulation results are presented with an analysis. Finally the future development of the Morven framework for modelling the dynamic biological systems is discussed. PMID:25864377

  9. Simulation of Underground Muon Flux with Application to Muon Tomography

    NASA Astrophysics Data System (ADS)

    Yamaoka, J. A. K.; Bonneville, A.; Flygare, J.; Lintereur, A.; Kouzes, R.

    2015-12-01

    Muon tomography uses highly energetic muons, produced by cosmic rays interacting within the upper atmosphere, to image dense materials. Like x-rays, an image can be constructed from the negative of the absorbed (or scattered) muons. Unlike x-rays, these muons can penetrate thousands of meters of earth. Muon tomography has been shown to be useful across a wide range of applications (such as imaging of the interior of volcanoes and cargo containers). This work estimates the sensitivity of muon tomography for various underground applications. We use simulations to estimate the change in flux as well as the spatial resolution when imaging static objects, such as mine shafts, and dynamic objects, such as a CO2 reservoir filling over time. We present a framework where we import ground density data from other sources, such as wells, gravity and seismic data, to generate an expected muon flux distribution at specified underground locations. This information can further be fed into a detector simulation to estimate a final experimental sensitivity. There are many applications of this method. We explore its use to image underground nuclear test sites, both the deformation from the explosion as well as the supporting infrastructure (access tunnels and shafts). We also made estimates for imaging a CO2 sequestration site similar to Futuregen 2.0 in Illinois and for imaging magma chambers beneath the Cascade Range volcanoes. This work may also be useful to basic science, such as underground dark matter experiments, where increasing experimental sensitivity requires, amongst other factors, a precise knowledge of the muon background.

  10. Diffraction tomography applied to simulated ultrasound through breast tissue

    NASA Astrophysics Data System (ADS)

    Chambers, David H.

    2002-11-01

    Diffraction tomography is used to obtain images of sound speed and attenuation of a slice of breast tissue obtained from the Visible Woman data set. Simulated ultrasound data was generated using an acoustic propagation code run on the ASCI Blue Pacific computer at Lawrence Livermore National Laboratory. Data was generated for a slice of healthy tissue, and a slice with simulated lesions to determine the ability of the imaging method to detect various abnormalities in the breast. In addition, the time reversal operator for the slice was constructed from the data and the eigenfunctions backpropagated into the slice as first suggested by Mast [Mast, Nachman, and Waag, J. Acoust. Soc. Am. 102(2)] to identify structures associated with each time reversal mode for both the healthy tissue and tissue with lesions.

  11. [High resolution peripheral quantitative computed tomography for the assessment of morphological and mechanical bone parameters].

    PubMed

    Fuller, Henrique; Fuller, Ricardo; Pereira, Rosa Maria R

    2015-01-01

    High resolution peripheral quantitative computed tomography (HR-pQCT) is a new technology commercially available for less than 10 years that allows performing in vivo assessment of bone parameters. HR-pQCT assesses the trabecular thickness, trabecular separation, trabecular number and connectivity density and, in addition, cortical bone density and thickness and total bone volume and density in high-definition mode, which additionally allows obtaining digital constructs of bone microarchitecture. The application of mathematics to captured data, a method called finite element analysis (FEA), allows the estimation of the physical properties of the tissue, simulating supported loads in a non-invasive way. Thus, HR-pQCT simultaneously acquires data previously provided separately by dual energy x-ray absorptiometry (DXA), magnetic resonance imaging and histomorphometry, aggregating biomechanical estimates previously only possible in extracted tissues. This method has a satisfactory reproducibility, with coefficients of variation rarely exceeding 3%. Regarding accuracy, the method shows a fair to good agreement (r(2) = 0.37-0.97). The main clinical application of this method is in the quantification and monitoring of metabolic bone disorders, more fully evaluating bone strength and fracture risk. In rheumatoid arthritis patients, this allows gauging the number and size of erosions and cysts, in addition to joint space. In osteoarthritis, it is possible to characterize the bone marrow edema-like areas that show a correlation with cartilage breakdown. Given its high cost, HR-pQCT is still a research tool, but the high resolution and efficiency of this method reveal advantages over the methods currently used for bone assessment, with a potential to become an important tool in clinical practice.

  12. Monte-Carlo-based inversion scheme for 3D quantitative photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Kaplan, Bernhard A.; Buchmann, Jens; Prohaska, Steffen; Laufer, Jan

    2017-03-01

    The goal of quantitative photoacoustic tomography (qPAT) is to recover maps of the chromophore distributions from multiwavelength images of the initial pressure. Model-based inversions that incorporate the physical processes underlying the photoacoustic (PA) signal generation represent a promising approach. Monte-Carlo models of the light transport are computationally expensive, but provide accurate fluence distributions predictions, especially in the ballistic and quasi-ballistic regimes. Here, we focus on the inverse problem of 3D qPAT of blood oxygenation and investigate the application of the Monte-Carlo method in a model-based inversion scheme. A forward model of the light transport based on the MCX simulator and acoustic propagation modeled by the k-Wave toolbox was used to generate a PA image data set acquired in a tissue phantom over a planar detection geometry. The combination of the optical and acoustic models is shown to account for limited-view artifacts. In addition, the errors in the fluence due to, for example, partial volume artifacts and absorbers immediately adjacent to the region of interest are investigated. To accomplish large-scale inversions in 3D, the number of degrees of freedom is reduced by applying image segmentation to the initial pressure distribution to extract a limited number of regions with homogeneous optical parameters. The absorber concentration in the tissue phantom was estimated using a coordinate descent parameter search based on the comparison between measured and modeled PA spectra. The estimated relative concentrations using this approach lie within 5 % compared to the known concentrations. Finally, we discuss the feasibility of this approach to recover the blood oxygenation from experimental data.

  13. Quantitative computer simulations of extraterrestrial processing operations

    NASA Technical Reports Server (NTRS)

    Vincent, T. L.; Nikravesh, P. E.

    1989-01-01

    The automation of a small, solid propellant mixer was studied. Temperature control is under investigation. A numerical simulation of the system is under development and will be tested using different control options. Control system hardware is currently being put into place. The construction of mathematical models and simulation techniques for understanding various engineering processes is also studied. Computer graphics packages were utilized for better visualization of the simulation results. The mechanical mixing of propellants is examined. Simulation of the mixing process is being done to study how one can control for chaotic behavior to meet specified mixing requirements. An experimental mixing chamber is also being built. It will allow visual tracking of particles under mixing. The experimental unit will be used to test ideas from chaos theory, as well as to verify simulation results. This project has applications to extraterrestrial propellant quality and reliability.

  14. Quantitative computed tomography assessment of lung structure and function in pulmonary emphysema.

    PubMed

    Madani, A; Keyzer, C; Gevenois, P A

    2001-10-01

    Accurate diagnosis and quantification of pulmonary emphysema during life is important to understand the natural history of the disease, to assess the extent of the disease, and to evaluate and follow-up therapeutic interventions. Since pulmonary emphysema is defined through pathological criteria, new methods of diagnosis and quantification should be validated by comparisons against histological references. Recent studies have addressed the capability of computed tomography (CT) to quantify pulmonary emphysema accurately. The studies reviewed in this article have been based on CT scans obtained after deep inspiration or expiration, on subjective visual grading and on objective measurements of attenuation values. Especially dedicated software was used for this purpose, which provided numerical data, on both two- and three-dimensional approaches, and compared CT data with pulmonary function tests. More recently, fractal and textural analyses were applied to computed tomography scans to assess the presence, the extent, and the types of emphysema. Quantitative computed tomography has already been used in patient selection for surgical treatment of pulmonary emphysema and in pharmacotherapeutical trials. However, despite numerous and extensive studies, this technique has not yet been standardized and important questions about how best to use computed tomography for the quantification of pulmonary emphysema are still unsolved.

  15. Diagnosis of simulated condylar bone defects using panoramic radiography, spiral tomography and cone-beam computed tomography: A comparison study

    PubMed Central

    Salemi, Fatemeh; Shokri, Abbas; Baharvand, Maryam

    2015-01-01

    Objectives: Radiographic examination is one of the most important parts of the clinical assessment routine for temporomandibular disorders. The aim of this study was to compare the diagnostic accuracy of cone-beam computed tomography(CBCT) with panoramic radiography and spiral computed tomography for the detection of the simulated mandibular condyle bone lesions. Study Design: The sample consisted of 10 TMJs from 5 dried human skulls. Simulated erosive and osteophytic lesions were created in 3 different sizes using round diamond bur and bone chips, respectively. Panoramic radiography, spiral tomography and cone-beam computed tomography were used in defect detection. Data were statistically analyzed with the Mann-Whitney test. The reliability and degrees of agreement between two observers were also determined by the mean of Cohen’s Kappa analysis. Results: CBCT had a statistically significant superiority than other studied techniques in detection of both erosive and osteophytic lesions with different sizes. There were significant differences between tomography and panoramic in correct detection of both erosive and osteophytic lesions with 1mm and 1.5 mm in size. However, there were no significant differences between Tomography and Panoramic in correct detection of both erosive and osteophytic lesions with 0.5 mm in size. Conclusions: CBCT images provide a greater diagnostic accuracy than spiral tomography and panoramic radiography in the detection of condylar bone erosions and osteophytes. Key words:Bone defect, Condyle, CBCT, Panoramic, radiography. PMID:25810839

  16. Quantitative computed tomography of the liver in juvenile green sea turtles (Chelonia mydas).

    PubMed

    Bonelli, Marília de Albuquerque; de Oliveira, Daniel Capucho; Costa, Lorena Adão Vescovi Séllos; Forattini, Jannine Garcia; Júnior, João Luiz Rossi; Leite, Flaviana Lima Guião; Costa, Fabiano Séllos

    2013-06-01

    Quantitative computed tomography (QCT) is a highly sensitive, applicable technique for determining the x-ray attenuation of organs. This technique reveals great precision in the detection of alterations in the x-ray attenuation of hepatic parenchyma, although the lack of studies establishing normal values limits its application in wild animals. The objective of this study was to establish mean hepatic attenuation values in four healthy juvenile sea turtles (Chelonia mydas) using QCT. Helical computed tomography scans were performed and regions of interest selected in the liver after multi-planar reconstruction images were obtained. The mean attenuation value for the hepatic parenchyma in these four turtles was 60.09 +/- 5.3 standard deviation Hounsfield units. Determining normal x-ray attenuation values of the liver increases knowledge of the computed tomographic anatomy of this species and may be useful in the investigation of hepatic diseases.

  17. Quantitative chemical-structure evaluation using atom probe tomography: Short-range order analysis of Fe-Al.

    PubMed

    Marceau, R K W; Ceguerra, A V; Breen, A J; Raabe, D; Ringer, S P

    2015-10-01

    Short-range-order (SRO) has been quantitatively evaluated in an Fe-18Al (at%) alloy using atom probe tomography (APT) data and by calculation of the generalised multicomponent short-range order (GM-SRO) parameters, which have been determined by shell-based analysis of the three-dimensional atomic positions. The accuracy of this method with respect to limited detector efficiency and spatial resolution is tested against simulated D03 ordered data. Whilst there is minimal adverse effect from limited atom probe instrument detector efficiency, the combination of this with imperfect spatial resolution has the effect of making the data appear more randomised. The value of lattice rectification of the experimental APT data prior to GM-SRO analysis is demonstrated through improved information sensitivity.

  18. [Quantitative assessment on artifacts of dental restorative materials in cone beam computed tomography].

    PubMed

    Yuan, Fu-song; Sun, Yu-chun; Xie, Xiao-yan; Wang, Yong; Lv, Pei-jun

    2013-12-18

    To quantitatively evaluate the artifacts appearance of eight kinds of common dental restorative materials, such as zirconia. For the full-crown tooth preparation of mandibular first molar, eight kinds of full-crowns, such as zirconia all-ceramic crown, glass ceramic crown, ceramage crown, Au-Pt based porcelain-fused-metal (PFM) crown, Pure Titanium PFM crown, Co-Cr PFM crown, Ni-Cr PFM crown, and Au-Pd metal crown were fabricated. And natural teeth in vitro were used as controls. These full-crown and natural teeth in vitro were mounted an ultraviolet-curable resin fixed plate. High resolution cone beam computed tomography (CBCT) was used to scan all of the crowns and natural teeth in vitro, and their DICOM data were imported into software MIMICS 10.0. Then, the number of stripes and the maximum diameters of artifacts around the full-crowns were evaluated quantitatively in two-dimensional tomography images. In the two-dimensional tomography images,the artifacts did not appear around the natural teeth in vitro, glass ceramic crown, and ceramage crown. But thr artifacts appeared around the zirconia all-ceramic and metal crown. The number of stripes of artifacts was five to nine per one crown. The maximum diameters of the artifacts were 2.4 to 2.6 cm and 2.2 to 2.7 cm. In the two-dimensional tomography images of CBCT, stripe-like and radical artifacts were caused around the zirconia all-ceramic crown and metal based porcelain-fused-metal crowns. These artifacts could lower the imaging quality of the full crown shape greatly. The artifact was not caused around the natural teeth in vitro, glass ceramic crown, and ceramage crown.

  19. Monte Carlo Simulations of Arterial Imaging with Optical Coherence Tomography

    SciTech Connect

    Amendt, P.; Estabrook, K.; Everett, M.; London, R.A.; Maitland, D.; Zimmerman, G.; Colston, B.; da Silva, L.; Sathyam, U.

    2000-02-01

    The laser-tissue interaction code LATIS [London et al., Appl. Optics 36, 9068 ( 1998)] is used to analyze photon scattering histories representative of optical coherence tomography (OCT) experiment performed at Lawrence Livermore National Laboratory. Monte Carlo photonics with Henyey-Greenstein anisotropic scattering is implemented and used to simulate signal discrimination of intravascular structure. An analytic model is developed and used to obtain a scaling law relation for optimization of the OCT signal and to validate Monte Carlo photonics. The appropriateness of the Henyey-Greenstein phase function is studied by direct comparison with more detailed Mie scattering theory using an ensemble of spherical dielectric scatterers. Modest differences are found between the two prescriptions for describing photon angular scattering in tissue. In particular, the Mie scattering phase functions provide less overall reflectance signal but more signal contrast compared to the Henyey-Greenstein formulation.

  20. Tomography of the ionosphere: Four-dimensional simulations

    NASA Astrophysics Data System (ADS)

    Howe, Bruce M.; Runciman, Kay; Secan, James A.

    1998-01-01

    Using a four-dimensional stochastic model of ionosphere perturbations, simulations are made of a tomography system based on data from the Global Positioning System and a low Earth-orbiting satellite. The perturbations are departures from a simple time-independent reference state. The spatial structure is parameterized in terms of empirical orthogonal functions (EOFs) in the vertical and spherical harmonics in the horizontal. The horizontal covariance structure is specified by variance and correlation length scales as functions of latitude and longitude. Time dependence is modeled as a first-order Markov process with a 6-hour timescale and white-noise forcing. A Sun-fixed coordinate system is used so that ionospheric features are more nearly steady in time. A Kaiman filter is used to objectively assimilate the simulated data into the simple time-dependent model. In addition to solving for the three-dimensional electron density field at each time step, the procedure solves for instrumental biases. The simulations show that the fractions of resolved variance for vertical EOF modes 1, 2, and 3 are 0.99, 0.93, and 0.73, respectively. The resolution of the vertically integrated total electron content is 0.99.

  1. Neutron stimulated emission computed tomography: a Monte Carlo simulation approach.

    PubMed

    Sharma, A C; Harrawood, B P; Bender, J E; Tourassi, G D; Kapadia, A J

    2007-10-21

    A Monte Carlo simulation has been developed for neutron stimulated emission computed tomography (NSECT) using the GEANT4 toolkit. NSECT is a new approach to biomedical imaging that allows spectral analysis of the elements present within the sample. In NSECT, a beam of high-energy neutrons interrogates a sample and the nuclei in the sample are stimulated to an excited state by inelastic scattering of the neutrons. The characteristic gammas emitted by the excited nuclei are captured in a spectrometer to form multi-energy spectra. Currently, a tomographic image is formed using a collimated neutron beam to define the line integral paths for the tomographic projections. These projection data are reconstructed to form a representation of the distribution of individual elements in the sample. To facilitate the development of this technique, a Monte Carlo simulation model has been constructed from the GEANT4 toolkit. This simulation includes modeling of the neutron beam source and collimation, the samples, the neutron interactions within the samples, the emission of characteristic gammas, and the detection of these gammas in a Germanium crystal. In addition, the model allows the absorbed radiation dose to be calculated for internal components of the sample. NSECT presents challenges not typically addressed in Monte Carlo modeling of high-energy physics applications. In order to address issues critical to the clinical development of NSECT, this paper will describe the GEANT4 simulation environment and three separate simulations performed to accomplish three specific aims. First, comparison of a simulation to a tomographic experiment will verify the accuracy of both the gamma energy spectra produced and the positioning of the beam relative to the sample. Second, parametric analysis of simulations performed with different user-defined variables will determine the best way to effectively model low energy neutrons in tissue, which is a concern with the high hydrogen content in

  2. Simulation-based artifact correction (SBAC) for metrological computed tomography

    NASA Astrophysics Data System (ADS)

    Maier, Joscha; Leinweber, Carsten; Sawall, Stefan; Stoschus, Henning; Ballach, Frederic; Müller, Tobias; Hammer, Michael; Christoph, Ralf; Kachelrieß, Marc

    2017-06-01

    Computed tomography (CT) is a valuable tool for the metrolocical assessment of industrial components. However, the application of CT to the investigation of highly attenuating objects or multi-material components is often restricted by the presence of CT artifacts caused by beam hardening, x-ray scatter, off-focal radiation, partial volume effects or the cone-beam reconstruction itself. In order to overcome this limitation, this paper proposes an approach to calculate a correction term that compensates for the contribution of artifacts and thus enables an appropriate assessment of these components using CT. Therefore, we make use of computer simulations of the CT measurement process. Based on an appropriate model of the object, e.g. an initial reconstruction or a CAD model, two simulations are carried out. One simulation considers all physical effects that cause artifacts using dedicated analytic methods as well as Monte Carlo-based models. The other one represents an ideal CT measurement i.e. a measurement in parallel beam geometry with a monochromatic, point-like x-ray source and no x-ray scattering. Thus, the difference between these simulations is an estimate for the present artifacts and can be used to correct the acquired projection data or the corresponding CT reconstruction, respectively. The performance of the proposed approach is evaluated using simulated as well as measured data of single and multi-material components. Our approach yields CT reconstructions that are nearly free of artifacts and thereby clearly outperforms commonly used artifact reduction algorithms in terms of image quality. A comparison against tactile reference measurements demonstrates the ability of the proposed approach to increase the accuracy of the metrological assessment significantly.

  3. Simulation and the Development of Clinical Judgment: A Quantitative Study

    ERIC Educational Resources Information Center

    Holland, Susan

    2015-01-01

    The purpose of this quantitative pretest posttest quasi-experimental research study was to explore the effect of the NESD on clinical judgment in associate degree nursing students and compare the differences between groups when the Nursing Education Simulation Design (NESD) guided simulation in order to identify educational strategies promoting…

  4. Simulation and the Development of Clinical Judgment: A Quantitative Study

    ERIC Educational Resources Information Center

    Holland, Susan

    2015-01-01

    The purpose of this quantitative pretest posttest quasi-experimental research study was to explore the effect of the NESD on clinical judgment in associate degree nursing students and compare the differences between groups when the Nursing Education Simulation Design (NESD) guided simulation in order to identify educational strategies promoting…

  5. Quantitative polarization and flow evaluation of choroid and sclera by multifunctional Jones matrix optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Sugiyama, S.; Hong, Y.-J.; Kasaragod, D.; Makita, S.; Miura, M.; Ikuno, Y.; Yasuno, Y.

    2016-03-01

    Quantitative evaluation of optical properties of choroid and sclera are performed by multifunctional optical coherence tomography. Five normal eyes, five glaucoma eyes and one choroidal atrophy eye are examined. The refractive error was found to be correlated with choroidal birefringence, polarization uniformity, and flow in addition to scleral birefringence among normal eyes. The significant differences were observed between the normal and the glaucoma eyes, as for choroidal polarization uniformity, flow and scleral birefringence. An automatic segmentation algorithm of retinal pigment epithelium and chorioscleral interface based on multifunctional signals is also presented.

  6. Quantitative evaluation of registration methods for atlas-based diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Wu, Xue; Eggebrecht, Adam T.; Culver, Joseph P.; Zhan, Yuxuan; Basevi, Hector; Dehghani, Hamid

    2013-06-01

    In Diffuse Optical Tomography (DOT), an atlas-based model can be used as an alternative to a subject-specific anatomical model for recovery of brain activity. The main step of the generation of atlas-based subject model is the registration of atlas model to the subject head. The accuracy of the DOT then relies on the accuracy of registration method. In this work, 11 registration methods are quantitatively evaluated. The registration method with EEG 10/20 systems with 19 landmarks and non-iterative point to point algorithm provides approximately 1.4 mm surface error and is considered as the most efficient registration method.

  7. Automatic segmentation of intravascular optical coherence tomography images for facilitating quantitative diagnosis of atherosclerosis

    NASA Astrophysics Data System (ADS)

    Wang, Zhao; Kyono, Hiroyuki; Bezerra, Hiram G.; Wilson, David L.; Costa, Marco A.; Rollins, Andrew M.

    2011-03-01

    Quantitative diagnosis of atherosclerosis can be facilitated by automatic segmentation of intravascular Optical Coherence Tomography (OCT) images. We report an automatic method of lumen and calcified plaque segmentation for commercial intravascular OCT systems. Lumen segmentation is based on a dynamic programming scheme. Calcified plaque is localized by edge detection and finely traced using an active contour model. The proposed methods yield promising results when applied to clinical images as validated by manual tracing. Lumen segmentation is useful for estimating the coronary artery stenosis and guiding stent implantation. Calcified plaque segmentation can be used to estimate the distribution of superficial calcification and inform strategies for coronary stenting.

  8. Quantitative simulation of extraterrestrial engineering devices

    NASA Technical Reports Server (NTRS)

    Arabyan, A.; Nikravesh, P. E.; Vincent, T. L.

    1991-01-01

    This is a multicomponent, multidisciplinary project whose overall objective is to build an integrated database, simulation, visualization, and optimization system for the proposed oxygen manufacturing plant on Mars. Specifically, the system allows users to enter physical description, engineering, and connectivity data through a uniform, user-friendly interface and stores the data in formats compatible with other software also developed as part of this project. These latter components include: (1) programs to simulate the behavior of various parts of the plant in Martian conditions; (2) an animation program which, in different modes, provides visual feedback to designers and researchers about the location of and temperature distribution among components as well as heat, mass, and data flow through the plant as it operates in different scenarios; (3) a control program to investigate the stability and response of the system under different disturbance conditions; and (4) an optimization program to maximize or minimize various criteria as the system evolves into its final design. All components of the system are interconnected so that changes entered through one component are reflected in the others.

  9. Quantitative three-dimensional photoacoustic tomography of the finger joints: an in vivo study

    NASA Astrophysics Data System (ADS)

    Sun, Yao; Sobel, Eric; Jiang, Huabei

    2009-11-01

    We present for the first time in vivo full three-dimensional (3-D) photoacoustic tomography (PAT) of the distal interphalangeal joint in a human subject. Both absorbed energy density and absorption coefficient images of the joint are quantitatively obtained using our finite-element-based photoacoustic image reconstruction algorithm coupled with the photon diffusion equation. The results show that major anatomical features in the joint along with the side arteries can be imaged with a 1-MHz transducer in a spherical scanning geometry. In addition, the cartilages associated with the joint can be quantitatively differentiated from the phalanx. This in vivo study suggests that the 3-D PAT method described has the potential to be used for early diagnosis of joint diseases such as osteoarthritis and rheumatoid arthritis.

  10. Experimental assessment of bone mineral density using quantitative computed tomography in holstein dairy cows

    PubMed Central

    MAETANI, Ayami; ITOH, Megumi; NISHIHARA, Kahori; AOKI, Takahiro; OHTANI, Masayuki; SHIBANO, Kenichi; KAYANO, Mitsunori; YAMADA, Kazutaka

    2016-01-01

    The aim of this study was to assess the measurement of bone mineral density (BMD) by quantitative computed tomography (QCT), comparing the relationships of BMD between QCT and dual-energy X-ray absorptiometry (DXA) and between QCT and radiographic absorptiometry (RA) in the metacarpal bone of Holstein dairy cows (n=27). A significant positive correlation was found between QCT and DXA measurements (r=0.70, P<0.01), and a significant correlation was found between QCT and RA measurements (r=0.50, P<0.01). We conclude that QCT provides quantitative evaluation of BMD in dairy cows, because BMD measured by QCT showed positive correlations with BMD measured by the two conventional methods: DXA and RA. PMID:27075115

  11. Quantitative microvascular hemoglobin mapping using visible light spectroscopic Optical Coherence Tomography

    PubMed Central

    Chong, Shau Poh; Merkle, Conrad W.; Leahy, Conor; Radhakrishnan, Harsha; Srinivasan, Vivek J.

    2015-01-01

    Quantification of chromophore concentrations in reflectance mode remains a major challenge for biomedical optics. Spectroscopic Optical Coherence Tomography (SOCT) provides depth-resolved spectroscopic information necessary for quantitative analysis of chromophores, like hemoglobin, but conventional SOCT analysis methods are applicable only to well-defined specular reflections, which may be absent in highly scattering biological tissue. Here, by fitting of the dynamic scattering signal spectrum in the OCT angiogram using a forward model of light propagation, we quantitatively determine hemoglobin concentrations directly. Importantly, this methodology enables mapping of both oxygen saturation and total hemoglobin concentration, or alternatively, oxyhemoglobin and deoxyhemoglobin concentration, simultaneously. Quantification was verified by ex vivo blood measurements at various pO2 and hematocrit levels. Imaging results from the rodent brain and retina are presented. Confounds including noise and scattering, as well as potential clinical applications, are discussed. PMID:25909026

  12. Simulation of emission tomography using grid middleware for distributed computing.

    PubMed

    Thomason, M G; Longton, R F; Gregor, J; Smith, G T; Hutson, R K

    2004-09-01

    SimSET is Monte Carlo simulation software for emission tomography. This paper describes a simple but effective scheme for parallel execution of SimSET using NetSolve, a client-server system for distributed computation. NetSolve (version 1.4.1) is "grid middleware" which enables a user (the client) to run specific computations remotely and simultaneously on a grid of networked computers (the servers). Since the servers do not have to be identical machines, computation may take place in a heterogeneous environment. To take advantage of diversity in machines and their workloads, a client-side scheduler was implemented for the Monte Carlo simulation. The scheduler partitions the total decay events by taking into account the inherent compute-speeds and recent average workloads, i.e., the scheduler assigns more decay events to processors expected to give faster service and fewer decay events to those expected to give slower service. When compute-speeds and sustained workloads are taken into account, the speed-up is essentially linear in the number of equivalent "maximum-service" processors. One modification in the SimSET code (version 2.6.2.3) was made to ensure that the total number of decay events specified by the user is maintained in the distributed simulation. No other modifications in the standard SimSET code were made. Each processor runs complete SimSET code for its assignment of decay events, independently of others running simultaneously. Empirical results are reported for simulation of a clinical-quality lung perfusion study.

  13. Quantitative analysis of brain edema and swelling on early postmortem computed tomography: comparison with antemortem computed tomography.

    PubMed

    Takahashi, Naoya; Satou, Chihiro; Higuchi, Takeshi; Shiotani, Motoi; Maeda, Haruo; Hirose, Yasuo

    2010-06-01

    The aim of this study was quantitatively to analyze brain edema and swelling due to early postmortem changes using computed tomography (CT) scans of the head. Review board approval was obtained, and informed consent was waived. A total of 41 patients who underwent head CT before and shortly after death were enrolled. Hounsfield units (HUs) of gray matter (GM) and white matter (WM) were measured at the levels of the basal ganglia, centrum semiovale, and high convexity area on both antemortem and postmortem CT. The length of the minor axis of the third ventricle at the level of the basal ganglia and the width of the central sulcus at the level of high convexity were measured. At each level tested, the HUs of GM and the GM/WM ratios on postmortem CT were significantly lower than those on antemortem CT (P < 0.001). HUs of WM on postmortem CT were slightly higher than those on antemortem CT but without significant difference (P > 0.1). Postmortem CT showed subtle loss of distinction between GM and WM. The size of the third ventricle and the width of the central sulcus did not vary before and after death (P > 0.1). Early postmortem CT shows mild brain edema but does not show brain swelling.

  14. Quantitative 3-D imaging of eukaryotic cells using soft X-ray tomography.

    PubMed

    Parkinson, Dilworth Y; McDermott, Gerry; Etkin, Laurence D; Le Gros, Mark A; Larabell, Carolyn A

    2008-06-01

    Imaging has long been one of the principal techniques used in biological and biomedical research. Indeed, the field of cell biology grew out of the first electron microscopy images of organelles in a cell. Since this landmark event, much work has been carried out to image and classify the organelles in eukaryotic cells using electron microscopy. Fluorescently labeled organelles can now be tracked in live cells, and recently, powerful light microscope techniques have pushed the limit of optical resolution to image single molecules. In this paper, we describe the use of soft X-ray tomography, a new tool for quantitative imaging of organelle structure and distribution in whole, fully hydrated eukaryotic Schizosaccharomyces pombe cells. In addition to imaging intact cells, soft X-ray tomography has the advantage of not requiring the use of any staining or fixation protocols--cells are simply transferred from their growth environment to a sample holder and immediately cryofixed. In this way the cells can be imaged in a near native state. Soft X-ray tomography is also capable of imaging relatively large numbers of cells in a short period of time, and is therefore a technique that has the potential to produce information on organelle morphology from statistically significant numbers of cells.

  15. Quantitative material decomposition using spectral computed tomography with an energy-resolved photon-counting detector.

    PubMed

    Lee, Seungwan; Choi, Yu-Na; Kim, Hee-Joung

    2014-09-21

    Dual-energy computed tomography (CT) techniques have been used to decompose materials and characterize tissues according to their physical and chemical compositions. However, these techniques are hampered by the limitations of conventional x-ray detectors operated in charge integrating mode. Energy-resolved photon-counting detectors provide spectral information from polychromatic x-rays using multiple energy thresholds. These detectors allow simultaneous acquisition of data in different energy ranges without spectral overlap, resulting in more efficient material decomposition and quantification for dual-energy CT. In this study, a pre-reconstruction dual-energy CT technique based on volume conservation was proposed for three-material decomposition. The technique was combined with iterative reconstruction algorithms by using a ray-driven projector in order to improve the quality of decomposition images and reduce radiation dose. A spectral CT system equipped with a CZT-based photon-counting detector was used to implement the proposed dual-energy CT technique. We obtained dual-energy images of calibration and three-material phantoms consisting of low atomic number materials from the optimal energy bins determined by Monte Carlo simulations. The material decomposition process was accomplished by both the proposed and post-reconstruction dual-energy CT techniques. Linear regression and normalized root-mean-square error (NRMSE) analyses were performed to evaluate the quantitative accuracy of decomposition images. The calibration accuracy of the proposed dual-energy CT technique was higher than that of the post-reconstruction dual-energy CT technique, with fitted slopes of 0.97-1.01 and NRMSEs of 0.20-4.50% for all basis materials. In the three-material phantom study, the proposed dual-energy CT technique decreased the NRMSEs of measured volume fractions by factors of 0.17-0.28 compared to the post-reconstruction dual-energy CT technique. It was concluded that the

  16. Simultaneous Neutron and X-ray Tomography for Quantitative analysis of Geological Samples

    NASA Astrophysics Data System (ADS)

    LaManna, J.; Hussey, D. S.; Baltic, E.; Jacobson, D. L.

    2016-12-01

    Multiphase flow is a critical area of research for shale gas, oil recovery, underground CO2 sequestration, geothermal power, and aquifer management. It is critical to understand the porous structure of the geological formations in addition to the fluid/pore and fluid/fluid interactions. Difficulties for analyzing flow characteristics of rock cores are in obtaining 3D distribution information on the fluid flow and maintaining the cores in a state for other analysis methods. Two powerful non-destructive methods for obtaining 3D structural and compositional information are X-ray and neutron tomography. X-ray tomography produces information on density and structure while neutrons excel at acquiring the liquid phase and produces compositional information. These two methods can offer strong complementary information but are typically conducted at separate times and often at different facilities. This poses issues for obtaining dynamic and stochastic information as the sample will change between analysis modes. To address this, NIST has developed a system that allows for multimodal, simultaneous tomography using thermal neutrons and X-rays by placing a 90 keVp micro-focus X-ray tube 90° to the neutron beam. High pressure core holders that simulate underground conditions have been developed to facilitate simultaneous tomography. These cells allow for the control of confining pressure, axial load, temperature, and fluid flow through the core. This talk will give an overview the simultaneous neutron and x-ray tomography capabilities at NIST, the benefits of multimodal imaging, environmental equipment for geology studies, and several case studies that have been conducted at NIST.

  17. A dual-frequency applied potential tomography technique: computer simulations.

    PubMed

    Griffiths, H; Ahmed, A

    1987-01-01

    Applied potential tomography has been discussed in relation to both static and dynamic imaging. We have investigated the feasibility of obtaining static images by measuring profiles at two frequencies of drive current to exploit the differing gradients of electrical conductivity with frequency for different tissues. This method has the advantages that no profile for the homogeneous medium is then needed, and the electrodes can be coupled directly to the skin. To demonstrate the principle, computer simulations have been carried out using published electrical parameters for mammalian tissues at frequencies of 100 and 150 kHz. The distribution of complex electric potentials was calculated by the successive over-relaxation method in two dimensions for an abdominal cross-section with 16 electrodes equally spaced around the surface. From the computed electrode potentials, images were reconstructed using a back-projection method (neglecting phase information). Liver and kidney appeared most distinctly on the image because of their comparatively large conductivity gradients. The perturbations in the electrode potential differences between the two frequencies had a mean value of 5%, requiring accurate measurement in a practical system, compared with 150% when the 100 kHz values were related to a simulation of homogeneous saline equal in conductivity to muscle. The perturbations could be increased by widening the separation of the frequencies. Static imaging using a dual-frequency technique appears to be feasible, but a more detailed consideration of the electrical properties of tissues is needed to determine the optimum choice of frequencies.

  18. Quantitative 3D high resolution transmission ultrasound tomography: creating clinically relevant images (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wiskin, James; Klock, John; Iuanow, Elaine; Borup, Dave T.; Terry, Robin; Malik, Bilal H.; Lenox, Mark

    2017-03-01

    There has been a great deal of research into ultrasound tomography for breast imaging over the past 35 years. Few successful attempts have been made to reconstruct high-resolution images using transmission ultrasound. To this end, advances have been made in 2D and 3D algorithms that utilize either time of arrival or full wave data to reconstruct images with high spatial and contrast resolution suitable for clinical interpretation. The highest resolution and quantitative accuracy result from inverse scattering applied to full wave data in 3D. However, this has been prohibitively computationally expensive, meaning that full inverse scattering ultrasound tomography has not been considered clinically viable. Here we show the results of applying a nonlinear inverse scattering algorithm to 3D data in a clinically useful time frame. This method yields Quantitative Transmission (QT) ultrasound images with high spatial and contrast resolution. We reconstruct sound speeds for various 2D and 3D phantoms and verify these values with independent measurements. The data are fully 3D as is the reconstruction algorithm, with no 2D approximations. We show that 2D reconstruction algorithms can introduce artifacts into the QT breast image which are avoided by using a full 3D algorithm and data. We show high resolution gross and microscopic anatomic correlations comparing cadaveric breast QT images with MRI to establish imaging capability and accuracy. Finally, we show reconstructions of data from volunteers, as well as an objective visual grading analysis to confirm clinical imaging capability and accuracy.

  19. Direct Estimation of Optical Parameters From Photoacoustic Time Series in Quantitative Photoacoustic Tomography.

    PubMed

    Pulkkinen, Aki; Cox, Ben T; Arridge, Simon R; Goh, Hwan; Kaipio, Jari P; Tarvainen, Tanja

    2016-11-01

    Estimation of optical absorption and scattering of a target is an inverse problem associated with quantitative photoacoustic tomography. Conventionally, the problem is expressed as two folded. First, images of initial pressure distribution created by absorption of a light pulse are formed based on acoustic boundary measurements. Then, the optical properties are determined based on these photoacoustic images. The optical stage of the inverse problem can thus suffer from, for example, artefacts caused by the acoustic stage. These could be caused by imperfections in the acoustic measurement setting, of which an example is a limited view acoustic measurement geometry. In this work, the forward model of quantitative photoacoustic tomography is treated as a coupled acoustic and optical model and the inverse problem is solved by using a Bayesian approach. Spatial distribution of the optical properties of the imaged target are estimated directly from the photoacoustic time series in varying acoustic detection and optical illumination configurations. It is numerically demonstrated, that estimation of optical properties of the imaged target is feasible in limited view acoustic detection setting.

  20. Thalamocortical input onto layer 5 pyramidal neurons measured using quantitative large-scale array tomography

    PubMed Central

    Rah, Jong-Cheol; Bas, Erhan; Colonell, Jennifer; Mishchenko, Yuriy; Karsh, Bill; Fetter, Richard D.; Myers, Eugene W.; Chklovskii, Dmitri B.; Svoboda, Karel; Harris, Timothy D.; Isaac, John T. R.

    2013-01-01

    The subcellular locations of synapses on pyramidal neurons strongly influences dendritic integration and synaptic plasticity. Despite this, there is little quantitative data on spatial distributions of specific types of synaptic input. Here we use array tomography (AT), a high-resolution optical microscopy method, to examine thalamocortical (TC) input onto layer 5 pyramidal neurons. We first verified the ability of AT to identify synapses using parallel electron microscopic analysis of TC synapses in layer 4. We then use large-scale array tomography (LSAT) to measure TC synapse distribution on L5 pyramidal neurons in a 1.00 × 0.83 × 0.21 mm3 volume of mouse somatosensory cortex. We found that TC synapses primarily target basal dendrites in layer 5, but also make a considerable input to proximal apical dendrites in L4, consistent with previous work. Our analysis further suggests that TC inputs are biased toward certain branches and, within branches, synapses show significant clustering with an excess of TC synapse nearest neighbors within 5–15 μm compared to a random distribution. Thus, we show that AT is a sensitive and quantitative method to map specific types of synaptic input on the dendrites of entire neurons. We anticipate that this technique will be of wide utility for mapping functionally-relevant anatomical connectivity in neural circuits. PMID:24273494

  1. Objective interpretation of induced polarization tomography using a quantitative approach for the investigation of periglacial environments

    NASA Astrophysics Data System (ADS)

    Banville, David Roy; Fortier, Richard; Dupuis, Christian

    2016-07-01

    The objective interpretation of induced polarization tomography for applications in periglacial environments is sometimes challenging using smoothness-regularized least square inversion because strong resistivity contrasts are often present. Ambiguities arise from the regularization process which smooths the contrast between layers and from artifacts created by the inversion. In periglacial environments, where frozen and thawed ground can coexist with large resistivity contrasts, such artefacts are often found in the models of electrical resistivity. To assess reliable cryohydrogeological models from the inversion of induced polarization tomography, quantitative interpretation criteria are needed. The present work describes a methodology based on forward-inverse modeling to build a cryohydrogeological model from induced polarization data and prior information using the resistivity and chargeability gradients to map transitions between adjacent layers. This methodology is tested on field-data acquired over a coarse grained aquifer within a glaciomarine deposit and ice-rich permafrost mounds within marine sediments. Delineation of the permafrost base is achieved despite the presence of an inversion artefact. The results of the interpretation are used to further constrain the inversion in order to map the ice-content based on the resistivity model and an empirical relationship. The proposed methodology provides a way to extract quantitative information even in difficult environmental settings.

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

    NASA Astrophysics Data System (ADS)

    Li, Jiao; Gao, Feng; Yi, Xi; Wang, Xin; Wu, Linhui; Zhu, Pingping; Zhang, Limin; Zhao, Huijuan

    2011-02-01

    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.

  3. Quantitative and Qualitative Imaging in Single Photon Emission Tomography for Nuclear Medicine Applications.

    NASA Astrophysics Data System (ADS)

    Masoomi, Mojtaba (Arash).

    Available from UMI in association with The British Library. An important goal of single photon emission tomography (SPECT) is the determination of absolute regional radionuclide concentration as a function of time. Quantitative and qualitative studies of SPECT with regard to clinical application is the object of this work. Three basic approaches for image reconstruction and factors which affect the choice of a reconstruction algorithm have been reviewed, discussed and the reconstruction techniques, GRADY and CBP evaluated, based on computer modelling. A sophisticated package of computational subroutines, RECLBL, for image reconstruction and for generation of phantoms, which was fully implemented on PRIME was used throughout this study. Two different systems, a rotating gamma-camera and a prototype scanning-rig have been used to carry out tomography experiments with different phantoms in emission and transmission mode. Performance assessment and reproducibility of the gamma-camera was tested prior to the experimental work. SPECT studies are generally hampered for a number of reasons, the most severe being attenuation and scattering. The effect of scattered photons on image quality was discussed, three distinct techniques were utilised to correct the images and results were compared. Determination of the depth of the source, Am-241 and Tc-99m in the attenuating media, water and TEMEX by analysing the spectroscopic data base on the SPR and spatial resolution was studied, results revealed that both techniques had the same range of depth sensitivity. A method of simultaneous emission and transmission tomography was developed to correct the images for attenuation. The reproducibility of the technique was examined. Results showed that the technique is able to present a promising and a practical approach to more accurate quantitative SPECT imaging. A procedure to evaluate images, under certain conditions has been defined, its properties were evaluated using computer

  4. Computed tomography-based quantitative assessment of lower extremity lymphedema following treatment for gynecologic cancer

    PubMed Central

    Chung, Seung Hyun; Kim, Young Jae; Kim, Kwang Gi; Hwang, Ji Hye

    2017-01-01

    Objective To develop an algorithmic quantitative skin and subcutaneous tissue volume measurement protocol for lower extremity lymphedema (LEL) patients using computed tomography (CT), to verify the usefulness of the measurement techniques in LEL patients, and to observe the structural characteristics of subcutaneous tissue according to the progression of LEL in gynecologic cancer. Methods A program for algorithmic quantitative analysis of lower extremity CT scans has been developed to measure the skin and subcutaneous volume, muscle compartment volume, and the extent of the peculiar trabecular area with a honeycombed pattern. The CT venographies of 50 lower extremities from 25 subjects were reviewed in two groups (acute and chronic lymphedema). Results A significant increase in the total volume, subcutaneous volume, and extent of peculiar trabecular area with a honeycombed pattern except quantitative muscle volume was identified in the more-affected limb. The correlation of CT-based total volume and subcutaneous volume measurements with volumetry measurement was strong (correlation coefficient: 0.747 and 0.749, respectively). The larger extent of peculiar trabecular area with a honeycombed pattern in the subcutaneous tissue was identified in the more-affected limb of chronic lymphedema group. Conclusion CT-based quantitative assessments could provide objective volume measurements and information about the structural characteristics of subcutaneous tissue in women with LEL following treatment for gynecologic cancer. PMID:28028991

  5. Evaluation of the BreastSimulator software platform for breast tomography

    NASA Astrophysics Data System (ADS)

    Mettivier, G.; Bliznakova, K.; Sechopoulos, I.; Boone, J. M.; Di Lillo, F.; Sarno, A.; Castriconi, R.; Russo, P.

    2017-08-01

    The aim of this work was the evaluation of the software BreastSimulator, a breast x-ray imaging simulation software, as a tool for the creation of 3D uncompressed breast digital models and for the simulation and the optimization of computed tomography (CT) scanners dedicated to the breast. Eight 3D digital breast phantoms were created with glandular fractions in the range 10%-35%. The models are characterised by different sizes and modelled realistic anatomical features. X-ray CT projections were simulated for a dedicated cone-beam CT scanner and reconstructed with the FDK algorithm. X-ray projection images were simulated for 5 mono-energetic (27, 32, 35, 43 and 51 keV) and 3 poly-energetic x-ray spectra typically employed in current CT scanners dedicated to the breast (49, 60, or 80 kVp). Clinical CT images acquired from two different clinical breast CT scanners were used for comparison purposes. The quantitative evaluation included calculation of the power-law exponent, β, from simulated and real breast tomograms, based on the power spectrum fitted with a function of the spatial frequency, f, of the form S(f)  =  α/f   β . The breast models were validated by comparison against clinical breast CT and published data. We found that the calculated β coefficients were close to that of clinical CT data from a dedicated breast CT scanner and reported data in the literature. In evaluating the software package BreastSimulator to generate breast models suitable for use with breast CT imaging, we found that the breast phantoms produced with the software tool can reproduce the anatomical structure of real breasts, as evaluated by calculating the β exponent from the power spectral analysis of simulated images. As such, this research tool might contribute considerably to the further development, testing and optimisation of breast CT imaging techniques.

  6. Retina-simulating phantom for optical coherence tomography.

    PubMed

    Baxi, Jigesh; Calhoun, William; Sepah, Yasir Jamal; Hammer, Daniel X; Ilev, Ilko; Pfefer, T Joshua; Nguyen, Quan Dong; Agrawal, Anant

    2014-02-01

    Optical coherence tomography (OCT) is a rapidly growing imaging modality, particularly in the field of ophthalmology. Accurate early diagnosis of diseases requires consistent and validated imaging performance. In contrast to more well-established medical imaging modalities, no standardized test methods currently exist for OCT quality assurance. We developed a retinal phantom which mimics the thickness and near-infrared optical properties of each anatomical retinal layer as well as the surface topography of the foveal pit. The fabrication process involves layer-by-layer spin coating of nanoparticle-embedded silicone films followed by laser micro-etching to modify the surface topography. The thickness of each layer and dimensions of the foveal pit are measured with high precision. The phantom is embedded into a commercially available, water-filled model eye to simulate ocular dispersion and emmetropic refraction, and for ease of use with clinical OCT systems. The phantom was imaged with research and clinical OCT systems to assess image quality and software accuracy. Our results indicate that this phantom may serve as a useful tool to evaluate and standardize OCT performance.

  7. Added prognostic value of myocardial blood flow quantitation in rubidium-82 positron emission tomography imaging.

    PubMed

    Farhad, Hoshang; Dunet, Vincent; Bachelard, Kim; Allenbach, Gilles; Kaufmann, Philipp A; Prior, John O

    2013-12-01

    We studied the respective added value of the quantitative myocardial blood flow (MBF) and the myocardial flow reserve (MFR) as assessed with (82)Rb positron emission tomography (PET)/CT in predicting major adverse cardiovascular events (MACEs) in patients with suspected myocardial ischaemia. Myocardial perfusion images were analysed semi-quantitatively (SDS, summed difference score) and quantitatively (MBF, MFR) in 351 patients. Follow-up was completed in 335 patients and annualized MACE (cardiac death, myocardial infarction, revascularization, or hospitalization for congestive heart failure or de novo stable angor) rates were analysed with the Kaplan-Meier method in 318 patients after excluding 17 patients with early revascularizations (<60 days). Independent predictors of MACEs were identified by multivariate analysis. During a median follow-up of 624 days (inter-quartile range 540-697), 35 MACEs occurred. An annualized MACE rate was higher in patients with ischaemia (SDS >2) (n = 105) than those without [14% (95% CI = 9.1-22%) vs. 4.5% (2.7-7.4%), P < 0.0001]. The lowest MFR tertile group (MFR <1.8) had the highest MACE rate [16% (11-25%) vs. 2.9% (1.2-7.0%) and 4.3% (2.1-9.0%), P < 0.0001]. Similarly, the lowest stress MBF tertile group (MBF <1.8 mL/min/g) had the highest MACE rate [14% (9.2-22%) vs. 7.3% (4.2-13%) and 1.8% (0.6-5.5%), P = 0.0005]. Quantitation with stress MBF or MFR had a significant independent prognostic power in addition to semi-quantitative findings. The largest added value was conferred by combining stress MBF to SDS. This holds true even for patients without ischaemia. Perfusion findings in (82)Rb PET/CT are strong MACE outcome predictors. MBF quantification has an added value allowing further risk stratification in patients with normal and abnormal perfusion images.

  8. Quantitative imaging of I-124 using positron emission tomography with applications to radioimmunodiagnosis and radioimmunotherapy

    SciTech Connect

    Pentlow, K.S.; Graham, M.C.; Lambrecht, R.M.; Cheung, N.K.; Larson, S.M. )

    1991-05-01

    Positron emission tomography (PET) is potentially useful for the quantitative imaging of radiolabeled antibodies, leading in turn to improved dosimetry in radioimmunotherapy. Iodine-124 is a positron-emitting nuclide with appropriate chemical properties and half-life (4.2 days) for such studies since the radiolabeling of antibodies with iodine is well understood and the half-life permits measurements over several days. Unfortunately, I-124 has a complex decay scheme with many high-energy gamma rays and a positron abundance of only 25%. It has therefore been largely ignored as a PET-imaging nuclide. However, measurements made with phantoms and animals under realistic conditions using a BGO-based PET scanner have shown that satisfactory imaging and quantitation can be achieved. Investigations of spatial resolution, the linearity of regional observed count rate versus activity in the presence of other activity, and the visualization and quantitation of activity in spheres with different surrounding background activities were carried out with phantoms up to 22 cm in diameter. Compared with F-18, spatial resolution was only slightly degraded (13.5 mm FWHM vs 12 mm FWHM) while linearity was the same over a 10:1 activity range (0.015 to 0.15 MBq/ml for I-124). The visualization and quantitation of spheres was also slightly degraded when using similar imaging times. Increasing the imaging time for I-124 reduced the difference. To verify that the technique would work in vivo, measurements were made of human neuroblastoma tumors in rats which had been injected with I-124 labeled 3F8 antibody. Although the number of samples was small, good agreement was achieved between image-based measurements and direct measurements of excised 4-g tumors. Thus quantitative imaging of I-124 labeled antibodies appears to be possible under realistic conditions.

  9. Quantitative three-dimensional analysis of embryonic chick morphogenesis via microcomputed tomography.

    PubMed

    Kim, Jun Sup; Min, Jouha; Recknagel, Andrew K; Riccio, Mark; Butcher, Jonathan T

    2011-01-01

    Embryonic development is a remarkably complex and rapidly evolving morphogenetic process. Although many of the early patterning events have been well described, understanding the anatomical changes at later stages where clinically relevant malformations are more likely to be survivable has been limited by the lack of quantitative 3D imaging tools. Microcomputed tomography (Micro-CT) has emerged as a powerful tool for embryonic imaging, but a quantitative analysis of organ and tissue growth has not been conducted. In this study, we present a simple method for acquiring highly detailed, quantitative 3D datasets of embryonic chicks with Micro-CT. Embryos between 4 and 12 days (HH23 and HH40) were labeled with osmium tetroxide (OT), which revealed highly detailed soft tissue anatomy when scanned at 25 μm resolution. We demonstrate tissue boundary and inter-tissue contrast fidelity in virtual 2D sections are quantitatively and qualitatively similar to those of histological sections. We then establish mathematical relationships for the volumetric growth of heart, limb, eye, and brain during this period of development. We show that some organs exhibit constant exponential growth (eye and heart), whereas others contained multiple phases of growth (forebrain and limb). Furthermore, we show that cardiac myocardial volumetric growth differs in a time and chamber specific manner. These results demonstrate Micro-CT is a powerful technique for quantitative imaging of embryonic growth. The data presented here establish baselines from which to compare the effects of genetic or experimental perturbations. Quantifying subtle differences in morphogenesis is increasingly important as research focuses on localized and conditional effects.

  10. Automated quantitative assessment of three-dimensional bioprinted hydrogel scaffolds using optical coherence tomography

    PubMed Central

    Wang, Ling; Xu, Mingen; Zhang, LieLie; Zhou, QingQing; Luo, Li

    2016-01-01

    Reconstructing and quantitatively assessing the internal architecture of opaque three-dimensional (3D) bioprinted hydrogel scaffolds is difficult but vital to the improvement of 3D bioprinting techniques and to the fabrication of functional engineered tissues. In this study, swept-source optical coherence tomography was applied to acquire high-resolution images of hydrogel scaffolds. Novel 3D gelatin/alginate hydrogel scaffolds with six different representative architectures were fabricated using our 3D bioprinting system. Both the scaffold material networks and the interconnected flow channel networks were reconstructed through volume rendering and binarisation processing to provide a 3D volumetric view. An image analysis algorithm was developed based on the automatic selection of the spatially-isolated region-of–interest. Via this algorithm, the spatially-resolved morphological parameters including pore size, pore shape, strut size, surface area, porosity, and interconnectivity were quantified precisely. Fabrication defects and differences between the designed and as-produced scaffolds were clearly identified in both 2D and 3D; the locations and dimensions of each of the fabrication defects were also defined. It concludes that this method will be a key tool for non-destructive and quantitative characterization, design optimisation and fabrication refinement of 3D bioprinted hydrogel scaffolds. Furthermore, this method enables investigation into the quantitative relationship between scaffold structure and biological outcome. PMID:27231597

  11. Experimental investigation of bone mineral density in Thoroughbreds using quantitative computed tomography

    PubMed Central

    YAMADA, Kazutaka; SATO, Fumio; HIGUCHI, Tohru; NISHIHARA, Kaori; KAYANO, Mitsunori; SASAKI, Naoki; NAMBO, Yasuo

    2015-01-01

    ABSTRACT Bone mineral density (BMD) is one of the indications of the strength and health. BMD measured by quantitative computed tomography (QCT) was compared with that measured by dual energy X-ray absorptiometry (DXA) and radiographic bone aluminum equivalence (RBAE). Limbs were removed from horses that had been euthanized for reasons not associated with this study. Sixteen limbs (left and right metacarpals and metatarsals) from 4 horses were used to compare BMD as measured by QCT with those measured by DXA and RBAE. There was a strong correlation between BMD values measured by QCT and those measured by DXA (R2=0.85); correlation was also observed between values obtained by QCT and those obtained by RBAE (R2=0.61). To investigate changes in BMD with age, 37 right metacarpal bones, including 7 from horses euthanized because of fracture were examined by QCT. The BMD value of samples from horses dramatically increased until 2 years of age and then plateaued, a pattern similar to the growth curve. The BMD values of bone samples from horses euthanized because of fracture were within the population range, and samples of morbid fracture were not included. The relationship between BMD and age provides a reference for further quantitative studies of bone development and remodeling. Quantitative measurement of BMD using QCT may have great potential for the evaluation of bone biology for breeding and rearing management. PMID:26435681

  12. Quantitative in vivo optical tomography of cancer progression & vasculature development in adult zebrafish

    PubMed Central

    Kumar, Sunil; Lockwood, Nicola; Ramel, Marie-Christine; Correia, Teresa; Ellis, Matthew; Alexandrov, Yuriy; Andrews, Natalie; Patel, Rachel; Bugeon, Laurence; Dallman, Margaret J.; Brandner, Sebastian; Arridge, Simon; Katan, Matilda; McGinty, James; Frankel, Paul; French, Paul M.W.

    2016-01-01

    We describe a novel approach to study tumour progression and vasculature development in vivo via global 3-D fluorescence imaging of live non-pigmented adult zebrafish utilising angularly multiplexed optical projection tomography with compressive sensing (CS-OPT). This “mesoscopic” imaging method bridges a gap between established ~μm resolution 3-D fluorescence microscopy techniques and ~mm-resolved whole body planar imaging and diffuse tomography. Implementing angular multiplexing with CS-OPT, we demonstrate the in vivo global imaging of an inducible fluorescently labelled genetic model of liver cancer in adult non-pigmented zebrafish that also present fluorescently labelled vasculature. In this disease model, addition of a chemical inducer (doxycycline) drives expression of eGFP tagged oncogenic K-RASV12 in the liver of immune competent animals. We show that our novel in vivo global imaging methodology enables non-invasive quantitative imaging of the development of tumour and vasculature throughout the progression of the disease, which we have validated against established methods of pathology including immunohistochemistry. We have also demonstrated its potential for longitudinal imaging through a study of vascular development in the same zebrafish from early embryo to adulthood. We believe that this instrument, together with its associated analysis and data management tools, constitute a new platform for in vivo cancer studies and drug discovery in zebrafish disease models. PMID:27259259

  13. Quantitative in vivo optical tomography of cancer progression & vasculature development in adult zebrafish.

    PubMed

    Kumar, Sunil; Lockwood, Nicola; Ramel, Marie-Christine; Correia, Teresa; Ellis, Matthew; Alexandrov, Yuriy; Andrews, Natalie; Patel, Rachel; Bugeon, Laurence; Dallman, Margaret J; Brandner, Sebastian; Arridge, Simon; Katan, Matilda; McGinty, James; Frankel, Paul; French, Paul M W

    2016-07-12

    We describe a novel approach to study tumour progression and vasculature development in vivo via global 3-D fluorescence imaging of live non-pigmented adult zebrafish utilising angularly multiplexed optical projection tomography with compressive sensing (CS-OPT). This "mesoscopic" imaging method bridges a gap between established ~μm resolution 3-D fluorescence microscopy techniques and ~mm-resolved whole body planar imaging and diffuse tomography. Implementing angular multiplexing with CS-OPT, we demonstrate the in vivo global imaging of an inducible fluorescently labelled genetic model of liver cancer in adult non-pigmented zebrafish that also present fluorescently labelled vasculature. In this disease model, addition of a chemical inducer (doxycycline) drives expression of eGFP tagged oncogenic K-RASV12 in the liver of immune competent animals. We show that our novel in vivo global imaging methodology enables non-invasive quantitative imaging of the development of tumour and vasculature throughout the progression of the disease, which we have validated against established methods of pathology including immunohistochemistry. We have also demonstrated its potential for longitudinal imaging through a study of vascular development in the same zebrafish from early embryo to adulthood. We believe that this instrument, together with its associated analysis and data management tools, constitute a new platform for in vivo cancer studies and drug discovery in zebrafish disease models.

  14. Quantitative X-ray computed tomography peritoneography in malignant peritoneal mesothelioma patients receiving intraperitoneal chemotherapy.

    PubMed

    Leinwand, Joshua C; Zhao, Binsheng; Guo, Xiaotao; Krishnamoorthy, Saravanan; Qi, Jing; Graziano, Joseph H; Slavkovic, Vesna N; Bates, Gleneara E; Lewin, Sharyn N; Allendorf, John D; Chabot, John A; Schwartz, Lawrence H; Taub, Robert N

    2013-12-01

    Intraperitoneal chemotherapy is used to treat peritoneal surface-spreading malignancies. We sought to determine whether volume and surface area of the intraperitoneal chemotherapy compartments are associated with overall survival and posttreatment glomerular filtration rate (GFR) in malignant peritoneal mesothelioma (MPM) patients. Thirty-eight MPM patients underwent X-ray computed tomography peritoneograms during outpatient intraperitoneal chemotherapy. We calculated volume and surface area of contrast-filled compartments by semiautomated computer algorithm. We tested whether these were associated with overall survival and posttreatment GFR. Decreased likelihood of mortality was associated with larger surface areas (p = 0.0201) and smaller contrast-filled compartment volumes (p = 0.0341), controlling for age, sex, histologic subtype, and presence of residual disease >0.5 cm postoperatively. Larger volumes were associated with higher posttreatment GFR, controlling for pretreatment GFR, body surface area, surface area, and the interaction between body surface area and volume (p = 0.0167). Computed tomography peritoneography is an appropriate modality to assess for maldistribution of intraperitoneal chemotherapy. In addition to identifying catheter failure and frank loculation, quantitative analysis of the contrast-filled compartment's surface area and volume may predict overall survival and cisplatin-induced nephrotoxicity. Prospective studies should be undertaken to confirm and extend these findings to other diseases, including advanced ovarian carcinoma.

  15. Imaging and quantitative assessment of long bone vascularization in the adult rat using microcomputed tomography.

    PubMed

    Fei, Jia; Jia, Fei; Peyrin, Françoise; Françoise, Peyrin; Malaval, Luc; Vico, Laurence; Laurence, Vico; Lafage-Proust, Marie-Hélène; Marie-Hélène, Lafage-Proust

    2010-02-01

    The objective of this study was to develop and validate a technique for both 3D imaging and quantification of the vascular network of bone tissue in the rat. Five month-old male Wistar rats were divided into tail-suspension (21 days) and control groups. Sixty percent barium sulfate solution was infused into the vena cava. The tibiae were evaluated in 2D and 3D before and after decalcification, using conventional microcomputerized tomography (muCT) at 10 and 5 mum resolution and synchrotron radiation (SR) muCT. The perfusion technique and tomography exhibited excellent bone vasculature imaging. Significant positive correlations were observed between 2D histomorphometric and 3D muCT vascular parameters (P < 0.05). 3DmuCT discriminated significant changes of vessel structures in unloading condition: vessel number decreased by 25%, (P < 0.005), vessel separation increased by 27%, P < 0.01. SRmuCT could image sinusoid clusters in bone. muCT is an accurate and reproducible technique for 3D quantitative evaluation of long bone vascularisation in the rat. 2009 Wiley-Liss, Inc.

  16. Swept source optical coherence tomography for quantitative and qualitative assessment of dental composite restorations

    NASA Astrophysics Data System (ADS)

    Sadr, Alireza; Shimada, Yasushi; Mayoral, Juan Ricardo; Hariri, Ilnaz; Bakhsh, Turki A.; Sumi, Yasunori; Tagami, Junji

    2011-03-01

    The aim of this work was to explore the utility of swept-source optical coherence tomography (SS-OCT) for quantitative evaluation of dental composite restorations. The system (Santec, Japan) with a center wavelength of around 1300 nm and axial resolution of 12 μm was used to record data during and after placement of light-cured composites. The Fresnel phenomenon at the interfacial defects resulted in brighter areas indicating gaps as small as a few micrometers. The gap extension at the interface was quantified and compared to the observation by confocal laser scanning microscope after trimming the specimen to the same cross-section. Also, video imaging of the composite during polymerization could provide information about real-time kinetics of contraction stress and resulting gaps, distinguishing them from those gaps resulting from poor adaptation of composite to the cavity prior to polymerization. Some samples were also subjected to a high resolution microfocus X-ray computed tomography (μCT) assessment; it was found that differentiation of smaller gaps from the radiolucent bonding layer was difficult with 3D μCT. Finally, a clinical imaging example using a newly developed dental SS-OCT system with an intra-oral scanning probe (Panasonic Healthcare, Japan) is presented. SS-OCT is a unique tool for clinical assessment and laboratory research on resin-based dental restorations. Supported by GCOE at TMDU and NCGG.

  17. Quantitative morphometric evaluation of critical size experimental bone defects by microcomputed tomography.

    PubMed

    Efeoglu, Candan; Fisher, Sheila E; Ertürk, Selda; Oztop, Fikri; Günbay, Sevtap; Sipahi, Aylin

    2007-04-01

    Our aim was to show that microcomputed tomography is a useful tool for acquiring high-resolution three-dimensional tomographic images to assess bone healing, the interface with materials, and the biocompatibility of bone substitutes. Acquired images can be used for non-invasive quantitative morphometric analysis of regenerating bone, leaving the option for conventional histology to be an adjunct used at defined intervals. The temporal characterisation of the mineralisation of bone potentially has a critical role in the understanding of the dynamics of mineralisation of healing bone. This has applications both for degradable and bioactive materials and for pharmaceutical products that act on bone. Formal validation of this promising new technique will be a critical part of continuing studies.

  18. A hybrid fluorescence tomography and x-ray CT system for quantitative molecular imaging

    NASA Astrophysics Data System (ADS)

    Lin, Yuting; Barber, William C.; Iwanczk, Jan S.; Roeck, Werner W.; Nalcioglu, Orhan; Gulsen, Gultekin

    2010-02-01

    A gantry-based hybrid fluorescence and x-ray computed tomography (FT/CT) system is developed for quantitative molecular imaging. The performance of the dual modality FT/CT system is evaluated using an irregular shaped phantom with an inclusion containing Indocyanine-Green (ICG). The anatomical data from CT provides structural a priori information for the FT inverse problem. Although a 4.2 mm diameter inclusion can be resolved in the reconstructed concentration image without any a priori information, ICG concentration in the inclusion is recovered with 75% error. On the other hand, the error in the recovered ICG concentration reduces to 15% when a priori information from CT is utilized. The results demonstrate that accurate fluorophore concentration can only be obtained when x-ray CT structural a priori information is available.

  19. Cell death detection by quantitative three-dimensional single-cell tomography

    PubMed Central

    Cheng, Nai-Chia; Hsieh, Tsung-Hsun; Wang, Yu-Ta; Lai, Chien-Chih; Chang, Chia-Kai; Lin, Ming-Yi; Huang, Ding-Wei; Tjiu, Jeng-Wei; Huang, Sheng-Lung

    2012-01-01

    Ultrahigh-resolution optical coherence tomography (UR-OCT) has been used for the first time to our knowledge to study single-cell basal cell carcinoma (BCC) in vitro. This noninvasive, in situ, label-free technique with deep imaging depth enables three-dimensional analysis of scattering properties of single cells with cellular spatial resolution. From three-dimensional UR-OCT imaging, live and dead BCC cells can be easily identified based on morphological observation. We developed a novel method to automatically extract characteristic parameters of a single cell from data volume, and quantitative comparison and parametric analysis were performed. The results demonstrate the capability of UR-OCT to detect cell death at the cellular level. PMID:23024905

  20. Finite element analysis of the hip and spine based on quantitative computed tomography.

    PubMed

    Carpenter, R Dana

    2013-06-01

    Quantitative computed tomography (QCT) provides three-dimensional information about bone geometry and the spatial distribution of bone mineral. Images obtained with QCT can be used to create finite element models, which offer the ability to analyze bone strength and the distribution of mechanical stress and physical deformation. This approach can be used to investigate different mechanical loading scenarios (stance and fall configurations at the hip, for example) and to estimate whole bone strength and the relative mechanical contributions of the cortical and trabecular bone compartments. Finite element analyses based on QCT images of the hip and spine have been used to provide important insights into the biomechanical effects of factors such as age, sex, bone loss, pharmaceuticals, and mechanical loading at sites of high clinical importance. Thus, this analysis approach has become an important tool in the study of the etiology and treatment of osteoporosis at the hip and spine.

  1. Quantitative characteristics of sickle cell retinopathy in optical coherence tomography angiography

    PubMed Central

    Alam, Minhaj; Thapa, Damber; Lim, Jennifer I.; Cao, Dingcai; Yao, Xincheng

    2017-01-01

    Early detection is an essential step for effective intervention of sickle cell retinopathy (SCR). Emerging optical coherence tomography angiography (OCTA) provides excellent three-dimensional (3D) resolution to enable label-free, noninvasive visualization of retinal vascular structures, promising improved sensitivity in detecting SCR. However, quantitative analysis of SCR characteristics in OCTA images is yet to be established. In this study, we conducted comprehensive analysis of six OCTA parameters, including blood vessel tortuosity, vessel diameter, vessel perimeter index (VPI), area of foveal avascular zone (FAZ), contour irregularity of FAZ and parafoveal avascular density. Compared to traditional retinal thickness analysis, five of these six OCTA parameters show improved sensitivity for SCR detection than retinal thickness. It is observed that the most sensitive parameters were the contour irregularity of FAZ in the superficial layer and avascular density in temporal regions, while the area of FAZ, tortuosity and mean diameter of the vessel were moderately sensitive. PMID:28663862

  2. Quantitative shear wave imaging optical coherence tomography for noncontact mechanical characterization of myocardium

    NASA Astrophysics Data System (ADS)

    Wang, Shang; Lopez, Andrew L.; Morikawa, Yuka; Tao, Ge; Li, Jiasong; Larina, Irina V.; Martin, James F.; Larin, Kirill V.

    2015-03-01

    Optical coherence elastography (OCE) is an emerging low-coherence imaging technique that provides noninvasive assessment of tissue biomechanics with high spatial resolution. Among various OCE methods, the capability of quantitative measurement of tissue elasticity is of great importance for tissue characterization and pathology detection across different samples. Here we report a quantitative OCE technique, termed quantitative shear wave imaging optical coherence tomography (Q-SWI-OCT), which enables noncontact measurement of tissue Young's modulus based on the ultra-fast imaging of the shear wave propagation inside the sample. A focused air-puff device is used to interrogate the tissue with a low-pressure short-duration air stream that stimulates a localized displacement with the scale at micron level. The propagation of this tissue deformation in the form of shear wave is captured by a phase-sensitive OCT system running with the scan of the M-mode imaging over the path of the wave propagation. The temporal characteristics of the shear wave is quantified based on the cross-correlation of the tissue deformation profiles at all the measurement locations, and linear regression is utilized to fit the data plotted in the domain of time delay versus wave propagation distance. The wave group velocity is thus calculated, which results in the quantitative measurement of the Young's modulus. As the feasibility demonstration, experiments are performed on tissuemimicking phantoms with different agar concentrations and the quantified elasticity values with Q-SWI-OCT agree well with the uniaxial compression tests. For functional characterization of myocardium with this OCE technique, we perform our pilot experiments on ex vivo mouse cardiac muscle tissues with two studies, including 1) elasticity difference of cardiac muscle under relaxation and contract conditions and 2) mechanical heterogeneity of the heart introduced by the muscle fiber orientation. Our results suggest the

  3. Quantitative microvascular analysis of retinal venous occlusions by spectral domain optical coherence tomography angiography

    PubMed Central

    Koulisis, Nicole; Kim, Alice Y.; Chu, Zhongdi; Shahidzadeh, Anoush; Burkemper, Bruce; Olmos de Koo, Lisa C.; Moshfeghi, Andrew A.; Ameri, Hossein; Puliafito, Carmen A.; Isozaki, Veronica L.; Wang, Ruikang K.; Kashani, Amir H.

    2017-01-01

    Purpose To quantitatively evaluate the retinal microvasculature in human subjects with retinal venous occlusions (RVO) using optical coherence tomography angiography (OCTA). Design Retrospective, cross-sectional, observational case series. Participants Sixty subjects (84 eyes) were included (20 BRVO, 14 CRVO, 24 unaffected fellow eyes, and 26 controls). Methods OCTA was performed on a prototype, spectral domain-OCTA system in the 3x3mm central macular region. Custom software was used to quantify morphology and density of retinal capillaries using four quantitative parameters. The vasculature of the segmented retinal layers and nonsegmented whole retina were analyzed. Main outcome measures Fractal dimension (FD), vessel density (VD), skeletal density (SD), and vessel diameter index (VDI) within the segmented retinal layers and nonsegmented whole retina vasculature. Results Nonsegmented analysis of RVO eyes demonstrated significantly lower FD (1.64±0.01 vs 1.715±0.002; p<0.001), VD (0.32±0.01 vs 0.432±0.002; p<0.001), and SD (0.073±0.004 vs 0.099±0.001; p<0.001) compared to controls. Compared to the fellow eye, FD, VD and SD were lower (p<0.001), and VDI was higher (p<0.001). FD, VD, and SD progressively decreased as the extent (or type) of RVO increased (control vs BRVO vs CRVO; p<0.001). In the unaffected fellow eye FD, VD and SD showed significant differences when compared to control eyes or affected RVO eyes (p<0.001). Conclusions Quantitative OCTA of the central 3x3mm macular region demonstrates significant differences in capillary density and morphology among subjects with BRVO and CRVO compared to controls or unaffected fellow eyes in all vascular layers. The unaffected fellow eyes also demonstrate significant differences when compared to controls. OCTA allows for noninvasive, layer-specific, quantitative evaluation of RVO-associated microvascular changes. PMID:28437483

  4. Quantitative imaging of murine osteoarthritic cartilage by phase-contrast micro-computed tomography.

    PubMed

    Ruan, Merry Z C; Dawson, Brian; Jiang, Ming-Ming; Gannon, Francis; Heggeness, Michael; Lee, Brendan H L

    2013-02-01

    The mouse is an optimal model organism in which gene-environment interactions can be used to study the pathogenesis of osteoarthritis (OA). The gold standard for arthritis research in mice is based on histopathology and immunohistochemistry, which are labor-intensive, prone to sampling bias and technical variability, and limited in throughput. The aim of this study was to develop a new technique that assesses mouse cartilage by integrating quantitative volumetric imaging techniques. A novel mouse model of OA was generated by cruciate ligament transection (CLT) and evaluated by histopathology and immunohistochemistry. Knee joint specimens were then imaged using a new technique that combines high-resolution micro-computed tomography (micro-CT) and phase-contrast optics followed by quantitative analyses. A comparative analysis was also performed in a previously established mouse model of OA generated by destabilization of the medial meniscus (DMM). Phase-contrast micro-CT achieved cellular resolution of chondrocytes and quantitative assessment of parameters such as articular cartilage volume and surface area. In mouse models of OA generated by either CLT or DMM, we showed that phase-contrast micro-CT distinguished control and OA cartilage by providing quantitative measures with high reproducibility and minimal variability. Features of OA at the cellular or tissue level could also be observed in images generated by phase-contrast micro-CT. We established an imaging technology that comprehensively assessed and quantified the 2-dimensional and 3-dimensional changes of articular cartilage. Application of this technology will facilitate the rapid and high-throughput assessment of genetic and therapeutic models of OA in mice. Copyright © 2013 by the American College of Rheumatology.

  5. Direct Numerical Simulation of Liquid Nozzle Spray with Comparison to Shadowgraphy and X-Ray Computed Tomography Experimental Results

    NASA Astrophysics Data System (ADS)

    van Poppel, Bret; Owkes, Mark; Nelson, Thomas; Lee, Zachary; Sowell, Tyler; Benson, Michael; Vasquez Guzman, Pablo; Fahrig, Rebecca; Eaton, John; Kurman, Matthew; Kweon, Chol-Bum; Bravo, Luis

    2014-11-01

    In this work, we present high-fidelity Computational Fluid Dynamics (CFD) results of liquid fuel injection from a pressure-swirl atomizer and compare the simulations to experimental results obtained using both shadowgraphy and phase-averaged X-ray computed tomography (CT) scans. The CFD and experimental results focus on the dense near-nozzle region to identify the dominant mechanisms of breakup during primary atomization. Simulations are performed using the NGA code of Desjardins et al (JCP 227 (2008)) and employ the volume of fluid (VOF) method proposed by Owkes and Desjardins (JCP 270 (2013)), a second order accurate, un-split, conservative, three-dimensional VOF scheme providing second order density fluxes and capable of robust and accurate high density ratio simulations. Qualitative features and quantitative statistics are assessed and compared for the simulation and experimental results, including the onset of atomization, spray cone angle, and drop size and distribution.

  6. Global Adjoint Tomography: Combining Big Data with HPC Simulations

    NASA Astrophysics Data System (ADS)

    Bozdag, E.; Lefebvre, M. P.; Lei, W.; Peter, D. B.; Smith, J. A.; Komatitsch, D.; Tromp, J.

    2014-12-01

    The steady increase in data quality and the number of global seismographic stations have substantially grown the amount of data available for construction of Earth models. Meanwhile, developments in the theory of wave propagation, numerical methods and HPC systems have enabled unprecedented simulations of seismic wave propagation in realistic 3D Earth models which lead the extraction of more information from data, ultimately culminating in the use of entire three-component seismograms.Our aim is to take adjoint tomography further to image the entire planet which is one of the extreme cases in seismology due to its intense computational requirements and vast amount of high-quality seismic data that can potentially be assimilated in inversions. We have started low resolution (T > 27 s, soon will be > 17 s) global inversions with 253 earthquakes for a transversely isotropic crust and mantle model on Oak Ridge National Laboratory's Cray XK7 "Titan" system. Recent improvements in our 3D solvers, such as the GPU version of the SPECFEM3D_GLOBE package, will allow us perform higher-resolution (T > 9 s) and longer-duration (~180 m) simulations to take the advantage of high-frequency body waves and major-arc surface waves to improve imbalanced ray coverage as a result of uneven distribution of sources and receivers on the globe. Our initial results after 10 iterations already indicate several prominent features reported in high-resolution continental studies, such as major slabs (Hellenic, Japan, Bismarck, Sandwich, etc.) and enhancement in plume structures (the Pacific superplume, the Hawaii hot spot, etc.). Our ultimate goal is to assimilate seismic data from more than 6,000 earthquakes within the magnitude range 5.5 ≤ Mw ≤ 7.0. To take full advantage of this data set on ORNL's computational resources, we need a solid framework for managing big data sets during pre-processing (e.g., data requests and quality checks), gradient calculations, and post-processing (e

  7. Automated quantitative coronary computed tomography correlates of myocardial ischaemia on gated myocardial perfusion SPECT.

    PubMed

    de Graaf, Michiel A; El-Naggar, Heba M; Boogers, Mark J; Veltman, Caroline E; Broersen, Alexander; Kitslaar, Pieter H; Dijkstra, Jouke; Kroft, Lucia J; Al Younis, Imad; Reiber, Johan H; Bax, Jeroen J; Delgado, Victoria; Scholte, Arthur J

    2013-08-01

    Automated software tools have permitted more comprehensive, robust and reproducible quantification of coronary stenosis, plaque burden and plaque location of coronary computed tomography angiography (CTA) data. The association between these quantitative CTA (QCT) parameters and the presence of myocardial ischaemia has not been explored. The aim of the present investigation was to evaluate the association between QCT parameters of coronary artery lesions and the presence of myocardial ischaemia on gated myocardial perfusion single-photon emission CT (SPECT). Included in the study were 40 patients (mean age 58.2 ± 10.9 years, 27 men) with known or suspected coronary artery disease (CAD) who had undergone multidetector row CTA and gated myocardial perfusion SPECT within 6 months. From the CTA datasets, vessel-based and lesion-based visual analyses were performed. Consecutively, lesion-based QCT was performed to assess plaque length, plaque burden, percentage lumen area stenosis and remodelling index. Subsequently, the presence of myocardial ischaemia was assessed using the summed difference score (SDS ≥2) on gated myocardial perfusion SPECT. Myocardial ischaemia was seen in 25 patients (62.5%) in 37 vascular territories. Quantitatively assessed significant stenosis and quantitatively assessed lesion length were independently associated with myocardial ischaemia (OR 7.72, 95% CI 2.41-24.7, p < 0.001, and OR 1.07, 95% CI 1.00-1.45, p = 0.032, respectively) after correcting for clinical variables and visually assessed significant stenosis. The addition of quantitatively assessed significant stenosis (χ(2) = 20.7) and lesion length (χ(2) = 26.0) to the clinical variables and the visual assessment (χ(2) = 5.9) had incremental value in the association with myocardial ischaemia. Coronary lesion length and quantitatively assessed significant stenosis were independently associated with myocardial ischaemia. Both quantitative parameters have incremental value

  8. Quantitative reconstruction of PIXE-tomography data for thin samples using GUPIX X-ray emission yields

    NASA Astrophysics Data System (ADS)

    Michelet, C.; Barberet, Ph.; Devès, G.; Bouguelmouna, B.; Bourret, S.; Delville, M.-H.; Le Trequesser, Q.; Gordillo, N.; Beasley, D. G.; Marques, A. C.; Farau, R.; Toko, B. R.; Campbell, J.; Maxwell, J.; Moretto, Ph.; Seznec, H.

    2015-04-01

    We present here a new development of the TomoRebuild software package, to perform quantitative Particle Induced X-ray Emission Tomography (PIXET) reconstruction. X-ray yields are obtained from the GUPIX code. The GUPIX data base is available for protons up to 5 MeV and also in the 20-100 MeV energy range, deuterons up to 6 MeV, 3He and alphas up to 12 MeV. In this version, X-ray yields are calculated for thin samples, i.e. without simulating X-ray attenuation. PIXET data reconstruction is kept as long as possible independent from Scanning Transmission Ion Microscopy Tomography (STIMT). In this way, the local mass distribution (in g/cm3) of each X-ray emitting element is reconstructed in all voxels of the analyzed volume, only from PIXET data, without the need of associated STIMT data. Only the very last step of data analysis requires STIMT data, in order to normalize PIXET data to obtain concentration distributions, in terms of normalized mass fractions (in μg/g). For this, a noise correction procedure has been designed in ImageJ. Moreover sinogram or image misalignment can be corrected, as well as the difference in beam size between the two experiments. The main features of the TomoRebuild code, user friendly design and modular C++ implementation, were kept. The software package is portable and can run on Windows and Linux operating systems. An optional user-friendly graphic interface was designed in Java, as a plugin for the ImageJ graphic software package. Reconstruction examples are presented from biological specimens of Caenorhabditis elegans - a small nematode constituting a reference model for biology studies. The reconstruction results are compared between the different codes TomoRebuild, DISRA and JPIXET, and different reconstruction methods: Filtered BackProjection (FBP) and Maximum Likelihood Expectation Maximization (MLEM).

  9. Simulating realistic predator signatures in quantitative fatty acid signature analysis

    USGS Publications Warehouse

    Bromaghin, Jeffrey F.

    2015-01-01

    Diet estimation is an important field within quantitative ecology, providing critical insights into many aspects of ecology and community dynamics. Quantitative fatty acid signature analysis (QFASA) is a prominent method of diet estimation, particularly for marine mammal and bird species. Investigators using QFASA commonly use computer simulation to evaluate statistical characteristics of diet estimators for the populations they study. Similar computer simulations have been used to explore and compare the performance of different variations of the original QFASA diet estimator. In both cases, computer simulations involve bootstrap sampling prey signature data to construct pseudo-predator signatures with known properties. However, bootstrap sample sizes have been selected arbitrarily and pseudo-predator signatures therefore may not have realistic properties. I develop an algorithm to objectively establish bootstrap sample sizes that generates pseudo-predator signatures with realistic properties, thereby enhancing the utility of computer simulation for assessing QFASA estimator performance. The algorithm also appears to be computationally efficient, resulting in bootstrap sample sizes that are smaller than those commonly used. I illustrate the algorithm with an example using data from Chukchi Sea polar bears (Ursus maritimus) and their marine mammal prey. The concepts underlying the approach may have value in other areas of quantitative ecology in which bootstrap samples are post-processed prior to their use.

  10. Quantitative analysis on PUVA-induced skin photodamages using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Zhai, Juan; Guo, Zhouyi; Liu, Zhiming; Xiong, Honglian; Zeng, Changchun; Jin, Ying

    2009-08-01

    Psoralen plus ultraviolet A radiation (PUVA) therapy is a very important clinical treatment of skin diseases such as vitiligo and psoriasis, but associated with an increased risk of skin photodamages especially photoaging. Since skin biopsy alters the original skin morphology and always requires an iatrogenic trauma, optical coherence tomography (OCT) appears to be a promising technique to study skin damage in vivo. In this study, the Balb/c mice had 8-methoxypsralen (8-MOP) treatment prior to UVA radiation was used as PUVA-induced photo-damaged modal. The OCT imaging of photo-damaged group (modal) and normal group (control) in vivo was obtained of mice dorsal skin at 0, 24, 48, 72 hours after irradiation respectively. And then the results were quantitatively analyzed combined with histological information. The experimental results showed that, PUVA-induced photo-damaged skin had an increase in epidermal thickness (ET), a reduction of attenuation coefficient in OCT images signal, and an increase in brightness of the epidermis layer compared with the control group. In conclusion, noninvasive high-resolution imaging techniques such as OCT may be a promising tool for photobiological studies aimed at assessing photo-damage and repair processes in vivo. It can be used to quantitative analysis of changes in photo-damaged skin, such as the ET and collagen in dermis, provides a theoretical basis for treatment and prevention of skin photodamages.

  11. Electrical impedance tomography-based sensing skin for quantitative imaging of damage in concrete

    NASA Astrophysics Data System (ADS)

    Hallaji, Milad; Seppänen, Aku; Pour-Ghaz, Mohammad

    2014-08-01

    This paper outlines the development of a large-area sensing skin for damage detection in concrete structures. The developed sensing skin consists of a thin layer of electrically conductive copper paint that is applied to the surface of the concrete. Cracking of the concrete substrate results in the rupture of the sensing skin, decreasing its electrical conductivity locally. The decrease in conductivity is detected with electrical impedance tomography (EIT) imaging. In previous works, electrically based sensing skins have provided only qualitative information on the damage on the substrate surface. In this paper, we study whether quantitative imaging of the damage is possible. We utilize application-specific models and computational methods in the image reconstruction, including a total variation (TV) prior model for the damage and an approximate correction of the modeling errors caused by the inhomogeneity of the painted sensing skin. The developed damage detection method is tested experimentally by applying the sensing skin to polymeric substrates and a reinforced concrete beam under four-point bending. In all test cases, the EIT-based sensing skin provides quantitative information on cracks and/or other damages on the substrate surface: featuring a very low conductivity in the damage locations, and a reliable indication of the lengths and shapes of the cracks. The results strongly support the applicability of the painted EIT-based sensing skin for damage detection in reinforced concrete elements and other substrates.

  12. Quantitative Three-Dimensional Imaging of Live Avian Embryonic Morphogenesis Via Micro-computed Tomography

    PubMed Central

    Henning, Alyssa L.; Jiang, Michael X.; Yalcin, Huseyin C.; Butcher, Jonathan T.

    2013-01-01

    Many clinically relevant congenital malformations arise during mid to late embryonic stages. This period is challenging to image quantitatively in live embryos, necessitating the use of multiple specimens with increased experimental variability. Here we establish X-ray and blood-pool computed tomography (CT) contrast agent toxicity and teratogenesis thresholds for 3D Micro-CT imaging of live avian embryos. Day 4 chick embryos micro-injected with Visipaque™ (VP) developed for an additional 6 days without defect. X-ray radiation up to 798 mGy was nontoxic. Peak average contrast of 1,060 HU occurred within 1 hr of imaging at 50 μm resolution. VP-enhanced contrast persisted past 24 hr with delayed accumulation in the allantois. Regional volumes of VP-injected embryos were statistically identical to those of fixed embryos perfused with osmium tetroxide. We further quantified longitudinal volumetric morphogenesis of the allantois over 30 hr. These results demonstrate the safety and efficacy of contrast enhanced quantitative micro-CT imaging for live embryos. PMID:21761480

  13. [Densitometry analysis with quantitative computerized tomography in 530 subjects from Southern Italy].

    PubMed

    Addesso, A M; Cinque, T; Del Vecchio, W; Salvi, V; Schillirò, F

    1996-10-01

    Quantitative measure of bone mineral content (BMC) loss is an important diagnostic indicator for determining the risk of fracture and in following the course of patients undergoing therapy for osteoporosis. Several techniques have been used to evaluate this parameter. Quantitative Computed Tomography (QCT) is the most precise and accurate method allowing selective measurement of trabecular compartment of the vertebrae. Age, sex, ethnic heritage and geographic factors influence BMC variability. The aim of this study is to describe the normal cross-section pattern of age-related spinal bone loss in a Southern Italy population (530 healthy subjects: 450 women, 80 men) and to provide a local data-base for better interpretation of the BMC values. The BMC of lumbar spine was measured by single energy QCT, using a reference phantom with five tubes containing known amounts of CaCO3, placed approximately at the vertebral bodies L2-L4. Results indicate an age-related bone loss with the lowest values at 55-70 years, particularly in women, while no major further decrease was observed in subjects over 65 years. Normal linear BMC decrease rate can be derived from this data.

  14. Noncontact quantitative biomechanical characterization of cardiac muscle using shear wave imaging optical coherence tomography.

    PubMed

    Wang, Shang; Lopez, Andrew L; Morikawa, Yuka; Tao, Ge; Li, Jiasong; Larina, Irina V; Martin, James F; Larin, Kirill V

    2014-07-01

    We report on a quantitative optical elastographic method based on shear wave imaging optical coherence tomography (SWI-OCT) for biomechanical characterization of cardiac muscle through noncontact elasticity measurement. The SWI-OCT system employs a focused air-puff device for localized loading of the cardiac muscle and utilizes phase-sensitive OCT to monitor the induced tissue deformation. Phase information from the optical interferometry is used to reconstruct 2-D depth-resolved shear wave propagation inside the muscle tissue. Cross-correlation of the displacement profiles at various spatial locations in the propagation direction is applied to measure the group velocity of the shear waves, based on which the Young's modulus of tissue is quantified. The quantitative feature and measurement accuracy of this method is demonstrated from the experiments on tissue-mimicking phantoms with the verification using uniaxial compression test. The experiments are performed on ex vivo cardiac muscle tissue from mice with normal and genetically altered myocardium. Our results indicate this optical elastographic technique is useful as a noncontact tool to assist the cardiac muscle studies.

  15. Quantitative Micro-Computed Tomography Imaging of Vascular Dysfunction in Progressive Kidney Diseases.

    PubMed

    Ehling, Josef; Bábíčková, Janka; Gremse, Felix; Klinkhammer, Barbara M; Baetke, Sarah; Knuechel, Ruth; Kiessling, Fabian; Floege, Jürgen; Lammers, Twan; Boor, Peter

    2016-02-01

    Progressive kidney diseases and renal fibrosis are associated with endothelial injury and capillary rarefaction. However, our understanding of these processes has been hampered by the lack of tools enabling the quantitative and noninvasive monitoring of vessel functionality. Here, we used micro-computed tomography (µCT) for anatomical and functional imaging of vascular alterations in three murine models with distinct mechanisms of progressive kidney injury: ischemia-reperfusion (I/R, days 1-56), unilateral ureteral obstruction (UUO, days 1-10), and Alport mice (6-8 weeks old). Contrast-enhanced in vivo µCT enabled robust, noninvasive, and longitudinal monitoring of vessel functionality and revealed a progressive decline of the renal relative blood volume in all models. This reduction ranged from -20% in early disease stages to -61% in late disease stages and preceded fibrosis. Upon Microfil perfusion, high-resolution ex vivo µCT allowed quantitative analyses of three-dimensional vascular networks in all three models. These analyses revealed significant and previously unrecognized alterations of preglomerular arteries: a reduction in vessel diameter, a prominent reduction in vessel branching, and increased vessel tortuosity. In summary, using µCT methodology, we revealed insights into macro-to-microvascular alterations in progressive renal disease and provide a platform that may serve as the basis to evaluate vascular therapeutics in renal disease.

  16. Intervertebral disc segmentation and volumetric reconstruction from peripheral quantitative computed tomography imaging.

    PubMed

    Wong, Alexander; Mishra, Akshaya; Yates, Justin; Fieguth, Paul; Clausi, David A; Callaghan, Jack P

    2009-11-01

    An automatic system for segmenting and constructing volumetric representations of excised intervertebral discs from peripheral quantitative computed tomography (PQCT) imagery is presented. The system is designed to allow for automatic quantitative analysis of progressive herniation damage to the intervertebral discs under flexion/extension motions combined with a compressive load. Automatic segmentation and volumetric reconstruction of intervertebral disc from PQCT imagery is a very challenging problem due to factors such as streak artifacts and unclear material density separation between contrasted intervertebral disc and surrounding bone in the PQCT imagery, as well as the formation of multiple contrasted regions under axial scans. To address these factors, a novel multiscale level set approach based on the Mumford-Shah energy functional in iterative bilateral scale space is employed to segment the intervertebral disc regions from the PQCT imagery. A Delaunay triangulation is then performed based on the set of points associated with the intervertebral disc regions to construct the volumetric representation of the intervertebral disc. Experimental results show that the proposed system achieves segmentation and volumetric reconstructions of intervertebral discs with mean absolute distance error below 0.8 mm when compared to ground truth measurements. The proposed system is currently in operational use as a visualization tool for studying progressive intervertebral disc damage.

  17. Quantitative Diagnosis of Colorectal Polyps by Spectral Domain Optical Coherence Tomography

    PubMed Central

    Wang, Chen; Zhang, Qinqin; Wu, Xiaojing; Tang, Tao; Liu, Hong; Zhu, S. W.; Gao, Bruce Z.; Yuan, X.-C.

    2014-01-01

    The principal aim of this study is to investigate the scattering coefficient of colorectal polyp tissues using an optical coherence tomography (OCT) technique. It combines the existing scattering coefficient model and spectral domain OCT to achieve method of early diagnosis of colorectal polyp in hospitals. Seventeen patients were studied, and a total of 1456 data points were extracted by curve-fitting the OCT signals into a confocal single-backscattering model. The results show that the mean scattering coefficient value for colorectal polyps is 1.91 mm−1 (std: ±0.54 mm−1), which is between the values for normal and malignant tissues. In addition, we studied the difference between adenomatous polyps (n = 15) and inflammatory polyps (n = 2) quantitatively and found that the adenomatous tissues had lower scattering coefficients than the inflammatory ones. The quantitative measurements confirmed that OCT can be used in primary diagnosis to compensate for the deficiencies in methods of pathological diagnosis, with a great potential for early diagnosis of tissues. PMID:24818145

  18. Volumetric Quantitative Computed Tomography Measurement Precision for Volumes and Densities of Tarsal and Metatarsal Bones

    PubMed Central

    Commean, Paul K.; Kennedy, Jared A.; Bahow, Karen A.; Hildebolt, Charles F.; Liu, Lu; Smith, Kirk E.; Hastings, Mary K.; Ju, Tao; Prior, Fred W.; Sinacore, David R.

    2011-01-01

    Diabetic foot diseases, such as ulcerations, infections, and neuropathic (Charcot’s) arthropathy are major complications of diabetes mellitus and peripheral neuropathy and may cause osteolysis (bone loss) in foot bones. The purposes of our study were to make computed tomography (CT) measurements of foot-bone volumes and densities and to determine measurement precision (percent coefficients of variation for root mean square-standard deviations) and least significant changes in these percentages that could be considered biologically real with 95% confidence. Volumetric quantitative CT scans were performed and repeated on 10 young, healthy subjects and 13 subjects with diabetes mellitus and peripheral neuropathy. Two raters used the original- and repeat-scan data sets to make measurements of volumes and bone mineral densities (BMDs) of the tarsal and metatarsal bones of the two feet (24 bones). Precisions for the bones ranged from 0.1% to 0.9% for volume measurements and from 0.6% to 1.9% for BMD measurements. The least significant changes ranged from 0.4% to 2.5% for volume measurements and from 1.5% to 5.4% for BMD measurements. Volumetric quantitative CT provides precise measurements of volume and BMD for metatarsal bones and tarsal bones where diabetic foot diseases commonly occur. PMID:21723764

  19. Application of microcomputed tomography for quantitative analysis of dental root canal obturations.

    PubMed

    Kierklo, Anna; Tabor, Zbisław; Petryniak, Rafał; Dohnalik, Marek; Jaworska, Małgorzata

    2014-03-24

    The aim of the study was to apply microcomputed tomography to quantitative evaluation of voids and to test any specific location of voids in tooth's root canal obturations. Twenty root canals were prepared and obturated with gutta-percha and Tubli-Seal sealer using the thermoplastic compaction method (System B+Obtura II). Roots were scanned and three-dimensional visualization was obtained. The volume and Feret's diameter of I-voids (at the filling/dentine interface) and S-voids (surrounded by filling material) were measured. The results revealed that none of the scanned root canal fillings were void-free. For I-voids, the volume fraction was significantly larger, but their number was lower (P=0.0007), than for S-voids. Both types of voids occurred in characteristic regions (P<0.001). I-voids occurred mainly in the apical third, while S-voids in the coronal third of the canal filling. Within the limitations of this study, our results indicate that microtomography, with proposed semi-automatic algorithm, is a useful tools for three-dimensional quantitative evaluation of dental root canal fillings. In canals filled with thermoplastic gutta-percha and Tubli-Seal, voids at the interface between the filling and canal dentine deserve special attention due to of their periapical location, which might promote apical microleakage. Further studies might help to elucidate the clinical relevance of these results.

  20. Impact of Multiple En Face Image Averaging on Quantitative Assessment from Optical Coherence Tomography Angiography Images.

    PubMed

    Uji, Akihito; Balasubramanian, Siva; Lei, Jianqin; Baghdasaryan, Elmira; Al-Sheikh, Mayss; Sadda, SriniVas R

    2017-07-01

    To investigate the impact of multiple en face image averaging on quantitative measurements of the retinal microvasculature using optical coherence tomography angiography (OCTA). Prospective, observational, cross-sectional case series. Twenty-one healthy individuals with normal eyes. Macular OCTA images were acquired from all participants using the Zeiss Cirrus 5000 with Angioplex OCTA software (Carl Zeiss Meditec, Dublin, CA). Nine OCTA cube scans per eye were obtained and 9 superficial retinal layer (SRL) and deep retinal layer (DRL) en face OCTA image slabs were averaged individually after registration. Quantitative parameters from the retinal microvasculature were measured on binarized and skeletonized OCTA images and compared with single OCTA images without averaging. Vessel density (VD), vessel length density (VLD), vessel diameter index (VDI), and fractal dimension (FD). Participants with artifact or poor image quality were excluded, leaving 18 eyes for the analysis. After averaging, qualitatively there was apparent reduction in background noise, and fragmented vessels in the images before averaging became continuous with smoother walls and showed sharper contrast in both the SRL and DRL. Binarized and skeletonized derivates of these averaged images also showed fewer line fragments and dots in nonvascular areas and more continuous vessel images than those of images without averaging. In both SRL and DRL, VD (P = 0.0010 and P = 0.0003, respectively), VLD (P < 0.0001 for both), and FD (P < 0.0001 for both) significantly decreased and VDI significantly increased after averaging (P < 0.0001 for both). Averaging of multiple en face OCTA images improves image quality and also significantly impacts quantitative measurements. Reducing noise that could be misinterpreted as flow and annealing discontinuous vessel segments seem to be major mechanisms by which averaging may be of benefit. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc

  1. Dual-medium quantitative measurement simulation on cells.

    PubMed

    Wang, Yawei; Jin, Weifeng; Ren, Naifei

    2011-12-10

    For research on inhomogeneous cells, we present a simulation method called the dual-medium quantitative (DMQ) measurement simulation method, which is realized by combining phase-shifting digital holography with DMQ analysis. The reliability of this method is confirmed by comparing the simulated phase map with the experimental one by the Hilbert phase microscope [J. Phys. Chem. A 113, 13327 (2009)10.1021/jp904746r], and its ability for studying inhomogeneous cells is demonstrated with measurements of a simulated HeLa cell. The average deviation and the relative deviation of physical thickness and axially averaged refractive index are 0.0339 μm, 0.69% and 0.0013, 0.094%, respectively. This approach can provide good guidance for experimental research on inhomogeneous cells. © 2011 Optical Society of America

  2. Comparison of low- and ultralow-dose computed tomography protocols for quantitative lung and airway assessment.

    PubMed

    Hammond, Emily; Sloan, Chelsea; Newell, John D; Sieren, Jered P; Saylor, Melissa; Vidal, Craig; Hogue, Shayna; De Stefano, Frank; Sieren, Alexa; Hoffman, Eric A; Sieren, Jessica C

    2017-09-01

    Quantitative computed tomography (CT) measures are increasingly being developed and used to characterize lung disease. With recent advances in CT technologies, we sought to evaluate the quantitative accuracy of lung imaging at low- and ultralow-radiation doses with the use of iterative reconstruction (IR), tube current modulation (TCM), and spectral shaping. We investigated the effect of five independent CT protocols reconstructed with IR on quantitative airway measures and global lung measures using an in vivo large animal model as a human subject surrogate. A control protocol was chosen (NIH-SPIROMICS + TCM) and five independent protocols investigating TCM, low- and ultralow-radiation dose, and spectral shaping. For all scans, quantitative global parenchymal measurements (mean, median and standard deviation of the parenchymal HU, along with measures of emphysema) and global airway measurements (number of segmented airways and pi10) were generated. In addition, selected individual airway measurements (minor and major inner diameter, wall thickness, inner and outer area, inner and outer perimeter, wall area fraction, and inner equivalent circle diameter) were evaluated. Comparisons were made between control and target protocols using difference and repeatability measures. Estimated CT volume dose index (CTDIvol) across all protocols ranged from 7.32 mGy to 0.32 mGy. Low- and ultralow-dose protocols required more manual editing and resolved fewer airway branches; yet, comparable pi10 whole lung measures were observed across all protocols. Similar trends in acquired parenchymal and airway measurements were observed across all protocols, with increased measurement differences using the ultralow-dose protocols. However, for small airways (1.9 ± 0.2 mm) and medium airways (5.7 ± 0.4 mm), the measurement differences across all protocols were comparable to the control protocol repeatability across breath holds. Diameters, wall thickness, wall area fraction

  3. Quantitative computed tomography-derived clusters: redefining airway remodeling in asthmatic patients.

    PubMed

    Gupta, Sumit; Hartley, Ruth; Khan, Umair T; Singapuri, Amisha; Hargadon, Beverly; Monteiro, William; Pavord, Ian D; Sousa, Ana R; Marshall, Richard P; Subramanian, Deepak; Parr, David; Entwisle, James J; Siddiqui, Salman; Raj, Vimal; Brightling, Christopher E

    2014-03-01

    Asthma heterogeneity is multidimensional and requires additional tools to unravel its complexity. Computed tomography (CT)-assessed proximal airway remodeling and air trapping in asthmatic patients might provide new insights into underlying disease mechanisms. The aim of this study was to explore novel, quantitative, CT-determined asthma phenotypes. Sixty-five asthmatic patients and 30 healthy subjects underwent detailed clinical, physiologic characterization and quantitative CT analysis. Factor and cluster analysis techniques were used to determine 3 novel, quantitative, CT-based asthma phenotypes. Patients with severe and mild-to-moderate asthma demonstrated smaller mean right upper lobe apical segmental bronchus (RB1) lumen volume (LV) in comparison with healthy control subjects (272.3 mm(3) [SD, 112.6 mm(3)], 259.0 mm(3) [SD, 53.3 mm(3)], 366.4 mm(3) [SD, 195.3 mm(3)], respectively; P = .007) but no difference in RB1 wall volume (WV). Air trapping measured based on mean lung density expiratory/inspiratory ratio was greater in patients with severe and mild-to-moderate asthma compared with that seen in healthy control subjects (0.861 [SD, 0.05)], 0.866 [SD, 0.07], and 0.830 [SD, 0.06], respectively; P = .04). The fractal dimension of the segmented airway tree was less in asthmatic patients compared with that seen in control subjects (P = .007). Three novel, quantitative, CT-based asthma clusters were identified, all of which demonstrated air trapping. Cluster 1 demonstrates increased RB1 WV and RB1 LV but decreased RB1 percentage WV. On the contrary, cluster 3 subjects have the smallest RB1 WV and LV values but the highest RB1 percentage WV values. There is a lack of proximal airway remodeling in cluster 2 subjects. Quantitative CT analysis provides a new perspective in asthma phenotyping, which might prove useful in patient selection for novel therapies. Copyright © 2013 The Authors. Published by Mosby, Inc. All rights reserved.

  4. Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues

    NASA Astrophysics Data System (ADS)

    Tzoumas, Stratis; Nunes, Antonio; Olefir, Ivan; Stangl, Stefan; Symvoulidis, Panagiotis; Glasl, Sarah; Bayer, Christine; Multhoff, Gabriele; Ntziachristos, Vasilis

    2016-06-01

    Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation, an effect that causes spectral corruption. Spectral corruption has limited the quantification accuracy of optical and optoacoustic spectroscopic methods, and impeded the goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical goal for the assessment of oxygenation in physiological processes and disease. Here we describe light fluence in the spectral domain and introduce eigenspectra multispectral optoacoustic tomography (eMSOT) to account for wavelength-dependent light attenuation, and estimate blood sO2 within deep tissue. We validate eMSOT in simulations, phantoms and animal measurements and spatially resolve sO2 in muscle and tumours, validating our measurements with histology data. eMSOT shows substantial sO2 accuracy enhancement over previous optoacoustic methods, potentially serving as a valuable tool for imaging tissue pathophysiology.

  5. Quantitative evaluation of benzodiazepine receptors in live Papio papio baboons using positron emission tomography

    SciTech Connect

    Brouillet, E.; Chavoix, C.; Khalili-Varasteh, M.; Bottlaender, M.; Hantraye, P.; Yorke, J.C.; Maziere, M. )

    1990-10-01

    The binding of the 11C-labeled benzodiazepine antagonist Ro 15-1788 (flumazenil) was measured in the neocortex of live Papio papio baboons by positron emission tomography. This allowed us to calculate in vivo (i.e., at physiological temperature, neurotransmitters concentrations, and ionic environment) the apparent density of available benzodiazepine receptors (B'max) and the dissociation constant of Ro 15-1788 (Kd). By coadministering increasing doses of unlabeled Ro 15-1788 with (11C)Ro 15-1788 and assuming that nonsaturable radioactivity indicated the free ligand concentration, we were able to obtain saturation isotherms. We showed that a state of quasiequilibrium was reached 50 min after the administration of the radioligand. Linear Scatchard plots allowed us to calculate B'max at 78 and 50 pmol/ml of cerebral tissue in the occipital and frontal cortices, respectively. In both these areas, Kd is on the order of 6 nM, with a Hill number very close to unity. This indicates that Ro 15-1788 binds in vivo with high affinity to an homogeneous population of saturable sites. A similar measurement was carried out on a naturally photosensitive P. papio baboon. Absolute values of B'max, Kd, and Hill number were similar to those of the control baboons. Although results concerning this baboon can only be considered as a case report, this similarity may suggest that its epileptic syndrome is not related to a large change in B'max or Kd, at least in occipital and frontal cortices. Our results showed that quantitative estimation by positron emission tomography of some characteristics of benzodiazepine receptors is possible in live baboons and may represent a supplementary tool for investigating further the molecular mechanisms of benzodiazepine receptor function in physiological and physiopathological conditions.

  6. Accuracy of high-resolution peripheral quantitative computed tomography for measurement of bone quality.

    PubMed

    MacNeil, Joshua A; Boyd, Steven K

    2007-12-01

    The introduction of three-dimensional high-resolution peripheral in vivo quantitative computed tomography (HR-pQCT) (XtremeCT, Scanco Medical, Switzerland; voxel size 82 microm) provides a new approach to monitor micro-architectural bone changes longitudinally. The accuracy of HR-pQCT for three important determinants of bone quality, including bone mineral density (BMD), architectural measurements and bone mechanics, was determined through a comparison with micro-computed tomography (microCT) and dual energy X-ray absorptiometry (DXA). Forty measurements from 10 cadaver radii with low bone mass were scanned using the three modalities, and image registration was used for 3D data to ensure identical regions were analyzed. The areal BMD of DXA correlated well with volumetric BMD by HR-pQCT despite differences in dimensionality (R(2) = 0.69), and the correlation improved when non-dimensional bone mineral content was assessed (R(2) = 0.80). Morphological parameters measured by HR-pQCT in a standard patient analysis, including bone volume ratio, trabecular number, derived trabecular thickness, derived trabecular separation, and cortical thickness correlated well with muCT measures (R(2) = 0.59-0.96). Additionally, some non-metric parameters such as connectivity density (R(2) = 0.90) performed well. The mechanical stiffness assessed by finite element analysis of HR-pQCT images was generally higher than for microCT data due to resolution differences, and correlated well at the continuum level (R(2) = 0.73). The validation here of HR-pQCT against gold-standards microCT and DXA provides insight into the accuracy of the system, and suggests that in addition to the standard patient protocol, additional indices of bone quality including connectivity density and mechanical stiffness may be appropriate to include as part of a standard patient analysis for clinical monitoring of bone quality.

  7. In vitro atherosclerotic plaque and calcium quantitation by intravascular ultrasound and electron-beam computed tomography.

    PubMed

    Gutfinger, D E; Leung, C Y; Hiro, T; Maheswaran, B; Nakamura, S; Detrano, R; Kang, X; Tang, W; Tobis, J M

    1996-05-01

    The purpose of this investigation was to compare the accuracy of intravascular ultrasound (IVUS) and electron-beam computed tomography (EBCT) in quantitating human atherosclerotic plaque and calcium. In experiment 1, 12 human atherosclerotic arterial segments were obtained at autopsy and imaged by using IVUS and EBCT. The plaque from each arterial segment was dissected and a volume measurement of the dissected plaque was obtained by water displacement. The plaque from each arterial segment was ashed at 700 degrees F, and the weight of the remaining ashes was used as an estimate of the calcium mass. In experiment II, 11 calcified arterial segments were obtained at autopsy and imaged by using IVUS at one site along the artery. A corresponding histologic cross section stained with Masson's trichrome was prepared. In experiment I, the mean plaque volume measured by water displacement was 165.3 +/- 118.4 microliters. The mean plaque volume calculated by IVUS was 166.1 +/- 114.4 microliters and correlated closely with that by water displacement (r = 0.98, p < 0.0001). The mean calcium mass measured by ashing was 19.4 +/- 15.8 mg. The mean calculated calcium mass by EBCT was 19.9 mg and correlated closely with that by ashing (r=0.98, p<0.001). The mean calculated calcium volume by IVUS was 18.6 +/- 11.2 microliters and correlated linearly with the calcium mass by ashing (r = 0.87, p < 0.0003). In experiment II, the mean cross-sectional area of the calcified matrix was 1.71 +/- 0.66 mm2 by histologic examination compared with 1.44 +/- 0.66 mm2 by IVUS. There was a good correlation between the calcified cross-sectional area by histologic examination and IVUS (r = 0.76, p < 0.007); however, IVUS may underestimate the amount of calcium present depending on the intralesional calcium morphologic characteristics. In conclusion, IVUS accurately quantitates atherosclerotic plaque volume as well as the cross-sectional area and volume of intralesional calcium, especially if the

  8. Quantitative surface evaluation by matching experimental and simulated ronchigram images

    NASA Astrophysics Data System (ADS)

    Kantún Montiel, Juana Rosaura; Cordero Dávila, Alberto; González García, Jorge

    2011-09-01

    To estimate qualitatively the surface errors with Ronchi test, the experimental and simulated ronchigrams are compared. Recently surface errors have been obtained quantitatively matching the intersection point coordinates of ronchigrama fringes with x-axis . In this case, gaussian fit must be done for each fringe, and interference orders are used in Malacara algorithm for the simulations. In order to evaluate surface errors, we added an error function in simulations, described with cubic splines, to the sagitta function of the ideal surface. We used the vectorial transversal aberration formula and a ruling with cosinusoidal transmittance, because these rulings reproduce better experimental ronchigram fringe profiles. Several error functions are tried until the whole experimental ronchigrama image is reproduced. The optimization process was done using genetic algorithms.

  9. Massively parallel data processing for quantitative total flow imaging with optical coherence microscopy and tomography

    NASA Astrophysics Data System (ADS)

    Sylwestrzak, Marcin; Szlag, Daniel; Marchand, Paul J.; Kumar, Ashwin S.; Lasser, Theo

    2017-08-01

    We present an application of massively parallel processing of quantitative flow measurements data acquired using spectral optical coherence microscopy (SOCM). The need for massive signal processing of these particular datasets has been a major hurdle for many applications based on SOCM. In view of this difficulty, we implemented and adapted quantitative total flow estimation algorithms on graphics processing units (GPU) and achieved a 150 fold reduction in processing time when compared to a former CPU implementation. As SOCM constitutes the microscopy counterpart to spectral optical coherence tomography (SOCT), the developed processing procedure can be applied to both imaging modalities. We present the developed DLL library integrated in MATLAB (with an example) and have included the source code for adaptations and future improvements. Catalogue identifier: AFBT_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AFBT_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPLv3 No. of lines in distributed program, including test data, etc.: 913552 No. of bytes in distributed program, including test data, etc.: 270876249 Distribution format: tar.gz Programming language: CUDA/C, MATLAB. Computer: Intel x64 CPU, GPU supporting CUDA technology. Operating system: 64-bit Windows 7 Professional. Has the code been vectorized or parallelized?: Yes, CPU code has been vectorized in MATLAB, CUDA code has been parallelized. RAM: Dependent on users parameters, typically between several gigabytes and several tens of gigabytes Classification: 6.5, 18. Nature of problem: Speed up of data processing in optical coherence microscopy Solution method: Utilization of GPU for massively parallel data processing Additional comments: Compiled DLL library with source code and documentation, example of utilization (MATLAB script with raw data) Running time: 1,8 s for one B-scan (150 × faster in comparison to the CPU

  10. Simulation evaluation of quantitative myocardial perfusion assessment from cardiac CT

    NASA Astrophysics Data System (ADS)

    Bindschadler, Michael; Modgil, Dimple; Branch, Kelley R.; La Riviere, Patrick J.; Alessio, Adam M.

    2014-03-01

    Contrast enhancement on cardiac CT provides valuable information about myocardial perfusion and methods have been proposed to assess perfusion with static and dynamic acquisitions. There is a lack of knowledge and consensus on the appropriate approach to ensure 1) sufficient diagnostic accuracy for clinical decisions and 2) low radiation doses for patient safety. This work developed a thorough dynamic CT simulation and several accepted blood flow estimation techniques to evaluate the performance of perfusion assessment across a range of acquisition and estimation scenarios. Cardiac CT acquisitions were simulated for a range of flow states (Flow = 0.5, 1, 2, 3 ml/g/min, cardiac output = 3,5,8 L/min). CT acquisitions were simulated with a validated CT simulator incorporating polyenergetic data acquisition and realistic x-ray flux levels for dynamic acquisitions with a range of scenarios including 1, 2, 3 sec sampling for 30 sec with 25, 70, 140 mAs. Images were generated using conventional image reconstruction with additional image-based beam hardening correction to account for iodine content. Time attenuation curves were extracted for multiple regions around the myocardium and used to estimate flow. In total, 2,700 independent realizations of dynamic sequences were generated and multiple MBF estimation methods were applied to each of these. Evaluation of quantitative kinetic modeling yielded blood flow estimates with an root mean square error (RMSE) of ~0.6 ml/g/min averaged across multiple scenarios. Semi-quantitative modeling and qualitative static imaging resulted in significantly more error (RMSE = ~1.2 and ~1.2 ml/min/g respectively). For quantitative methods, dose reduction through reduced temporal sampling or reduced tube current had comparable impact on the MBF estimate fidelity. On average, half dose acquisitions increased the RMSE of estimates by only 18% suggesting that substantial dose reductions can be employed in the context of quantitative myocardial

  11. The Modern Art of Reading Computed Tomography Images of the Lungs: Quantitative CT.

    PubMed

    Herth, Felix J F; Kirby, Miranda; Sieren, Jered; Herth, Jonas; Schirm, Joshua; Wood, Susan; Schuhmann, Maren

    2017-09-16

    Lung diseases are increasing in prevalence and overall burden worldwide. To stem the tide, more and more national and international guidelines are recommending the use of various diagnostic algorithms that are disease specific. There is growing consensus among the respiratory community that although patient histories and lung function testing are the minimum required for clinical examinations, these tests alone are not sufficient for disease characterization. Therefore, the use of computed tomography (CT) imaging is increasing used in clinical decision making for lung diseases. Lung diseases affect various components of lung, including the small airways, lung parenchyma, the interstitial space and the pulmonary vasculature. Quantitative CT (QCT) methods are emerging and are increasingly available using commercial software to quantify the underlying disease components, and a growing body of evidence suggests that QCT is an important tool in the clinical setting to help accurately and reproducibly detect where the disease is located in the lung, and to quantify the extent and overall severity for several lung diseases. Furthermore, this growing body of evidence has promoted the use of thoracic QCT to the point that it is now considered by many as an indispensable technology for longitudinal analysis and intervention trials. Many QCT imaging measurements are available to the respiratory physician, and the aim of this review is to introduce and describe pulmonary QCT imaging measurements and methodologies. © 2017 S. Karger AG, Basel.

  12. A Quantitative Approach to Distinguish Pneumonia From Atelectasis Using Computed Tomography Attenuation.

    PubMed

    Edwards, Rachael M; Godwin, J David; Hippe, Dan S; Kicska, Gregory

    2016-01-01

    It is known that atelectasis demonstrates greater contrast enhancement than pneumonia on computed tomography (CT). However, the effectiveness of using a Hounsfield unit (HU) threshold to distinguish pneumonia from atelectasis has never been shown. The objective of the study is to demonstrate that an HU threshold can be quantitatively used to effectively distinguish pneumonia from atelectasis. Retrospectively identified CT pulmonary angiogram examinations that did not show pulmonary embolism but contained nonaerated lungs were classified as atelectasis or pneumonia based on established clinical criteria. The HU attenuation was measured in these nonaerated lungs. Receiver operating characteristic (ROC) analysis was performed to determine the area under the ROC curve, sensitivity, and specificity of using the attenuation to distinguish pneumonia from atelectasis. Sixty-eight nonaerated lungs were measured in 55 patients. The mean (SD) enhancement was 62 (18) HU in pneumonia and 119 (24) HU in atelectasis (P < 0.001). A threshold of 92 HU diagnosed pneumonia with 97% sensitivity (confidence interval [CI], 80%-99%) and 85% specificity (CI, 70-93). Accuracy, measured as area under the ROC curve, was 0.97 (CI, 0.89-0.99). We have established that a threshold HU value can be used to confidently distinguish pneumonia from atelectasis with our standard CT pulmonary angiogram imaging protocol and patient population. This suggests that a similar threshold HU value may be determined for other scanning protocols, and application of this threshold may facilitate a more confident diagnosis of pneumonia and thus speed treatment.

  13. Micro/nano-computed tomography technology for quantitative dynamic, multi-scale imaging of morphogenesis.

    PubMed

    Gregg, Chelsea L; Recknagel, Andrew K; Butcher, Jonathan T

    2015-01-01

    Tissue morphogenesis and embryonic development are dynamic events challenging to quantify, especially considering the intricate events that happen simultaneously in different locations and time. Micro- and more recently nano-computed tomography (micro/nanoCT) has been used for the past 15 years to characterize large 3D fields of tortuous geometries at high spatial resolution. We and others have advanced micro/nanoCT imaging strategies for quantifying tissue- and organ-level fate changes throughout morphogenesis. Exogenous soft tissue contrast media enables visualization of vascular lumens and tissues via extravasation. Furthermore, the emergence of antigen-specific tissue contrast enables direct quantitative visualization of protein and mRNA expression. Micro-CT X-ray doses appear to be non-embryotoxic, enabling longitudinal imaging studies in live embryos. In this chapter we present established soft tissue contrast protocols for obtaining high-quality micro/nanoCT images and the image processing techniques useful for quantifying anatomical and physiological information from the data sets.

  14. Quantitative Three-Dimensional Imaging of Heterogeneous Materials by Thermal Tomography

    SciTech Connect

    Sun, J. G.

    2016-07-19

    Infrared thermal imaging based on active thermal excitations has been widely used for nondestructive evaluation ( NDE) of materials. While the experimental systems have remained essentially the same during the last few decades, development of advanced data-processing methods has significantly improved the capabilities of this technology. However, many limitations still exist. One fundamental limitation is the requirement, either explicitly or implicitly, of the tested material to be homogeneous such that detected thermal contrasts may be used to determine an average material property or attributed to flaws. In this paper, a new thermal tomography ( TT) method is introduced, which for the first time can evaluate heterogeneous materials by directly imaging their thermal-property variations with space. It utilizes one-sided flash thermal-imaging data to construct the three-dimensional ( 3D) distribution of thermal effusivity in the entire volume of a test sample. Theoretical analyses for single and multilayer material systems were conducted to validate its formulation and to demonstrate its performance. Experimental results for a ceramic composite plate and a thermal barrier coating ( TBC) sample are also presented. It was shown that thermal diffusion is the primary factor that degrades the spatial resolution with depth for TT; the spatial resolutions in the lateral and axial directions were quantitatively evaluated.

  15. Quantitative Assessment of Cervical Vertebral Maturation Using Cone Beam Computed Tomography in Korean Girls

    PubMed Central

    Byun, Bo-Ram; Kim, Yong-Il; Maki, Koutaro; Son, Woo-Sung

    2015-01-01

    This study was aimed to examine the correlation between skeletal maturation status and parameters from the odontoid process/body of the second vertebra and the bodies of third and fourth cervical vertebrae and simultaneously build multiple regression models to be able to estimate skeletal maturation status in Korean girls. Hand-wrist radiographs and cone beam computed tomography (CBCT) images were obtained from 74 Korean girls (6–18 years of age). CBCT-generated cervical vertebral maturation (CVM) was used to demarcate the odontoid process and the body of the second cervical vertebra, based on the dentocentral synchondrosis. Correlation coefficient analysis and multiple linear regression analysis were used for each parameter of the cervical vertebrae (P < 0.05). Forty-seven of 64 parameters from CBCT-generated CVM (independent variables) exhibited statistically significant correlations (P < 0.05). The multiple regression model with the greatest R2 had six parameters (PH2/W2, UW2/W2, (OH+AH2)/LW2, UW3/LW3, D3, and H4/W4) as independent variables with a variance inflation factor (VIF) of <2. CBCT-generated CVM was able to include parameters from the second cervical vertebral body and odontoid process, respectively, for the multiple regression models. This suggests that quantitative analysis might be used to estimate skeletal maturation status. PMID:25878721

  16. Mapping Bone Mineral Density Obtained by Quantitative Computed Tomography to Bone Volume Fraction

    NASA Technical Reports Server (NTRS)

    Pennline, James A.; Mulugeta, Lealem

    2017-01-01

    Methods for relating or mapping estimates of volumetric Bone Mineral Density (vBMD) obtained by Quantitative Computed Tomography to Bone Volume Fraction (BVF) are outlined mathematically. The methods are based on definitions of bone properties, cited experimental studies and regression relations derived from them for trabecular bone in the proximal femur. Using an experimental range of values in the intertrochanteric region obtained from male and female human subjects, age 18 to 49, the BVF values calculated from four different methods were compared to the experimental average and numerical range. The BVF values computed from the conversion method used data from two sources. One source provided pre bed rest vBMD values in the intertrochanteric region from 24 bed rest subject who participated in a 70 day study. Another source contained preflight vBMD values from 18 astronauts who spent 4 to 6 months on the ISS. To aid the use of a mapping from BMD to BVF, the discussion includes how to formulate them for purpose of computational modeling. An application of the conversions would be used to aid in modeling of time varying changes in vBMD as it relates to changes in BVF via bone remodeling and/or modeling.

  17. Noninvasive Quantitative Evaluation of the Dentin Layer during Dental Procedures Using Optical Coherence Tomography

    PubMed Central

    Sinescu, Cosmin; Negrutiu, Meda Lavinia; Bradu, Adrian; Duma, Virgil-Florin; Podoleanu, Adrian Gh.

    2015-01-01

    A routine cavity preparation of a tooth may lead to opening the pulp chamber. The present study evaluates quantitatively, in real time, for the first time to the best of our knowledge, the drilled cavities during dental procedures. An established noninvasive imaging technique, Optical Coherence Tomography (OCT), is used. The main scope is to prevent accidental openings of the dental pulp chamber. Six teeth with dental cavities have been used in this ex vivo study. The real time assessment of the distances between the bottom of the drilled cavities and the top of the pulp chamber was performed using an own assembled OCT system. The evaluation of the remaining dentin thickness (RDT) allowed for the positioning of the drilling tools in the cavities in relation to the pulp horns. Estimations of the safe and of the critical RDT were made; for the latter, the opening of the pulp chamber becomes unavoidable. Also, by following the fractures that can occur when the extent of the decay is too large, the dentist can decide upon the right therapy to follow, endodontic or conventional filling. The study demonstrates the usefulness of OCT imaging in guiding such evaluations during dental procedures. PMID:26078779

  18. Light fluence correction for quantitative determination of tissue absorption coefficient using multi-spectral optoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Brochu, Frederic M.; Joseph, James; Tomaszewski, Michal; Bohndiek, Sarah E.

    2015-07-01

    MultiSpectral Optoacoustic Tomography (MSOT) is a fast developing imaging modality, combining the high resolution and penetration depth of ultrasound with the excellent contrast from optical imaging of tissue. Absorption and scattering of the near infrared excitation light modulates the spectral profile of light as it propagates deep into biological tissue, meaning the images obtained provide only qualitative insight into the distribution of tissue chromophores. The goal of this work is to accurately recover the spectral profile of excitation light by modelling light fluence in the data reconstruction, to enable quantitative imaging. We worked with a commercial small animal MSOT scanner and developed our light fluence correction for its' cylindrical geometry. Optoacoustic image reconstruction pinpoints the sources of acoustic waves detected by the transducers and returns the initial pressure amplitude at these points. This pressure is the product of the dimensionless Grüneisen parameter, the absorption coefficient and the light fluence. Under the condition of constant Grüneisen parameter and well modelled light fluence, there is a linear relationship between the initial pressure amplitude measured in the optoacoustic image and the absorption coefficient. We were able to reproduce this linear relationship in different physical regions of an agarose gel phantom containing targets of known optical absorption coefficient, demonstrating that our light fluence model was working. We also demonstrate promising results of light fluence correction effects on in vivo data.

  19. Quantitative analysis of iris parameters in keratoconus patients using optical coherence tomography.

    PubMed

    Bonfadini, Gustavo; Arora, Karun; Vianna, Lucas M; Campos, Mauro; Friedman, David; Muñoz, Beatriz; Jun, Albert S

    2015-01-01

    To investigate the relationship between quantitative iris parameters and the presence of keratoconus. Cross-sectional observational study that included 15 affected eyes of 15 patients with keratoconus and 26 eyes of 26 normal age- and sex-matched controls. Iris parameters (area, thickness, and pupil diameter) of affected and unaffected eyes were measured under standardized light and dark conditions using anterior segment optical coherence tomography (AS-OCT). To identify optimal iris thickness cutoff points to maximize the sensitivity and specificity when discriminating keratoconus eyes from normal eyes, the analysis included the use of receiver operating characteristic (ROC) curves. Iris thickness and area were lower in keratoconus eyes than in normal eyes. The mean thickness at the pupillary margin under both light and dark conditions was found to be the best parameter for discriminating normal patients from keratoconus patients. Diagnostic performance was assessed by the area under the ROC curve (AROC), which had a value of 0.8256 with 80.0% sensitivity and 84.6% specificity, using a cutoff of 0.4125 mm. The sensitivity increased to 86.7% when a cutoff of 0.4700 mm was used. In our sample, iris thickness was lower in keratoconus eyes than in normal eyes. These results suggest that tomographic parameters may provide novel adjunct approaches for keratoconus screening.

  20. Quantitation of postexercise lung thallium-201 uptake during single photon emission computed tomography

    SciTech Connect

    Kahn, J.K.; Carry, M.M.; McGhie, I.; Pippin, J.J.; Akers, M.S.; Corbett, J.R.

    1989-03-01

    To test the hypothesis that analysis of lung thallium uptake measured during single photon emission computed tomography (SPECT) yields supplementary clinical information as reported for planar imaging, quantitative analysis of lung thallium uptake following maximal exercise was performed in 40 clinically normal subjects (Group 1) and 15 angiographically normal subjects (Group 2). Lung thallium uptake was measured from anterior projection images using a ratio of heart-to-lung activities. Seventy subjects with coronary artery disease (CAD) (Group 3) determined by angiography (greater than or equal to 70% luminal stenosis) underwent thallium perfusion SPECT. Thirty-nine percent of these subjects had multivessel and 61% had single vessel CAD. Lung thallium uptake was elevated in 47 of 70 (67%) Group 3 subjects. Group 3 subjects with elevated lung thallium uptake did not differ from Group 3 subjects with normal lung thallium uptake with respect to extent or distribution of coronary artery disease, left ventricular function, or severity of myocardial ischemia as determined by exercise and redistribution thallium SPECT. Thus, the measurement of thallium lung uptake from anterior projection images obtained during SPECT frequently identifies patients with CAD, but it may not provide supplementary information regarding the extent of myocardial ischemia or ventricular dysfunction.

  1. Quantitative upper airway endoscopy with swept-source anatomical optical coherence tomography

    PubMed Central

    Wijesundara, Kushal; Zdanski, Carlton; Kimbell, Julia; Price, Hillel; Iftimia, Nicusor; Oldenburg, Amy L.

    2014-01-01

    Minimally invasive imaging of upper airway obstructions in children and adults is needed to improve clinical decision-making. Toward this goal, we demonstrate an anatomical optical coherence tomography (aOCT) system delivered via a small-bore, flexible endoscope to quantify the upper airway lumen geometry. Helical scans were obtained from a proximally-scanned fiber-optic catheter of 820 μm outer diameter and >2 mm focal length. Coupled with a long coherence length wavelength-swept light source, the system exhibited an SNR roll-off of < 10 dB over a 10 mm range. Operating at 10 rotations/s, the average accuracy of segmented cross-sectional areas was found to be −1.4 ± 1.0%. To demonstrate the capability of this system, aOCT was performed on a pediatric airway phantom and on ex vivo swine trachea. The ability for quantitative endoscopy afforded by this system can aid in diagnosis, medical and surgical decision making, and predictive modeling of upper airway obstructive disorders. PMID:24688814

  2. Quantitative computed tomography of humpback whale (Megaptera novaeangliae) mandibles: mechanical implications for rorqual lunge-feeding.

    PubMed

    Field, Daniel J; Campbell-Malone, Regina; Goldbogen, Jeremy A; Shadwick, Robert E

    2010-07-01

    Rorqual whales (Balaenopteridae) lunge at high speed with mouth open to nearly 90 degrees to engulf large volumes of prey-laden water. This feeding process is enabled by extremely large skulls and mandibles that increase mouth area, thereby facilitating the flux of water into the mouth. When these mandibles are lowered during lunge-feeding, they are exposed to high drag, and therefore, may be subject to significant bending forces. We hypothesized that these mandibles exhibited a mechanical design (shape and density distribution) that enables these bones to accommodate high loads during lunge-feeding without exceeding their breaking strength. We used quantitative computed tomography (QCT) to determine the three-dimensional geometry and density distribution of a pair of subadult humpback whale (Megaptera novaeangliae) mandibles (length = 2.10 m). QCT data indicated highest bone density and cross-sectional area, and therefore, high resistance to bending and deflection, from the coronoid process to the middle of the dentary, which then decreased towards the anterior end of the mandible. These results differ from the caudorostral trends of increasing mandibular bone density in mammals, such as humans and the right whale, Eubalaena glacialis, indicating that adaptive bone remodeling is a significant contributing factor in establishing mandibular bone density distributions in rorquals.

  3. Micro/Nano-Computed Tomography Technology for Quantitative Dynamic, Multi-scale Imaging of Morphogenesis

    PubMed Central

    Gregg, Chelsea L.; Recknagel, Andrew K.; Butcher, Jonathan T.

    2015-01-01

    Tissue morphogenesis and embryonic development are dynamic events challenging to quantify, especially considering the intricate events that happen simultaneously in different locations and time. Micro-, and more recently nano-computed tomography (micro/nanoCT), has been used for the past 15 years to characterize large 3D fields of tortuous geometries at high spatial resolution. We and others have advanced micro/nanoCT imaging strategies for quantifying tissue and organ level fate changes throughout morphogenesis. Exogenous soft tissue contrast media enables visualization of vascular lumens and tissues via extravasation. Furthermore, the emergence of antigen specific tissue contrast enables direct quantitative visualization of protein and mRNA expression. Micro-CT X-ray doses appear to be non-embryotoxic, enabling longitudinal imaging studies in live embryos. In this paper we present established soft tissue contrast protocols for obtaining high quality micro/nanoCT images and the image processing techniques useful for quantifying anatomical and physiological information from the datasets. PMID:25245686

  4. Quantitative evaluation of the disintegration of orally rapid disintegrating tablets by X-ray computed tomography.

    PubMed

    Otsuka, Makoto; Yamanaka, Azusa; Uchino, Tomohiro; Otsuka, Kuniko; Sadamoto, Kiyomi; Ohshima, Hiroyuki

    2012-01-01

    To measure the rapid disintegration of Oral Disintegrating Tablets (ODT), a new test (XCT) was developed using X-ray computing tomography (X-ray CT). Placebo ODT, rapid disintegration candy (RDC) and Gaster®-D-Tablets (GAS) were used as model samples. All these ODTs were used to measure oral disintegration time (DT) in distilled water at 37±2°C by XCT. DTs were affected by the width of mesh screens, and degree to which the tablet holder vibrated from air bubbles. An in-vivo tablet disintegration test was performed for RDC using 11 volunteers. DT by the in-vivo method was significantly longer than that using the conventional tester. The experimental conditions for XCT such as the width of the mesh screen and degree of vibration were adjusted to be consistent with human DT values. Since DTs by the XCT method were almost the same as the human data, this method was able to quantitatively evaluate the rapid disintegration of ODT under the same conditions as inside the oral cavity. The DTs of four commercially available ODTs were comparatively evaluated by the XCT method, conventional tablet disintegration test and in-vivo method.

  5. Quantitative analysis of angle-resolved scattering properties of ovarian tissue using optical coherence tomography

    PubMed Central

    Yang, Yi; Wang, Tianheng; Brewer, Molly

    2012-01-01

    Abstract. Angle-resolved optical scattering properties of ovarian tissue, on different optical coherence tomography (OCT) imaging planes, were quantitatively measured by fitting the compounded OCT A-lines into a single scattering model. Higher cross correlation value of angle-resolved scattering coefficients between different OCT imaging planes was found in normal ovaries than was present in malignant ovaries. The mean cross correlation coefficient (MCC) was introduced in this pilot study to characterize and differentiate normal, n=6, and malignant, n=4, ovaries. A specificity of 100 percent and a sensitivity of 100 percent were achieved by setting MCC threshold at 0.6. Collagen properties, within the OCT imaging penetration depth, were also qualitatively studied in terms of their content, structure and directivity. The homogeneous three-dimensional collagen fiber network, observed in the normal ovary, effectively explains the stronger cross correlation of angle-resolved scattering properties on different imaging planes while the heterogeneity, observed in the malignant ovary, suggests a weaker correlation. PMID:23085900

  6. Quantitative experimental monitoring of molecular diffusion in clay with positron emission tomography

    NASA Astrophysics Data System (ADS)

    Kulenkampff, Johannes; Zakhnini, Abdelhamid; Gründig, Marion; Lippmann-Pipke, Johanna

    2016-08-01

    Clay plays a prominent role as barrier material in the geosphere. The small particle sizes cause extremely small pore sizes and induce low permeability and high sorption capacity. Transport of dissolved species by molecular diffusion, driven only by a concentration gradient, is less sensitive to the pore size. Heterogeneous structures on the centimetre scale could cause heterogeneous effects, like preferential transport zones, which are difficult to assess. Laboratory measurements with diffusion cells yield limited information on heterogeneity, and pore space imaging methods have to consider scale effects. We established positron emission tomography (PET), applying a high-resolution PET scanner as a spatially resolved quantitative method for direct laboratory observation of the molecular diffusion process of a PET tracer on the prominent scale of 1-100 mm. Although PET is rather insensitive to bulk effects, quantification required significant improvements of the image reconstruction procedure with respect to Compton scatter and attenuation. The experiments were conducted with 22Na and 124I over periods of 100 and 25 days, respectively. From the images we derived trustable anisotropic diffusion coefficients and, in addition, we identified indications of preferential transport zones. We thus demonstrated the unique potential of the PET imaging modality for geoscientific process monitoring under conditions where other methods fail, taking advantage of the extremely high detection sensitivity that is typical of radiotracer applications.

  7. Characterization of human oral tissues based on quantitative analysis of optical coherence tomography images

    NASA Astrophysics Data System (ADS)

    Salehi, Hassan S.; Kosa, Ali; Mahdian, Mina; Moslehpour, Saeid; Alnajjar, Hisham; Tadinada, Aditya

    2017-02-01

    In this paper, five types of tissues, human enamel, human cortical bone, human trabecular bone, muscular tissue, and fatty tissue were imaged ex vivo using optical coherence tomography (OCT). The specimens were prepared in blocks of 5 x 5 x 3 mm (width x length x height). The OCT imaging system was a swept source OCT system operating at wavelengths ranging between 1250 nm and 1360 nm with an average power of 18 mW and a scan rate of 50 to 100 kHz. The imaging probe was placed on top of a 2 x 2 cm stabilizing device to maintain a standard distance from the samples. Ten image samples from each type of tissue were obtained. To acquire images with minimum inhomogeneity, imaging was performed multiple times at different points. Based on the observed texture differences between OCT images of soft and hard tissues, spatial and spectral features were quantitatively extracted from the OCT images. The Radon transform from angles of 0 deg to 90 deg was computed, averaged over all the angles, normalized to peak at unity, and then fitted with Gaussian function. The mean absolute values of the spatial frequency components of the OCT image were considered as a feature, where 2-D fast Fourier transform (FFT) was done to OCT images. These OCT features can reliably differentiate between a range of hard and soft tissues, and could be extremely valuable in assisting dentists for in vivo evaluation of oral tissues and early detection of pathologic changes in tissues.

  8. Emphysema- and airway-dominant COPD phenotypes defined by standardised quantitative computed tomography.

    PubMed

    Subramanian, Deepak R; Gupta, Sumit; Burggraf, Dorothe; Vom Silberberg, Suzan J; Heimbeck, Irene; Heiss-Neumann, Marion S; Haeussinger, Karl; Newby, Chris; Hargadon, Beverley; Raj, Vimal; Singh, Dave; Kolsum, Umme; Hofer, Thomas P; Al-Shair, Khaled; Luetzen, Niklas; Prasse, Antje; Müller-Quernheim, Joachim; Benea, Giorgio; Leprotti, Stefano; Boschetto, Piera; Gorecka, Dorota; Nowinski, Adam; Oniszh, Karina; Castell, Wolfgang Zu; Hagen, Michael; Barta, Imre; Döme, Balázs; Strausz, Janos; Greulich, Timm; Vogelmeier, Claus; Koczulla, Andreas R; Gut, Ivo; Hohlfeld, Jens; Welte, Tobias; Lavae-Mokhtari, Mahyar; Ziegler-Heitbrock, Loems; Brightling, Christopher; Parr, David G

    2016-07-01

    EvA (Emphysema versus Airway disease) is a multicentre project to study mechanisms and identify biomarkers of emphysema and airway disease in chronic obstructive pulmonary disease (COPD). The objective of this study was to delineate objectively imaging-based emphysema-dominant and airway disease-dominant phenotypes using quantitative computed tomography (QCT) indices, standardised with a novel phantom-based approach.441 subjects with COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 1-3) were assessed in terms of clinical and physiological measurements, laboratory testing and standardised QCT indices of emphysema and airway wall geometry.QCT indices were influenced by scanner non-conformity, but standardisation significantly reduced variability (p<0.001) and led to more robust phenotypes. Four imaging-derived phenotypes were identified, reflecting "emphysema-dominant", "airway disease-dominant", "mixed" disease and "mild" disease. The emphysema-dominant group had significantly higher lung volumes, lower gas transfer coefficient, lower oxygen (PO2 ) and carbon dioxide (PCO2 ) tensions, higher haemoglobin and higher blood leukocyte numbers than the airway disease-dominant group.The utility of QCT for phenotyping in the setting of an international multicentre study is improved by standardisation. QCT indices of emphysema and airway disease can delineate within a population of patients with COPD, phenotypic groups that have typical clinical features known to be associated with emphysema-dominant and airway-dominant disease.

  9. The effect of slice thickness on quantitation of in vivo renal volume with cine computed tomography

    SciTech Connect

    Lerman, L.O.; Bentley, M.D.; Bell, M.R.; Rumberger, J.A.; Romero, J.C. )

    1990-02-26

    The development of fast computed tomography (CT) scanners allows the accurate quantitations of the volume (V) of the in-vivo kidney (K) and its component tissues, using 3 mm thick slices. Utilizing thicker slices may potentially enable the use of shorter scan times with less exposure to contrast media. To determine the relative accuracy of such scans, the right Ks of 14 anesthetized dogs were first scanned, using 3mm thick slices, after a venous bolus injection of iohexol (0.5 cc/kg). The images were then averaged to produce 6 and 10 mm thick slices, and the Vs of the Ks, and their cortical and medullary Vs, determined after boundary identification. Following the scans, the Ks were excised and their Vs determined post-mortem by fluid displacement. The whole K Vs obtained with the 6 and 10 mm thick slices correlated well with those obtained with the 3 mm thick slices. The difference between the in vivo and the post-mortem renal and medullary Vs was consistent with the blood, filtrate and urine contents of the in vivo kidney. In conclusion, the use of 6 and 10 mm thick slices resulted in an overestimation of the in vivo cortical V due to a partial volume effect, which was reflected in a consistent overestimation of KV.

  10. Assessing vertebral fracture risk on volumetric quantitative computed tomography by geometric characterization of trabecular bone structure

    NASA Astrophysics Data System (ADS)

    Checefsky, Walter A.; Abidin, Anas Z.; Nagarajan, Mahesh B.; Bauer, Jan S.; Baum, Thomas; Wismüller, Axel

    2016-03-01

    The current clinical standard for measuring Bone Mineral Density (BMD) is dual X-ray absorptiometry, however more recently BMD derived from volumetric quantitative computed tomography has been shown to demonstrate a high association with spinal fracture susceptibility. In this study, we propose a method of fracture risk assessment using structural properties of trabecular bone in spinal vertebrae. Experimental data was acquired via axial multi-detector CT (MDCT) from 12 spinal vertebrae specimens using a whole-body 256-row CT scanner with a dedicated calibration phantom. Common image processing methods were used to annotate the trabecular compartment in the vertebral slices creating a circular region of interest (ROI) that excluded cortical bone for each slice. The pixels inside the ROI were converted to values indicative of BMD. High dimensional geometrical features were derived using the scaling index method (SIM) at different radii and scaling factors (SF). The mean BMD values within the ROI were then extracted and used in conjunction with a support vector machine to predict the failure load of the specimens. Prediction performance was measured using the root-mean-square error (RMSE) metric and determined that SIM combined with mean BMD features (RMSE = 0.82 +/- 0.37) outperformed MDCT-measured mean BMD (RMSE = 1.11 +/- 0.33) (p < 10-4). These results demonstrate that biomechanical strength prediction in vertebrae can be significantly improved through the use of SIM-derived texture features from trabecular bone.

  11. Noninvasive Quantitative Evaluation of the Dentin Layer during Dental Procedures Using Optical Coherence Tomography.

    PubMed

    Sinescu, Cosmin; Negrutiu, Meda Lavinia; Bradu, Adrian; Duma, Virgil-Florin; Podoleanu, Adrian Gh

    2015-01-01

    A routine cavity preparation of a tooth may lead to opening the pulp chamber. The present study evaluates quantitatively, in real time, for the first time to the best of our knowledge, the drilled cavities during dental procedures. An established noninvasive imaging technique, Optical Coherence Tomography (OCT), is used. The main scope is to prevent accidental openings of the dental pulp chamber. Six teeth with dental cavities have been used in this ex vivo study. The real time assessment of the distances between the bottom of the drilled cavities and the top of the pulp chamber was performed using an own assembled OCT system. The evaluation of the remaining dentin thickness (RDT) allowed for the positioning of the drilling tools in the cavities in relation to the pulp horns. Estimations of the safe and of the critical RDT were made; for the latter, the opening of the pulp chamber becomes unavoidable. Also, by following the fractures that can occur when the extent of the decay is too large, the dentist can decide upon the right therapy to follow, endodontic or conventional filling. The study demonstrates the usefulness of OCT imaging in guiding such evaluations during dental procedures.

  12. Quantitative Functional Imaging Using Dynamic Positron Computed Tomography and Rapid Parameter Estimation Techniques

    NASA Astrophysics Data System (ADS)

    Koeppe, Robert Allen

    Positron computed tomography (PCT) is a diagnostic imaging technique that provides both three dimensional imaging capability and quantitative measurements of local tissue radioactivity concentrations in vivo. This allows the development of non-invasive methods that employ the principles of tracer kinetics for determining physiological properties such as mass specific blood flow, tissue pH, and rates of substrate transport or utilization. A physiologically based, two-compartment tracer kinetic model was derived to mathematically describe the exchange of a radioindicator between blood and tissue. The model was adapted for use with dynamic sequences of data acquired with a positron tomograph. Rapid estimation techniques were implemented to produce functional images of the model parameters by analyzing each individual pixel sequence of the image data. A detailed analysis of the performance characteristics of three different parameter estimation schemes was performed. The analysis included examination of errors caused by statistical uncertainties in the measured data, errors in the timing of the data, and errors caused by violation of various assumptions of the tracer kinetic model. Two specific radioindicators were investigated. ('18)F -fluoromethane, an inert freely diffusible gas, was used for local quantitative determinations of both cerebral blood flow and tissue:blood partition coefficient. A method was developed that did not require direct sampling of arterial blood for the absolute scaling of flow values. The arterial input concentration time course was obtained by assuming that the alveolar or end-tidal expired breath radioactivity concentration is proportional to the arterial blood concentration. The scale of the input function was obtained from a series of venous blood concentration measurements. The method of absolute scaling using venous samples was validated in four studies, performed on normal volunteers, in which directly measured arterial concentrations

  13. Quantitative analysis of the right auricle with 256-slice computed tomography.

    PubMed

    Li, Cai-Ying; Gao, Bu-Lang; Pan, Tong; Xiang, Cheng; Zhang, Xue-Jing; Liu, Xiao-Wei; Fan, Qiong-Ying

    2017-04-01

    To quantitatively measure the morphology parameters of the right auricle with 256-slice multidetector computed tomography angiography (MDCTA) in healthy people. A retrospective analysis of 200 patients who had undergone coronary MDCTA with negative findings was performed. The raw imaging data were reconstructed and the right auricular volume, right atrial volume, right auricle height, base long and short axes, base perimeter and area, normal angle, and distance were quantitatively measured. Men had significantly (P < 0.05) greater values than women in the right auricular volume (13.3 ± 4.0 vs. 11.7 ± 3.7 mL) and height (33.0 ± 5.0 vs. 30.5 ± 5.2 mm), the base long axis (34.4 ± 4.1 vs. 33.2 ± 3.9 mm), area (787.6 ± 177.6 vs. 771.0 ± 143.2 mm(2)) and perimeter (119.2 ± 17.5 vs. 115.0 ± 13.0), and the normal distance (22.4 ± 6.6 vs. 20.2 ± 6.7 mm). The normal 95 % reference range for the right auricular parameters was put forward. The right auricular parameters had a good correlation with the right atrium volume, aortic diameter, the body weight, height, and body surface area but a bad correlation with the vertebral body height. Significantly (P < 0.05) greater values were found in the normal angle and distance in subjects below than over 40 years of age. No other significant (P > 0.05) difference existed in the other right auricular parameters. Quantitative measurements of the right auricle can help us get a good understanding of the right auricular morphology and its relationship with surrounding structures and are helpful for cardiac interventions of electrophysiology and radiofrequency ablation.

  14. The effect of in situ/in vitro three-dimensional quantitative computed tomography image voxel size on the finite element model of human vertebral cancellous bone.

    PubMed

    Lu, Yongtao; Engelke, Klaus; Glueer, Claus-C; Morlock, Michael M; Huber, Gerd

    2014-11-01

    Quantitative computed tomography-based finite element modeling technique is a promising clinical tool for the prediction of bone strength. However, quantitative computed tomography-based finite element models were created from image datasets with different image voxel sizes. The aim of this study was to investigate whether there is an influence of image voxel size on the finite element models. In all 12 thoracolumbar vertebrae were scanned prior to autopsy (in situ) using two different quantitative computed tomography scan protocols, which resulted in image datasets with two different voxel sizes (0.29 × 0.29 × 1.3 mm(3) vs 0.18 × 0.18 × 0.6 mm(3)). Eight of them were scanned after autopsy (in vitro) and the datasets were reconstructed with two voxel sizes (0.32 × 0.32 × 0.6 mm(3) vs. 0.18 × 0.18 × 0.3 mm(3)). Finite element models with cuboid volume of interest extracted from the vertebral cancellous part were created and inhomogeneous bilinear bone properties were defined. Axial compression was simulated. No effect of voxel size was detected on the apparent bone mineral density for both the in situ and in vitro cases. However, the apparent modulus and yield strength showed significant differences in the two voxel size group pairs (in situ and in vitro). In conclusion, the image voxel size may have to be considered when the finite element voxel modeling technique is used in clinical applications.

  15. Novel Application of Quantitative Single-Photon Emission Computed Tomography/Computed Tomography to Predict Early Response to Methimazole in Graves' Disease

    PubMed Central

    Kim, Hyun Joo; Bang, Ji-In; Kim, Ji-Young; Moon, Jae Hoon; So, Young

    2017-01-01

    Objective Since Graves' disease (GD) is resistant to antithyroid drugs (ATDs), an accurate quantitative thyroid function measurement is required for the prediction of early responses to ATD. Quantitative parameters derived from the novel technology, single-photon emission computed tomography/computed tomography (SPECT/CT), were investigated for the prediction of achievement of euthyroidism after methimazole (MMI) treatment in GD. Materials and Methods A total of 36 GD patients (10 males, 26 females; mean age, 45.3 ± 13.8 years) were enrolled for this study, from April 2015 to January 2016. They underwent quantitative thyroid SPECT/CT 20 minutes post-injection of 99mTc-pertechnetate (5 mCi). Association between the time to biochemical euthyroidism after MMI treatment and %uptake, standardized uptake value (SUV), functional thyroid mass (SUVmean × thyroid volume) from the SPECT/CT, and clinical/biochemical variables, were investigated. Results GD patients had a significantly greater %uptake (6.9 ± 6.4%) than historical control euthyroid patients (n = 20, 0.8 ± 0.5%, p < 0.001) from the same quantitative SPECT/CT protocol. Euthyroidism was achieved in 14 patients at 156 ± 62 days post-MMI treatment, but 22 patients had still not achieved euthyroidism by the last follow-up time-point (208 ± 80 days). In the univariate Cox regression analysis, the initial MMI dose (p = 0.014), %uptake (p = 0.015), and functional thyroid mass (p = 0.016) were significant predictors of euthyroidism in response to MMI treatment. However, only %uptake remained significant in a multivariate Cox regression analysis (p = 0.034). A %uptake cutoff of 5.0% dichotomized the faster responding versus the slower responding GD patients (p = 0.006). Conclusion A novel parameter of thyroid %uptake from quantitative SPECT/CT is a predictive indicator of an early response to MMI in GD patients. PMID:28458607

  16. Novel Application of Quantitative Single-Photon Emission Computed Tomography/Computed Tomography to Predict Early Response to Methimazole in Graves' Disease.

    PubMed

    Kim, Hyun Joo; Bang, Ji-In; Kim, Ji-Young; Moon, Jae Hoon; So, Young; Lee, Won Woo

    2017-01-01

    Since Graves' disease (GD) is resistant to antithyroid drugs (ATDs), an accurate quantitative thyroid function measurement is required for the prediction of early responses to ATD. Quantitative parameters derived from the novel technology, single-photon emission computed tomography/computed tomography (SPECT/CT), were investigated for the prediction of achievement of euthyroidism after methimazole (MMI) treatment in GD. A total of 36 GD patients (10 males, 26 females; mean age, 45.3 ± 13.8 years) were enrolled for this study, from April 2015 to January 2016. They underwent quantitative thyroid SPECT/CT 20 minutes post-injection of (99m)Tc-pertechnetate (5 mCi). Association between the time to biochemical euthyroidism after MMI treatment and %uptake, standardized uptake value (SUV), functional thyroid mass (SUVmean × thyroid volume) from the SPECT/CT, and clinical/biochemical variables, were investigated. GD patients had a significantly greater %uptake (6.9 ± 6.4%) than historical control euthyroid patients (n = 20, 0.8 ± 0.5%, p < 0.001) from the same quantitative SPECT/CT protocol. Euthyroidism was achieved in 14 patients at 156 ± 62 days post-MMI treatment, but 22 patients had still not achieved euthyroidism by the last follow-up time-point (208 ± 80 days). In the univariate Cox regression analysis, the initial MMI dose (p = 0.014), %uptake (p = 0.015), and functional thyroid mass (p = 0.016) were significant predictors of euthyroidism in response to MMI treatment. However, only %uptake remained significant in a multivariate Cox regression analysis (p = 0.034). A %uptake cutoff of 5.0% dichotomized the faster responding versus the slower responding GD patients (p = 0.006). A novel parameter of thyroid %uptake from quantitative SPECT/CT is a predictive indicator of an early response to MMI in GD patients.

  17. Feasibility Study of Computational Fluid Dynamics Simulation of Coronary Computed Tomography Angiography Based on Dual-Source Computed Tomography

    PubMed Central

    Lu, Jing; Yu, Jie; Shi, Heshui

    2017-01-01

    Background Adding functional features to morphological features offers a new method for non-invasive assessment of myocardial perfusion. This study aimed to explore technical routes of assessing the left coronary artery pressure gradient, wall shear stress distribution and blood flow velocity distribution, combining three-dimensional coronary model which was based on high resolution dual-source computed tomography (CT) with computational fluid dynamics (CFD) simulation. Methods Three cases of no obvious stenosis, mild stenosis and severe stenosis in left anterior descending (LAD) were enrolled. Images acquired on dual-source CT were input into software Mimics, ICEMCFD and FLUENT to simulate pressure gradient, wall shear stress distribution and blood flow velocity distribution. Measuring coronary enhancement ratio of coronary artery was to compare with pressure gradient. Results Results conformed to theoretical values and showed difference between normal and abnormal samples. Conclusions The study verified essential parameters and basic techniques in blood flow numerical simulation preliminarily. It was proved feasible. PMID:27924174

  18. Quantitative spectral K-edge imaging in preclinical photon-counting x-ray computed tomography.

    PubMed

    de Vries, Anke; Roessl, Ewald; Kneepkens, Esther; Thran, Axel; Brendel, Bernhard; Martens, Gerhard; Proska, Roland; Nicolay, Klaas; Grüll, Holger

    2015-04-01

    The objective of this study was to investigate the feasibility and the accuracy of spectral computed tomography (spectral CT) to determine the tissue concentrations and localization of high-attenuation, iodine-based contrast agents in mice. Iodine tissue concentrations determined with spectral CT are compared with concentrations measured with single-photon emission computed tomography (SPECT) and inductively coupled plasma mass spectrometry (ICP-MS). All animal procedures were performed according to the US National Institutes of Health principles of laboratory animal care and were approved by the ethical review committee of Maastricht, The Netherlands. Healthy Swiss mice (n = 4) were injected with an iodinated emulsion radiolabeled with indium as multimodal contrast agent for CT and SPECT. The CT and SPECT scans were acquired using a dedicated small-animal SPECT/CT system. Subsequently, scans were performed with a preclinical spectral CT scanner equipped with a photon-counting detector and 6 energy threshold levels. Quantitative data analysis of SPECT and spectral CT scans were obtained using 3-dimensional volumes-of-interest drawing methods. The ICP-MS on dissected organs was performed to determine iodine uptake per organ and was compared with the amounts determined from spectral CT and SPECT. Iodine concentrations obtained with image-processed spectral CT data correlated well with data obtained either with noninvasive SPECT imaging (slope = 0.96, r = 0.75) or with ICP-MS (slope = 0.99, r = 0.89) in tissue samples. This preclinical proof-of-concept study shows the in vivo quantification of iodine concentrations in tissues using spectral CT. Our multimodal imaging approach with spectral CT and SPECT using radiolabeled iodinated emulsions together with ICP-based quantification allows a direct comparison of all methods. Benchmarked against ICP-MS data, spectral CT in the present implementation shows a slight underestimation of organ iodine concentrations compared

  19. Simulating the focal volume effect: a quantitative analysis

    NASA Astrophysics Data System (ADS)

    Scarborough, Timothy D.; Uiterwaal, Cornelis J. G. J.

    2013-12-01

    We present quantitative simulations of the focal volume effect. Intensity distributions in detection volumes with two- and three-dimensional spatial resolution are calculated. Results include an analysis of translations of these volumes in the focus along the direction of laser propagation as well as discussion of varying sizes of the spatially resolved volumes. We find that detection volumes less than half the 1/e full-width beam waist and less than half the Rayleigh length along the propagation direction offer an optimal compromise of maintaining intensity resolution without sacrificing peak intensity.

  20. Emission Computed Tomography: A New Technique for the Quantitative Physiologic Study of Brain and Heart in Vivo

    DOE R&D Accomplishments Database

    Phelps, M. E.; Hoffman, E. J.; Huang, S. C.; Schelbert, H. R.; Kuhl, D. E.

    1978-01-01

    Emission computed tomography can provide a quantitative in vivo measurement of regional tissue radionuclide tracer concentrations. This facility when combined with physiologic models and radioactively labeled physiologic tracers that behave in a predictable manner allow measurement of a wide variety of physiologic variables. This integrated technique has been referred to as Physiologic Tomography (PT). PT requires labeled compounds which trace physiologic processes in a known and predictable manner, and physiologic models which are appropriately formulated and validated to derive physiologic variables from ECT data. In order to effectively achieve this goal, PT requires an ECT system that is capable of performing truly quantitative or analytical measurements of tissue tracer concentrations and which has been well characterized in terms of spatial resolution, sensitivity and signal to noise ratios in the tomographic image. This paper illustrates the capabilities of emission computed tomography and provides examples of physiologic tomography for the regional measurement of cerebral and myocardial metabolic rate for glucose, regional measurement of cerebral blood volume, gated cardiac blood pools and capillary perfusion in brain and heart. Studies on patients with stroke and myocardial ischemia are also presented.

  1. Computer Monte Carlo simulation in quantitative resource estimation

    USGS Publications Warehouse

    Root, D.H.; Menzie, W.D.; Scott, W.A.

    1992-01-01

    The method of making quantitative assessments of mineral resources sufficiently detailed for economic analysis is outlined in three steps. The steps are (1) determination of types of deposits that may be present in an area, (2) estimation of the numbers of deposits of the permissible deposit types, and (3) combination by Monte Carlo simulation of the estimated numbers of deposits with the historical grades and tonnages of these deposits to produce a probability distribution of the quantities of contained metal. Two examples of the estimation of the number of deposits (step 2) are given. The first example is for mercury deposits in southwestern Alaska and the second is for lode tin deposits in the Seward Peninsula. The flow of the Monte Carlo simulation program is presented with particular attention to the dependencies between grades and tonnages of deposits and between grades of different metals in the same deposit. ?? 1992 Oxford University Press.

  2. Quantification of lower leg arterial calcifications by high-resolution peripheral quantitative computed tomography.

    PubMed

    Patsch, Janina M; Zulliger, Martin A; Vilayphou, Nicolas; Samelson, Elizabeth J; Cejka, Daniel; Diarra, Danielle; Berzaczy, Gundula; Burghardt, Andrew J; Link, Thomas M; Weber, Michael; Loewe, Christian

    2014-01-01

    Vascular calcifications and bone health seem to be etiologically linked via common risk factors such as aging and subclinical chronic inflammation. Epidemiologic studies have shown significant associations between low bone mineral density (BMD), fragility fractures and calcifications of the coronary arteries and the abdominal aorta. In the last decade, high-resolution peripheral quantitative computed tomography (HR-pQCT) has emerged as in-vivo research tool for the assessment of peripheral bone geometry, density, and microarchitecture. Although vascular calcifications are frequently observed as incidental findings in HR-pQCT scans, they have not yet been incorporated into quantitative HR-pQCT analyses. We developed a semi-automated algorithm to quantify lower leg arterial calcifications (LLACs), captured by HR-pQCT. The objective of our study was to determine validity and reliability of the LLAC measure. HR-pQCT scans were downscaled to a voxel size of 250μm. After subtraction of bone volumes from the scans, LLACs were detected and contoured by a semi-automated, dual-threshold seed-point segmentation. LLAC mass (in mg hydroxyapatite; HA) was calculated as the product of voxel-based calcification volume (mm(3)) and mean calcification density (mgHA/cm(3))/1000. To determine validity, we compared LLACs to coronary artery calcifications (CACs), as quantified by multi-detector computed tomography (MDCT) and Agatston scoring in forty-six patients on chronic hemodialysis. Moreover, we investigated associations of LLACs with age, time on dialysis, type-2 diabetes mellitus, history of stroke, and myocardial infarction. In a second step, we determined intra- and inter-reader reliability of the LLAC measure. In the validity study, LLACs were present (>0mgHA) in 76% of patients, 78% of patients had CACs (>0mgHA). Median LLAC was 6.65 (0.08-24.40)mgHA and median CAC as expressed by Agatston score was 266.3 (15.88-1877.28). We found a significant positive correlation between

  3. Quantitative Morphology Measures in Galaxies: Ground-Truthing from Simulations

    NASA Astrophysics Data System (ADS)

    Narayanan, Desika T.; Abruzzo, Matthew W.; Dave, Romeel; Thompson, Robert

    2017-01-01

    The process of galaxy assembly is a prevalent question in astronomy; there are a variety of potentially important effects, including baryonic accretion from the intergalactic medium, as well as major galaxy mergers. Recent years have ushered in the development of quantitative measures of morphology such as the Gini coefficient (G), the second-order moment of the brightest quintile of a galaxy’s light (M20), and the concentration (C), asymmetry (A), and clumpiness (S) of galaxies. To investigate the efficacy of these observational methods at identifying major mergers, we have run a series of very high resolution cosmological zoom simulations, and coupled these with 3D Monte Carlo dust radiative transfer. Our methodology is powerful in that it allows us to “observe” the simulation as an observer would, while maintaining detailed knowledge of the true merger history of the galaxy. In this presentation, we will present our main results from our analysis of these quantitative morphology measures, with a particular focus on high-redshift (z>2) systems.

  4. Geometric properties of distal radius and pathogenesis of Colles fracture: a peripheral quantitative computed tomography study.

    PubMed

    Nielsen, S P; Xie, X; Bärenholdt, O

    2001-01-01

    It is well known among clinicians that Colles fracture patients may have normal projected axial bone mineral density and that bone mass is not synonymous with bone strength. The aim of this work was to investigate whether cross-sectional properties of the distal radius in female patients with recent Colles fracture differ from those of a younger group of normal women without fracture. It was hypothesized that patients with Colles fracture had petite distal radii and that cortical thinning and reduced cortical and trabecular volumetric density are dominant features of this fracture type. We used a multilayer high-precision peripheral quantitative computed tomography (pQCT) device with a long-term precision error of 0.1% for a dedicated phantom during the measurement period (152 d). Clinical measurements were made at an ultradistal site rich in trabecular bone and a less ultradistal site rich in cortical bone. The results show that the following pQCT variables were significantly reduced in the nonfractured radius of the Colles fracture cases: mean ultradistal trabecular volumetric density, mean ultradistal and distal cortical volumetric density, mean ultradistal and distal cortical thickness (p < 0.001 for all differences). The outer cortical diameter, cross-sectional bone area, and cortical bending moment of inertia were not statistically different in the two groups. Thus, it would appear that Colles fracture cases did not have petite distal radii. The results suggest that the deforming force of Colles fracture has a transaxial direction (fall on outstretched arm), resulting in a crush fracture, and that it is not a bending force. We suggest that Colles fracture occurs as a result of the combined effect of a fall on the out-stretched arm, low trabecular and cortical volumetric bone density, and reduced cortical thickness.

  5. High Resolution Peripheral Quantitative Computed Tomography for Assessment of Bone Quality

    NASA Astrophysics Data System (ADS)

    Kazakia, Galateia

    2014-03-01

    The study of bone quality is motivated by the high morbidity, mortality, and societal cost of skeletal fractures. Over 10 million people are diagnosed with osteoporosis in the US alone, suffering 1.5 million osteoporotic fractures and costing the health care system over 17 billion annually. Accurate assessment of fracture risk is necessary to ensure that pharmacological and other interventions are appropriately administered. Currently, areal bone mineral density (aBMD) based on 2D dual-energy X-ray absorptiometry (DXA) is used to determine osteoporotic status and predict fracture risk. Though aBMD is a significant predictor of fracture risk, it does not completely explain bone strength or fracture incidence. The major limitation of aBMD is the lack of 3D information, which is necessary to distinguish between cortical and trabecular bone and to quantify bone geometry and microarchitecture. High resolution peripheral quantitative computed tomography (HR-pQCT) enables in vivo assessment of volumetric BMD within specific bone compartments as well as quantification of geometric and microarchitectural measures of bone quality. HR-pQCT studies have documented that trabecular bone microstructure alterations are associated with fracture risk independent of aBMD.... Cortical bone microstructure - specifically porosity - is a major determinant of strength, stiffness, and fracture toughness of cortical tissue and may further explain the aBMD-independent effect of age on bone fragility and fracture risk. The application of finite element analysis (FEA) to HR-pQCT data permits estimation of patient-specific bone strength, shown to be associated with fracture incidence independent of aBMD. This talk will describe the HR-pQCT scanner, established metrics of bone quality derived from HR-pQCT data, and novel analyses of bone quality currently in development. Cross-sectional and longitudinal HR-pQCT studies investigating the impact of aging, disease, injury, gender, race, and

  6. Characterizing trabecular bone structure for assessing vertebral fracture risk on volumetric quantitative computed tomography

    NASA Astrophysics Data System (ADS)

    Nagarajan, Mahesh B.; Checefsky, Walter A.; Abidin, Anas Z.; Tsai, Halley; Wang, Xixi; Hobbs, Susan K.; Bauer, Jan S.; Baum, Thomas; Wismüller, Axel

    2015-03-01

    While the proximal femur is preferred for measuring bone mineral density (BMD) in fracture risk estimation, the introduction of volumetric quantitative computed tomography has revealed stronger associations between BMD and spinal fracture status. In this study, we propose to capture properties of trabecular bone structure in spinal vertebrae with advanced second-order statistical features for purposes of fracture risk assessment. For this purpose, axial multi-detector CT (MDCT) images were acquired from 28 spinal vertebrae specimens using a whole-body 256-row CT scanner with a dedicated calibration phantom. A semi-automated method was used to annotate the trabecular compartment in the central vertebral slice with a circular region of interest (ROI) to exclude cortical bone; pixels within were converted to values indicative of BMD. Six second-order statistical features derived from gray-level co-occurrence matrices (GLCM) and the mean BMD within the ROI were then extracted and used in conjunction with a generalized radial basis functions (GRBF) neural network to predict the failure load of the specimens; true failure load was measured through biomechanical testing. Prediction performance was evaluated with a root-mean-square error (RMSE) metric. The best prediction performance was observed with GLCM feature `correlation' (RMSE = 1.02 ± 0.18), which significantly outperformed all other GLCM features (p < 0.01). GLCM feature correlation also significantly outperformed MDCTmeasured mean BMD (RMSE = 1.11 ± 0.17) (p< 10-4). These results suggest that biomechanical strength prediction in spinal vertebrae can be significantly improved through characterization of trabecular bone structure with GLCM-derived texture features.

  7. Quantitative Fundus Autofluorescence and Optical Coherence Tomography in Best Vitelliform Macular Dystrophy

    PubMed Central

    Duncker, Tobias; Greenberg, Jonathan P.; Ramachandran, Rithambara; Hood, Donald C.; Smith, R. Theodore; Hirose, Tatsuo; Woods, Russell L.; Tsang, Stephen H.; Delori, François C.; Sparrow, Janet R.

    2014-01-01

    Purpose. Quantitative fundus autofluorescence (qAF), spectral domain optical coherence tomography (SD-OCT) segmentation, and multimodal imaging were performed to elucidate the pathogenesis of Best vitelliform macular dystrophy (BVMD) and to identify abnormalities in lesion versus nonlesion fundus areas. Methods. Sixteen patients with a clinical diagnosis of BVMD were studied. Autofluorescence images (30°, 488-nm excitation) were acquired with a confocal scanning laser ophthalmoscope equipped with an internal fluorescent reference to account for variable laser power and detector sensitivity. The grey levels (GLs) of each image were calibrated to the reference, zero GL, magnification, and normative optical media density, to yield qAF. Horizontal SD-OCT scans were obtained and retinal layers manually segmented. Additionally, color and near-infrared reflectance (NIR-R) images were registered to AF images. All patients were screened for mutations in BEST1. In three additional BVMD patients, in vivo spectrofluorometric measurements were obtained within the vitelliform lesion. Results. Mean nonlesion qAF was within normal limits for age. Maximum qAF within the lesion was markedly increased compared with controls. By SD-OCT segmentation, outer segment equivalent thickness was increased and outer nuclear layer thickness decreased in the lesion. Changes were also present in a transition zone beyond the lesion border. In subclinical patients, no abnormalities in retinal layer thickness were identified. Fluorescence spectra recorded from the vitelliform lesion were consistent with those of retinal pigment epithelial cell lipofuscin. Conclusions. Based on qAF, mutations in BEST1 do not cause increased lipofuscin levels in nonlesion fundus areas. PMID:24526438

  8. Improved reproducibility of high-resolution peripheral quantitative computed tomography for measurement of bone quality.

    PubMed

    MacNeil, Joshua A; Boyd, Steven K

    2008-07-01

    A human high-resolution peripheral quantitative computed tomography scanner (HR-pQCT) (XtremeCT, Scanco Medical, Switzerland) capable of measuring three important indicators of bone quality (micro-architectural morphology, mineralization and mechanical stiffness) has been developed. The goal of this study was to evaluate the reproducibility of male and female HR-pQCT in vivo measurements, and elucidate the causes of error in these measurements through a comparison with in vitro measurements. The best possible short-term reproducibility was found using a set of 10 in vitro measurements without repositioning, and a set of 10 with repositioning. Subsequently, in vivo measurements were performed on 15 male and 15 female subjects at baseline and follow-ups of 1 week and 4 months to determine the short- and long-term reproducibility of the system. In addition to the 2D area matching method used in the standard evaluation protocol, a custom developed 3D registration method was used to find the common region between repeated scans. The best possible reproducibility without movement artifacts and repositioning error was less than 0.5%, while the reproducibility with repositioning error was less than 1.5%. The in vivo reproducibility of density (<1%), morphological (<4.5%) and stiffness (<3.5) measurements was consistently poorer than the reproducibility of cadaver measurements, presumably due to small movement artifacts and repositioning errors. Using 3D image registration, repositioning error was reduced on average by 23% and 8% for measurements of the radius and tibia sites, respectively. This study has provided bounds for the reproducibility of HR-pQCT to monitor bone quality longitudinally, and a basis for clinical study design to determine detectable changes.

  9. Assessment of Regional Bone Density in Fractured Vertebrae Using Quantitative Computed Tomography

    PubMed Central

    Soliman, Hany A.G.; Mac-Thiong, Jean-Marc; Levasseur, Annie; Parent, Stefan

    2017-01-01

    Study Design Cohort study. Purpose The aim of this study is to propose and evaluate a new technique to assess bone mineral density of fractured vertebrae using quantitative computed tomography (QCT). Overview of Literature There is no available technique to estimate bone mineral density (BMD) at the fractured vertebra because of the alterations in bony structures at the fracture site. Methods Forty patients with isolated fracture from T10 to L2 were analyzed from the vertebrae above and below the fracture level. Apparent density (AD) was measured based on the relationship between QCT images attenuation coefficients and the density of calibration objects. AD of 8 independent regions of interest (ROI) within the vertebral body and 2 ROI within the pedicles of vertebrae above and below the fractured vertebra were measured. At the level of the fractured vertebra, AD was measured at the pedicles, which are typically intact. AD of the fractured vertebral body was linearly interpolated, based on the assumption that AD at the fractured vertebra is equivalent to the average AD measured in vertebrae adjacent to the fracture. Estimated and measured AD of the pedicles at the fractured level were compared to verify our assumption of linear interpolation from adjacent vertebrae. Results The difference between the measured and the interpolated density of the pedicles at the fractured vertebra was 0.006 and 0.003 g/cm3 for right and left pedicle respectively. The highest mean AD located at the pedicles and the lowest mean AD was found at the anterior ROI of the vertebral body. Significant negative correlation exist between age and AD of ROI in the vertebral body. Conclusions This study suggests that the proposed technique is adequate to estimate the AD of a fractured vertebra from the density of adjacent vertebrae. PMID:28243370

  10. Distinct Quantitative Computed Tomography Emphysema Patterns Are Associated with Physiology and Function in Smokers

    PubMed Central

    San José Estépar, Raúl; Mendoza, Carlos S.; Hersh, Craig P.; Laird, Nan; Crapo, James D.; Lynch, David A.; Silverman, Edwin K.; Washko, George R.

    2013-01-01

    Rationale: Emphysema occurs in distinct pathologic patterns, but little is known about the epidemiologic associations of these patterns. Standard quantitative measures of emphysema from computed tomography (CT) do not distinguish between distinct patterns of parenchymal destruction. Objectives: To study the epidemiologic associations of distinct emphysema patterns with measures of lung-related physiology, function, and health care use in smokers. Methods: Using a local histogram-based assessment of lung density, we quantified distinct patterns of low attenuation in 9,313 smokers in the COPDGene Study. To determine if such patterns provide novel insights into chronic obstructive pulmonary disease epidemiology, we tested for their association with measures of physiology, function, and health care use. Measurements and Main Results: Compared with percentage of low-attenuation area less than −950 Hounsfield units (%LAA-950), local histogram-based measures of distinct CT low-attenuation patterns are more predictive of measures of lung function, dyspnea, quality of life, and health care use. These patterns are strongly associated with a wide array of measures of respiratory physiology and function, and most of these associations remain highly significant (P < 0.005) after adjusting for %LAA-950. In smokers without evidence of chronic obstructive pulmonary disease, the mild centrilobular disease pattern is associated with lower FEV1 and worse functional status (P < 0.005). Conclusions: Measures of distinct CT emphysema patterns provide novel information about the relationship between emphysema and key measures of physiology, physical function, and health care use. Measures of mild emphysema in smokers with preserved lung function can be extracted from CT scans and are significantly associated with functional measures. PMID:23980521

  11. Quantitative analysis of vascular dimension and plaque composition in coronary multidetector computed tomography images

    NASA Astrophysics Data System (ADS)

    Olszewski, Mark E.; Wahle, Andreas; Vembar, Mani; Ciancibello, Les; Kerner, Arthur; Beyar, Rafael; Ghersin, Eduard; Subramanyan, Krishna; Sonka, Milan

    2006-03-01

    The noninvasive assessment of coronary atherosclerosis holds great promise for the future of cardiovascular medicine, and multidetector computed tomography (MDCT) has recently taken the lead in this area. Earlier studies have shown the ability of MDCT to visualize the coronary lumen and various types of atherosclerotic plaque. The aims of this project are to design, implement, and validate a complete system for the automated, quantitative analysis of coronary MDCT images. The developed system uses graph algorithms and knowledge-based cost functions to automatically segment the lumen and wall, and then uses pattern classification techniques to identify and quantify the tissue types found within the detected vascular wall. The system has been validated in comparison with expert tracings and labels, as well as in comparison with intravascular ultrasound (IVUS). In the former, the radial position of the lumen and adventitia were compared at 360 corresponding angular locations in 299 vascular cross sections (from 13 vessels in 5 patients: 5 RCA, 4 LAD, 4 LCX). Results show a border positioning error of 0.150 +/- 0.090 mm unsigned / 0.007 +/- 0.001 mm signed for the lumen, and 0.210 +/- 0.120 mm unsigned / 0.020 +/- 0.030 mm signed for the vessel wall. In the comparison with IVUS, the luminal and vascular cross sectional areas were compared in 7 vessels; good correlation was shown for both the lumen (R=0.83) and the vessel wall (R=0.76). The plaque characterization algorithm correctly classified 92% of calcified plaques and 87% of non-calcified plaques.

  12. Detection of Human Brain Cancer Infiltration ex vivo and in vivo Using Quantitative Optical Coherence Tomography*

    PubMed Central

    Kut, Carmen; Chaichana, Kaisorn L.; Xi, Jiefeng; Raza, Shaan M.; Ye, Xiaobu; McVeigh, Elliot R.; Rodriguez, Fausto J.; Quinones-Hinojosa, Alfredo; Li, Xingde

    2015-01-01

    More complete brain cancer resection can prolong survival and delay recurrence. However, it is challenging to distinguish cancer from non-cancer tissues intraoperatively, especially at the transitional, infiltrative zones. This is especially critical in eloquent regions (e.g. speech and motor areas). This study tested the feasibility of label-free, quantitative optical coherence tomography (OCT) for differentiating cancer from non-cancer in human brain tissues. Fresh ex vivo human brain tissues were obtained from 32 patients with grades II-IV brain cancer and 5 patients with non-cancer brain pathologies. Based on volumetric OCT imaging data, pathologically confirmed brain cancer tissues (both high-grade and low-grade) had significantly lower optical attenuation values at both cancer core and infiltrated zones when compared with non-cancer white matter, and OCT achieved high sensitivity and specificity at an attenuation threshold of 5.5 mm-1 for brain cancer patients. We also used this attenuation threshold to confirm the intraoperative feasibility of performing in vivo OCT-guided surgery using a murine model harboring human brain cancer. Our OCT system was capable of processing and displaying a color-coded optical property map in real time at a rate of 110-215 frames per second, or 1.2-2.4 seconds for an 8-16 mm3 tissue volume, thus providing direct visual cues for cancer versus non-cancer areas. Our study demonstrates the translational and practical potential of OCT in differentiating cancer from non-cancer tissue. Its intraoperative use may facilitate safe and extensive resection of infiltrative brain cancers and consequently lead to improved outcomes when compared with current clinical standards. PMID:26084803

  13. Quantitative carbon ion beam radiography and tomography with a flat-panel detector.

    PubMed

    Telsemeyer, Julia; Jäkel, Oliver; Martišíková, Mária

    2012-12-07

    High dose gradients are inherent to ion beam therapy. This results in high sensitivity to discrepancies between planned and delivered dose distributions. Therefore an accurate knowledge of the ion stopping power of the traversed tissue is critical. One proposed method to ensure high quality dose deposition is to measure the stopping power by ion radiography. Although the idea of imaging with highly energetic ions is more than forty years old, there is a lack of simple detectors suitable for this purpose. In this study the performance of an amorphous silicon flat-panel detector, originally designed for photon imaging, was investigated for quantitative carbon ion radiography and tomography. The flat-panel detector was exploited to measure the water equivalent thickness (WET) and water equivalent path length (WEPL) of a phantom at the Heidelberg Ion-Beam Therapy Center (HIT). To do so, the ambiguous correlation of detector signal to particle energy was overcome by active or passive variation of carbon ion beam energy and measurement of the signal-to-beam energy correlation. The active method enables one to determine the WET of the imaged object with an uncertainty of 0.5 mm WET. For tomographic WEPL measurements the passive method was exploited resulting in an accuracy of 0.01 WEPL. The developed imaging technique presents a method to measure the two-dimensional maps of WET and WEPL of phantoms with a simple and commercially available detector. High spatial resolution of 0.8 × 0.8 mm(2) is given by the detector design. In the future this powerful tool will be used to evaluate the performance of the treatment planning algorithm by studying WET uncertainties.

  14. Quantitative monitoring of laser-treated engineered skin using optical coherence tomography.

    PubMed

    Ahn, Yujin; Lee, Chan-Young; Baek, Songyee; Kim, Taeho; Kim, Pilun; Lee, Sunghoon; Min, Daejin; Lee, Haekwang; Kim, Jeehyun; Jung, Woonggyu

    2016-03-01

    Nowadays, laser therapy is a common method for treating various dermatological troubles such as acne and wrinkles because of its efficient and immediate skin enhancement. Although laser treatment has become a routine procedure in medical and cosmetic fields, the prevention of side-effects, such as hyperpigmentation, redness and burning, still remains a critical issue that needs to be addressed. In order to reduce the side-effects while attaining efficient therapeutic outcomes, it is essential to understand the light-skin interaction through evaluation of physiological changes before and after laser therapy. In this study, we introduce a quantitative tissue monitoring method based on optical coherence tomography (OCT) for the evaluation of tissue regeneration after laser irradiation. To create a skin injury model, we applied a fractional CO2 laser on a customized engineered skin model, which is analogous to human skin in terms of its basic biological function and morphology. The irradiated region in the skin was then imaged by a high-speed OCT system, and its morphologic changes were analyzed by automatic segmentation software. Volumetric OCT images in the laser treated area clearly visualized the wound healing progress at different time points and provided comprehensive information which cannot be acquired through conventional monitoring methods. The results showed that the laser wound in engineered skins was mostly recovered from within 1~2 days with a fast recovery time in the vertical direction. However, the entire recovery period varied widely depending on laser doses and skin type. Our results also indicated that OCT-guided laser therapy would be a very promising protocol for optimizing laser treatment for skin therapy.

  15. Screening for osteoporosis after trauma: a new approach using quantitative computed tomography of the skull.

    PubMed

    Taylor, Amber; Waxman, Kenneth; Izfar, Seema; Grotts, Jonathan; Yim, Samantha

    2014-10-01

    The diagnosis of osteoporosis is important in the care of elderly patients at risk of trauma. While pelvis computed tomography (CT) is accurate in the measurement of bone mineral density, axial skull CT has not previously been evaluated for this purpose. This study investigated whether data from axial skull CT scans can screen for osteoporosis. Bone density measurements were derived from digital analysis of routine scans of the head and pelvis using quantitative CT. The study took place from October 2010 to November 2011 at a medium-sized community hospital. The first study phase included patients older than 18 years who had both a head and a pelvis CT scan within 30 days. The known diagnostic value for osteoporosis on pelvis CT scans was used to derive a diagnostic value for head CT. The second study phase included adult trauma patients who underwent noncontrast head CT during an initial trauma evaluation. A subgroup analysis was performed during Phase II on patients older than 65 years to identify the incidence of fracture as it is affected by age and bone mineral density. Our data demonstrated that head CT was able to identify osteoporosis with a sensitivity of 0.70, a specificity of 0.81, and an accuracy of 0.76 compared with pelvic CT. Of 261 trauma patients, 54% had bone disease based on axial skull CT criteria. Patients older than 65 years with a positive screen result for osteoporosis on head CT were twice as likely to have a fracture. Analysis of data from head CT scans has the potential to provide a useful screen for osteoporosis. Adding this analysis to CT scans performed for elderly trauma patients could result in improved diagnosis and treatment of osteoporosis. Diagnostic study, level II.

  16. Computational anatomy of the dens axis evaluated by quantitative computed tomography: Implications for anterior screw fixation.

    PubMed

    Gehweiler, Dominic; Wähnert, Dirk; Meier, Norbert; Spruit, Maarten; Raschke, Michael Johannes; Richards, Robert Geoff; Noser, Hansrudi; Kamer, Lukas

    2017-01-05

    The surgical fracture fixation of the odontoid process (dens) of the second cervical vertebra (C2/axis) is a challenging procedure, particularly in elderly patients affected by bone loss, and includes screw positioning close to vital structures. The aim of this study was to provide an extended anatomical knowledge of C2, the bone mass distribution and bone loss, and to understand the implications for anterior screw fixation. One hundred and twenty standard clinical quantitative computed tomography (QCT) scans of the intact cervical spine from 60 female and 60 male European patients, aged 18-90 years, were used to compute a three-dimensional statistical model and an averaged bone mass model of C2. Shape and size variability was assessed via principal component analysis (PCA), bone mass distribution by thresholding and via virtual core drilling, and the screw placement via virtual positioning of screw templates. Principal component analysis (PCA) revealed a highly variable anatomy of the dens with size as the predominant variation according to the first principal component (PC) whereas shape changes were primarily described by the remaining PCs. The bone mass distribution demonstrated a characteristic 3D pattern, and remained unchanged in the presence of bone loss. Virtual screw positioning of two 3.5 mm dens screws with a 1 mm safety zone was possible in 81.7% in a standard, parallel position and in additional 15.8% in a twisted position. The approach permitted a more detailed anatomical assessment of the dens axis. Combined with a preoperative QCT it may further improve the diagnostic procedure of odontoid fractures. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  17. Assessment of trabecular bone mineral density using quantitative computed tomography in normal cats.

    PubMed

    Cheon, Haengbok; Choi, Wooshin; Lee, Youngjae; Lee, Donghoon; Kim, Juhyung; Kang, Ji-Houn; Na, Kijeong; Chang, Jinhwa; Chang, Dongwoo

    2012-11-01

    The aim of this study was to assess age-related changes and anatomic variation in trabecular bone mineral density (tBMD) using quantitative computed tomography (QCT) in normal cats. Seventeen normal cats were included in this study and divided into the following 3 age groups:<6 months (n=4), 2-5 years (n=10) and >6 years (n=3). A computed tomographic scan of each vertebra from the 12th thoracic to the 7th lumbar spine and the pelvis was performed with a bone-density phantom (50, 100 and 150 mg/cm(3), calcium hydroxyapatite, CIRS phantom(®)). On the central transverse section, the elliptical region of interest (ROI) was drawn to measure the mean Hounsfield unit (HU) value. Those values were converted to equivalent tBMD (mg/cm(3)) by use of the bone-density phantom and linear regression analysis (r(2) >0.95). The mean tBMD value of the thoracic vertebrae (369.4 ± 31.8 mg/cm(3)) was significantly higher than that of the lumbar vertebrae (285 ± 58.1 mg/cm(3)). The maximum tBMD occurred at the T12, T13 and L1 levels in all age groups. There was a statistically significant difference in the mean tBMD value among the 3 age groups at the T12 (P<0.001), T13 (P<0.001) and L4 levels (P=0.013), respectively. The present study suggests that age-related changes and anatomic variation in tBMD values should be considered when assessing tBMD using QCT in cats with bone disorders.

  18. The measurement of liver fat from single-energy quantitative computed tomography scans.

    PubMed

    Cheng, Xiaoguang; Blake, Glen M; Brown, J Keenan; Guo, Zhe; Zhou, Jun; Wang, Fengzhe; Yang, Liqiang; Wang, Xiaohong; Xu, Li

    2017-06-01

    Studies of soft tissue composition using computed tomography (CT) scans are often semi-quantitative and based on Hounsfield units (HU) measurements that have not been calibrated with a quantitative CT (QCT) phantom. We describe a study to establish the water (H2O) and dipotassium hydrogen phosphate (K2HPO4) basis set equivalent densities of fat and fat-free liver tissue. With this information liver fat can be accurately measured from any abdominal CT scan calibrated with a suitable phantom. Liver fat content was measured by comparing single-energy QCT (SEQCT) HU measurements of the liver with predicted HU values for fat and fat-free liver tissue calculated from their H2O and K2HPO4 equivalent densities and calibration data from a QCT phantom. The equivalent densities of fat were derived from a listing of its constituent fatty acids, and those of fat-free liver tissue from a dual-energy QCT (DEQCT) study performed in 14 healthy Chinese subjects. This information was used to calculate liver fat from abdominal SEQCT scans performed in a further 541 healthy Chinese subjects (mean age 62 years; range, 31-95 years) enrolled in the Prospective Urban Rural Epidemiology (PURE) Study. The equivalent densities of fat were 941.75 mg/cm(3) H2O and -43.72 mg/cm(3) K2HPO4, and for fat-free liver tissue 1,040.13 mg/cm(3) H2O and 21.34 mg/cm(3) K2HPO4. Liver fat in the 14 subjects in the DEQCT study varied from 0-17.9% [median: 4.5%; interquartile range (IQR): 3.0-7.9%]. Liver fat in the 541 PURE study subjects varied from -0.3-29.9% (median: 4.9%; IQR: 3.4-6.9%). We have established H2O and K2HPO4 equivalent densities for fat and fat-free liver tissue that allow a measurement of liver fat to be obtained from any abdominal CT scan acquired with a QCT phantom. Although radiation dose considerations preclude the routine use of QCT to measure liver fat, the method described here facilitates its measurement in patients having CT scans performed for other purposes. Further studies

  19. Quantitative optical coherence tomography angiography of choroidal neovascularization in age-related macular degeneration

    PubMed Central

    Jia, Yali; Bailey, Steven T.; Wilson, David J.; Tan, Ou; Klein, Michael L.; Flaxel, Christina J.; Potsaid, Benjamin; Liu, Jonathan J.; Lu, Chen D.; Kraus, Martin F.; Fujimoto, James G.; Huang, David

    2014-01-01

    Purpose To detect and quantify choroidal neovascularization (CNV) in age-related macular degeneration (AMD) patients using optical coherence tomography (OCT) angiography. Design Observational, cross-sectional study. Participants Five normal subjects and five neovascular AMD patients were included. Methods Five eyes with neovascular AMD and five normal age-matched controls were scanned by a high-speed (100,000 A-scans/sec) 1050 nm wavelength swept-source OCT. The macular angiography scan covered a 3×3 mm area and comprised 200×200×8 A-scans acquired in 3.5 sec. Flow was detected using the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm. Motion artifacts were removed by three dimensional (3D) orthogonal registration and merging of 4 scans. The 3D angiography was segmented into 3 layers: inner retina (to show retinal vasculature), outer retina (to identify CNV), and choroid. En face maximum projection was used to obtain 2D angiograms from the 3 layers. CNV area and flow index were computed from the en face OCT angiogram of the outer retinal layer. Flow (decorrelation) and structural data were combined in composite color angiograms for both en face and cross-sectional views. Main Outcome Measurements CNV angiogram, CNV area, and CNV flow index. Results En face OCT angiograms of CNVs showed sizes and locations that were confirmed by fluorescein angiography. OCT angiography provided more distinct vascular network patterns that were less obscured by subretinal hemorrhage. The en face angiograms also showed areas of reduced choroidal flow adjacent to the CNV in all cases and significantly reduced retinal flow in one case. Cross-sectional angiograms were used to visualize CNV location relative to the retinal pigment epithelium and Bruch’s layer and classify type I and type II CNV. A feeder vessel could be identified in one case. Higher flow indexes were associated with larger CNV and type II CNV. Conclusions OCT angiography provides depth

  20. The measurement of liver fat from single-energy quantitative computed tomography scans

    PubMed Central

    Cheng, Xiaoguang; Brown, J. Keenan; Guo, Zhe; Zhou, Jun; Wang, Fengzhe; Yang, Liqiang; Wang, Xiaohong; Xu, Li

    2017-01-01

    Background Studies of soft tissue composition using computed tomography (CT) scans are often semi-quantitative and based on Hounsfield units (HU) measurements that have not been calibrated with a quantitative CT (QCT) phantom. We describe a study to establish the water (H2O) and dipotassium hydrogen phosphate (K2HPO4) basis set equivalent densities of fat and fat-free liver tissue. With this information liver fat can be accurately measured from any abdominal CT scan calibrated with a suitable phantom. Methods Liver fat content was measured by comparing single-energy QCT (SEQCT) HU measurements of the liver with predicted HU values for fat and fat-free liver tissue calculated from their H2O and K2HPO4 equivalent densities and calibration data from a QCT phantom. The equivalent densities of fat were derived from a listing of its constituent fatty acids, and those of fat-free liver tissue from a dual-energy QCT (DEQCT) study performed in 14 healthy Chinese subjects. This information was used to calculate liver fat from abdominal SEQCT scans performed in a further 541 healthy Chinese subjects (mean age 62 years; range, 31–95 years) enrolled in the Prospective Urban Rural Epidemiology (PURE) Study. Results The equivalent densities of fat were 941.75 mg/cm3 H2O and –43.72 mg/cm3 K2HPO4, and for fat-free liver tissue 1,040.13 mg/cm3 H2O and 21.34 mg/cm3 K2HPO4. Liver fat in the 14 subjects in the DEQCT study varied from 0–17.9% [median: 4.5%; interquartile range (IQR): 3.0–7.9%]. Liver fat in the 541 PURE study subjects varied from –0.3–29.9% (median: 4.9%; IQR: 3.4–6.9%). Conclusions We have established H2O and K2HPO4 equivalent densities for fat and fat-free liver tissue that allow a measurement of liver fat to be obtained from any abdominal CT scan acquired with a QCT phantom. Although radiation dose considerations preclude the routine use of QCT to measure liver fat, the method described here facilitates its measurement in patients having CT scans

  1. Quantitative assessment of scatter correction techniques incorporated in next generation dual-source computed tomography

    NASA Astrophysics Data System (ADS)

    Mobberley, Sean David

    Accurate, cross-scanner assessment of in-vivo air density used to quantitatively assess amount and distribution of emphysema in COPD subjects has remained elusive. Hounsfield units (HU) within tracheal air can be considerably more positive than -1000 HU. With the advent of new dual-source scanners which employ dedicated scatter correction techniques, it is of interest to evaluate how the quantitative measures of lung density compare between dual-source and single-source scan modes. This study has sought to characterize in-vivo and phantom-based air metrics using dual-energy computed tomography technology where the nature of the technology has required adjustments to scatter correction. Anesthetized ovine (N=6), swine (N=13: more human-like rib cage shape), lung phantom and a thoracic phantom were studied using a dual-source MDCT scanner (Siemens Definition Flash. Multiple dual-source dual-energy (DSDE) and single-source (SS) scans taken at different energy levels and scan settings were acquired for direct quantitative comparison. Density histograms were evaluated for the lung, tracheal, water and blood segments. Image data were obtained at 80, 100, 120, and 140 kVp in the SS mode (B35f kernel) and at 80, 100, 140, and 140-Sn (tin filtered) kVp in the DSDE mode (B35f and D30f kernels), in addition to variations in dose, rotation time, and pitch. To minimize the effect of cross-scatter, the phantom scans in the DSDE mode was obtained by reducing the tube current of one of the tubes to its minimum (near zero) value. When using image data obtained in the DSDE mode, the median HU values in the tracheal regions of all animals and the phantom were consistently closer to -1000 HU regardless of reconstruction kernel (chapters 3 and 4). Similarly, HU values of water and blood were consistently closer to their nominal values of 0 HU and 55 HU respectively. When using image data obtained in the SS mode the air CT numbers demonstrated a consistent positive shift of up to 35 HU

  2. Thermal tracer tomography: from numerical simulation to field implementation

    NASA Astrophysics Data System (ADS)

    Somogyvári, Márk; Brauchler, Ralf; Bayer, Peter

    2016-04-01

    Choosing heat for subsurface investigations is attractive because changes in temperature can be easily measured, and natural variations are typically slower than the timescale of the experiments. The tomographical setup expands the applicability of such tests to reconstruct the spatial distribution of hydraulic aquifer properties. A new inversion methodology is presented for thermal tracer tomography, using tracer travel times to invert the hydraulic conductivity distribution of the aquifer. If we can assume that heat transport is driven by advection, the travel time of the thermal tracer can be related to the hydraulic parameters of the aquifer. With this assumption other thermal effects such as thermal diffusion or density driven flow appear as noise in the results. To reduce these effects the early time diagnostics of the recorded breakthrough curves are used, focusing on the fastest transport routes between the sources and receivers. The inverse problem of the experiment thus can be formulated as a classical travel time problem, and it can be solved using standard eikonal solver algorithms known from seismic or hydraulic tomography. The method is demonstrated with a high resolution 3-D aquifer analog dataset. The generated 3-D reconstruction reveals the potential of the method, especially in finding the preferential flow paths within the aquifer. Aside from this, the developed method is computationally efficient and can provide results in a fragment of the time required for full-physics model calibration. The method is also tested under field conditions. Four heat tracer injections were performed during a three day field campaign at the Widen field site in northeast Switzerland. Pulse signals were used and the temperature evolution was measured downstream using a distributed measurement system. The preliminary results of the tomographic inversion correspond well with the findings of earlier studies from the field site imaging the same geological features as

  3. Illumination pattern optimization for fluorescence tomography: theory and simulation studies.

    PubMed

    Dutta, Joyita; Ahn, Sangtae; Joshi, Anand A; Leahy, Richard M

    2010-05-21

    Fluorescence molecular tomography is a powerful tool for 3D visualization of molecular targets and pathways in vivo in small animals. Owing to the high degrees of absorption and scattering of light through tissue, the fluorescence tomographic inverse problem is inherently ill-posed. In order to improve source localization and the conditioning of the light propagation model, multiple sets of data are acquired by illuminating the animal surface with different spatial patterns of near-infrared light. However, the choice of these patterns in most experimental setups is ad hoc and suboptimal. This paper presents a systematic approach for designing efficient illumination patterns for fluorescence tomography. Our objective here is to determine how to optimally illuminate the animal surface so as to maximize the information content in the acquired data. We achieve this by improving the conditioning of the Fisher information matrix. We parameterize the spatial illumination patterns and formulate our problem as a constrained optimization problem that, for a fixed number of illumination patterns, yields the optimal set of patterns. For geometric insight, we used our method to generate a set of three optimal patterns for an optically homogeneous, regular geometrical shape and observed expected symmetries in the result. We also generated a set of six optimal patterns for an optically homogeneous cuboidal phantom set up in the transillumination mode. Finally, we computed optimal illumination patterns for an optically inhomogeneous realistically shaped mouse atlas for different given numbers of patterns. The regularized pseudoinverse matrix, generated using the singular value decomposition, was employed to reconstruct the point spread function for each set of patterns in the presence of a sample fluorescent point source deep inside the mouse atlas. We have evaluated the performance of our method by examining the singular value spectra as well as plots of average spatial

  4. CLASSIFICATION AND QUANTITATIVE ANALYSIS OF GEOGRAPHIC ATROPHY JUNCTIONAL ZONE USING SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY.

    PubMed

    Qu, Jinfeng; Velaga, Swetha Bindu; Hariri, Amir H; Nittala, Muneeswar Gupta; Sadda, Srinivas

    2017-08-22

    The junctional zone at the border of areas of geographic atrophy (GA) in eyes with nonneovascular age-related macular degeneration is an important target region for future therapeutic strategies. The goal of this study was to perform a detailed classification and quantitative characterization of the junctional zone using spectral domain optical coherence tomography. Spectral domain optical coherence tomography volume cube scans (Spectralis OCT, 1024 × 37, Automatic Real Time > 9) were obtained from 15 eyes of 11 patients with GA because of nonneovascular age-related macular degeneration. Volume optical coherence tomography data were imported into previously described validated grading software (3D-OCTOR), and manual segmentation of the retinal pigment epithelium (RPE) and photoreceptor layers was performed on all B-scans (total of 555). Retinal pigment epithelium and photoreceptor defect maps were produced for each case. The borders of the photoreceptor defect area and RPE defect area were delineated individually on separate annotation layers. The two outlines were then superimposed to compare the areas of overlap and nonoverlap. The perimeter of the RPE defect area was calculated by the software in pixels. The superimposed outline of the photoreceptor defect area and the RPE defect area was scrutinized to classify the overlap configuration of the junctional zone into one of three categories: Type 0, exact correspondence between the edge of the RPE defect and photoreceptor defect; Type 1, loss of photoreceptors outside and beyond the edge of the RPE defect; Type 2, preservation of photoreceptors beyond the edge of the RPE defect. The relative proportion of the various border configurations was expressed as a percentage of the perimeter of the RPE defect. Each configuration was then classified into four subgroups according to irregularity of the RPE band and the presence of debris. Fifteen eyes of 11 patients (mean age: 79.3 ± 4.3 years; range: 79-94 years) were

  5. Quantitative strain analysis in analogue modelling experiments: insights from X-ray computed tomography and tomographic image correlation

    NASA Astrophysics Data System (ADS)

    Adam, J.; Klinkmueller, M.; Schreurs, G.; Wieneke, B.

    2009-04-01

    The combination of scaled analogue modelling experiments, advanced research in analogue material mechanics (Lohrmann et al. 2003, Panien et al. 2006), X-ray computed tomography and new high-resolution deformation monitoring techniques (2D/3D Digital Image Correlation) is a new powerful tool not only to examine the evolution and interaction of faulting in analogue models, but also to evaluate relevant controlling factors such as mechanics, sedimentation, erosion and climate. This is of particular interest for applied problems in the energy sector (e.g., structurally complex reservoirs, LG & CO2 underground storage) because the results are essential for geological and seismic interpretation as well as for more realistically constrained fault/fracture simulations and reservoir characterisation. X-ray computed tomography (CT) analysis has been successfully applied to analogue models since the late 1980s. This technique permits visualisation of the interior of an analogue model without destroying it. Technological improvements have resulted in more powerful X-ray CT scanners that allow periodic acquisition of volumetric data sets thus making it possible to follow the 3-D evolution of the model structures with time (e.g. Schreurs et al., 2002, 2003). Optical strain monitoring (Digital Image Correlation, DIC) in analogue experiments (Adam et al., 2005) represents an important advance in quantitative physical modelling and in helping to understand non-linear rock deformation processes. Optical non-intrusive 2D/3D strain and surface flow analysis by DIC is a new methodology in physical modelling that enables the complete quantification of localised and distributed model deformation. The increase in spatial/temporal strain data resolution of several orders of magnitude makes physical modelling - used for decades to visualize the kinematic processes of geological deformation processes - a unique research tool to determine what fundamental physical processes control tectonic

  6. Quantitative Assessment of Early [(18)F]Sodium Fluoride Positron Emission Tomography/Computed Tomography Response to Treatment in Men With Metastatic Prostate Cancer to Bone.

    PubMed

    Harmon, Stephanie A; Perk, Timothy; Lin, Christie; Eickhoff, Jens; Choyke, Peter L; Dahut, William L; Apolo, Andrea B; Humm, John L; Larson, Steven M; Morris, Michael J; Liu, Glenn; Jeraj, Robert

    2017-08-20

    Purpose [(18)F]Sodium fluoride (NaF) positron emission tomography (PET)/computed tomography (CT) is a promising radiotracer for quantitative assessment of bone metastases. This study assesses changes in early NaF PET/CT response measures in metastatic prostate cancer for correlation to clinical outcomes. Patients and Methods Fifty-six patients with metastatic castration-resistant prostate cancer (mCRPC) with osseous metastases had NaF PET/CT scans performed at baseline and after three cycles of chemotherapy (n = 16) or androgen receptor pathway inhibitors (n = 40). A novel technology, Quantitative Total Bone Imaging, was used for analysis. Global imaging metrics, including maximum standardized uptake value (SUVmax) and total functional burden (SUVtotal), were extracted from composite lesion-level statistics for each patient and tracked throughout treatment. Progression-free survival (PFS) was calculated as a composite end point of progressive events using conventional imaging and/or physician discretion of clinical benefit; NaF imaging was not used for clinical evaluation. Cox proportional hazards regression analyses were conducted between imaging metrics and PFS. Results Functional burden (SUVtotal) assessed midtreatment was the strongest univariable PFS predictor (hazard ratio, 1.97; 95% CI, 1.44 to 2.71; P < .001). Classification of patients based on changes in functional burden showed stronger correlation to PFS than did the change in number of lesions. Various global imaging metrics outperformed baseline clinical markers in predicting outcome, including SUVtotal and SUVmean. No differences in imaging response or PFS correlates were found for different treatment cohorts. Conclusion Quantitative total bone imaging enables comprehensive disease quantification on NaF PET/CT imaging, showing strong correlation to clinical outcomes. Total functional burden assessed after three cycles of hormonal therapy or chemotherapy was predictive of PFS for men with mCRPC. This

  7. Investigation of qualitative and quantitative factors related to radiological exposure to nursing staff during computed tomography examinations.

    PubMed

    Mori, Hiroshige; Koshida, Kichiro; Ishigamori, Osamu; Matsubara, Kosuke

    2014-11-01

    Radiologists or nurses intermittently stay in computed tomography rooms during computed tomography examinations; these actions are defined as “entrance actions.” The qualitative and quantitative factors related to radiological exposure to computed tomography nursing staff were investigated to identify the protective measures against entrance actions. A questionnaire survey was used to investigate the frequency, motives, and causalities of entrance actions. Individual and area monitoring were simultaneously performed. The mean frequency of entrance actions was 1.2 times mo(−1). The primary motive for entrance actions was to dispel anxieties regarding collateral accidents during computed tomography. The nursing staff particularly engaged in close supervision to help the patients cope with contrast media extravasation. The average personal dose equivalent [Hp(10)] to the nurses was 0.21 mSv mo(−1). The ambient dose equivalent [H*(10)] rate was 1.4–3.7 mSv min(−1) at a distance of 1 m from CT gantry centre. Avoidance of entrance actions and collateral accidents would decrease the occupational exposures to nurses.

  8. Monte Carlo simulation of optical coherence tomography for turbid media with arbitrary spatial distributions.

    PubMed

    Malektaji, Siavash; Lima, Ivan T; Sherif, Sherif S

    2014-04-01

    We developed a Monte Carlo-based simulator of optical coherence tomography (OCT) imaging for turbid media with arbitrary spatial distributions. This simulator allows computation of both Class I diffusive reflectance due to ballistic and quasiballistic scattered photons and Class II diffusive reflectance due to multiple scattered photons. It was implemented using a tetrahedron-based mesh and importance sampling to significantly reduce computational time. Our simulation results were verified by comparing them with results from two previously validated OCT simulators for multilayered media. We present simulation results for OCT imaging of a sphere inside a background slab, which would not have been possible with earlier simulators. We also discuss three important aspects of our simulator: (1) resolution, (2) accuracy, and (3) computation time. Our simulator could be used to study important OCT phenomena and to design OCT systems with improved performance.

  9. Quantitative micro-computed tomography: a non-invasive method to assess equivalent bone mineral density.

    PubMed

    Nazarian, Ara; Snyder, Brian D; Zurakowski, David; Müller, Ralph

    2008-08-01

    One of the many applications of micro computed tomography (microCT) is to accurately visualize and quantify cancellous bone microstructure. However, microCT based assessment of bone mineral density has yet to be thoroughly investigated. Specifically, the effects of varying imaging parameters, such as tube voltage (kVp), current (microA), integration time (ms), object to X-ray source distance (mm), projection number, detector array size and imaging media (surrounding the specimen), on the relationship between equivalent tissue density (rhoEQ) and its linear attenuation coefficient (micro) have received little attention. In this study, in house manufactured, hydrogen dipotassium phosphate liquid calibration phantoms (K2HPO4) were employed in addition to a resin embedded hydroxyapatite solid calibration phantoms supplied by Scanco Medical AG Company. Variations in current, integration time and projection number had no effect on the conversion relationship between micro and rhoEQ for the K2HPO4 and Scanco calibration phantoms [p>0.05 for all cases]. However, as expected, variations in scanning tube voltage, object to X-ray source distance, detector array size and imaging media (referring to the solution that surrounds the specimen in the imaging vial) significantly affected the conversion relationship between mu and rhoEQ for K2HPO4 and Scanco calibration phantoms [p<0.05 for all cases]. A multivariate linear regression approach was used to estimate rhoEQ based on attenuation coefficient, tube voltage, object to X-ray source distance, detector array size and imaging media for K2HPO4 liquid calibration phantoms, explaining 90% of the variation in rhoEQ. Furthermore, equivalent density values of bovine cortical bone (converted from attenuation coefficient to equivalent density using the K2HPO4 liquid calibration phantoms) samples highly correlated [R2=0.92] with the ash densities of the samples. In conclusion, Scanco calibration phantoms can be used to assess equivalent

  10. Automatic multi-parametric quantification of the proximal femur with quantitative computed tomography

    PubMed Central

    Bonaretti, Serena; Saeed, Isra; Harnish, Roy; Recker, Robert; Burghardt, Andrew J.; Keyak, Joyce H.; Harris, Tamara; Khosla, Sundeep; Lang, Thomas F.

    2015-01-01

    Background Quantitative computed tomography (QCT) imaging is the basis for multiple assessments of bone quality in the proximal femur, including volumetric bone mineral density (vBMD), tissue volume, estimation of bone strength using finite element modeling (FEM), cortical bone thickness, and computational-anatomy-based morphometry assessments. Methods Here, we present an automatic framework to perform a multi-parametric QCT quantification of the proximal femur. In this framework, the proximal femur is cropped from the bilateral hip scans, segmented using a multi-atlas based segmentation approach, and then assigned volumes of interest through the registration of a proximal femoral template. The proximal femur is then subjected to compartmental vBMD, compartmental tissue volume, FEM bone strength, compartmental surface-based cortical bone thickness, compartmental surface-based vBMD, local surface-based cortical bone thickness, and local surface-based cortical vBMD computations. Consequently, the template registrations together with vBMD and surface-based cortical bone parametric maps enable computational anatomy studies. The accuracy of the segmentation was validated against manual segmentations of 80 scans from two clinical facilities, while the multi-parametric reproducibility was evaluated using repeat scans with repositioning from 22 subjects obtained on CT imaging systems from two manufacturers. Results Accuracy results yielded a mean dice similarity coefficient of 0.976±0.006, and a modified Haussdorf distance of 0.219±0.071 mm. Reproducibility of QCT-derived parameters yielded root mean square coefficients of variation (CVRMS) between 0.89-1.66% for compartmental vBMD; 0.20-1.82% for compartmental tissue volume; 3.51-3.59% for FEM bone strength; 1.89-2.69% for compartmental surface-based cortical bone thickness; and 1.08-2.19% for compartmental surface-based cortical vBMD. For local surface-based assessments, mean CVRMS were between 3.45-3.91% and 2

  11. Does peripheral quantitative computed tomography ignore tissue density of cancellous bone?

    PubMed

    Banse, X; Devogelaer, J P

    2002-01-01

    The purpose of this work was to determine the capacity of peripheral quantitative computed tomography (pQCT) to accurately measure the true physical properties of vertebral cancellous bone samples and to predict their stiffness. pQCT bone mineral density (BMD) was first measured in ideal conditions. Ten cubic specimens of vertebral cancellous bone (10 x 10 x 10 mm) were washed with a water jet, defatted, and scanned in saline after elimination of air bubbles; thirteen slices were obtained. Seventy-one unprepared cylindrical samples were scanned in more realistic conditions, which allow further biomechanical testing. After extraction from the vertebral body, the samples were pushed into a plastic tube (no effort was made to remove the marrow or air bubbles), and only four slices were obtained to reduce the duration of scan. For the 81 samples, the true bone volume fraction (BV/TV, %), true apparent density (rho(app), g/cm(3)), and tissue density (rho(tiss), g/cm(3)) (an indicator of the degree of mineralization of the matrix) were then measured using Archimedes principle. rho(app) was closely correlated to BV/TV (r(2) = 0.97). rho(tiss) (1.58 +/- 0.08 g/cm(2)) was almost constant but had some influence on rho(app) (r(2) = 0.03, p < 0.001). The pQCT BMD predicted accurately rho(app) (r(2) = 0.96) and BV/TV (r(2) = 0.93) for the cylinders. For the cubes, in ideal conditions, the same correlations were even better (r(2) > 0.99, both). Analysis of covariance indicated no difference (p > 0.05) in the regressions due to preparation of the samples. The stiffness was better predicted by the true rho(app) (r(2) = 0.87) than by BV/TV (r(2) = 0.83), indicating that stiffness was influenced by small differences in the tissue density. Consequently, the correlation between pQCT BMD and stiffness was excellent (r(2) = 0.84). The fact that pQCT did not ignore this tissue density information compensated for the inaccuracies linked to realistic scanning conditions of the cylinder.

  12. Quantitative analysis of retinal perfusion in mice using optical coherence tomography angiography.

    PubMed

    Alnawaiseh, Maged; Brand, Cristin; Bormann, Eike; Wistuba, Joachim; Eter, Nicole; Heiduschka, Peter

    2017-09-07

    To evaluate repeatability of the quantitative analysis of vessel density in the retinas of healthy mice using optical coherence tomography angiography (OCT-A). Seventeen eyes of seventeen healthy mice aged 10-15 weeks (young) and 75-95 weeks (old) were included in this study. OCT-A was performed using RTVue XR Avanti (Optovue Inc., Fremont, California, USA) under general anaesthesia. The retina was imaged twice using a 3 × 3 mm(2) scan. Retinal thickness and flow density data in the superficial and deep retinal OCT angiograms were extracted and analysed. The differences between the flow density values (whole en face) in the first and second sessions were non-significant (superficial retinal OCT angiogram: first session: 45.4 ± 4.1% (39.1-55.3%); second session: 46.1 ± 4.7% (39.1-59.1%); p = 0.14; deep retinal OCT angiogram: first session: 47.1 ± 3.8% (39.4-53.4%); second session: 47.3 ± 3.7% (39.4-53.8%); p = 0.50). The repeatability assessment of retinal thickness yielded intraclass correlation coefficient (ICC) values ranging between (0.86-0.99) while the ICCs for the flow density measurements ranged from 0.87 to 0.92 for the superficial retinal OCT angiogram and 0.68 to 0.93 for the deep retinal OCT angiogram. Repeated OCT-A measurement of mice retinal vessel density (VD) revealed valid repeatability, indicating that this non-invasive technology is sufficient for longitudinal assessment of vascular changes in various mouse models and thereby opening the way to in-depth, experimental analysis of the vascular aspects of different retinal diseases and monitoring of disease progression and the effects of treatments. Copyright © 2017. Published by Elsevier Ltd.

  13. Reliability of clinically relevant 3D foot bone angles from quantitative computed tomography

    PubMed Central

    2013-01-01

    Background Surgical treatment and clinical management of foot pathology requires accurate, reliable assessment of foot deformities. Foot and ankle deformities are multi-planar and therefore difficult to quantify by standard radiographs. Three-dimensional (3D) imaging modalities have been used to define bone orientations using inertial axes based on bone shape, but these inertial axes can fail to mimic established bone angles used in orthopaedics and clinical biomechanics. To provide improved clinical relevance of 3D bone angles, we developed techniques to define bone axes using landmarks on quantitative computed tomography (QCT) bone surface meshes. We aimed to assess measurement precision of landmark-based, 3D bone-to-bone orientations of hind foot and lesser tarsal bones for expert raters and a template-based automated method. Methods Two raters completed two repetitions each for twenty feet (10 right, 10 left), placing anatomic landmarks on the surfaces of calcaneus, talus, cuboid, and navicular. Landmarks were also recorded using the automated, template-based method. For each method, 3D bone axes were computed from landmark positions, and Cardan sequences produced sagittal, frontal, and transverse plane angles of bone-to-bone orientations. Angular reliability was assessed using intraclass correlation coefficients (ICCs) and the root mean square standard deviation (RMS-SD) for intra-rater and inter-rater precision, and rater versus automated agreement. Results Intra- and inter-rater ICCs were generally high (≥ 0.80), and the ICCs for each rater compared to the automated method were similarly high. RMS-SD intra-rater precision ranged from 1.4 to 3.6° and 2.4 to 6.1°, respectively, for the two raters, which compares favorably to uni-planar radiographic precision. Greatest variability was in Navicular: Talus sagittal plane angle and Cuboid: Calcaneus frontal plane angle. Precision of the automated, atlas-based template method versus the raters was comparable to

  14. COMPARISON OF QUANTITATIVE COMPUTED TOMOGRAPHY-BASED MEASURES IN PREDICTING VERTEBRAL COMPRESSIVE STRENGTH

    PubMed Central

    Buckley, Jenni M.; Loo, Kenneth; Motherway, Julie

    2007-01-01

    Patient-specific measures derived from quantitative computed tomography (QCT) scans are currently being developed as a clinical tool for vertebral strength prediction. QCT-based measurement techniques vary greatly in structural complexity and generally fall into one of three categories: 1) bone mineral density (BMD), 2) “mechanics of solids” (MOS) models, such as minimum axial rigidity (the product of axial stiffness and vertebral height), or 3) three dimensional finite element (FE) models. There is no clear consensus as to the relative performance of these measures due to differences in experimental protocols, sample sizes and demographics, and outcome metrics. The goal of this study was to directly compare the performance of QCT-based assessment techniques of varying degrees of structural sophistication in predicting experimental vertebral compressive strength. Eighty-one human thoracic vertebrae (T6 – T10) from 44 donors cadavers (F = 32, M = 12; 85 + 8 y.o., max = 97 y.o., min = 54 y.o.) were QCT scanned and destructively tested in uniaxial compression. The QCT scans were processed to generate FE models and various BMD and MOS measures, including trabecular bone mineral density (tBMD), integral bone mineral density (iBMD), and axial rigidity. Bone mineral density was weakly to moderately predictive of compressive strength (R2 = 0.16 and 0.62 for tBMD and iBMD, respectively). Ex vivo vertebral strength was strongly correlated with both axial rigidity (R2 = 0.81) and FE strength measurements (R2 = 0.80), and the predictive capabilities of these two metrics were statistically equivalent (p > 0.05 for differences between FE and axial rigidity). The results of this study indicate that non-invasive predictive measures of vertebral strength should include some level of structural sophistication, specifically, gross geometric and material property distribution information. However, for uniaxial compression of isolated vertebrae, which is the current biomechanical

  15. Nanoparticles as contrast-enhancing agents in optical coherence tomography imaging of the structural components of skin: Quantitative evaluation

    SciTech Connect

    Kirillin, M Yu; Agrba, P D; Kamenskii, V A; Sirotkina, M A; Shiryamova, M V; Zagainova, E V

    2010-08-27

    This work examines the effect of gold nanoshells and titania nanoparticles on the imaging contrast of structural components of skin in optical coherence tomography (OCT). Experimental data are compared to Monte Carlo (MC) simulation results. In experiments with pig skin in vivo, the epidermis - dermis contrast is improved from 0.78 {+-} 0.03 to 0.92 {+-} 0.04 by gold nanoshells applied to the skin surface and from 0.78 {+-} 0.03 to 0.86 {+-} 0.04 by titania nanoparticles. The contrast of glands is enhanced by titania from 0.68 {+-} 0.12 to 0.84 {+-} 0.07. The highest contrast is reached 120 - 150 min after applying gold nanoshells and 160 - 200 min after applying titania. According to the MC simulation results, the contrast of inclusions increases from zero to 0.85 and 0.65, respectively. (optical tomography)

  16. The effects of iterative reconstruction and kernel selection on quantitative computed tomography measures of lung density.

    PubMed

    Rodriguez, Alfonso; Ranallo, Frank N; Judy, Philip F; Fain, Sean B

    2017-06-01

    To determine the effects of iterative reconstruction (IR) and high-frequency kernels on quantitative computed tomography (qCT) density measures at reduced X-ray dose. The COPDGene 2 Phantom (CTP 698, The Phantom Laboratory, Salem, NY) with four embedded lung mimicking foam densities (12lb, 20lb, and 4lb), as well as water, air, and acrylic reference inserts, was imaged using a GE 64 slice CT750 HD scanner in helical mode with four current-time products ranging from 12 to 100 mAs. The raw acquired data were reconstructed using standard (STD - low frequency) and Bone (high frequency) kernels with filtered back projection (FBP), 100% ASiR, and Veo reconstruction algorithms. The reference density inserts were manually segmented using Slicer3D (www.slicer.org), and the mean, standard deviation, and histograms of the segmented regions were generated using Fiji (http://fiji.sc/Fiji) for each reconstruction. Measurements of threshold values placed on the cumulative frequency distribution of voxels determined by these measured histograms at 5%, PD5phant , and 15%, PD15phant , (analogous to the relative area below -950 HU (RA-950) and percent density 15 (PD15) in human lung emphysema quantification, respectively), were also performed. The use of high-resolution kernels in conjunction with ASiR and Veo did not significantly affect the mean Hounsfield units (HU) of each of the density standards (< 4 HU deviation) and current-time products within the phantom when compared with the STD+FBP reconstruction conventionally used in clinical applications. A truncation of the scanner reported HU values at -1024 that shifts the mean toward more positive values was found to cause a systematic error in lower attenuating regions. Use of IR drove convergence toward the mean of measured histograms (~100-137% increase in the number measured voxels at the mean of the histogram), while the combination of Bone+ASiR preserved the standard deviation of HU values about the mean compared to STD

  17. Differentiating malignant from benign gastric mucosal lesions with quantitative analysis in dual energy spectral computed tomography

    PubMed Central

    Meng, Xiaoyan; Ni, Cheng; Shen, Yaqi; Hu, Xuemei; Chen, Xiao; Li, Zhen; Hu, Daoyu

    2017-01-01

    Abstract To investigate the value of quantitative analysis in dual energy spectral computed tomography (DESCT) for differentiating malignant gastric mucosal lesions from benign gastric mucosal lesions (including gastric inflammation [GI] and normal gastric mucosa [NGM]). This study was approved by the ethics committee, and all patients provided written informed consent. A total of 161 consecutive patients (63 with gastric cancer [GC], 48 with GI, and 50 with NGM) who underwent dual-phase contrast enhanced DESCT scans in the arterial phase (AP) and portal venous phase (PVP) were included in this study. Iodine concentration (IC) in lesions was derived from the iodine-based material-decomposition images and normalized to that in the aorta to obtain normalized IC (nIC). The ratios of IC and nIC between the AP and PVP were calculated. Diagnostic confidence for GC and GI was evaluated with reviewing the features including gastric wall thickness, focal, and eccentric on the conventional polychromatic images. All statistical analyses were performed by using statistical software SPSS 17.0 (SPSS, Chicago, IL). IC and nIC in GC differed significantly from those in GI and NGM, except for nICAP in comparing GC with GI. Mean nIC values of GC (0.18 ± 0.06 in AP and 0.62 ± 0.16 in PVP) were significantly higher than that of NGM (0.12 ± 0.03 in AP and 0.37 ± 0.08 in PVP) (all P < 0.05). There was also significant difference for IC values in GC, GI, and NGM (24.19 ± 8.27, 19.07 ± 5.82, and 13.61 ± 2.52 mg/mL, respectively, in AP and 28.00 ± 7.01, 24.66 ± 6.55, and 16.94 ± 3.06 mg/mL, respectively, in PVP). Based on Receiver Operating Characteristic Curve analysis, nIC and IC in PVP had high sensitivities of 88.89% and 90.48%, respectively, in differentiating GC from NGM, while the sensitivities were 71.43% and 88.89% during AP. Ratios IC and nIC ratios did not provide adequate diagnostic accuracy with their area under curves

  18. Integration of Quantitative Positron Emission Tomography Absolute Myocardial Blood Flow Measurements in the Clinical Management of Coronary Artery Disease.

    PubMed

    Gewirtz, Henry; Dilsizian, Vasken

    2016-05-31

    In the >40 years since planar myocardial imaging with(43)K-potassium was introduced into clinical research and management of patients with coronary artery disease (CAD), diagnosis and treatment have undergone profound scientific and technological changes. One such innovation is the current state-of-the-art hardware and software for positron emission tomography myocardial perfusion imaging, which has advanced it from a strictly research-oriented modality to a clinically valuable tool. This review traces the evolving role of quantitative positron emission tomography measurements of myocardial blood flow in the evaluation and management of patients with CAD. It presents methodology, currently or soon to be available, that offers a paradigm shift in CAD management. Heretofore, radionuclide myocardial perfusion imaging has been primarily qualitative or at best semiquantitative in nature, assessing regional perfusion in relative terms. Thus, unlike so many facets of modern cardiovascular practice and CAD management, which depend, for example, on absolute values of key parameters such as arterial and left ventricular pressures, serum lipoprotein, and other biomarker levels, the absolute levels of rest and maximal myocardial blood flow have yet to be incorporated into routine clinical practice even in most positron emission tomography centers where the potential to do so exists. Accordingly, this review focuses on potential value added for improving clinical CAD practice by measuring the absolute level of rest and maximal myocardial blood flow. Physiological principles and imaging fundamentals necessary to understand how positron emission tomography makes robust, quantitative measurements of myocardial blood flow possible are highlighted. © 2016 American Heart Association, Inc.

  19. Quantitative analysis of microscopic X-ray computed tomography imaging: Japanese quail embryonic soft tissues with iodine staining.

    PubMed

    Tahara, Rui; Larsson, Hans C E

    2013-09-01

    Rapid three-dimensional imaging of embryos to better understand the complex process of morphogenesis has been challenging. Recently introduced iodine staining protocols (I2 KI and alcoholic iodine stains) combined with microscopic X-ray computed tomography allows visualization of soft tissues in diverse small organisms and tissue specimens. I2 KI protocols have been developed specifically for small animals, with a limited number of quantitative studies of soft tissue contrasts. To take full advantage of the low X-ray attenuation of ethanol and retain bound iodine while dehydrating the specimen in ethanol, we developed an ethanol I2 KI protocol. We present comparative microscopic X-ray computed tomography analyses of ethanol I2 KI and I2 KI staining protocols to assess the performance of this new protocol to visualize soft tissue anatomy in late stage Japanese quail embryos using quantitative measurements of soft tissue contrasts and sample shrinkage. Both protocols had only 5% shrinkage compared with the original harvested specimen, supporting the use of whole mounts to minimize tissue shrinkage effects. Discrimination within and among the selected organs with each staining protocol and microscopic X-ray computed tomography imaging were comparable to those of a gray scale histological section. Tissue discrimination was assessed using calibrated computed tomography values and a new discrimination index to quantify the degree of computed tomography value overlaps between selected soft tissue regions. Tissue contrasts were dependent on the depth of the tissue within the embryos before the embryos were saturated with each stain solution, and optimal stain saturations for the entire embryo were achieved at 14 and 28 days staining for I2 KI and ethanol I2 KI, respectively. Ethanol I2 KI provided superior soft tissue contrasts by reducing overstaining of fluid-filled spaces and differentially modulating staining of some tissues, such as bronchial and esophageal walls and

  20. Quantitative analysis of microscopic X-ray computed tomography imaging: Japanese quail embryonic soft tissues with iodine staining

    PubMed Central

    Tahara, Rui; Larsson, Hans C E

    2013-01-01

    Rapid three-dimensional imaging of embryos to better understand the complex process of morphogenesis has been challenging. Recently introduced iodine staining protocols (I2KI and alcoholic iodine stains) combined with microscopic X-ray computed tomography allows visualization of soft tissues in diverse small organisms and tissue specimens. I2KI protocols have been developed specifically for small animals, with a limited number of quantitative studies of soft tissue contrasts. To take full advantage of the low X-ray attenuation of ethanol and retain bound iodine while dehydrating the specimen in ethanol, we developed an ethanol I2KI protocol. We present comparative microscopic X-ray computed tomography analyses of ethanol I2KI and I2KI staining protocols to assess the performance of this new protocol to visualize soft tissue anatomy in late stage Japanese quail embryos using quantitative measurements of soft tissue contrasts and sample shrinkage. Both protocols had only 5% shrinkage compared with the original harvested specimen, supporting the use of whole mounts to minimize tissue shrinkage effects. Discrimination within and among the selected organs with each staining protocol and microscopic X-ray computed tomography imaging were comparable to those of a gray scale histological section. Tissue discrimination was assessed using calibrated computed tomography values and a new discrimination index to quantify the degree of computed tomography value overlaps between selected soft tissue regions. Tissue contrasts were dependent on the depth of the tissue within the embryos before the embryos were saturated with each stain solution, and optimal stain saturations for the entire embryo were achieved at 14 and 28 days staining for I2KI and ethanol I2KI, respectively. Ethanol I2KI provided superior soft tissue contrasts by reducing overstaining of fluid-filled spaces and differentially modulating staining of some tissues, such as bronchial and esophageal walls and spinal

  1. Correlation of quantitative dual-energy computed tomography iodine maps and abdominal computed tomography perfusion measurements: are single-acquisition dual-energy computed tomography iodine maps more than a reduced-dose surrogate of conventional computed tomography perfusion?

    PubMed

    Stiller, Wolfram; Skornitzke, Stephan; Fritz, Franziska; Klauss, Miriam; Hansen, Jens; Pahn, Gregor; Grenacher, Lars; Kauczor, Hans-Ulrich

    2015-10-01

    Study objectives were the quantitative evaluation of whether conventional abdominal computed tomography (CT) perfusion measurements mathematically correlate with quantitative single-acquisition dual-energy CT (DECT) iodine concentration maps, the determination of the optimum time of acquisition for achieving maximum correlation, and the estimation of the potential for radiation exposure reduction when replacing conventional CT perfusion by single-acquisition DECT iodine concentration maps. Dual-energy CT perfusion sequences were dynamically acquired over 51 seconds (34 acquisitions every 1.5 seconds) in 24 patients with histologically verified pancreatic carcinoma using dual-source DECT at tube potentials of 80 kVp and 140 kVp. Using software developed in-house, perfusion maps were calculated from 80-kVp image series using the maximum slope model after deformable motion correction. In addition, quantitative iodine maps were calculated for each of the 34 DECT acquisitions per patient. Within a manual segmentation of the pancreas, voxel-by-voxel correlation between the perfusion map and each of the iodine maps was calculated for each patient to determine the optimum time of acquisition topt defined as the acquisition time of the iodine map with the highest correlation coefficient. Subsequently, regions of interest were placed inside the tumor and inside healthy pancreatic tissue, and correlation between mean perfusion values and mean iodine concentrations within these regions of interest at topt was calculated for the patient sample. The mean (SD) topt was 31.7 (5.4) seconds after the start of contrast agent injection. The mean (SD) perfusion values for healthy pancreatic and tumor tissues were 67.8 (26.7) mL per 100 mL/min and 43.7 (32.2) mL per 100 mL/min, respectively. At topt, the mean (SD) iodine concentrations were 2.07 (0.71) mg/mL in healthy pancreatic and 1.69 (0.98) mg/mL in tumor tissue, respectively. Overall, the correlation between perfusion values and

  2. OPTICAL TOMOGRAPHY: Nanoparticles as contrast-enhancing agents in optical coherence tomography imaging of the structural components of skin: Quantitative evaluation

    NASA Astrophysics Data System (ADS)

    Kirillin, M. Yu; Agrba, P. D.; Sirotkina, M. A.; Shiryamova, M. V.; Zagainova, E. V.; Kamenskii, V. A.

    2010-08-01

    This work examines the effect of gold nanoshells and titania nanoparticles on the imaging contrast of structural components of skin in optical coherence tomography (OCT). Experimental data are compared to Monte Carlo (MC) simulation results. In experiments with pig skin in vivo, the epidermis — dermis contrast is improved from 0.78 ± 0.03 to 0.92 ± 0.04 by gold nanoshells applied to the skin surface and from 0.78 ± 0.03 to 0.86 ± 0.04 by titania nanoparticles. The contrast of glands is enhanced by titania from 0.68 ± 0.12 to 0.84 ± 0.07. The highest contrast is reached 120 — 150 min after applying gold nanoshells and 160 — 200 min after applying titania. According to the MC simulation results, the contrast of inclusions increases from zero to 0.85 and 0.65, respectively.

  3. Simulations of acoustic tomography using a particle filter

    NASA Astrophysics Data System (ADS)

    Zhang, Ming; Xu, Wen; Li, Jianlong

    2012-11-01

    This paper uses the state-space model to track the sound speed profile between a moving source suspended from a ship and a fixed vertical linear array. The particle filtering approach is presented to handle this nonlinear and non-Gaussian inverse problem. Simulation results show that the particle filter with a high particle number outperforms the extended Kalman filter; however, the performance degrades when the dimension of the state increases.

  4. Simulation study on compressive laminar optical tomography for cardiac action potential propagation.

    PubMed

    Harada, Takumi; Tomii, Naoki; Manago, Shota; Kobayashi, Etsuko; Sakuma, Ichiro

    2017-04-01

    To measure the activity of tissue at the microscopic level, laminar optical tomography (LOT), which is a microscopic form of diffuse optical tomography, has been developed. However, obtaining sufficient recording speed to determine rapidly changing dynamic activity remains major challenges. For a high frame rate of the reconstructed data, we here propose a new LOT method using compressed sensing theory, called compressive laminar optical tomography (CLOT), in which novel digital micromirror device-based illumination and data reduction in a single reconstruction are applied. In the simulation experiments, the reconstructed volumetric images of the action potentials that were acquired from 5 measured images with random pattern featured a wave border at least to a depth of 2.5 mm. Consequently, it was shown that CLOT has potential for over 200 fps required for the cardiac electrophysiological phenomena.

  5. 3D quantitative analysis of graphite morphology in high strength cast iron by high-energy x-ray tomography

    SciTech Connect

    Chuang, Chih-Pin; Singh, Dileep; Kenesei, Peter; Almer, Jonathan; Hryn, John N.; Huff, Richard

    2015-09-01

    The size and morphology of the graphite particles play a crucial role in determining various mechanical and thermal properties of cast iron. In the present study, we utilized high-energy synchrotron X-ray tomography to perform quantitative 3D-characterization of the distribution of graphite particles in high-strength compacted graphite iron (CGI). The size, shape, and spatial connectivity of graphite were examined. The analysis reveals that the compacted graphite can grow with a coral-tree-like morphology and span several hundred microns in the iron matrix.

  6. A realistic computed tomography simulator for small motion analysis of cerebral aneurysms.

    PubMed

    Sepehri, Shima; Zouaoui, Karim; Thiran, Jean-Philippe

    2013-01-01

    This paper describes a realistic simulator for the Computed Tomography (CT) scan process for motion analysis. In fact, we are currently developing a new framework to find small motion from the CT scan. In order to prove the fidelity of this framework, or potentially any other algorithm, we present in this paper a simulator to simulate the whole CT acquisition process with a priori known parameters. In other words, it is a digital phantom for the motion analysis that can be used to compare the results of any related algorithm with the ground-truth realistic analytical model. Such a simulator can be used by the community to test different algorithms in the biomedical imaging domain. The most important features of this simulator are its different considerations to simulate the best the real acquisition process and its generality.

  7. Quantitative, Three-dimensional Analysis of the Global Corona with Multi-spacecraft Differential Emission Measure Tomography

    NASA Astrophysics Data System (ADS)

    Frazin, Richard A.; Vásquez, Alberto M.; Kamalabadi, Farzad

    2009-08-01

    A previous paper (Frazin et al. 2005b) introduced the concept of differential emission measure tomography (DEMT), which is a three-dimensional (3D) extension of the classical differential emission measure technique for determining the distribution of temperatures in a volume of plasma. The information for the reconstruction in the three spatial dimensions is provided by solar rotation and/or multi-spacecraft views. This paper describes, quantitatively, the procedure for implementing DEMT with data from NASA's STEREO/EUVI instrument, including the radiometry, line-of-sight geometry, and image preparation steps. An example of a quantitative, multiband, 3D reconstruction and local differential emission measure curves are given, and it is demonstrated that, when applicable, DEMT is a simple 3D analysis tool that obviates the need for structure-specific modeling.

  8. TU-F-CAMPUS-J-05: Effect of Uncorrelated Noise Texture On Computed Tomography Quantitative Image Features

    SciTech Connect

    Oliver, J; Budzevich, M; Moros, E; Zhang, G; Hunt, D

    2015-06-15

    Purpose: To investigate the relationship between quantitative image features (i.e. radiomics) and statistical fluctuations (i.e. electronic noise) in clinical Computed Tomography (CT) using the standardized American College of Radiology (ACR) CT accreditation phantom and patient images. Methods: Three levels of uncorrelated Gaussian noise were added to CT images of phantom and patients (20) acquired in static mode and respiratory tracking mode. We calculated the noise-power spectrum (NPS) of the original CT images of the phantom, and of the phantom images with added Gaussian noise with means of 50, 80, and 120 HU. Concurrently, on patient images (original and noise-added images), image features were calculated: 14 shape, 19 intensity (1st order statistics from intensity volume histograms), 18 GLCM features (2nd order statistics from grey level co-occurrence matrices) and 11 RLM features (2nd order statistics from run-length matrices). These features provide the underlying structural information of the images. GLCM (size 128x128) was calculated with a step size of 1 voxel in 13 directions and averaged. RLM feature calculation was performed in 13 directions with grey levels binning into 128 levels. Results: Adding the electronic noise to the images modified the quality of the NPS, shifting the noise from mostly correlated to mostly uncorrelated voxels. The dramatic increase in noise texture did not affect image structure/contours significantly for patient images. However, it did affect the image features and textures significantly as demonstrated by GLCM differences. Conclusion: Image features are sensitive to acquisition factors (simulated by adding uncorrelated Gaussian noise). We speculate that image features will be more difficult to detect in the presence of electronic noise (an uncorrelated noise contributor) or, for that matter, any other highly correlated image noise. This work focuses on the effect of electronic, uncorrelated, noise and future work shall

  9. Automated quantification of three-dimensional subject motion to monitor image quality in high-resolution peripheral quantitative computed tomography

    NASA Astrophysics Data System (ADS)

    Pauchard, Yves; Ayres, Fábio J.; Boyd, Steven K.

    2011-10-01

    Subject motion during acquisition of high-resolution peripheral quantitative computed tomography (HR-pQCT) results in image artifacts and interferes with quantification of bone architecture used to study bone-related diseases such as osteoporosis. We propose an automatic method to measure physical subject motion that frequently takes place during acquisition. Three measures derived from projection data are proposed to quantify motion artifacts: in-plane translation (εT) and in-plane rotation (εR) utilizing projection moments and longitudinal translation (εz) based on tracking projection profiles. Validation was performed using a phantom containing sections of distal human cadaver radii attached to a mechanical device to precisely control in-plane rotation and longitudinal translation that was intentionally performed during HR-pQCT data acquisition. Motion measured by the new automated technique was compared to the known applied motion, and related to percent errors in morphological parameters quantifying bone properties. It was determined that of the three proposed measures, εT best captured a quantified representation of image quality. εT linearly relates to true physical in-plane translational motion (r2 = 0.95, p<0.001) and is independent from longitudinal translational motion as well as the object being scanned. Additionally, εz captures large longitudinal movements and combines well with εT to fully characterize physical motion artifacts. The magnitude of εT corresponds to morphological parameter error and is an excellent basis to select high-quality images. Morphological parameter errors from these experiments confirmed our earlier computer simulations which showed that increased subject motion resulted in artificially higher trabecular number, and artificially lower bone mineral density and cortical thickness. The magnitude and, notably, the uncertainty of the morphological errors increased with increased physical motion, and this impedes a direct

  10. Neutron Radiography and Tomography Investigations of the Secondary Hydriding of Zircaloy-4 during Simulated Loss of Coolant Nuclear Accidents

    NASA Astrophysics Data System (ADS)

    Grosse, Mirco K.; Stuckert, Juri; Steinbrück, Martin; Kaestner, Anders P.; Hartmann, Stefan

    In the framework of the post-test examinations of the large-scale LOCA simulation tests at the fuel rod bundle scale, the hydrogen distributions in specimens prepared from the QUENCH-L0 and -L1 tests were studied by means of neutron radiography and tomography. In order to determine quantitative hydrogen concentrations, both, neutron radiography and tomography were calibrated using cladding tube segments with known hydrogen concentrations. The linear dependence of the total macroscopic neutron cross section with the H/Zr atomic ratio was determined for both methods. The hydrogen distributions in samples prepared from the two tests differ significantly as a first glance to the results obtained for the QUENCH-L1 shows. Whereas clearly visible hydrogen bands were found in samples of the QUENCH-L0 test with a time between burst and quenching of more than 70 s; in some specimens prepared from the QUENCH-L1 test only blurred bands could be detected. The reasons for these different behaviors can be the different times between reaching the temperature maxima and the quenching, as well as bending of the QUENCH-L1 bundle. In the QUENCH-L0 test the bundle was quenched immediately after reaching the maximal temperature. In QUENCH-L1 the hydrogen had about 130 s to diffuse and reach more homogeneous distributions without clear contrasts between the hydrogen bands and the neighboring regions in the neutron images.

  11. [Quantitative cartilage analysis with magnetic resonance tomography (qMRI)--a new era in arthrosis diagnosis?].

    PubMed

    Eckstein, F; Englmeier, K H; Reiser, M

    2002-06-01

    Magnetic resonance imaging (MRI) is a new and very powerful method for the diagnostics and monitoring of osteoarthritis. Its advantage is that all articular tissues can be visualized directly and are accessible for three-dimensional analysis. This article reviews qualitative, semi-quantitative, and quantitative studies on articular cartilage with MRI. In particular we discuss pulse sequences and three-dimensional postprocessing methods for quantitative analysis of cartilage volume and thickness, along with their accuracy and precision in healthy volunteers and patients with osteoarthritis. It addition, we present approaches for quantitative analyses of structural/biochemical parameters and for the deformational behavior of cartilage in vivo.

  12. Quantitative Assessment of Anterior Segment Inflammation in a Rat Model of Uveitis Using Spectral-Domain Optical Coherence Tomography

    PubMed Central

    Pepple, Kathryn L.; Choi, Woo June; Wilson, Leslie; Van Gelder, Russell N.; Wang, Ruikang K.

    2016-01-01

    Purpose To develop anterior segment spectral-domain optical coherence tomography (SD-OCT) and quantitative image analysis for use in experimental uveitis in rats. Methods Acute anterior uveitis was generated in Lewis rats. A spectral domain anterior segment OCT system was used to image the anterior chamber (AC) and ciliary body at baseline and during peak inflammation 2 days later. Customized MatLab image analysis algorithms were developed to segment the AC, count AC cells, calculate central corneal thickness (CCT), segment the ciliary body and zonules, and quantify the level of ciliary body inflammation with the ciliary body index (CBI). Images obtained at baseline and during peak inflammation were compared. Finally, longitudinal imaging and image analysis was performed over the 2-week course of inflammation. Results Spectral-domain optical coherence tomography identifies structural features of inflammation. Anterior chamber cell counts at peak inflammation obtained by automated image analysis and human grading were highly correlated (r = 0.961), and correlated well with the histologic score of inflammation (r = 0.895). Inflamed eyes showed a significant increase in average CCT (27 μm, P = 0.02) and an increase in average CBI (P < 0.0001). Longitudinal imaging and quantitative image analysis identified a significant change in AC cell and CBI on day 2 with spontaneous resolution of inflammation by day 14. Conclusions Spectral-domain optical coherence tomography provides high-resolution images of the structural changes associated with anterior uveitis in rats. Anterior chamber cell count and CBI determined by semi-automated image analysis strongly correlates with inflammation, and can be used to quantify inflammation longitudinally in single animals. PMID:27388049

  13. Effects of optical beam angle on quantitative optical coherence tomography (OCT) in normal and surface degenerated bovine articular cartilage

    NASA Astrophysics Data System (ADS)

    Huang, Yan-Ping; Saarakkala, Simo; Toyras, Juha; Wang, Li-Ke; Jurvelin, Jukka S.; Zheng, Yong-Ping

    2011-01-01

    Quantitative measurement of articular cartilage using optical coherence tomography (OCT) is a potential approach for diagnosing the early degeneration of cartilage and assessing the quality of its repair. However, a non-perpendicular angle of the incident optical beam with respect to the tissue surface may cause uncertainty to the quantitative analysis, and therefore, significantly affect the reliability of measurement. This non-perpendicularity was systematically investigated in the current study using bovine articular cartilage with and without mechanical degradation. Ten fresh osteochondral disks were quantitatively measured before and after artificially induced surface degradation by mechanical grinding. The following quantitative OCT parameters were determined with a precise control of the surface inclination up to an angle of 10° using a step of 2°: optical reflection coefficient (ORC), variation of surface reflection (VSR) along the surface profile, optical roughness index (ORI) and optical backscattering (OBS). It was found that non-perpendicularity caused systematic changes to all of the parameters. ORC was the most sensitive and OBS the most insensitive to the inclination angle. At the optimal perpendicular angle, all parameters could detect significant changes after surface degradation (p < 0.01), except OBS (p > 0.05). Nonsignificant change of OBS after surface degradation was expected since OBS reflected properties of the internal cartilage tissue and was not affected by the superficial mechanical degradation. As a conclusion, quantitative OCT parameters are diagnostically potential for characterizing the cartilage degeneration. However, efforts through a better controlled operation or corrections based on computational compensation mechanism should be made to minimize the effects of non-perpendicularity of the incident optical beam when clinical use of quantitative OCT is considered for assessing the articular cartilage.

  14. Toward standardized quantitative image quality (IQ) assessment in computed tomography (CT): A comprehensive framework for automated and comparative IQ analysis based on ICRU Report 87.

    PubMed

    Pahn, Gregor; Skornitzke, Stephan; Schlemmer, Hans-Peter; Kauczor, Hans-Ulrich; Stiller, Wolfram

    2016-01-01

    Based on the guidelines from "Report 87: Radiation Dose and Image-quality Assessment in Computed Tomography" of the International Commission on Radiation Units and Measurements (ICRU), a software framework for automated quantitative image quality analysis was developed and its usability for a variety of scientific questions demonstrated. The extendable framework currently implements the calculation of the recommended Fourier image quality (IQ) metrics modulation transfer function (MTF) and noise-power spectrum (NPS), and additional IQ quantities such as noise magnitude, CT number accuracy, uniformity across the field-of-view, contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) of simulated lesions for a commercially available cone-beam phantom. Sample image data were acquired with different scan and reconstruction settings on CT systems from different manufacturers. Spatial resolution is analyzed in terms of edge-spread function, line-spread-function, and MTF. 3D NPS is calculated according to ICRU Report 87, and condensed to 2D and radially averaged 1D representations. Noise magnitude, CT numbers, and uniformity of these quantities are assessed on large samples of ROIs. Low-contrast resolution (CNR, SNR) is quantitatively evaluated as a function of lesion contrast and diameter. Simultaneous automated processing of several image datasets allows for straightforward comparative assessment. The presented framework enables systematic, reproducible, automated and time-efficient quantitative IQ analysis. Consistent application of the ICRU guidelines facilitates standardization of quantitative assessment not only for routine quality assurance, but for a number of research questions, e.g. the comparison of different scanner models or acquisition protocols, and the evaluation of new technology or reconstruction methods. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  15. [Investigation of vessel visibility in the iterative reconstruction method in coronary computed tomography angiography using simulated vessel phantom].

    PubMed

    Inoue, Takeshi; Ichikawa, Katsuhiro; Hara, Takanori; Urikura, Atsushi; Hoshino, Takashi; Miura, Youhei; Terakawa, Syouichi; Uto, Fumiaki

    2012-01-01

    Iterative reconstruction methods can reduce the noise of computed tomography (CT) images, which are expected to contribute to the reduction of patient dose CT examinations. The purpose of this study was to investigate impact of an iterative reconstruction method (iDose(4), Philips Healthcare) on vessel visibility in coronary CT angiography (CTA) by using phantom studies. A simulated phantom was scanned by a CT system (iCT, Philips Healthcare), and the axial images were reconstructed by filtered back projection (FBP) and given a level of 1 to 7 (L1-L7) of the iterative reconstruction (IR). The vessel visibility was evaluated by a quantitative analysis using profiles across a 1.5-mm diameter simulated vessel as well as visual evaluation for multi planar reformation (MPR) images and volume rendering (VR) images in terms of the normalized-rank method with analysis of variance. The peak CT value of the profiles decreased with IR level and full width at half maximum of the profile also decreased with the IR level. For normalized-rank method, there was no statistical difference between FBP and L1 (20% dose reduction) for both MPR and VR images. The IR levels higher than L1 sacrificed the spatial resolution for the 1.5-mm simulated vessel, and their visual vessel visibilities were significantly inferior to that of the FBP.

  16. Simulation of polarization-sensitive optical coherence tomography images by a Monte Carlo method.

    PubMed

    Meglinski, Igor; Kirillin, Mikhail; Kuzmin, Vladimir; Myllylä, Risto

    2008-07-15

    We introduce a new Monte Carlo (MC) method for simulating optical coherence tomography (OCT) images of complex multilayered turbid scattering media. We demonstrate, for the first time of our knowledge, the use of a MC technique to imitate two-dimensional polarization-sensitive OCT images with nonplanar boundaries of layers in the medium like a human skin. The simulation of polarized low-coherent optical radiation is based on the vector approach generalized from the iterative procedure of the solution of Bethe-Saltpeter equation. The performances of the developed method are demonstrated both for conventional and polarization-sensitive OCT modalities.

  17. Quantitative exercise thallium-201 single photon emission computed tomography for the enhanced diagnosis of ischemic heart disease

    SciTech Connect

    Mahmarian, J.J.; Boyce, T.M.; Goldberg, R.K.; Cocanougher, M.K.; Roberts, R.; Verani, M.S. )

    1990-02-01

    The clinical utility of exercise thallium-201 single photon emission computed tomography was investigated in 360 consecutive patients who had concomitant coronary arteriography. Tomographic images were assessed visually and from computer-quantified polar maps. Sensitivity for detecting coronary artery disease was comparably high using quantitative and visual analysis, although specificity tended to improve using the former method (87% versus 76%, p = 0.09). Quantitative analysis was superior to the visual method for identifying left anterior descending (81% versus 68%, p less than 0.05) and circumflex coronary artery (77% versus 60%, p less than 0.05) stenoses and detected most patients (92%) with multivessel coronary artery disease. Multivessel involvement was correctly predicted in 65% of the patients with more than one critically stenosed vessel. Exercise variables in patients with significant coronary artery disease were similar whether the tomographic images were normal or abnormal. However, patients with coronary stenoses and normal versus abnormal tomograms had a trend toward more single vessel disease (79% versus 62%, p = 0.07) and moderate coronary stenosis (66% versus 28%, p less than 0.001), but had less proximal left anterior descending artery involvement (8% versus 34%, p = 0.05). Computer-quantified perfusion defect size was directly related to the extent of coronary artery disease. Intra- and interobserver agreement for quantifying defects were excellent (r = 0.98 and 0.97, respectively). In conclusion, quantitative thallium-201 tomography offers improved detection of coronary artery disease, localization of the anatomic site of coronary stenosis, prediction of multivessel involvement and accurate determination of perfusion defect size, while maintaining a high specificity.

  18. Quantitative computed tomographic indexes in diffuse interstitial lung disease: correlation with physiologic tests and computed tomography visual scores.

    PubMed

    Shin, Kyung Eun; Chung, Myung Jin; Jung, Man Pyo; Choe, Bong Keun; Lee, Kyung Soo

    2011-01-01

    To assess the correlation among quantitative indexes of computed tomography (CT), spirometric pulmonary function tests (PFTs), and visual scores (VSs) of CT in patients with diffuse interstitial lung disease (DILD) and to prove the estimated value of CT quantification for the prediction of the possibility of pulmonary function impairment. A total of 157 patients (male to female ratio, 96:61; mean age, 63 ± 11 years) with DILD were enrolled in this study. All patients underwent volume thin-section CT in the supine position at full inspiration. During the same period, 23 people (male to female ratio, 10:13; mean age, 55 ± 13 years) with no history of DILD and with normal PFTs and CT findings were used as a control group. Quantitative indexes were obtained using a commercial CAD system (Brilliance Workspace v3.0; Philips Medical Systems). Quantitative indexes included total lung volume (TLV), mean lung attenuation, variation of lung attenuation, emphysema volume (<-950 Hounsfield units [HU]), functioning lung volume (-700 HU > pixel > -950 HU), and interstitial lung disease volume (>-700 HU). Visual scores were measured semiquantitatively and included the overall extent of pulmonary parenchymal abnormality as well as the extent of consolidation, ground glass opacity, reticulation, and honeycomb opacities. Quantitative indexes were correlated with PFT and VSs using the Pearson correlation test. Quantitative indexes, PFT results, and VSs differed significantly between the DILD group and the control group, except for emphysematous parameters (P < 0.05).Pulmonary function test results showed significant correlation with quantitative indexes in the DILD group. Functioning lung volume showed positive correlation with forced vital capacity and forced expiratory volume in 1 second (r = 0.80 and 0.73, P < 0.001). Total lung capacity showed positive correlation with TLV (r = 0.83, P < 0.001).Visual scores were correlated with the ratio of a specific volume to TLV (indicated

  19. Simulation of a fast diffuse optical tomography system based on radiative transfer equation

    NASA Astrophysics Data System (ADS)

    Motevalli, S. M.; Payani, A.

    2016-12-01

    Studies show that near-infrared (NIR) light (light with wavelength between 700nm and 1300nm) undergoes two interactions, absorption and scattering, when it penetrates a tissue. Since scattering is the predominant interaction, the calculation of light distribution in the tissue and the image reconstruction of absorption and scattering coefficients are very complicated. Some analytical and numerical methods, such as radiative transport equation and Monte Carlo method, have been used for the simulation of light penetration in tissue. Recently, some investigators in the world have tried to develop a diffuse optical tomography system. In these systems, NIR light penetrates the tissue and passes through the tissue. Then, light exiting the tissue is measured by NIR detectors placed around the tissue. These data are collected from all the detectors and transferred to the computational parts (including hardware and software), which make a cross-sectional image of the tissue after performing some computational processes. In this paper, the results of the simulation of an optical diffuse tomography system are presented. This simulation involves two stages: a) Simulation of the forward problem (or light penetration in the tissue), which is performed by solving the diffusion approximation equation in the stationary state using FEM. b) Simulation of the inverse problem (or image reconstruction), which is performed by the optimization algorithm called Broyden quasi-Newton. This method of image reconstruction is faster compared to the other Newton-based optimization algorithms, such as the Levenberg-Marquardt one.

  20. Quantitative Evaluation of the Natural Progression of Keratoconus Using Three-Dimensional Optical Coherence Tomography.

    PubMed

    Fujimoto, Hisataka; Maeda, Naoyuki; Shintani, Ayumi; Nakagawa, Tomoya; Fuchihata, Mutsumi; Higashiura, Ritsuko; Nishida, Kohji

    2016-07-01

    We quantified the chronologic progression of keratoconus using anterior segment optical coherence tomography (AS-OCT). A total of 217 eyes from 113 patients with keratoconus, keratoconus suspect, or forme fruste keratoconus were evaluated by corneal tomography using swept-source OCT. Age-dependent changes in the radius of the posterior best-fit sphere (Rpost), minimum corneal thickness (Tmin), and distance from the thinnest point to the corneal vertex (Dmin) were examined over follow-up periods of up to 5.79 years and were analyzed using generalized estimating equation (GEE) nonlinear regression model. Annual changes in Rpost (mean, -0.017 mm) and Tmin (-2.69 μm) were significantly higher in younger patients (P < 0.01, GEE nonlinear regression) and in patients with higher maximal K value (Kmax; P < 0.01, GEE nonlinear regression), whereas no changes were observed in Dmin. Even in patients 30 years or older, 14% of eyes revealed remarkable progression in Rpost. In eyes with acute hydrops, annual changes in Rpost (-0.22 mm) and Tmin (-33.8 μm) before acute corneal hydrops were more than 10 times faster than those in other eyes (P < 0.001, GEE nonlinear regression). Chronologic measurements of corneal tomography in keratoconus demonstrated that the progression of steepening at posterior corneal surface was found not only in patients under 30 years but also in older patients, particularly in advanced keratoconus. The rate of progression can be measured by mapping of corneal curvature and thickness using OCT, and the risk of progression was greater in younger patients with steeper Kmax.

  1. Non-small cell lung cancer: Spectral computed tomography quantitative parameters for preoperative diagnosis of metastatic lymph nodes.

    PubMed

    Yang, Fengfeng; Dong, Jie; Wang, Xiuting; Fu, Xiaojiao; Zhang, Tong

    2017-04-01

    To investigate the application value of spectral computed tomography (CT)quantitative parameters for preoperative diagnosis of metastatic lymph nodes in patients with non-small cell lung cancer (NSLC). 84 patients with suspected lung cancer who underwent chest dual-phase enhanced scan with gemstone spectral CT imaging (GSI) mode were selected. GSI quantitative parameters including normalized iodine concentrations (NIC), water concentration, slope of the spectral Hounsfield unit curve (λHU) were measured. The two-sample t test was used to statistically compare these quantitative parameters. Receiver operating characteristic (ROC) curves were drawn to establish the optimal threshold values. A total of 144 lymph nodes were included, with 48 metastatic lymph nodes and 96 non-metastatic lymph nodes. The slope of the spectral Hounsfeld unit curve (λHU) measured during both arterial and venous phases were signifcantly higher in metastatic than in benign lymph nodes (P<0.05). The area under the ROC curve (AUC=0.951) of λHU of the arterial phase (AP) was the largest. When the optimal threshold values of λHU was 2.75, the sensitivity, specificity, and overall accuracy in the diagnosis of metastatic lymph nodes were 88.2%, 88.4%, 87.0%, respectively. Conventional CT diagnostic criteria established in accordance with size (lymph node maximal short axis diameter ≥10mm) as the basis for judging metastatic lymph node. In quantitative assessment using spectral CT imaging, quantitative parameters showed higher accuracy than qualitative assessment of conventional CT based on the size for preoperative diagnosis of metastatic lymph nodes. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Quantitative evaluation of dental abfraction and attrition using a swept-source optical coherence tomography system.

    PubMed

    Marcauteanu, Corina; Bradu, Adrian; Sinescu, Cosmin; Topala, Florin Ionel; Negrutiu, Meda Lavinia; Podoleanu, Adrian Gh

    2014-02-01

    A fast swept-source optical coherence tomography (SS-OCT) system is employed to acquire volumes of dental tissue, in order to monitor the temporal evolution of dental wear. An imaging method is developed to evaluate the volume of tissue lost in ex vivo artificially induced abfractions and attritions. The minimal volume (measured in air) that our system could measure is 2352 μm3. A volume of 25,000 A-scans is collected in 2.5 s. All these recommend the SS-OCT method as a valuable tool for dynamic evaluation of the abfraction and attrition with remarkable potential for clinical use.

  3. Application of quantitative computed tomography for assessment of trabecular bone mineral density, microarchitecture and mechanical property.

    PubMed

    Mao, Song Shou; Li, Dong; Luo, Yanting; Syed, Younus Saleem; Budoff, Matthew J

    2016-01-01

    Osteoporosis is a common metabolic bone disease, causing increased skeletal fragility characterized by a low bone mass and trabecular microarchitectural deterioration. Assessment of the bone mineral density (BMD) is the primary determinant of skeletal fragility. Computed tomography (CT)-based trabecular microarchitectural and mechanical assessments are important methods to evaluate the skeletal strength. In this review, we focus the feasibility of QCT BMD measurement using a calibration phantom or phantomless. The application of QCT could extend the bone mineral density assessment to all patients who underwent a heart, lung, whole-body, and as well as all routine clinical implications of CT scan. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Europium-155 as a source for dual energy cone beam computed tomography in adaptive proton therapy: A simulation study.

    PubMed

    Zhu, Jiahua; Penfold, Scott N

    2017-07-04

    To investigate the feasibility of a 3D imaging system utilizing a (155) Eu source and pixelated cadmium-zinc-telluride (CZT) detector for applications in adaptive radiotherapy. Specifically, to compare the reconstructed stopping power ratio (SPR) values of a head phantom obtained with the proposed imaging technique with theoretical SPR values. A Geant4 Monte Carlo simulation was performed with the novel imaging system. The simulation was repeated with a typical 120 kV X-ray tube spectrum while maintaining all other parameters. Dual energy (155) Eu source cone beam computed tomography (CBCT) images were reconstructed with an iterative projection algorithm known as total variation superiorization with diagonally relaxed orthogonal projections (TVS-DROP). Single energy 120 kV source CBCT images were also reconstructed with TVS-DROP. Reconstructed images were converted to SPR with stoichiometric calibration techniques based on ICRU 44 tissues. Quantitative accuracy of reconstructed attenuation coefficient images as well as SPR images were compared. Images generated by gamma emissions of (155) Eu showed superior contrast resolution to those generated by the 120 kV spectrum. Quantitatively, all reconstructed images correlated with reference attenuation coefficients of the head phantom within 1 standard deviation. Images generated with the (155) Eu source showed a smaller standard deviation of pixel values. Use of a dual energy conversion into SPR resulted in superior SPR accuracy with the (155) Eu source. (155) Eu was found to display desirable qualities when used as a source for dual energy CBCT. Further work is required to demonstrate whether the simulation results presented here can be translated into an experimental prototype. © 2017 American Association of Physicists in Medicine.

  5. Noninvasive, repetitive, quantitative measurement of gene expression from a bicistronic message by positron emission tomography, following gene transfer with adenovirus.

    PubMed

    Liang, Qianwa; Gotts, Jeff; Satyamurthy, Nagichettiar; Barrio, Jorge; Phelps, Michael E; Gambhir, Sanjiv S; Herschman, Harvey R

    2002-07-01

    Gene therapy protocols are hampered by the inability to monitor the location, magnitude, and duration of ectopic gene expression following DNA delivery. Consequently, it is difficult to establish quantitative correlations and/or causal relationships between therapeutic gene expression and phenotypic responses in treated individuals. One approach to monitor "therapeutic gene" expression indirectly is to incorporate reporter genes that can be imaged in vivo into bicistronic transcription units, along with the therapeutic genes. Expression of the dopamine D2 receptor (D2R) and herpes simplex virus thymidine kinase (HSV1-TK) can both be monitored, in vivo, by positron-emission tomography (PET). We created ad.DTm, an adenovirus containing a cytomegalovirus (CMV) early promoter-driven transcription unit, in which the D2R gene is placed proximal to an encephalomyocarditis virus internal ribosomal entry site (IRES) and a modified HSV1-tk gene is placed distal to the IRES. Following intravenous ad.DTm injection into mice, correlated hepatic D2R and HSV1-sr39tk PET reporter gene expression was demonstrated. Repeated microPET scanning quantitated both D2R-dependent sequestration of a positron-emitting ligand and HSV1-TK-dependent sequestration of a positron-emitting product. It is possible, in living mice, to investigate noninvasively and to measure quantitatively and repeatedly correlated expression of two coding regions from a bicistronic transcription unit over a 3-month period following adenovirus delivery.

  6. Quantitative analysis of heterogeneous spatial distribution of Arabidopsis leaf trichomes using micro X-ray computed tomography.

    PubMed

    Kaminuma, Eli; Yoshizumi, Takeshi; Wada, Takuji; Matsui, Minami; Toyoda, Tetsuro

    2008-11-01

    Quantitative morphological traits may be defined based on the 3D anatomy reconstructed from micro X-ray computed tomography (microCT) images. In this study, the heterogeneous spatial distribution of trichomes (hairs) on the adaxial leaf blade surface in Arabidopsis was evaluated in terms of 3D quantitative traits, including trichome number, average nearest-neighbour distance between trichomes, and proportion of large trichomes. The data reflect spatial heterogeneity in the radial direction, in that a greater number of trichomes were observed on the leaf blade margins relative to the non-margins, a distribution effect caused by the CAPRICE (CPC) and GLABRA3 (GL3) genes, which have previously been shown to affect trichome density. We further determined that the proportion of large trichomes on the blade mid-rib increases from the proximal end to the distal leaf tip in both wild-type plants and GL3 mutants. Our results indicate that the CPC [corrected] gene affects trichome distribution, rather than trichome growth, causing trichome initiation at the proximal base rather than the distal tip. On the other hand, CPC does affect trichome growth and developmental progression. Hence, quantitative phenotyping based on microCT enables precise phenotypic description for elucidation of gene control in morphological mutants.

  7. Quantitative assessment on coronary computed tomography angiography (CCTA) image quality: comparisons between genders and different tube voltage settings

    PubMed Central

    Chian, Teo Chee; Nassir, Norziana Mat; Ibrahim, Mohd Izuan; Yusof, Ahmad Khairuddin Md

    2017-01-01

    Background This study was carried out to quantify and compare the quantitative image quality of coronary computed tomography angiography (CCTA) between genders as well as between different tube voltages scan protocols. Methods Fifty-five cases of CCTA were collected retrospectively and all images including reformatted axial images at systolic and diastolic phases as well as images with curved multi planar reformation (cMPR) were obtained. Quantitative image quality including signal intensity, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of right coronary artery (RCA), left anterior descending artery (LAD), left circumflex artery (LCx) and left main artery (LM) were quantified using Analyze 12.0 software. Results Six hundred and fifty-seven coronary arteries were evaluated. There were no significant differences in any quantitative image quality parameters between genders. 100 kilovoltage peak (kVp) scanning protocol produced images with significantly higher signal intensity compared to 120 kVp scanning protocol (P<0.001) in all coronary arteries in all types of images. Higher SNR was also observed in 100 kVp scan protocol in all coronary arteries except in LCx where 120 kVp showed better SNR than 100 kVp. Conclusions There were no significant differences in image quality of CCTA between genders and different tube voltages. Lower tube voltage (100 kVp) scanning protocol is recommended in clinical practice to reduce the radiation dose to patient. PMID:28275559

  8. Quantitative characterization of mechanically indented in vivo human skin in adults and infants using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Huang, Pin-Chieh; Pande, Paritosh; Shelton, Ryan L.; Joa, Frank; Moore, Dave; Gillman, Elisa; Kidd, Kimberly; Nolan, Ryan M.; Odio, Mauricio; Carr, Andrew; Boppart, Stephen A.

    2017-03-01

    Influenced by both the intrinsic viscoelasticity of the tissue constituents and the time-evolved redistribution of fluid within the tissue, the biomechanical response of skin can reflect not only localized pathology but also systemic physiology of an individual. While clinical diagnosis of skin pathologies typically relies on visual inspection and manual palpation, a more objective and quantitative approach for tissue characterization is highly desirable. Optical coherence tomography (OCT) is an interferometry-based imaging modality that enables in vivo assessment of cross-sectional tissue morphology with micron-scale resolution, which surpasses those of most standard clinical imaging tools, such as ultrasound imaging and magnetic resonance imaging. This pilot study investigates the feasibility of characterizing the biomechanical response of in vivo human skin using OCT. OCT-based quantitative metrics were developed and demonstrated on the human subject data, where a significant difference between deformed and nondeformed skin was revealed. Additionally, the quantified postindentation recovery results revealed differences between aged (adult) and young (infant) skin. These suggest that OCT has the potential to quantitatively assess the mechanically perturbed skin as well as distinguish different physiological conditions of the skin, such as changes with age or disease.

  9. Using stochastic borehole seismic velocity tomography and Bayesian simulation to estimate Ni, Cu and Co grades.

    NASA Astrophysics Data System (ADS)

    Perozzi, Lorenzo; Gloaguen, Erwan; Rondenay, Stephane; Leite, André; McDowell, Glenn; Wheeler, Robert

    2010-05-01

    In the mining industry, classic methods to build a grade model for ore deposits are based on kriging or cokriging of grades for targeted minerals measured in drill core in fertile geological units. As the complexity of the geological geometry increases, so does the complexity of grade estimations. For example, in layered mafic or ultramafic intrusions, it is necessary to know the layering geometry in order to perform kriging of grades in the most fertile zones. Without additional information on geological framwork, the definition of fertile zones is a low-precision exercise that requires extensive experience and good ability from the geologist. Recently, thanks to computer and geophysical tool improvements, seismic tomography became very attractive for many application fields. Indeed, this non-intrusive technique allows inferring the mechanical properties of the ground using travel times and amplitude analysis of the transmitted wavelet between two boreholes, hence provide additional information on the nature of the deposit. Commonly used crosshole seismic velocity tomography algorithms estimate 2D slowness models (inverse of velocity) in the plane between the boreholes using the measured direct wave travel times from the transmitter (located in one of the hole) to the receivers (located in the other hole). Furthermore, geophysical borehole logging can be used to constrain seismic tomography between drill holes. Finally, this project aims to estimate grade of economically worth mineral by integrating seismic tomography data with respectively drill core measured grades acquired by Vale Inco for one of their mine sites in operation. In this study, a new type algorithm that combines geostatistical simulation and tomography in the same process (namely stochastic tomography) has been used. The principle of the stochastic tomography is based on the straight ray approximation and use the linear relationship between travel time and slowness to estimate the slowness

  10. Excitation spectroscopy in multispectral optical fluorescence tomography: methodology, feasibility and computer simulation studies

    NASA Astrophysics Data System (ADS)

    Chaudhari, Abhijit J.; Ahn, Sangtae; Levenson, Richard; Badawi, Ramsey D.; Cherry, Simon R.; Leahy, Richard M.

    2009-08-01

    using singular value decomposition and analysis of reconstructed spatial resolution versus noise. For simplicity, quantitative results have been shown for one representative fluorescent probe (Alexa 700®) and effects due to tissue autofluorescence have not been taken into account. We also demonstrate the performance of our method for 3D reconstruction of tumors in a simulated mouse model of metastatic human hepatocellular carcinoma.

  11. Quantitative Technique for Comparing Simulant Materials through Figures of Merit

    NASA Technical Reports Server (NTRS)

    Rickman, Doug; Hoelzer, Hans; Fourroux, Kathy; Owens, Charles; McLemore, Carole; Fikes, John

    2007-01-01

    The 1989 workshop report entitled Workshop on Production and Uses of Simulated Lunar Materials and the Lunar Regolith Simulant Materials: Recommendations for Standardization, Production, and Usage, NASA Technical Publication both identified and reinforced a need for a set of standards and requirements for the production and usage of the Lunar simulant materials. As NASA prepares to return to the Moon, and set out to Mars, a set of early requirements have been developed for simulant materials and the initial methods to produce and measure those simulants have been defined. Addressed in the requirements document are: 1) a method for evaluating the quality of any simulant of a regolith, 2) the minimum characteristics for simulants of Lunar regolith, and 3) a method to produce simulants needed for NASA's Exploration mission. As an extension of the requirements document a method to evaluate new and current simulants has been rigorously defined through the mathematics of Figures of Merit (FoM). Requirements and techniques have been developed that allow the simulant provider to compare their product to a standard reference material through Figures of Merit. Standard reference material may be physical material such as the Apollo core samples or material properties predicted for any landing site. The simulant provider is not restricted to providing a single "high fidelity" simulant, which may be costly to produce. The provider can now develop "lower fidelity" simulants for engineering applications such as drilling and mobility applications.

  12. Combined Fluorescence and X-Ray Tomography for Quantitative In Vivo Detection of Fluorophore

    PubMed Central

    Barber, W. C.; Lin, Y.; Nalcioglu, O.; Iwanczyk, J. S.; Hartsough, N. E.; Gulsen, G.

    2010-01-01

    Initial results from a novel dual modality preclinical imager which combines non-contact fluorescence tomography (FT) and x-ray computed tomography (CT) for preclinical functional and anatomical in vivo imaging are presented. The anatomical data from CT provides a priori information to the FT reconstruction to create overlaid functional and anatomical images with accurate localization and quantification of fluorophore distribution. Phantoms with inclusions containing Indocyanine-Green (ICG), and with heterogeneous backgrounds including iodine in compartments at different concentrations for CT contrast, have been imaged with the dual modality FT/CT system. Anatomical information from attenuation maps and optical morphological information from absorption and scattering maps are used as a priori information in the FT reconstruction. Although ICG inclusions can be located without the a priori information, the recovered ICG concentration shows 75% error. When the a priori information is utilized, the ICG concentration can be recovered with only 15% error. Developing the ability to accurately quantify fluorophore concentration in anatomical regions of interest may provide a powerful tool for in vivo small animal imaging. PMID:20082529

  13. Effect of particle-size selectivity on quantitative X-ray dark-field computed tomography using a grating interferometer

    NASA Astrophysics Data System (ADS)

    Bao, Yuan; Shao, Qigang; Hu, Renfang; Wang, Shengxiang; Gao, Kun; Wang, Yan; Tian, Yangchao; Zhu, Peiping

    2017-08-01

    According to the conclusion of Khelashvili et al. [Phys. Med. Biol. 51, 221 (2006)], the minus logarithm of the visibility ratio fulfills the line integral condition; consequently the scattering information can be reconstructed quantitatively by conventional computed tomography (CT) algorithms. Based on Fresnel diffraction theory, we analyzed the influence of particle-size selectivity on the performance of an X-ray grating interferometer (GI) applied for dark-field CT. The results state the signal-to-noise ratio (SNR) of dark-field imaging is sensitive to the particle size, which demonstrate that the X-ray dark-field CT using a GI can efficiently differentiate materials of identical X-ray absorption and help to choose optimal X-ray energy for known particle size, thus extending the application range of grating interferometer.

  14. Determining Metacarpophalangeal Flexion Angle Tolerance for Reliable Volumetric Joint Space Measurements by High-resolution Peripheral Quantitative Computed Tomography.

    PubMed

    Tom, Stephanie; Frayne, Mark; Manske, Sarah L; Burghardt, Andrew J; Stok, Kathryn S; Boyd, Steven K; Barnabe, Cheryl

    2016-10-01

    The position-dependence of a method to measure the joint space of metacarpophalangeal (MCP) joints using high-resolution peripheral quantitative computed tomography (HR-pQCT) was studied. Cadaveric MCP were imaged at 7 flexion angles between 0 and 30 degrees. The variability in reproducibility for mean, minimum, and maximum joint space widths and volume measurements was calculated for increasing degrees of flexion. Root mean square coefficient of variance values were < 5% under 20 degrees of flexion for mean, maximum, and volumetric joint spaces. Values for minimum joint space width were optimized under 10 degrees of flexion. MCP joint space measurements should be acquired at < 10 degrees of flexion in longitudinal studies.

  15. Quantitative evaluation of atherosclerotic plaques using cross-polarization optical coherence tomography, nonlinear, and atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Gubarkova, Ekaterina V.; Kirillin, Mikhail Yu.; Dudenkova, Varvara V.; Timashev, Peter S.; Kotova, Svetlana L.; Kiseleva, Elena B.; Timofeeva, Lidia B.; Belkova, Galina V.; Solovieva, Anna B.; Moiseev, Alexander A.; Gelikonov, Gregory V.; Fiks, Ilya I.; Feldchtein, Felix I.; Gladkova, Natalia D.

    2016-12-01

    A combination of approaches to the image analysis in cross-polarization optical coherence tomography (CP OCT) and high-resolution imaging by nonlinear microscopy and atomic force microscopy (AFM) at the different stages of atherosclerotic plaque development is studied. This combination allowed us to qualitatively and quantitatively assess the disorganization of collagen in the atherosclerotic arterial tissue (reduction and increase of CP backscatter), at the fiber (change of the geometric distribution of fibers in the second-harmonic generation microscopy images) and fibrillar (violation of packing and different nature of a basket-weave network of fibrils in the AFM images) organization levels. The calculated CP channel-related parameters are shown to have a statistically significant difference between stable and unstable (also called vulnerable) plaques, and hence, CP OCT could be a potentially powerful, minimally invasive method for vulnerable plaques detection.

  16. How do trees grow? Response from the graphical and quantitative analyses of computed tomography scanning data collected on stem sections.

    PubMed

    Dutilleul, Pierre; Han, Li Wen; Beaulieu, Jean

    2014-06-01

    Tree growth, as measured via the width of annual rings, is used for environmental impact assessment and climate back-forecasting. This fascinating natural process has been studied at various scales in the stem (from cell and fiber within a growth ring, to ring and entire stem) in one, two, and three dimensions. A new approach is presented to study tree growth in 3D from stem sections, at a scale sufficiently small to allow the delineation of reliable limits for annual rings and large enough to capture directional variation in growth rates. The technology applied is computed tomography scanning, which provides - for one stem section - millions of data (indirect measures of wood density) that can be mapped, together with a companion measure of dispersion and growth ring limits in filigree. Graphical and quantitative analyses are reported for white spruce trees with circular vs non-circular growth. Implications for dendroclimatological research are discussed.

  17. Bone Health Monitoring in Astronauts: Recommended Use of Quantitative Computed Tomography [QCT] for Clinical and Operational Decisions

    NASA Technical Reports Server (NTRS)

    Sibonga, J. D.; Truskowski, P.

    2010-01-01

    This slide presentation reviews the concerns that astronauts in long duration flights might have a greater risk of bone fracture as they age than the general population. A panel of experts was convened to review the information and recommend mechanisms to monitor the health of bones in astronauts. The use of Quantitative Computed Tomography (QCT) scans for risk surveillance to detect the clinical trigger and to inform countermeasure evaluation is reviewed. An added benefit of QCT is that it facilitates an individualized estimation of bone strength by Finite Element Modeling (FEM), that can inform approaches for bone rehabilitation. The use of FEM is reviewed as a process that arrives at a composite number to estimate bone strength, because it integrates multiple factors.

  18. Assessment of Technical and Biological Parameters of Volumetric Quantitative Computed Tomography in the Foot: A Phantom Study

    PubMed Central

    Smith, Kirk E.; Whiting, Bruce R.; Reiker, Gregory G.; Commean, Paul K.; Sinacore, David R.; Prior, Fred W.

    2012-01-01

    Few studies exist for bone densitometry of the whole foot. A phantom study demonstrated the sources of error and necessary controls for accurate quantitative computed tomography of the foot. A loss in bone mineral density in the small foot bones may be an early indicator of diabetic foot complications. Purpose Volumetric quantitative computed tomography (vQCT) facilitates assessment of pedal bone osteopenia, which in the presence of peripheral neuropathy may well be an early sign of diabetic foot deformity. To date, sources and magnitudes of error in foot vQCT measurements have not been reported. Methods Foot phantoms were scanned using a 64-slice CT scanner. Energy (kVp), table height, phantom size and orientation, location of “bone” inserts, insert material, location of calibration phantom, and reconstruction kernel were systematically varied during scan acquisition. Results Energy (kVp) and distance from the isocenter (table height) resulted in relative attenuation changes from −5% to 22% and −5% to 0%, respectively, and average bone mineral density (BMD) changes from −0.9% to 0.0% and −1.1% to 0.3%, respectively, compared to a baseline 120 kVp scan performed at the isocenter. BMD compared to manufacturer specified values ranged on average from −2.2% to 0.9%. Phantom size and location of bone-equivalent material inserts resulted in relative attenuation changes of −1.2% to 1.4% compared to the medium sized phantom. Conclusion This study demonstrated that variations in kVp and table height can be controlled using a calibration phantom scanned at the same energy and height as a foot phantom; however, error due to soft tissue thickness and location of bones within a foot cannot be controlled using a calibration phantom alone. PMID:22147208

  19. Children and adolescents with cystic fibrosis display moderate bone microarchitecture abnormalities: data from high-resolution peripheral quantitative computed tomography.

    PubMed

    Braun, C; Bacchetta, J; Braillon, P; Chapurlat, R; Drai, J; Reix, P

    2017-08-09

    We investigated whether bone microstructure assessed by high-resolution peripheral quantitative tomography (HR-pQCT) could be altered in children and teenagers with cystic fibrosis (CF). In comparison to their healthy counterparts, bone microstructure was mildly affected at the tibial level only. Cystic fibrosis-related bone disease (CFBD) may alter bone health, ultimately predisposing patients to bone fractures. Our aim was to assess bone microstructure using high-resolution peripheral quantitative tomography (HR-pQCT) in a cohort of children and teenagers with CF in comparison to age-, puberty-, and gender-matched healthy volunteers (HVs). In this single-center, prospective, cross-sectional study, we evaluated the HR-pQCT bone parameters of CF patients and compared them to those of the healthy volunteers. At a median age of 15.4 [range, 10.5-17.9] years, 37 CF patients (21 boys) with 91% [range, 46-138%] median forced expiratory volume in 1 s were included. At the ultradistal tibia, CF patients had a smaller bone cross-sectional area (579 [range, 399-1087] mm(2)) than HVs (655 [range, 445-981] mm(2)) (p = 0.027), related to a decreased trabecular area, without any significant differences for height. No other differences were found (trabecular number, separation, thickness, or distribution) at the radial or tibial levels. Bone structure was different in patients receiving ursodeoxycholic acid and those bearing two F508del mutations. In our cohort of children and teenagers with good nutritional and lung function status, bone microstructure evaluated with HR-pQCT was not severely affected. Minimal microstructure abnormalities observed at the tibial level may be related to the cystic fibrosis transmembrane conductance regulator defect alone; the long-term consequences of such impairment will require further evaluation.

  20. A methodology for finding the optimal iteration number of the SIRT algorithm for quantitative Electron Tomography.

    PubMed

    Okariz, Ana; Guraya, Teresa; Iturrondobeitia, Maider; Ibarretxe, Julen

    2017-02-01

    The SIRT (Simultaneous Iterative Reconstruction Technique) algorithm is commonly used in Electron Tomography to calculate the original volume of the sample from noisy images, but the results provided by this iterative procedure are strongly dependent on the specific implementation of the algorithm, as well as on the number of iterations employed for the reconstruction. In this work, a methodology for selecting the iteration number of the SIRT reconstruction that provides the most accurate segmentation is proposed. The methodology is based on the statistical analysis of the intensity profiles at the edge of the objects in the reconstructed volume. A phantom which resembles a a carbon black aggregate has been created to validate the methodology and the SIRT implementations of two free software packages (TOMOJ and TOMO3D) have been used. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Semi-quantitative Multispectral Optoacoustic Tomography (MSOT) for volumetric PK imaging of gastric emptying.

    PubMed

    Morscher, Stefan; Driessen, Wouter H P; Claussen, Jing; Burton, Neal C

    2014-09-01

    A common side effect of medication is gastrointestinal intolerance. Symptoms can include reduced appetite, diarrhea, constipation, GI inflammation, nausea and vomiting. Such effects often have a dramatic impact on compliance with a treatment regimen. Therefore, characterization of GI tolerance is an important step when establishing a novel therapeutic approach. In this study, Multispectral Optoacoustic Tomography (MSOT) is used to monitor gastrointestinal motility by in vivo whole body imaging in mice. MSOT combines high spatial and temporal resolution based on ultrasound detection with strong optical contrast in the near infrared. Animals were given Indocyanine Green (ICG) by oral gavage and imaged by MSOT to observe the fate of ICG in the gastrointestinal tract. Exponential decay of ICG signal was observed in the stomach in good correlation with ex vivo validation. We discuss how kinetic imaging in MSOT allows visualization of parameters unavailable to other imaging methods, both in 2D and 3D.

  2. Quantitative optical coherence tomography imaging of intermediate flow defect phenotypes in ciliary physiology and pathophysiology

    NASA Astrophysics Data System (ADS)

    Huang, Brendan K.; Gamm, Ute A.; Jonas, Stephan; Khokha, Mustafa K.; Choma, Michael A.

    2015-03-01

    Cilia-driven fluid flow is a critical yet poorly understood aspect of pulmonary physiology. Here, we demonstrate that optical coherence tomography-based particle tracking velocimetry can be used to quantify subtle variability in cilia-driven flow performance in Xenopus, an important animal model of ciliary biology. Changes in flow performance were quantified in the setting of normal development, as well as in response to three types of perturbations: mechanical (increased fluid viscosity), pharmacological (disrupted serotonin signaling), and genetic (diminished ciliary motor protein expression). Of note, we demonstrate decreased flow secondary to gene knockdown of kif3a, a protein involved in ciliogenesis, as well as a dose-response decrease in flow secondary to knockdown of dnah9, an important ciliary motor protein.

  3. Textural analysis of optical coherence tomography skin images: quantitative differentiation between healthy and cancerous tissues

    NASA Astrophysics Data System (ADS)

    Adabi, Saba; Conforto, Silvia; Hosseinzadeh, Matin; Noe, Shahryar; Daveluy, Steven; Mehregan, Darius; Nasiriavanaki, Mohammadreza

    2017-02-01

    Optical Coherence Tomography (OCT) offers real-time high-resolution three-dimensional images of tissue microstructures. In this study, we used OCT skin images acquired from ten volunteers, neither of whom had any skin conditions addressing the features of their anatomic location. OCT segmented images are analyzed based on their optical properties (attenuation coefficient) and textural image features e.g., contrast, correlation, homogeneity, energy, entropy, etc. Utilizing the information and referring to their clinical insight, we aim to make a comprehensive computational model for the healthy skin. The derived parameters represent the OCT microstructural morphology and might provide biological information for generating an atlas of normal skin from different anatomic sites of human skin and may allow for identification of cell microstructural changes in cancer patients. We then compared the parameters of healthy samples with those of abnormal skin and classified them using a linear Support Vector Machines (SVM) with 82% accuracy.

  4. Noncontact three-dimensional quantitative profiling of fast aspheric lenses by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Goud, Bujagouni Karthik; Udupa, Dinesh Venkatesh; Prathap, Chilakala; Shinde, Deepak Dilip; Rao, Kompalli Divakar; Sahoo, Naba Kishore

    2016-12-01

    The use of optical coherence tomography (OCT) for noncontact three-dimensional aspheric lens profiling and retrieval of aspheric surface parameters is demonstrated. Two commercially available aspheric lenses with different focal length-to-diameter ratio have been imaged using OCT, and the measured optical path length distribution has been least square fitted with the aspheric lens surface retrieving the radius of curvature, aspheric constant, and conic constants. The refractive index of these lenses has also been measured referencing with a standard Zerodur glass flat. The fitted aspheric surface coefficients of the lenses are in close agreement with the manufacturer's values, thus, envisaging the potential of OCT in rapid screening, testing of aspheric lenses, and other micro-optical components such as those used in illumination optics.

  5. [Quantitative structure characteristics and fractal dimension of Chinese medicine granules measured by synchrotron radiation X-ray computed micro tomography].

    PubMed

    Lu, Xiao-long; Zheng, Qin; Yin, Xian-zhen; Xiao, Guang-qing; Liao, Zu-hua; Yang, Ming; Zhang, Ji-wen

    2015-06-01

    The shape and structure of granules are controlled by the granulation process, which is one of the main factors to determine the nature of the solid dosage forms. In this article, three kinds of granules of a traditional Chinese medicine for improving appetite and promoting digestion, namely, Jianwei Granules, were prepared using granulation technologies as pendular granulation, high speed stirring granulation, and fluidized bed granulation and the powder properties of them were investigated. Meanwhile, synchrotron radiation X-ray computed micro tomography (SR-µCT) was applied to quantitatively determine the irregular internal structures of the granules. The three-dimensional (3D) structure models were obtained by 3D reconstruction, which were more accurately to characterize the three-dimensional structures of the particles through the quantitative data. The models were also used to quantitatively compare the structural differences of granules prepared by different granulation processes with the same formula, so as to characterize how the production process plays a role in the pharmaceutical behaviors of the granules. To focus on the irregularity of the particle structure, the box counting method was used to calculate the fractal dimensions of the granules. The results showed that the fractal dimension is more sensitive to reflect the minor differences in the structure features than the conventional parameters, and capable to specifically distinct granules in structure. It is proved that the fractal dimension could quantitatively characterize the structural information of irregular granules. It is the first time suggested by our research that the fractal dimension difference (Df,c) between two fractal dimension parameters, namely, the volume matrix fractal dimension and the surface matrix fractal dimension, is a new index to characterize granules with irregular structures and evaluate the effects of production processes on the structures of granules as a new

  6. Quantitative technique for robust and noise-tolerant speed measurements based on speckle decorrelation in optical coherence tomography

    PubMed Central

    Uribe-Patarroyo, Néstor; Villiger, Martin; Bouma, Brett E.

    2014-01-01

    Intensity-based techniques in optical coherence tomography (OCT), such as those based on speckle decorrelation, have attracted great interest for biomedical and industrial applications requiring speed or flow information. In this work we present a rigorous analysis of the effects of noise on speckle decorrelation, demonstrate that these effects frustrate accurate speed quantitation, and propose new techniques that achieve quantitative and repeatable measurements. First, we derive the effect of background noise on the speckle autocorrelation function, finding two detrimental effects of noise. We propose a new autocorrelation function that is immune to the main effect of background noise and permits quantitative measurements at high and moderate signal-to-noise ratios. At the same time, this autocorrelation function is able to provide motion contrast information that accurately identifies areas with movement, similar to speckle variance techniques. In order to extend the SNR range, we quantify and model the second effect of background noise on the autocorrelation function through a calibration. By obtaining an explicit expression for the decorrelation time as a function of speed and diffusion, we show how to use our autocorrelation function and noise calibration to measure a flowing liquid. We obtain accurate results, which are validated by Doppler OCT, and demonstrate a very high dynamic range (> 600 mm/s) compared to that of Doppler OCT (±25 mm/s). We also derive the behavior for low flows, and show that there is an inherent non-linearity in speed measurements in the presence of diffusion due to statistical fluctuations of speckle. Our technique allows quantitative and robust measurements of speeds using OCT, and this work delimits precisely the conditions in which it is accurate. PMID:25322018

  7. Comparative evaluation of modified canal staining and clearing technique, cone-beam computed tomography, peripheral quantitative computed tomography, spiral computed tomography, and plain and contrast medium-enhanced digital radiography in studying root canal morphology.

    PubMed

    Neelakantan, Prasanna; Subbarao, Chandana; Subbarao, Chandragiri V

    2010-09-01

    This study investigated the accuracy of cone-beam computed tomography (CBCT), peripheral quantitative computed tomography (pQCT), spiral computed tomography (SCT), plain (plain digi), and contrast medium-enhanced digital radiographs (contrast digi) in studying root canal morphology. The root canal anatomy was analyzed in 95 teeth using CBCT, pQCT, SCT, plain digi, and contrast digi. After flushing out the radiopaque dye, access cavities were sealed, and the teeth were subject to the modified canal staining and clearing technique. The number of root canals (Vertucci classification and Gulabivala's additional classes) was calculated by three calibrated endodontists and two maxillofacial radiologists. Erroneous or unsuccessful identifications of root canals were statistically analyzed by one-way analysis of variance (p = 0.05). The modified canal staining and clearing technique identified an average of 1.8 root canals per mandibular central incisor, 2.3 per maxillary first premolar, 3.9 per maxillary first molar, 3.8 per maxillary and mandibular second molar, and 4.3 per mandibular first molar. CBCT and pQCT were erroneous in 0.29% and 2.05% cases, whereas SCT, contrast digi, and plain digi were unsuccessful in 15.58%, 14.7%, and 23.8%, respectively. There was a significant difference between all the methods (p < 0.05) in the unsuccessful identification of root canals except between CBCT and modified canal staining and clearing technique where there was no significant difference (p > 0.05). CBCT and pQCT were as accurate as the modified canal staining and tooth clearing technique in identifying root canal systems. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  8. Correlation analysis of cortical geometry of tibia and humerus of white leghorns using clinical quantitative computed tomography and microcomputed tomography scans1.

    PubMed

    Regmi, P; Cox, A G; Robison, C I; Karcher, D M

    2017-03-24

    Peripheral quantitative computed tomography (QCT) has been used in poultry bone research in recent years to analyze cortical and cross-sectional geometry. For QCT to be used as a standard research tool for analysis of bones of laying hens (cortical thickness <2 mm), the accuracy of the scans must be assessed. The primary difference between the QCT and micro-computed tomography (micro-CT) is image resolution. Image resolution is inversely related to the pixel size. The aim of the current study was to correlate the cortical parameters measured using clinical CT scans with the measurements from micro-CT, the current gold standard. A total of 15 tibiae and 14 humeri of Lohmann White hens was scanned using clinical CT and micro-CT. Reconstruction of the scans generated images with final voxel resolution of 195 μm for clinical CT scans and 46 μm for micro-CT scans. Cortical and total area were measured using MIMICS® software at proximal, middle, and distal locations of 20 mm sections of humerus diaphysis and 30 mm sections of tibia diaphysis. The total area for proximal and middle locations as well as proximal cortical area measurements for humeri produced strong correlation coefficients (R ≥ 0.70). Moderate strength correlation coefficients (R = 0.40 to 0.60) in humeri were seen in middle and distal cortical areas. Distal total area in humeri displayed a weak correlation coefficient (R ≤ 0.3; P = 0.25). Overall, tibiae demonstrated a weaker correlation. Proximal and middle cortical areas indicated moderate correlation coefficients (R = 0.40 to 0.60), while proximal and middle total areas accompanied by distal cortical and total area displayed weak correlation coefficients (R ≤ 0.3). Only the middle cortical area measurement for tibiae was significant (P = 0.03). These results indicate stronger correlation for humeri measurements among the scans than tibia. Overall, cross-sectional area measurements were only low to moderately correlated between clinical

  9. Evaluation of Three-Dimensional Printed Materials for Simulation by Computed Tomography and Ultrasound Imaging.

    PubMed

    Mooney, James J; Sarwani, Nabeel; Coleman, Melissa L; Fotos, Joseph S

    2017-06-01

    The use of three-dimensional (3D) printing allows for creation of custom models for clinical care, education, and simulation. Medical imaging, given the significant role it plays in both clinical diagnostics and procedures, remains an important area for such education and simulation. Unfortunately, the materials appropriate for use in simulation involving radiographic or ultrasound imaging remains poorly understood. Therefore, our study was intended to explore the characteristics of readily available 3D printing materials when visualized by computed tomography (CT) and ultrasound. Seven 3D printing materials were examined in standard shapes (cube, cylinder, triangular prism) with a selection of printing methods ("open," "whole," and "solid" forms). For CT imaging, these objects were suspended in a gelatin matrix molded to match a standard human CT phantom. For ultrasound imaging, the objects were placed in acrylic forms filled with a gelatin matrix. All images were examined using OsiriX software. Computed tomography imaging revealed marked variation in materials' Hounsfield units as well as patterning and artifact. The Hounsfield unit variations revealed a number of materials suitable for simulation various human tissues. Ultrasound imaging showed echogenicity in all materials, with some variability in shadowing and posterior wall visualization. We were able to demonstrate the potential utility for 3D printing in the creation of CT and ultrasound simulation models. The similar appearance of materials via ultrasound supports their broad utility for select tissue types, whereas the more variable appearance via CT suggests greater potential for simulating differing tissues but requiring multiple printer technologies to do so.

  10. Tomography based numerical simulation of the demagnetizing field in soft magnetic composites

    SciTech Connect

    Arzbacher, S.; Petrasch, J.; Amann, P.; Weidenfeller, B.; Loerting, T.; Ostermann, A.

    2015-04-28

    The magneto-static behaviour of soft magnetic composites (SMCs) is investigated using tomography based direct numerical simulation. The microgeometry crucially affects the magnetic properties of the composite since a geometry dependent demagnetizing field is established inside the composite, which lowers the magnetic permeability. We determine the magnetic field information inside the SMC using direct numerical simulation of the magnetic field based on high resolution micro-computed tomography data of the SMC's microstructure as well as artificially generated data made of statistically homogeneous systems of identical fully penetrable spheres and prolate spheroids. Quasi-static electromagnetic behaviour and linear material response are assumed. The 3D magnetostatic Maxwell equations are solved using Whitney finite elements. Simulations show that clustering and percolation behaviour determine the demagnetizing factor of SMCs rather than the particle shape. The demagnetizing factor correlates with the slope of a 2-point probability function at its origin, which is related to the specific surface area of the SMC. Comparison with experimental results indicates that the relatively low permeability of SMCs cannot be explained by demagnetizing effects alone and suggests that the permeability of SMC particles has to be orders of magnitude smaller than the bulk permeability of the particle material.

  11. Quantitative optical tomography of sub-surface heterogeneities using spatially modulated structured light.

    PubMed

    Konecky, Soren D; Mazhar, Amaan; Cuccia, David; Durkin, Anthony J; Schotland, John C; Tromberg, Bruce J

    2009-08-17

    We present a wide-field method for obtaining three-dimensional images of turbid media. By projecting patterns of light of varying spatial frequencies on a sample, we reconstruct quantitative, depth resolved images of absorption contrast. Images are reconstructed using a fast analytic inversion formula and a novel correction to the diffusion approximation for increased accuracy near boundaries. The method provides more accurate quantification of optical absorption and higher resolution than standard diffuse reflectance measurements.

  12. [A comparison between quantitative computed tomography and dual-energy densitometry in the study of patients at risk for postmenopausal osteoporosis].

    PubMed

    La Fianza, A; Campani, R; Dore, R; Torretta, L; Bertoni, G

    1992-01-01

    A comparison was made of the densitometric values of the lumbar vertebrae obtained using quantitative Computed Tomography, and those measured with dual energy X-ray absorptiometry. A selected group of patients at increased risk of developing postmenopausal osteoporosis was chosen: women who had undergone bilateral oophorectomy in child-bearing years. The densitometric data recorded revealed a considerable decrease in bone mass, in particular in the cancellous portion of the vertebrae (a 17% change in the quantitative Computed Tomography value and a 13% decrease in that of dual energy X-ray absorptiometry a one year after oophorectomy). Although quantitative Computed Tomography and dual energy X-ray absorptiometry demonstrated a similar trend in bone mass reduction, given the marked and unexplained variability of both absolute values and percent variations, it was impossible to establish a clinically useful mathematical correlation between the two sets of data. Quantitative Computed Tomography is the densitometric procedure of choice to study metabolic bone disorders that involve mainly tha cancellous portion, such as postmenopausal osteoporosis. Nevertheless, given its accuracy, short execution time, lower radiation dose required, as well as good sensitivity in the measurement of bone mass variations, it would seem that dual energy X-ray absorptiometry could also find a place in clinical studies on postmenopausal osteoporosis.

  13. Validation of electrical impedance tomography qualitative and quantitative values and comparison of the numeric pain distress score against mammography.

    PubMed

    Juliana, Norsham; Shahar, Suzana; Chelliah, Kanaga Kumari; Ghazali, Ahmad Rohi; Osman, Fazilah; Sahar, Mohd Azmani

    2014-01-01

    Electrical impedance tomography (EIT) is a potential supplement for mammogram screening. This study aimed to evaluate and feasibility of EIT as opposed to mammography and to determine pain perception with both imaging methods. Women undergoing screening mammography at the Radiology Department of National University of Malaysia Medical Centre were randomly selected for EIT imaging. All women were requested to give a pain score after each imaging session. Two independent raters were chosen to define the image findings of EIT. A total of 164 women in the age range from 40 to 65-year-old participated and were divided into two groups; normal and abnormal. EIT sensitivity and specificity for rater 1 were 69.4% and 63.3, whereas for rater 2 they were 55.3% and 57.0% respectively. The reliability for each rater ranged between good to very good (p<0.05). Quantitative values of EIT showed there were significant differences in all values between groups (ANCOVA, p<0.05). Interestingly, EIT scored a median pain score of 1.51±0.75 whereas mammography scored 4.15±0.87 (Mann Whitney U test, p<0.05). From these quantitative values, EIT has the potential as a health discriminating index. Its ability to replace image findings from mammography needs further investigation.

  14. Crosshole Tomography, Waveform Inversion, and Anisotropy: A Combined Approach Using Simulated Annealing

    NASA Astrophysics Data System (ADS)

    Afanasiev, M.; Pratt, R. G.; Kamei, R.; McDowell, G.

    2012-12-01

    Crosshole seismic tomography has been used by Vale to provide geophysical images of mineralized massive sulfides in the Eastern Deeps deposit at Voisey's Bay, Labrador, Canada. To date, these data have been processed using traveltime tomography, and we seek to improve the resolution of these images by applying acoustic Waveform Tomography. Due to the computational cost of acoustic waveform modelling, local descent algorithms are employed in Waveform Tomography; due to non-linearity an initial model is required which predicts first-arrival traveltimes to within a half-cycle of the lowest frequency used. Because seismic velocity anisotropy can be significant in hardrock settings, the initial model must quantify the anisotropy in order to meet the half-cycle criterion. In our case study, significant velocity contrasts between the target massive sulfides and the surrounding country rock led to difficulties in generating an accurate anisotropy model through traveltime tomography, and our starting model for Waveform Tomography failed the half-cycle criterion at large offsets. We formulate a new, semi-global approach for finding the best-fit 1-D elliptical anisotropy model using simulated annealing. Through random perturbations to Thompson's ɛ parameter, we explore the L2 norm of the frequency-domain phase residuals in the space of potential anisotropy models: If a perturbation decreases the residuals, it is always accepted, but if a perturbation increases the residuals, it is accepted with the probability P = exp(-(Ei-E)/T). This is the Metropolis criterion, where Ei is the value of the residuals at the current iteration, E is the value of the residuals for the previously accepted model, and T is a probability control parameter, which is decreased over the course of the simulation via a preselected cooling schedule. Convergence to the global minimum of the residuals is guaranteed only for infinitely slow cooling, but in practice good results are obtained from a variety

  15. Validation of a Low Dose Simulation Technique for Computed Tomography Images

    PubMed Central

    Muenzel, Daniela; Koehler, Thomas; Brown, Kevin; Žabić, Stanislav; Fingerle, Alexander A.; Waldt, Simone; Bendik, Edgar; Zahel, Tina; Schneider, Armin; Dobritz, Martin; Rummeny, Ernst J.; Noël, Peter B.

    2014-01-01

    Purpose Evaluation of a new software tool for generation of simulated low-dose computed tomography (CT) images from an original higher dose scan. Materials and Methods Original CT scan data (100 mAs, 80 mAs, 60 mAs, 40 mAs, 20 mAs, 10 mAs; 100 kV) of a swine were acquired (approved by the regional governmental commission for animal protection). Simulations of CT acquisition with a lower dose (simulated 10–80 mAs) were calculated using a low-dose simulation algorithm. The simulations were compared to the originals of the same dose level with regard to density values and image noise. Four radiologists assessed the realistic visual appearance of the simulated images. Results Image characteristics of simulated low dose scans were similar to the originals. Mean overall discrepancy of image noise and CT values was −1.2% (range −9% to 3.2%) and −0.2% (range −8.2% to 3.2%), respectively, p>0.05. Confidence intervals of discrepancies ranged between 0.9–10.2 HU (noise) and 1.9–13.4 HU (CT values), without significant differences (p>0.05). Subjective observer evaluation of image appearance showed no visually detectable difference. Conclusion Simulated low dose images showed excellent agreement with the originals concerning image noise, CT density values, and subjective assessment of the visual appearance of the simulated images. An authentic low-dose simulation opens up opportunity with regard to staff education, protocol optimization and introduction of new techniques. PMID:25247422

  16. High-Resolution and Quantitative X-Ray Phase-Contrast Tomography for Mouse Brain Research.

    PubMed

    Xi, Yan; Lin, Xiaojie; Yuan, Falei; Yang, Guo-Yuan; Zhao, Jun

    2015-01-01

    Imaging techniques for visualizing cerebral vasculature and distinguishing functional areas are essential and critical to the study of various brain diseases. In this paper, with the X-ray phase-contrast imaging technique, we proposed an experiment scheme for the ex vivo mouse brain study, achieving both high spatial resolution and improved soft-tissue contrast. This scheme includes two steps: sample preparation and volume reconstruction. In the first step, we use heparinized saline to displace the blood inside cerebral vessels and then replace it with air making air-filled mouse brain. After sample preparation, X-ray phase-contrast tomography is performed to collect the data for volume reconstruction. Here, we adopt a phase-retrieval combined filtered backprojection method to reconstruct its three-dimensional structure and redesigned the reconstruction kernel. To evaluate its performance, we carried out experiments at Shanghai Synchrotron Radiation Facility. The results show that the air-tissue structured cerebral vasculatures are highly visible with propagation-based phase-contrast imaging and can be clearly resolved in reconstructed cross-images. Besides, functional areas, such as the corpus callosum, corpus striatum, and nuclei, are also clearly resolved. The proposed method is comparable with hematoxylin and eosin staining method but represents the studied mouse brain in three dimensions, offering a potential powerful tool for the research of brain disorders.

  17. A novel 3D absorption correction method for quantitative EDX-STEM tomography.

    PubMed

    Burdet, Pierre; Saghi, Z; Filippin, A N; Borrás, A; Midgley, P A

    2016-01-01

    This paper presents a novel 3D method to correct for absorption in energy dispersive X-ray (EDX) microanalysis of heterogeneous samples of unknown structure and composition. By using STEM-based tomography coupled with EDX, an initial 3D reconstruction is used to extract the location of generated X-rays as well as the X-ray path through the sample to the surface. The absorption correction needed to retrieve the generated X-ray intensity is then calculated voxel-by-voxel estimating the different compositions encountered by the X-ray. The method is applied to a core/shell nanowire containing carbon and oxygen, two elements generating highly absorbed low energy X-rays. Absorption is shown to cause major reconstruction artefacts, in the form of an incomplete recovery of the oxide and an erroneous presence of carbon in the shell. By applying the correction method, these artefacts are greatly reduced. The accuracy of the method is assessed using reference X-ray lines with low absorption.

  18. Quantitative measurement of regional lung gas volume by synchrotron radiation computed tomography

    NASA Astrophysics Data System (ADS)

    Monfraix, Sylvie; Bayat, Sam; Porra, Liisa; Berruyer, Gilles; Nemoz, Christian; Thomlinson, William; Suortti, Pekka; Sovijärvi, Anssi R. A.

    2005-01-01

    The aim of this study was to assess the feasibility of a novel respiration-gated spiral synchrotron radiation computed tomography (SRCT) technique for direct quantification of absolute regional lung volumes, using stable xenon (Xe) gas as an inhaled indicator. Spiral SRCT with K-edge subtraction using two monochromatic x-ray beams was used to visualize and directly quantify inhaled Xe concentrations and airspace volumes in three-dimensional (3D) reconstructed lung images. Volume measurements were validated using a hollow Xe-filled phantom. Spiral images spanning 49 mm in lung height were acquired following 60 breaths of an 80% Xe-20% O2 gas mixture, in two anaesthetized and mechanically ventilated rabbits at baseline and after histamine aerosol inhalation. Volumetric images of 20 mm lung sections were obtained at functional residual capacity (FRC) and at end-inspiration. 3D images showed large patchy filling defects in peripheral airways and alveoli following histamine provocation. Local specific lung compliance was calculated based on FRC/end-inspiration images in normal lung. This study demonstrates spiral SRCT as a new technique for direct determination of regional lung volume, offering possibilities for non-invasive investigation of regional lung function and mechanics, with a uniquely high spatial resolution. An example of non-uniform volume distribution in rabbit lung following histamine inhalation is presented.

  19. Non-contact type time-domain fluorescence diffuse optical tomography for quantitative analysis of fluorophores

    NASA Astrophysics Data System (ADS)

    Nishimura, Goro; Furukawa, Daisuke; Awasthi, Kamlesh

    2013-03-01

    A non-contact type time-domain system for the fluorescence diffuse optical tomography was designed. The system is evaluated by a phantom with a fluorescence target. The contamination of the non-specific scattering superimposed on the excitation profile but it could be reduced with closely locating the detection fiber to the surface (~1 mm). Next, we analyzed the contamination in the temporal profiles with an Intralipid solution phantom with a fluorescent target. The contamination to the excitation profile is not clearly observed but that to the fluorescence is strong with a short distance between the excitation source and detection. Finally, we have concluded that a larger distance of source and detector yields better fluorescence sensitivity because the background is limiting the fluorescence detection. On the other hand, the signal quality depends on the statistics and thus the optimum range of the distance comes around 30 mm. Finally, this research gives the idea for the design of the source and detection configuration.

  20. In vivo quantitative imaging of normal and cancerous breast tissue using broadband diffuse optical tomography

    PubMed Central

    Wang, Jia; Jiang, Shudong; Li, Zhongze; diFlorio-Alexander, Roberta M.; Barth, Richard J.; Kaufman, Peter A.; Pogue, Brian W.; Paulsen, Keith D.

    2010-01-01

    Purpose: A NIR tomography system that combines frequency domain (FD) and continuous wave (CW) measurements was used to image normal and malignant breast tissues. Methods: FD acquisitions were confined to wavelengths less than 850 nm because of detector limitations, whereas light from longer wavelengths (up to 948 nm) was measured in CW mode with CCD-coupled spectrometer detection. The two data sets were combined and processed in a single spectrally constrained reconstruction to map concentrations of hemoglobin, water, and lipid, as well as scattering parameters in the breast. Results: Chromophore concentrations were imaged in the breasts of nine asymptomatic volunteers to evaluate their intrasubject and intersubject variability. Normal subject data showed physiologically expected trends. Images from three cancer patients indicate that the added CW data is critical to recovering the expected increases in water and decreases in lipid content within malignancies. Contrasts of 1.5 to twofold in hemoglobin and water values were found in cancers. Conclusions:In vivo breast imaging with instrumentation that combines FD and CW NIR data acquisition in a single spectral reconstruction produces more accurate hemoglobin, water, and lipid results relative to FD data alone. PMID:20831079

  1. Quantitative Computer Tomography for Determining Composition of Microgravity and Ground Based Solid Solutions

    NASA Technical Reports Server (NTRS)

    Gillies, D. C.; Engel, H. P.

    1999-01-01

    Advances in x-ray Computer Tomography (CT) have been led by the medical profession, and by evaluation of industrial products, particularly castings. Porosity can readily be determined as a function of the density of a material, and CT is thus an industrially important NDE tool. Providing high purity, 100% dense standards of pure elements and compounds can be fabricated, the composition of solid solution alloys can be determined by measuring the CT number, which is a function of the absorption of the sample. Average densities across slices 1 mm thick can generally be determined to better than 1 percent. With present technology this spatial sensitivity is less than ideal, but important benefits can nevertheless be obtained by using CT, particularly single crystals, prior to making any destructive assault upon the sample. The sample can in fact be examined prior to removal from the mold within which it has been grown and, in the cases of microgravity flight samples, before removal from the cartridge assembly. This greatly assists the researcher in the characterization of the products, particularly as a guide to cutting and sampling. Examples of work with germanium-silicon alloys and mercury cadmium telluride taken with a radioactive cobalt source will be demonstrated.

  2. Quantitative Computer Tomography for Determining Composition of Microgravity and Ground Based Solid Solutions

    NASA Technical Reports Server (NTRS)

    Gillies, D. C.; Engel, H. P.

    1999-01-01

    Advances in x-ray Computer Tomography (CT) have been led by the medical profession, and by evaluation of industrial products, particularly castings. Porosity can readily be determined as a function of the density of a material, and CT is thus an industrially important NDE tool. Providing high purity, 100% dense standards of pure elements and compounds can be fabricated, the composition of solid solution alloys can be determined by measuring the CT number, which is a function of the absorption of the sample. Average densities across slices 1 mm thick can generally be determined to better than 1 percent. With present technology this spatial sensitivity is less than ideal, but important benefits can nevertheless be obtained by using CT, particularly single crystals, prior to making any destructive assault upon the sample. The sample can in fact be examined prior to removal from the mold within which it has been grown and, in the cases of microgravity flight samples, before removal from the cartridge assembly. This greatly assists the researcher in the characterization of the products, particularly as a guide to cutting and sampling. Examples of work with germanium-silicon alloys and mercury cadmium telluride taken with a radioactive cobalt source will be demonstrated.

  3. Quantitation of translocator protein binding in human brain with the novel radioligand [18F]-FEPPA and positron emission tomography.

    PubMed

    Rusjan, Pablo M; Wilson, Alan A; Bloomfield, Peter M; Vitcu, Irina; Meyer, Jeffrey H; Houle, Sylvain; Mizrahi, Romina

    2011-08-01

    This article describes the kinetic modeling of [(18)F]-FEPPA binding to translocator protein 18 kDa in the human brain using high-resolution research tomograph (HRRT) positron emission tomography. Positron emission tomography scans were performed in 12 healthy volunteers for 180 minutes. A two-tissue compartment model (2-CM) provided, with no exception, better fits to the data than a one-tissue model. Estimates of total distribution volume (V(T)), specific distribution volume (V(S)), and binding potential (BP(ND)) demonstrated very good identifiability (based on coefficient of variation (COV)) for all the regions of interest (ROIs) in the gray matter (COV V(T)<7%, COV V(S)<8%, COV BP(ND)<11%). Reduction of the length of the scan to 2 hours is feasible as V(S) and V(T) showed only a small bias (6% and 7.5%, respectively). Monte Carlo simulations showed that, even under conditions of a 500% increase in specific binding, the identifiability of V(T) and V(S) was still very good with COV<10%, across high-uptake ROIs. The excellent identifiability of V(T) values obtained from an unconstrained 2-CM with data from a 2-hour scan support the use of V(T) as an appropriate and feasible outcome measure for [(18)F]-FEPPA.

  4. Quantitative measurement of blood velocity in zebrafish with optical vector field tomography.

    PubMed

    Fieramonti, Luca; Foglia, Efrem A; Malavasi, Stefano; D'Andrea, Cosimo; Valentini, Gianluca; Cotelli, Franco; Bassi, Andrea

    2015-01-01

    Microscopy techniques can readily visualize the finest details of embryo vasculature, but still lack to provide a complete three-dimensional representation of blood flow parameters. We present an in-vivo 3D imaging technique, able to reconstruct the blood cell velocity vector over a large volume of zebrafish embryos. This low cost and relatively simple technique is exploited to quantitatively assess blood velocity in the zebrafish tail at different stages of development. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Quantification of mitral regurgitation on cardiac computed tomography: comparison with qualitative and quantitative echocardiographic parameters.

    PubMed

    Arnous, Samer; Killeen, Ronan P; Martos, Ramon; Quinn, Martin; McDonald, Kenneth; Dodd, Jonathan Dermot

    2011-01-01

    To assess whether cardiac computed tomographic angiography (CCTA) can quantify the severity of chronic mitral regurgitation (MR) compared to qualitative and quantitative echocardiographic parameters. Cardiac computed tomographic angiography was performed in 23 patients (mean ± SD age, 63 ± 16 years; range, 24-86 years) with MR and 20 patients without MR (controls) as determined by transthoracic echocardiography. Multiphasic reconstructions (20 data sets reconstructed at 5% increments of the electrocardiographic gated R-R interval) were used to analyze the mitral valve. Using CCTA planimetry, 2 readers measured the regurgitant mitral orifice area (CCTA ROA) during systole. A qualitative echocardiographic assessment of severity of MR was made by visual assessment of the length of the regurgitant jet. Quantitative echocardiographic measurements included the vena contracta, proximal isovelocity surface area, regurgitant volume, and estimated regurgitant orifice (ERO). Comparisons were performed using the independent t test, and correlations were assessed using the Spearman rank test. All controls and the patients with MR were correctly identified by CCTA. For patients with mild, moderate, or severe MR, mean ± SD EROs were 0.16 ± 0.03, 0.31 ± 0.08, and 0.52 ± 0.03 cm² (P < 0.0001) compared with mean ± SD CCTA ROAs 0.09 ± 0.05, 0.30 ± 0.04, and 0.97 ± 0.26 cm² (P < 0.0001), respectively. When echocardiographic measurements were graded qualitatively as mild, moderate, or severe, strong correlations were seen with CCTA ROA (R = 0.89; P < 0.001). When echocardiographic measurements were graded quantitatively, the vena contracta and the ERO showed modest correlations with CCTA ROA (0.48 and 0.50; P < 0.05 for both). Neither the proximal isovelocity surface area nor the regurgitant volume demonstrated significant correlations with CCTA ROA. Single-source 64-slice CCTA provides a strong agreement with qualitative echocardiographic parameters but only a moderate

  6. Quantitative analysis applied to contrast medium extravasation by using the computed-tomography number within the region of interest

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Seung; Im, In-Chul; Kim, Moon-Jib; Goo, Eun-Hoe; Kim, Sun-Ju; Kim, Kwang; Kwak, Byung-Joon

    2014-02-01

    The present study was carried out to present a method to analyze extravasation quantitatively by measuring the computed tomography (CT) number after determining the region of interest (ROI) in the CT images obtained from patients suspected of extravasation induced by contrast medium auto-injection. To achieve this, we divided the study subjects into a group of patients who incurred extravasation and a group of patients who underwent routine scans without incurring extravasation. The CT numbers at IV sites were obtained as reference values, and CT numbers at extravasation sites and hepatic portal veins, respectively, were obtained as relative values. Thereupon, the predicted time for extravasation ( T EP ) and the predicted ratio for extravasation ( R EP ) of an extravasation site were obtained and analyzed quantitatively. In the case of extravasation induced by a dual auto-injector, the values of the CT numbers were confirmed to be lower and the extravasation site to be enlarged when compared to the extravasation induced by a single autoinjector. This is because the physiological saline introduced after the injection of the contrast agent diluted the concentration of the extravasated contrast agent. Additionally, the T EP caused by the auto-injector was about 40 seconds, and we could perform a precise quantitative assessment of the site suspected of extravasation. In conclusion, the dual auto-injection method, despite its advantage of reducing the volume of contrast agent and improving the quality of images for patients with good vascular integrity, was judged to be likely to increase the risk of extravasation and aggravate outcomes for patients with poor vascular integrity by enlarging extravasation sites.

  7. Quantitative Computed Tomography Features for Predicting Tumor Recurrence in Patients with Surgically Resected Adenocarcinoma of the Lung

    PubMed Central

    Shim, Woo Hyun; Xu, Hai; Choi, Chang-Min; Kim, Hyeong Ryul; Lee, Jung Bok

    2017-01-01

    Purpose The purpose of this study was to determine if preoperative quantitative computed tomography (CT) features including texture and histogram analysis measurements are associated with tumor recurrence in patients with surgically resected adenocarcinoma of the lung. Methods The study included 194 patients with surgically resected lung adenocarcinoma who underwent preoperative CT between January 2013 and December 2013. Quantitative CT feature analysis of the lung adenocarcinomas were performed using in-house software based on plug-in package for ImageJ. Ten quantitative features demonstrating the tumor size, attenuation, shape and texture were extracted. The CT parameters obtained from 1-mm and 5-mm data were compared using intraclass correlation coefficients. Univariate and multivariable logistic regression methods were used to investigate the association between tumor recurrence and preoperative CT findings. Results The 1-mm and 5-mm data were highly correlated in terms of diameter, perimeter, area, mean attenuation and entropy. Circularity and aspect ratio were moderately correlated. However, skewness and kurtosis were poorly correlated. Multivariable logistic regression analysis revealed that area (odds ratio [OR], 1.002 for each 1-mm2 increase; P = 0.003) and mean attenuation (OR, 1.005 for each 1.0-Hounsfield unit increase; P = 0.022) were independently associated with recurrence. The receiver operating curves using these two independent predictive factors showed high diagnostic performance in predicting recurrence (C-index = 0.81, respectively). Conclusion Tumor area and mean attenuation are independently associated with recurrence in patients with surgically resected adenocarcinoma of the lung. PMID:28068363

  8. Flat-Panel Versus 64-Channel Computed Tomography for In Vivo Quantitative Characterization of Aortic Atherosclerotic Plaques

    PubMed Central

    Aboshady, Ibrahim; Cody, Dianna D.; Johnson, Evan M.; Gahremanpour, Amir; Vela, Deborah; Khalil, Kamal G.; DuPont, Herbert L.; Willerson, James T.; Buja, L. Maximilian; Gladish, Gregory W.

    2010-01-01

    Background Flat-panel computed tomography (FpCT) provides better spatial resolution than 64-channel CT (64-CT) and may improve in vivo quantitative assessment of atherosclerotic plaques. Methods and Results Lesions in 184 aortic histology sections from 6 Watanabe heritable hyperlipidemic rabbits were quantitatively compared with 64-CT (image thickness, 0.625 mm) and FpCT (image thickness, 0.150 mm) images. Images were re-oriented perpendicular to the vessel centerline. For detecting plaque, FpCT and 64-CT were not significantly different (sensitivity, 76 % vs 66%; P=NS). Although FpCT was significantly more sensitive (42 % vs 0%; P<0.001) for detecting eccentric lesions, the area under the curve (AUC) for FpCT (0.6) was not significantly different from that for 64-CT (0.45; P=NS). In detecting plaques with ≤10% lipid (low attenuation foci), FpCT was significantly more sensitive than 64-CT (24% vs 0.7%; P<0.01) and had a significantly greater AUC (0.6 vs 0.5; P<0.006). Additionally, FpCT was more sensitive (65% vs 0%; P<0.01) in detecting plaques with ≤5% calcium (high attenuation foci) but not in detecting branch points. Both FpCT and histology allowed us to detect low-attenuation foci as small as 0.3 mm in diameter, whereas 64-CT allowed us to detect only low-attenuation foci ≥1.5 mm in diameter. Conclusions Flat-panel CT seemed to have more potential for quantitative screening low-risk small atherosclerotic lesions, whereas 64-CT was apparently more useful when imaging established, well-characterized lesions particularly when measuring the vascular wall thickness in a rabbit model of atherosclerosis. PMID:21185613

  9. Flat-panel versus 64-channel computed tomography for in vivo quantitative characterization of aortic atherosclerotic plaques.

    PubMed

    Aboshady, Ibrahim; Cody, Dianna D; Johnson, Evan M; Gahremanpour, Amir; Vela, Deborah; Khalil, Kamal G; Dupont, Herbert L; Willerson, James T; Buja, L Maximilian; Gladish, Gregory W

    2012-05-03

    Flat-panel computed tomography (FpCT) provides better spatial resolution than 64-channel CT (64-CT) and may improve in vivo quantitative assessment of atherosclerotic plaques. Lesions in 184 aortic histology sections from 6 Watanabe heritable hyperlipidemic rabbits were quantitatively compared with 64-CT (image thickness, 0.625 mm) and FpCT (image thickness, 0.150 mm) images. Images were re-oriented perpendicular to the vessel centerline. For detecting plaque, FpCT and 64-CT were not significantly different (sensitivity, 76% vs 66%; P=NS). Although FpCT was significantly more sensitive (42% vs 0%; P=<0.001) for detecting eccentric lesions, the area under the curve (AUC) for FpCT (0.6) was not significantly different from that for 64-CT (0.45; P=NS). In detecting plaques with ≤ 10% lipid (low attenuation foci), FpCT was significantly more sensitive than 64-CT (24% vs 0.7%; P<0.00) and had a significantly greater AUC (0.6 vs 0.5; P<0.006). Additionally, FpCT was more sensitive (65% vs 0%; P<0.00) in detecting plaques with ≤ 5% calcium (high attenuation foci) but not in detecting branch points. Both FpCT and histology allowed us to detect low-attenuation foci as small as 0.3mm in diameter, whereas 64-CT allowed us to detect only low-attenuation foci ≥ 1.5mm in diameter. Flat-panel CT seemed to have more potential for quantitatively screening low-risk small atherosclerotic lesions, whereas 64-CT was apparently more useful when imaging established, well-characterized lesions, particularly when measuring the vascular wall thickness in a rabbit model of atherosclerosis. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  10. Experimental investigation of target and transducer effects on quantitative image reconstruction in photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Gamelin, John K.; Aguirre, Andres C.; Huang, Fei; Maurudis, Anastasios; Castillo, Diego; Wang, Lihong V.; Zhu, Quing

    2007-02-01

    In principle, absorbed energy profiles can be exactly reconstructed from photoacoustic measurements on a closed surface. Clinical applications, however, involve compromises due to transducer focus, frequency characteristics, and incomplete measurement apertures. These tradeoffs introduce artifacts and errors in reconstructed absorption distributions that affect quantitative interpretations as well as qualitative contrast between features. The quantitative effects of target geometry, limited measurement surfaces, and bandpass transducer frequency response have been investigated using a ring transducer system designed for small animal imaging. The directionality of photoacoustic radiation is shown to increase with target aspect ratio, producing proportionate overestimates of absorption values for two-dimension apertures less than approximately 150 degrees. For all target geometries and orientations, mean absorption values approach the full view values for hemicircular measurement surfaces although the true spatial uniformity is recovered only with the complete surface. The bandpass transducer frequency spectrum produces a peaked amplitude response biased toward spatial features ranging from 1 to 8 times the system resolution. We discuss the implications of these results for design of clinical systems.

  11. Quantitative 3D petrography using X-ray tomography 2: Combining information at various resolutions

    SciTech Connect

    Pamukcu, Ayla S.; Gualda, Guilherme A.R.

    2010-12-02

    X-ray tomography is a nondestructive technique that can be used to study rocks and other materials in three dimensions over a wide range of sizes. Samples that range from decimeters to micrometers in size can be analyzed, and micrometer- to centimeter-sized crystals, vesicles, and other particles can be identified and quantified. In many applications, quantification of a large spectrum of sizes is important, but this cannot be easily accomplished using a single tomogram due to a common trade-off between sample size and image resolution. This problem can be circumvented by combining tomograms acquired for a single sample at a variety of resolutions. We have successfully applied this method to obtain crystal size distributions (CSDs) for magnetite, pyroxene + biotite, and quartz + feldspar in Bishop Tuff pumice. Five cylinders of systematically varying size (1-10 mm diameter and height) were analyzed from each of five pumice clasts. Cylinder size is inversely proportional to image resolution, such that resolution ranges from 2.5 to 17 {micro}m/voxel with increasing sample size. This allows quantification of crystals 10-1000 {micro}m in size. We obtained CSDs for each phase in each sample by combining information from all resolutions, each size bin containing data from the resolution that best characterizes crystals of that size. CSDs for magnetite and pyroxene + biotite in late-erupted Bishop pumice obtained using this method are fractal, but do not seem to result from crystal fragmentation. CSDs for quartz + feldspar reveal a population of abundant crystals <35 {micro}m in size, and a population of crystals >50 {micro}m in size, which will be the focus of a separate publication.

  12. Quantitative Analyses of Pediatric Cervical Spine Ossification Patterns Using Computed Tomography

    PubMed Central

    Yoganandan, Narayan; Pintar, Frank A.; Lew, Sean M.; Rao, Raj D.; Rangarajan, Nagarajan

    2011-01-01

    The objective of the present study was to quantify ossification processes of the human pediatric cervical spine. Computed tomography images were obtained from a high resolution scanner according to clinical protocols. Bone window images were used to identify the presence of the primary synchondroses of the atlas, axis, and C3 vertebrae in 101 children. Principles of logistic regression were used to determine probability distributions as a function of subject age for each synchondrosis for each vertebra. The mean and 95% upper and 95% lower confidence intervals are given for each dataset delineating probability curves. Posterior ossifications preceded bilateral anterior closures of the synchondroses in all vertebrae. However, ossifications occurred at different ages. Logistic regression results for closures of different synchondrosis indicated p-values of <0.001 for the atlas, ranging from 0.002 to <0.001 for the axis, and 0.021 to 0.005 for the C3 vertebra. Fifty percent probability of three, two, and one synchondroses occurred at 2.53, 6.97, and 7.57 years of age for the atlas; 3.59, 4.74, and 5.7 years of age for the axis; and 1.28, 2.22, and 3.17 years of age for the third cervical vertebrae, respectively. Ossifications occurring at different ages indicate non-uniform maturations of bone growth/strength. They provide an anatomical rationale to reexamine dummies, scaling processes, and injury metrics for improved understanding of pediatric neck injuries PMID:22105393

  13. Quantitative evaluation of anatomical noise in chest digital tomosynthesis, digital radiography, and computed tomography

    NASA Astrophysics Data System (ADS)

    Lee, D.; Choi, S.; Lee, H.; Kim, D.; Choi, S.; Kim, H.-J.

    2017-04-01

    Lung cancer is currently the worldwide leading cause of death from cancer. Thus, detection of lung cancer at its early stages is critical for improving the survival rate of patients. Chest digital tomosynthesis (CDT) is a recently developed imaging modality, combining many advantages of digital radiography (DR) and computed tomography (CT). This method has the potential to be widely used in the clinical setting. In this study, we introduce a developed CDT R/F system and compare its image quality with those of DR and CT, especially with respect to anatomical noise and lung nodule conspicuity, for LUNGMAN phantoms. The developed CDT R/F system consists of a CsI scintillator flat panel detector, X-ray tube, and tomosynthesis data acquisition geometry. For CDT R/F imaging, 41 projections were acquired at different angles, over the ± 20° angular range, in a linear translation geometry. To evaluate the clinical effectiveness of the CDT R/F system, the acquired images were compared with CT (Philips brilliance CT 64, Philips healthcare, U.S.) and DR (ADR-M, LISTEM, Korea) phantom images in terms of the anatomical noise power spectrum (aNPS). DR images exhibited low conspicuity for a small-size lung nodule, while CDT R/F and CT exhibited relatively high sensitivity for all lung nodule sizes. The aNPS of the CDT R/F system was better than that of DR, by resolving anatomical overlapping problems. In conclusion, the developed CDT R/F system is likely to contribute to early diagnosis of lung cancer, while requiring a relatively low patient dose, compared with CT.

  14. Quantitative analysis of high-resolution computed tomography scans in severe asthma subphenotypes

    PubMed Central

    Gupta, Sumit; Siddiqui, Salman; Haldar, Pranab; Entwisle, James J; Mawby, Dean; Wardlaw, Andrew J; Bradding, Peter; Pavord, Ian D; Green, Ruth H

    2010-01-01

    Background Severe asthma is a heterogeneous condition. Airway remodelling is a feature of severe asthma and can be determined by the assessment of high-resolution computed tomography (HRCT) scans. The aim of this study was to assess whether airway remodelling is restricted to specific subphenotypes of severe asthma. Methods A retrospective analysis was performed of HRCT scans from subjects who had attended a single-centre severe asthma clinic between 2003 and 2008. The right upper lobe apical segmental bronchus (RB1) dimensions were measured and the clinical and sputum inflammatory characteristics associated with RB1 geometry were assessed by univariate and multivariate regression analyses. Longitudinal sputum data were available and were described as area under the time curve (AUC). Comparisons were made in RB1 geometry across subjects in four subphenotypes determined by cluster analysis, smokers and non-smokers, and subjects with and without persistent airflow obstruction. Results Ninety-nine subjects with severe asthma and 16 healthy controls were recruited. In the subjects with severe asthma the RB1 percentage wall area (%WA) was increased (p=0.009) and lumen area (LA)/body surface area (BSA) was decreased (p=0.008) compared with controls but was not different across the four subphenotypes. Airway geometry was not different between smokers and non-smokers and RB1 %WA was increased in those with persistent airflow obstruction. RB1 %WA in severe asthma was best associated with airflow limitation and persistent neutrophilic airway inflammation (model R2=0.27, p=0.001). Conclusions Airway remodelling of proximal airways occurs in severe asthma and is associated with impaired lung function and neutrophilic airway inflammation. PMID:20805170

  15. Quantitative wood–adhesive penetration with X-ray computed tomography

    SciTech Connect

    Paris, Jesse L.; Kamke, Frederick A.

    2015-09-01

    Micro X-ray computed tomography (XCT) was used to analyze the 3D adhesive penetration behavior of different wood–adhesive bondlines. Three adhesives, a phenol formaldehyde (PF), a polymeric diphenylmethane diisocyanate (pMDI), and a hybrid polyvinyl acetate (PVA), all tagged with iodine for enhanced X-ray attenuation, were used to prepare single-bondline laminates in two softwoods, Douglas-fir and loblolly pine, and one hardwood, a hybrid polar. Adhesive penetration depth was measured with two separate calculations, and results were compared with 2D fluorescent micrographs. A total of 54 XCT scans were collected, representing six replicates of each treatment type; each replicate, however, consisted of approximately 1500 individual, cross-section slices stacked along the specimen length. As these adhesives were highly modified, the presented results do not indicate typical behavior for their broader adhesive classes. Still, clear penetration differences were observed between each adhesive type, and between wood species bonded with both the PF and pMDI adhesives. Furthermore, penetration results depended on the calculation method used. Two adhesive types with noticeably different resin distributions in the cured bondline, showed relatively similar penetration depths when calculated with a traditional effective penetration equation. However, when the same data was calculated with a weighted penetration calculation, which accounts for both adhesive area and depth, the results appeared to better represent the different distributions depicted in the photomicrographs and tomograms. Additionally, individual replicate comparisons showed variation due to specimen anatomy, not easily observed or interpreted from 2D images. Finally, 3D views of segmented 3D adhesive phases offered unique, in-situ views of the cured adhesive structures. In particular, voids formed by CO2 bubbles generated during pMDI cure were clearly visible in penetrated columns of the solidified

  16. Quantitative Fourier Domain Optical Coherence Tomography Imaging of the Ocular Anterior Segment

    NASA Astrophysics Data System (ADS)

    McNabb, Ryan Palmer

    Clinical imaging within ophthalmology has had transformative effects on ocular health over the last century. Imaging has guided clinicians in their pharmaceutical and surgical treatments of macular degeneration, glaucoma, cataracts and numerous other pathologies. Many of the imaging techniques currently used are photography based and are limited to imaging the surface of ocular structures. This limitation forces clinicians to make assumptions about the underlying tissue which may reduce the efficacy of their diagnoses. Optical coherence tomography (OCT) is a non-invasive, non-ionizing imaging modality that has been widely adopted within the field of ophthalmology in the last 15 years. As an optical imaging technique, OCT utilizes low-coherence interferometry to produce micron-scale three-dimensional datasets of a tissue's structure. Much of the human body consists of tissues that significantly scatter and attenuate optical signals limiting the imaging depth of OCT in those tissues to only 1-2mm. However, the ocular anterior segment is unique among human tissue in that it is primarily transparent or translucent. This allows for relatively deep imaging of tissue structure with OCT and is no longer limited by the optical scattering properties of the tissue. This goal of this work is to develop methods utilizing OCT that offer the potential to reduce the assumptions made by clinicians in their evaluations of their patients' ocular anterior segments. We achieved this by first developing a method to reduce the effects of patient motion during OCT volume acquisitions allowing for accurate, three dimensional measurements of corneal shape. Having accurate corneal shape measurements then allowed us to determine corneal spherical and astigmatic refractive contribution in a given individual. This was then validated in a clinical study that showed OCT better measured refractive change due to surgery than other clinical devices. Additionally, a method was developed to combine

  17. Recent advances in 3D computed tomography techniques for simulation and navigation in hepatobiliary pancreatic surgery.

    PubMed

    Uchida, Masafumi

    2014-04-01

    A few years ago it could take several hours to complete a 3D image using a 3D workstation. Thanks to advances in computer science, obtaining results of interest now requires only a few minutes. Many recent 3D workstations or multimedia computers are equipped with onboard 3D virtual patient modeling software, which enables patient-specific preoperative assessment and virtual planning, navigation, and tool positioning. Although medical 3D imaging can now be conducted using various modalities, including computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and ultrasonography (US) among others, the highest quality images are obtained using CT data, and CT images are now the most commonly used source of data for 3D simulation and navigation image. If the 2D source image is bad, no amount of 3D image manipulation in software will provide a quality 3D image. In this exhibition, the recent advances in CT imaging technique and 3D visualization of the hepatobiliary and pancreatic abnormalities are featured, including scan and image reconstruction technique, contrast-enhanced techniques, new application of advanced CT scan techniques, and new virtual reality simulation and navigation imaging.

  18. Design and simulation of superconducting Lorentz Force Electrical Impedance Tomography (LFEIT)

    NASA Astrophysics Data System (ADS)

    Shen, Boyang; Fu, Lin; Geng, Jianzhao; Zhang, Xiuchang; Zhang, Heng; Dong, Qihuan; Li, Chao; Li, Jing; Coombs, T. A.

    2016-05-01

    Lorentz Force Electrical Impedance Tomography (LFEIT) is a hybrid diagnostic scanner with strong capability for biological imaging, particularly in cancer and haemorrhages detection. This paper presents the design and simulation of a novel combination: a superconducting magnet together with LFEIT system. Superconducting magnets can generate magnetic field with high intensity and homogeneity, which could significantly enhance the imaging performance. The modelling of superconducting magnets was carried out using Finite Element Method (FEM) package, COMSOL Multiphysics, which was based on Partial Differential Equation (PDE) model with H-formulation coupling B-dependent critical current density and bulk approximation. The mathematical model for LFEIT system was built based on the theory of magneto-acoustic effect. The magnetic field properties from magnet design were imported into the LFEIT model. The basic imaging of electrical signal was developed using MATLAB codes. The LFEIT model simulated two samples located in three different magnetic fields with varying magnetic strength and homogeneity.

  19. Simultaneous multivessel coronary artery spasm demonstrated by quantitative analysis of thallium-201 single photon emission computed tomography

    SciTech Connect

    Kugiyama, K.; Yasue, H.; Okumura, K.; Minoda, K.; Takaoka, K.; Matsuyama, K.; Kojima, A.; Koga, Y.; Takahashi, M.

    1987-11-01

    Thallium-201 myocardial scintigraphy with quantitative analysis of emission computed tomography was performed during episodes of angina in 19 patients with variant angina and nearly normal coronary arteriographic findings. Eleven patients (group I) were shown by arteriography to have spasm in 2 or more large coronary arteries. Eight patients (group II) had spasm in only 1 coronary artery. In 7 patients in group I, significant diffuse perfusion defects simultaneously appeared in multiple coronary artery regions on the scintigram (group IA). The extent and severity of the perfusion defect as measured by thallium-201 tomography were significantly greater in group IA than in group II (p less than 0.001 and p less than 0.01, respectively). The duration of transient ST-segment elevation during the attack in group IA was significantly longer than in group II (p less than 0.001). The incidence of ventricular arrhythmias, including ventricular tachycardia, or complete atrioventricular block during the anginal attack was significantly higher (p less than 0.05) in group IA than in group II. In all study patients, neither attack nor scintigraphic perfusion defect appeared on the repeat test after oral administration of nifedipine. In conclusion, multivessel coronary artery spasm simultaneously appears and causes the attack in many patients with variant angina and nearly normal coronary arteriographic findings, and myocardial ischemia due to simultaneous multivessel coronary spasm is likely to be more extensive and severe, persist longer and have a higher frequency of potentially dangerous arrhythmias than that due to spasm of only 1 coronary artery.

  20. Evaluation of Quantitative Computed Tomography Cortical Hip Quadrant in a Clinical Trial With Rosiglitazone: A Potential New Study Endpoint.

    PubMed

    Miller, Colin G; Bogado, Cesar C; Nino, Antonio J; Northcutt, Allison R; Yu, Hui Jing; Lewiecki, E Michael; Paul, G; Cobitz, Alexander R; Wooddell, Margaret J; Bilezikian, John P; Fitzpatrick, Lorraine A

    2016-10-01

    Quantitative computed tomography (QCT) measurements have been used extensively to ascertain information about bone quality and density due to the 3-dimensional information provided and the ability to segment out trabecular and cortical bones. QCT imaging helps to improve our understanding of the role that each bone compartment plays in the pathogenesis and prognosis of fracture. This study was conducted to explore longitudinal changes in femoral neck (FN) cortical bone structure using both volumetric bone mineral density (vBMD) and cortical shell thickness assessments via QCT in a double-blind, randomized, multicenter clinical trial in postmenopausal women with type 2 diabetes mellitus. This study also examined whether treatment-associated changes in the cortical bone vBMD and thickness in femoral neck quadrants could be evaluated. Subjects were randomized to rosiglitazone (RSG) or metformin (MET) for 52 wk followed by 24 wk of open-label MET. A subset of 87 subjects underwent QCT scans of the hip at baseline, after 52 wk of double-blind treatment, and after 24 wk of treatment with MET using standard full-body computed tomography scanners. All scans were evaluated and analyzed centrally. Cortical vBMD at the FN was precisely segmented from trabecular bone and used to assess a possible therapeutic effect on this bone compartment. QCT analysis showed reductions in adjusted mean percentage change in vBMD and in absolute cortical thickness occurred with RSG treatment from baseline to week 52, whereas changes with MET were generally minimal. The reductions observed during RSG treatment for 1 yr appeared to partially reverse during the open-label MET phase from weeks 52 to 76. The femoral neck quadrant may provide utility as a potential endpoint in clinical trials for the understanding of the therapeutic effect of new entities on cortical bone vs trabecular bone; however, further clinical validation is needed.

  1. Qualitative and quantitative interpretation of computed tomography of the lungs in healthy neonatal foals.

    PubMed

    Lascola, Kara M; O'Brien, Robert T; Wilkins, Pamela A; Clark-Price, Stuart C; Hartman, Susan K; Mitchell, Mark A

    2013-09-01

    To qualitatively describe lung CT images obtained from sedated healthy equine neonates (≤ 14 days of age), use quantitative analysis of CT images to characterize attenuation and distribution of gas and tissue volumes within the lungs, and identify differences between lung characteristics of foals ≤ 7 days of age and foals > 7 days of age. 10 Standardbred foals between 2.5 and 13 days of age. Foals were sedated with butorphanol, midazolam, and propofol and positioned in sternal recumbency for thoracic CT. Image analysis software was used to exclude lung from nonlung structures. Lung attenuation was measured in Hounsfield units (HU) for analysis of whole lung and regional changes in attenuation and lung gas and tissue components. Degree of lung attenuation was classified as follows: hyperinflated or emphysema, -1,000 to -901 HU; well aerated, -900 to -501 HU; poorly aerated, -500 to -101 HU; and nonaerated, > -100 HU. Qualitative evidence of an increase in lung attenuation and patchy alveolar patterns in the ventral lung region were more pronounced in foals ≤ 7 days of age than in older foals. Quantitative analysis revealed that mean ± SD lung attenuation was greater in foals ≤ 7 days of age (-442 ± 28 HU) than in foals > 7 days of age (-521 ± 24 HU). Lung aeration and gas volumes were lower than in other regions ventrally and in the mid lung region caudal to the heart. CONCLUSIONS AND CLINICAL RELEVANCE-Identified radiographic patterns and changes in attenuation were most consistent with atelectasis and appeared more severe in foals ≤ 7 days of age than in older neonatal foals. Recognition of these changes may have implications for accurate CT interpretation in sedated neonatal foals with pulmonary disease.

  2. Magnetoacoustic tomography with magnetic induction (MAT-MI) for breast tumor imaging: numerical modeling and simulation

    NASA Astrophysics Data System (ADS)

    Zhou, Lian; Li, Xu; Zhu, Shanan; He, Bin

    2011-04-01

    Magnetoacoustic tomography with magnetic induction (MAT-MI) was recently introduced as a noninvasive electrical conductivity imaging approach with high spatial resolution close to ultrasound imaging. In this study, we test the feasibility of the MAT-MI method for breast tumor imaging using numerical modeling and computer simulation. Using the finite element method, we have built three-dimensional numerical breast models with varieties of embedded tumors for this simulation study. In order to obtain an accurate and stable forward solution that does not have numerical errors caused by singular MAT-MI acoustic sources at conductivity boundaries, we first derive an integral forward method for calculating MAT-MI acoustic sources over the entire imaging volume. An inverse algorithm for reconstructing the MAT-MI acoustic source is also derived with spherical measurement aperture, which simulates a practical setup for breast imaging. With the numerical breast models, we have conducted computer simulations under different imaging parameter setups and all the results suggest that breast tumors that have large conductivity in contrast to the surrounding tissue as reported in the literature may be readily detected in the reconstructed MAT-MI images. In addition, our simulations also suggest that the sensitivity of imaging breast tumors using the presented MAT-MI setup depends more on the tumor location and the conductivity contrast between the tumor and its surrounding tissue than on the tumor size.

  3. Optical Coherence Tomography for Quantitative Assessment of Microstructural and Microvascular Alterations in Late Oral Radiation Toxicity

    NASA Astrophysics Data System (ADS)

    Davoudi, Bahar

    More than half of head-and-neck cancer patients undergo radiotherapy at some point during their treatment. Even though the use of conformed therapeutic beams has increased radiation dose localization to the tumor, resulting in more normal tissue sparing, still, in many head-and-neck cancer patients, the healthy tissue of the oral cavity still receives a sizeable amount of radiation. This causes acute and / or late complications in these patients. The latter occur as late as several months or even years after the completion of treatment and are typically associated with severe symptoms. Currently, the clinical method for diagnosing these complications is visual examination of the oral tissue surface. However, it has been well established that such complications originate in subsurface oral tissue layers including its microvasculature. Therefore, to better understand the mechanism of these complications and to be able to diagnose them earlier, there exists a need for subsurface monitoring of the irradiated oral tissue. Histology has been used as such a tool for research purposes; however, its use in clinical diagnosis is limited due to its invasive and hazardous nature. Therefore, in this thesis, I propose to use optical coherence tomography (OCT) as a subsurface, micron-scale resolution optical imaging tool that can provide images of oral tissue subsurface layers down to a depth of 1-2 mm (structural OCT), as well as images demonstrating vessel morphology (speckle variance OCT) and blood flow information (Doppler OCT). This thesis explains the development of an OCT setup and an oral probe to acquire images in-vivo. Moreover, it introduces a software-based quantification platform for extracting specific biologically-meaningful metrics from the structural and vascular OCT images. It then describes the application of the developed imaging and quantification platform in a feasibility clinical study that was performed on 15 late oral radiation toxicity patients and 5 age

  4. Exploring the utility of high resolution "nano-" computed tomography imaging to place quantitative constraints on shell biometric changes in marine pteropods in response to ocean acidification

    NASA Astrophysics Data System (ADS)

    Eagle, R.; Howes, E.; Lischka, S.; Rudolph, R.; Büdenbender, J.; Bijma, J.; Gattuso, J. P.; Riebesell, U.

    2014-12-01

    Understanding and quantifying the response of marine organisms to present and future ocean acidification remains a major challenge encompassing observations on single species in culture and scaling up to the ecosystem and global scale. Understanding calcification changes in culture experiments designed to simulate present and future ocean conditions under potential CO2 emissions scenarios, and especially detecting the likely more subtle changes that may occur prior to the onset of more extreme ocean acidification, depends on the tools available. Here we explore the utility of high-resolution computed tomography (nano-CT) to provide quantitative biometric data on field collected and cultured marine pteropods, using the General Electric Company Phoenix Nanotom S Instrument. The technique is capable of quantitating the whole shell of the organism, allowing shell dimensions to be determined as well as parameters such as average shell thickness, the variation in thickness across the whole shell and in localized areas, total shell volume and surface area and when combined with weight measurements shell density can be calculated. The potential power of the technique is the ability to derive these parameters even on very small organisms less than 1 millimeter in size. Tuning the X-ray strength of the instrument allows organic material to be excluded from the analysis. Through replicate analysis of standards, we assess the reproducibility of data, and by comparison with dimension measurements derived from light microscopy we assess the accuracy of dimension determinations. We present results from historical and modern pteropod populations from the Mediterranean and cultured polar pteropods, resolving statistically significant differences in shell biometrics in both cases that may represent responses to ocean acidification.

  5. Developing multifunctional tissue simulating phantoms for quantitative biomedical optical imaging

    NASA Astrophysics Data System (ADS)

    Xu, Ronald; Xu, Jeff; Qin, Ruogu; Huang, Jiwei

    2010-02-01

    Many advantages of biomedical optical imaging modalities include low cost, portability, no radiation hazard, molecular sensitivity, and real-time non-invasive measurements of multiple tissue parameters. However, clinical acceptance of optical imaging is hampered by the lack of calibration standards and validation techniques. In this context, developing phantoms that simulate tissue structural, functional, and molecular properties is important for reliable performance and successful translation of biomedical optical imaging techniques to clinical applications. Over the years, we have developed various tissue simulating phantoms to validate imaging algorithms, to optimize instrument performance, to test contrast agents, and to calibrate acquisition systems. We also developed phantoms with multimodal contrasts for co-registration between different imaging modalities. In order to study tissue dynamic changes during medical intervention, we develop gel wax phantoms to simulate tissue optical and mechanical dynamics in response to compression load. We also dispersed heat sensitive microbubbles in agar agar gel phantoms to simulate heatinduced tissue coagulative necrosis in a cancer ablation procedure. The phantom systems developed in our lab have the potential to provide standardized traceable tools for multimodal imaging and image-guided intervention.

  6. Direct reconstruction in CT-analogous pharmacokinetic diffuse fluorescence tomography: two-dimensional simulative and experimental validations

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Zhang, Yanqi; Zhang, Limin; Li, Jiao; Zhou, Zhongxing; Zhao, Huijuan; Gao, Feng

    2016-04-01

    We present a generalized strategy for direct reconstruction in pharmacokinetic diffuse fluorescence tomography (DFT) with CT-analogous scanning mode, which can accomplish one-step reconstruction of the indocyanine-green pharmacokinetic-rate images within in vivo small animals by incorporating the compartmental kinetic model into an adaptive extended Kalman filtering scheme and using an instantaneous sampling dataset. This scheme, compared with the established indirect and direct methods, eliminates the interim error of the DFT inversion and relaxes the expensive requirement of the instrument for obtaining highly time-resolved date-sets of complete 360 deg projections. The scheme is validated by two-dimensional simulations for the two-compartment model and pilot phantom experiments for the one-compartment model, suggesting that the proposed method can estimate the compartmental concentrations and the pharmacokinetic-rates simultaneously with a fair quantitative and localization accuracy, and is well suitable for cost-effective and dense-sampling instrumentation based on the highly-sensitive photon counting technique.

  7. Direct reconstruction in CT-analogous pharmacokinetic diffuse fluorescence tomography: two-dimensional simulative and experimental validations.

    PubMed

    Wang, Xin; Zhang, Yanqi; Zhang, Limin; Li, Jiao; Zhou, Zhongxing; Zhao, Huijuan; Gao, Feng

    2016-04-30

    We present a generalized strategy for direct reconstruction in pharmacokinetic diffuse fluorescence tomography (DFT) with CT-analogous scanning mode, which can accomplish one-step reconstruction of the indocyanine-green pharmacokinetic-rate images within in vivo small animals by incorporating the compartmental kinetic model into an adaptive extended Kalman filtering scheme and using an instantaneous sampling dataset. This scheme, compared with the established indirect and direct methods, eliminates the interim error of the DFT inversion and relaxes the expensive requirement of the instrument for obtaining highly time-resolved date-sets of complete 360 deg projections. The scheme is validated by two-dimensional simulations for the two-compartment model and pilot phantom experiments for the one-compartment model, suggesting that the proposed method can estimate the compartmental concentrations and the pharmacokinetic-rates simultaneously with a fair quantitative and localization accuracy, and is well suitable for cost-effective and dense-sampling instrumentation based on the highly-sensitive photon counting technique.

  8. Quantitative monitoring of subsurface CO2 emplacement and leakage using muon tomography

    NASA Astrophysics Data System (ADS)

    Coleman, M. L.; Kudryavtsev, V.; Spooner, N.; Gluyas, J.; Fung, C.

    2011-12-01

    Monitoring CO2 emplacement and possible leakage is a major challenge; methods, such as repeat seismic surveys, are episodic and expensive. A relevant alternative approach will use detection of cosmic ray muons, which has been used previously in archaeological and geological research as a technique for mapping features hidden underground. We developed a model to test if this concept would work for monitoring CO2 storage and show that muon detection is a viable method. To achieve this we used the well-established MUSUN/MUSIC computer codes to model changes in muon fluxes resulting from the introduction of supercritical CO2 into a simulated sandstone reservoir. Results from our first simulation indicate that we could detect as little as 0.4% change in the mean reservoir density at about 1 km depth, resulting from changing the relative proportions of CO2 and existing brine pore fluid. This change is equivalent to 7% of the pore volume in this particular case. However, other scenarios offer the promise of considerable increase in sensitivity. We will show how practical implementation can be achieved using state of the art drilling technology to place an array of detectors in short-radius side-track horizontal wells beneath the storage site. We conclude that with an appropriate design it will be possible to monitor and image the migration or loss of injected CO2 continuously using cosmic ray muons, a significant step towards implementing widescale CCS safely and help rapid introduction of this essential technology.

  9. In vivo quantitative evaluation of gold nanocages' kinetics in sentinel lymph nodes by photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Cai, Xin; Li, Weiyang; Kim, Chulhong; Yuan, Yuchen; Xia, Younan; Wang, Lihong V.

    2012-02-01

    As a new class of sentinel lymph node (SLN) tracers for photoacoustic (PA) imaging, Au nanocages offer the advantages of noninvasiveness, strong optical absorption in the near-infrared region (for deep penetration), and accumulation in higher concentrations than the initial injected solution. By monitoring the amplitude changes of PA signals in an animal model, we quantified the accumulations of nanocages in SLNs over time. Based on this method, we quantitatively evaluated the kinetics of gold nanocages in SLN in terms of concentration, size, and surface modification. We could detect the SLN at an Au nanocage injection concentration of 50 pM and a dose of 100 μL in vivo. This concentration is about 40 times less than the previously reported value. We also investigated the influence of nanocages' size (50 nm and 30 nm in edge length), and the effects of surface modification (with positive, or neutral, or negative surface charges). The results are helpful to develop this AuNC-based PA imaging system for noninvasive lymph node mapping, providing valuable information about metastatic cancer staging.

  10. Ultrahigh resolution optical coherence tomography for quantitative topographic mapping of retinal and intraretinal architectural morphology

    NASA Astrophysics Data System (ADS)

    Ko, Tony H.; Hartl, Ingmar; Drexler, Wolfgang; Ghanta, Ravi K.; Fujimoto, James G.

    2002-06-01

    Quantitative, three-dimensional mapping of retinal architectural morphology was achieved using an ultrahigh resolution ophthalmic OCT system. This OCT system utilizes a broad bandwidth titanium-sapphire laser light source generating bandwidths of up to 300 nm near 800 nm center wavelength. The system enables real-time cross-sectional imaging of the retina with ~3 micrometers axial resolution. The macula and the papillomacular axis of a normal human subject were systematically mapped using a series of linear scans. Edge detection and segmentation algorithms were developed to quantify retinal and intraretinal thicknesses. Topographic mapping of the total retinal thickness and the total ganglion cell/inner plexiform layer thickness was achieved around the macula. A topographic mapping quantifying the progressive thickening of the nerve fiber layer (NFL) nasally approaching the optic disk was also demonstrated. The ability to create three-dimensional topographic mapping of retinal architectural morphology at ~3 micrometers axial resolution will be relevant for the diagnosis of many retinal diseases. The topographic quantification of these structures can serve as a powerful tool for developing algorithms and clinical scanning protocols for the screening and staging of ophthalmic diseases such as glaucoma.

  11. Ultrasonic computed tomography based on full-waveform inversion for bone quantitative imaging

    NASA Astrophysics Data System (ADS)

    Bernard, Simon; Monteiller, Vadim; Komatitsch, Dimitri; Lasaygues, Philippe

    2017-09-01

    We introduce an ultrasonic quantitative imaging method for long bones based on full-waveform inversion. The cost function is defined as the difference in the L 2-norm sense between observed data and synthetic results at a given iteration of the iterative inversion process. For simplicity, and in order to reduce the computational cost, we use a two-dimensional acoustic approximation. The inverse problem is solved iteratively based on a quasi-Newton technique called the Limited-memory Broyden-Fletcher-Goldfarb-Shanno method. We show how the technique can be made to work fine for benchmark models consisting of a single cylinder, and then five cylinders, the latter case including significant multiple diffraction effects. We then show pictures obtained for a tibia-fibula bone pair model. Convergence is fast, typically in 15 to 30 iterations in practice in each frequency band used. We discuss the so-called ‘cycle skipping’ effect that can occur in such full waveform inversion techniques and make them remain trapped in a local minimum of the cost function. We illustrate strategies that can be used in practice to avoid this. Future work should include viscoelastic materials rather than acoustic, and real data instead of synthetic data.

  12. Quantitative analysis of rectal cancer by spectral domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Q. Q.; Wu, X. J.; Tang, T.; Zhu, S. W.; Yao, Q.; Gao, Bruce Z.; Yuan, X. C.

    2012-08-01

    To quantify OCT images of rectal tissue for clinic diagnosis, the scattering coefficient of the tissue is extracted by curve fitting the OCT signals to a confocal single model. A total of 1000 measurements (half and half of normal and malignant tissues) were obtained from 16 recta. The normal rectal tissue has a larger scattering coefficient ranging from 1.09 to 5.41 mm-1 with a mean value of 2.29 mm-1 (std:±0.32), while the malignant group shows lower scattering property and the values ranging from 0.25 to 2.69 mm-1 with a mean value of 1.41 mm-1 (std:±0.18). The peri-cancer of recta has also been investigated to distinguish the difference between normal and malignant rectal tissue. The results demonstrate that the quantitative analysis of the rectal tissue can be used as a promising diagnostic criterion of early rectal cancer, which has great value for clinical medical applications.

  13. Massively parallel simulator of optical coherence tomography of inhomogeneous turbid media.

    PubMed

    Malektaji, Siavash; Lima, Ivan T; Escobar I, Mauricio R; Sherif, Sherif S

    2017-10-01

    An accurate and practical simulator for Optical Coherence Tomography (OCT) could be an important tool to study the underlying physical phenomena in OCT such as multiple light scattering. Recently, many researchers have investigated simulation of OCT of turbid media, e.g., tissue, using Monte Carlo methods. The main drawback of these earlier simulators is the long computational time required to produce accurate results. We developed a massively parallel simulator of OCT of inhomogeneous turbid media that obtains both Class I diffusive reflectivity, due to ballistic and quasi-ballistic scattered photons, and Class II diffusive reflectivity due to multiply scattered photons. This Monte Carlo-based simulator is implemented on graphic processing units (GPUs), using the Compute Unified Device Architecture (CUDA) platform and programming model, to exploit the parallel nature of propagation of photons in tissue. It models an arbitrary shaped sample medium as a tetrahedron-based mesh and uses an advanced importance sampling scheme. This new simulator speeds up simulations of OCT of inhomogeneous turbid media by about two orders of magnitude. To demonstrate this result, we have compared the computation times of our new parallel simulator and its serial counterpart using two samples of inhomogeneous turbid media. We have shown that our parallel implementation reduced simulation time of OCT of the first sample medium from 407 min to 92 min by using a single GPU card, to 12 min by using 8 GPU cards and to 7 min by using 16 GPU cards. For the second sample medium, the OCT simulation time was reduced from 209 h to 35.6 h by using a single GPU card, and to 4.65 h by using 8 GPU cards, and to only 2 h by using 16 GPU cards. Therefore our new parallel simulator is considerably more practical to use than its central processing unit (CPU)-based counterpart. Our new parallel OCT simulator could be a practical tool to study the different physical phenomena underlying OCT

  14. Radiation safety issues with positron-emission/computed tomography simulation for stereotactic body radiation therapy.

    PubMed

    Kearns, William T; Urbanic, James J; Hampton, Carnell J; McMullen, Kevin P; Blackstock, A William; Stieber, Volker W; Hinson, William H

    2008-06-23

    Stereotactic body radiation therapy (SBRT) simulations using a Stereotactic Body Frame (SBF: Elekta, Stockholm, Sweden) were expanded to include 18F-deoxyglucosone positron-emission tomography (FDG PET) for treatment planning. Because of the length of time that staff members are in close proximity to the patient, concerns arose over the radiation safety issues associated with these simulations. The present study examines the radiation exposures of the staff performing SBRT simulations, and provides some guidance on limiting staff exposure during these simulations. Fifteen patients were simulated with PET/CT using the SBF. Patients were immobilized in the SBF before the FDG was administered. The patients were removed from the frame, injected with FDG, and allowed to uptake for approximately 45 minutes. After uptake, the patients were repositioned in the SBF. During the repositioning, exposure rates were recorded at the patient's surface, at the SBF surface, and at 15 cm, 30 cm, and 1 m from the SBF. Administered dose and the approximate time spent on patient repositioning were also recorded. The estimated dose to staff was compared with the dose to staff performing conventional diagnostic PET studies. The average length of time spent in close proximity (<50 cm) to the patient after injection was 11.7 minutes, or more than twice the length of time reported for diagnostic PET staff. That time yielded an estimated average dose to the staff of 26.5 microSv per simulation. The annual occupational exposure limit is 50 mSv. Based on dose per simulation, staff would have to perform nearly 1900 SBRT simulations annually to exceed the occupational limit. Therefore, at the current rate of 50-100 simulations annually, the addition of PET studies to SBRT simulations is safe for our staff. However, ALARA ("as low as reasonably achievable") principles still require some radiation safety considerations during SBRT simulations. The PET/CT-based SBRT simulations are safe and

  15. Validation of a novel technique for creating simulated radiographs using computed tomography datasets.

    PubMed

    Mendoza, Patricia; d'Anjou, Marc-André; Carmel, Eric N; Fournier, Eric; Mai, Wilfried; Alexander, Kate; Winter, Matthew D; Zwingenberger, Allison L; Thrall, Donald E; Theoret, Christine

    2014-01-01

    Understanding radiographic anatomy and the effects of varying patient and radiographic tube positioning on image quality can be a challenge for students. The purposes of this study were to develop and validate a novel technique for creating simulated radiographs using computed tomography (CT) datasets. A DICOM viewer (ORS Visual) plug-in was developed with the ability to move and deform cuboidal volumetric CT datasets, and to produce images simulating the effects of tube-patient-detector distance and angulation. Computed tomographic datasets were acquired from two dogs, one cat, and one horse. Simulated radiographs of different body parts (n = 9) were produced using different angles to mimic conventional projections, before actual digital radiographs were obtained using the same projections. These studies (n = 18) were then submitted to 10 board-certified radiologists who were asked to score visualization of anatomical landmarks, depiction of patient positioning, realism of distortion/magnification, and image quality. No significant differences between simulated and actual radiographs were found for anatomic structure visualization and patient positioning in the majority of body parts. For the assessment of radiographic realism, no significant differences were found between simulated and digital radiographs for canine pelvis, equine tarsus, and feline abdomen body parts. Overall, image quality and contrast resolution of simulated radiographs were considered satisfactory. Findings from the current study indicated that radiographs simulated using this new technique are comparable to actual digital radiographs. Further studies are needed to apply this technique in developing interactive tools for teaching radiographic anatomy and the effects of varying patient and tube positioning.

  16. Age estimation during the blow fly intra-puparial period: a qualitative and quantitative approach using micro-computed tomography.

    PubMed

    Martín-Vega, Daniel; Simonsen, Thomas J; Wicklein, Martina; Hall, Martin J R

    2017-05-04

    Minimum post-mortem interval (minPMI) estimates often rely on the use of developmental data from blow flies (Diptera: Calliphoridae), which are generally the first colonisers of cadavers and, therefore, exemplar forensic indicators. Developmental data of the intra-puparial period are of particular importance, as it can account for more than half of the developmental duration of the blow fly life cycle. During this period, the insect undergoes metamorphosis inside the opaque, barrel-shaped puparium, formed by the hardening and darkening of the third instar larval cuticle, which shows virtually no external changes until adult emergence. Regrettably, estimates based on the intra-puparial period are severely limited due to the lack of reliable, non-destructive ageing methods and are frequently based solely on qualitative developmental markers. In this study, we use non-destructive micro-computed tomography (micro-CT) for (i) performing qualitative and quantitative analyses of the morphological changes taking place during the intra-puparial period of two forensically relevant blow fly species, Calliphora vicina and Lucilia sericata, and (ii) developing a novel and reliable method for estimating insect age in forensic practice. We show that micro-CT provides age-diagnostic qualitative characters for most 10% time intervals of the total intra-puparial period, which can be used over a range of temperatures and with a resolution comparable to more invasive and time-consuming traditional imaging techniques. Moreover, micro-CT can be used to yield a quantitative measure of the development of selected organ systems to be used in combination with qualitative markers. Our results confirm micro-CT as an emerging, powerful tool in medico-legal investigations.

  17. In situ flash x-ray high-speed computed tomography for the quantitative analysis of highly dynamic processes

    NASA Astrophysics Data System (ADS)

    Moser, Stefan; Nau, Siegfried; Salk, Manfred; Thoma, Klaus

    2014-02-01

    The in situ investigation of dynamic events, ranging from car crash to ballistics, often is key to the understanding of dynamic material behavior. In many cases the important processes and interactions happen on the scale of milli- to microseconds at speeds of 1000 m s-1 or more. Often, 3D information is necessary to fully capture and analyze all relevant effects. High-speed 3D-visualization techniques are thus required for the in situ analysis. 3D-capable optical high-speed methods often are impaired by luminous effects and dust, while flash x-ray based methods usually deliver only 2D data. In this paper, a novel 3D-capable flash x-ray based method, in situ flash x-ray high-speed computed tomography is presented. The method is capable of producing 3D reconstructions of high-speed processes based on an undersampled dataset consisting of only a few (typically 3 to 6) x-ray projections. The major challenges are identified, discussed and the chosen solution outlined. The application is illustrated with an exemplary application of a 1000 m s-1 high-speed impact event on the scale of microseconds. A quantitative analysis of the in situ measurement of the material fragments with a 3D reconstruction with 1 mm voxel size is presented and the results are discussed. The results show that the HSCT method allows gaining valuable visual and quantitative mechanical information for the understanding and interpretation of high-speed events.

  18. Dynamic contrast optical coherence tomography: quantitative measurement of microvascular transit-time distributions in vivo (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Merkle, Conrad W.; Srinivasan, Vivek J.

    2016-03-01

    Transit time is a fundamental microcirculatory parameter that is critical in determining oxygen delivery from capillaries to surrounding tissue. Recently, it was demonstrated theoretically that capillary transit-time heterogeneity potentially leads to non-uniform oxygen extraction in micro-domains. However, in spite of its importance, capillary transit-time distribution has been challenging to quantify comprehensively and efficiently at the microscopic level. Here, we introduce a method, called Dynamic Contrast Optical Coherence Tomography (DyC-OCT), based on dynamic cross-sectional OCT imaging of the kinetics of an intravascular tracer during its passage through the field-of-view. DyC-OCT is used to quantitatively measure the transit-time distribution in microvascular networks in cross-section at the single-capillary level. Transit-time metrics are derived from analysis of the temporal characteristics of the dynamic scattering signal, related to tracer concentration, using indicator-dilution theory. Since DyC-OCT does not require calibration of the optical focus, quantitative accuracy is achieved even deep in highly scattering brain tissue where the focal spot degrades. After direct validation of DyC-OCT against the dilution curves measured using a fluorescent plasma label in the surface pial vessels of a mouse brain, imaged through a thinned-skull, glass coverslip-reinforced cranial window, the laminar transit-time distribution was investigated in microvasculature across the entire depth of the mouse somatosensory cortex. Laminar trends were identified, with the earliest transit times in the middle cortical layers, and the lowest heterogeneity in cortical layer 4. The new DyC-OCT technique affords a novel perspective of microvascular networks, with the unique capability of performing simultaneous measurements of transit-time distributions across cortical laminae.

  19. Quantitative Dual-Energy Computed Tomography Supports a Vascular Etiology of Smoking-induced Inflammatory Lung Disease

    PubMed Central

    Iyer, Krishna S.; Newell, John D.; Jin, Dakai; Fuld, Matthew K.; Saha, Punam K.; Hansdottir, Sif

    2016-01-01

    Rationale: Endothelial dysfunction is of interest in relation to smoking-associated emphysema, a component of chronic obstructive pulmonary disease (COPD). We previously demonstrated that computed tomography (CT)-derived pulmonary blood flow (PBF) heterogeneity is greater in smokers with normal pulmonary function tests (PFTs) but who have visual evidence of centriacinar emphysema (CAE) on CT. Objectives: We introduced dual-energy CT (DECT) perfused blood volume (PBV) as a PBF surrogate to evaluate whether the CAE-associated increased PBF heterogeneity is reversible with sildenafil. Methods: Seventeen PFT-normal current smokers were divided into CAE-susceptible (SS; n = 10) and nonsusceptible (NS; n = 7) smokers, based on the presence or absence of CT-detected CAE. DECT-PBV images were acquired before and 1 hour after administration of 20 mg oral sildenafil. Regional PBV and PBV coefficients of variation (CV), a measure of spatial blood flow heterogeneity, were determined, followed by quantitative assessment of the central arterial tree. Measurements and Main Results: After sildenafil administration, regional PBV-CV decreased in SS subjects but did not decrease in NS subjects (P < 0.05), after adjusting for age and pack-years. Quantitative evaluation of the central pulmonary arteries revealed higher arterial volume and greater cross-sectional area (CSA) in the lower lobes of SS smokers, which suggested arterial enlargement in response to increased peripheral resistance. After sildenafil, arterial CSA decreased in SS smokers but did not decrease in NS smokers (P < 0.01). Conclusions: These results demonstrate that sildenafil restores peripheral perfusion and reduces central arterial enlargement in normal SS subjects with little effect in NS subjects, highlighting DECT-PBV as a biomarker of reversible endothelial dysfunction in smokers with CAE. PMID:26569033

  20. A Quantitative Study of Simulated Bicuspid Aortic Valves

    NASA Astrophysics Data System (ADS)

    Szeto, Kai; Nguyen, Tran; Rodriguez, Javier; Pastuszko, Peter; Nigam, Vishal; Lasheras, Juan

    2010-11-01

    Previous studies have shown that congentially bicuspid aortic valves develop degenerative diseases earlier than the standard trileaflet, but the causes are not well understood. It has been hypothesized that the asymmetrical flow patterns and turbulence found in the bileaflet valves together with abnormally high levels of strain may result in an early thickening and eventually calcification and stenosis. Central to this hypothesis is the need for a precise quantification of the differences in the strain rate levels between bileaflets and trileaflet valves. We present here some in-vitro dynamic measurements of the spatial variation of the strain rate in pig aortic vales conducted in a left ventricular heart flow simulator device. We measure the strain rate of each leaflet during the whole cardiac cycle using phase-locked stereoscopic three-dimensional image surface reconstruction techniques. The bicuspid case is simulated by surgically stitching two of the leaflets in a normal valve.

  1. Verification of Scientific Simulations via Hypothesis-Driven Comparative and Quantitative Visualization

    SciTech Connect

    Ahrens, James P; Heitmann, Katrin; Petersen, Mark R; Woodring, Jonathan; Williams, Sean; Fasel, Patricia; Ahrens, Christine; Hsu, Chung-Hsing; Geveci, Berk

    2010-11-01

    This article presents a visualization-assisted process that verifies scientific-simulation codes. Code verification is necessary because scientists require accurate predictions to interpret data confidently. This verification process integrates iterative hypothesis verification with comparative, feature, and quantitative visualization. Following this process can help identify differences in cosmological and oceanographic simulations.

  2. Exploring the Perceptions of College Instructors towards Computer Simulation Software Programs: A Quantitative Study

    ERIC Educational Resources Information Center

    Punch, Raymond J.

    2012-01-01

    The purpose of the quantitative regression study was to explore and to identify relationships between attitudes toward use and perceptions of value of computer-based simulation programs, of college instructors, toward computer based simulation programs. A relationship has been reported between attitudes toward use and perceptions of the value of…

  3. [A quantitative evaluation of brain computerized tomography in children using color image analyzer].

    PubMed

    Yamatani, M; Naganuma, Y; Hongoh, K; Murakami, M; Konishi, T; Okada, T

    1989-11-01

    We attempted the quantitative analysis of brain computerized tomographic scans in children using Color Image Analyzer. A consecutive series of 167 computerized tomographic scans were reviewed. Areas of subarachnoid spaces, cavums, ventricles and cerebellums were measured on three slices: A slice is at the level of head of caudate nucleus, anterior horn of lateral ventricle and third ventricle. B slice is at the level of body of lateral ventricle. C slice is at the level of sella turcica and pons. We investigated these values compared with Evans ratio, Cella Media Index, cerebellar atrophy score and visually evaluations. Serial brain CT scans of eight patient with infantile spasms were also evaluated for the assessment of the brain shrinkage after ACTH therapy. 1) The ratios of the subarachnoid space/the intracranial area on A and B slices (SAS A%, SAS B%) were significantly higher in the patients of severe brain atrophy. 2) There were linear relationship between Evans ratio and SAS A% (r = 0.405, p less than 0.001), Cella Media Index and the ratio of the lateral ventricles/the intracranial areas on B slice (r = -0.501, p less than 0.001), and the cerebellar atrophy score by Une and SAS C% (r = 0.369, p less than 0.001). 3) In the normal patients, the values of SAS A% and SAS B% were much greater in less than 1.5 years old children. These results suggest that the trend of CT findings related to age may reflect physiological changes of the space between the skull and the brain with age. 4) Brain shrinkage after ACTH therapy was more pronounced in the subarachnoid space than the ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Monte-Carlo simulations and image reconstruction for novel imaging scenarios in emission tomography

    NASA Astrophysics Data System (ADS)

    Gillam, John E.; Rafecas, Magdalena

    2016-02-01

    Emission imaging incorporates both the development of dedicated devices for data acquisition as well as algorithms for recovering images from that data. Emission tomography is an indirect approach to imaging. The effect of device modification on the final image can be understood through both the way in which data are gathered, using simulation, and the way in which the image is formed from that data, or image reconstruction. When developing novel devices, systems and imaging tasks, accurate simulation and image reconstruction allow performance to be estimated, and in some cases optimized, using computational methods before or during the process of physical construction. However, there are a vast range of approaches, algorithms and pre-existing computational tools that can be exploited and the choices made will affect the accuracy of the in silico results and quality of the reconstructed images. On the one hand, should important physical effects be neglected in either the simulation or reconstruction steps, specific enhancements provided by novel devices may not be represented in the results. On the other hand, over-modeling of device characteristics in either step leads to large computational overheads that can confound timely results. Here, a range of simulation methodologies and toolkits are discussed, as well as reconstruction algorithms that may be employed in emission imaging. The relative advantages and disadvantages of a range of options are highlighted using specific examples from current research scenarios.

  5. In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography

    PubMed Central

    van Deel, Elza; Ridwan, Yanto; van Vliet, J. Nicole; Belenkov, Sasha; Essers, Jeroen

    2016-01-01

    The use of Micro-Computed Tomography (MicroCT) for in vivo studies of small animals as models of human disease has risen tremendously due to the fact that MicroCT provides quantitative high-resolution three-dimensional (3D) anatomical data non-destructively and longitudinally. Most importantly, with the development of a novel preclinical iodinated contrast agent called eXIA160, functional and metabolic assessment of the heart became possible. However, prior to the advent of commercial MicroCT scanners equipped with X-ray flat-panel detector technology and easy-to-use cardio-respiratory gating, preclinical studies of cardiovascular disease (CVD) in small animals required a MicroCT technologist with advanced skills, and thus were impractical for widespread implementation. The goal of this work is to provide a practical guide to the use of the high-speed Quantum FX MicroCT system for comprehensive determination of myocardial global and regional function along with assessment of myocardial perfusion, metabolism and viability in healthy mice and in a cardiac ischemia mouse model induced by permanent occlusion of the left anterior descending coronary artery (LAD). PMID:26967592

  6. Lung extraction, lobe segmentation and hierarchical region assessment for quantitative analysis on high resolution computed tomography images.

    PubMed

    Ross, James C; Estépar, Raúl San José; Díaz, Alejandro; Westin, Carl-Fredrik; Kikinis, Ron; Silverman, Edwin K; Washko, George R

    2009-01-01

    Regional assessment of lung disease (such as chronic obstructive pulmonary disease) is a critical component to accurate patient diagnosis. Software tools than enable such analysis are also important for clinical research studies. In this work, we present an image segmentation and data representation framework that enables quantitative analysis specific to different lung regions on high resolution computed tomography (HRCT) datasets. We present an offline, fully automatic image processing chain that generates airway, vessel, and lung mask segmentations in which the left and right lung are delineated. We describe a novel lung lobe segmentation tool that produces reproducible results with minimal user interaction. A usability study performed across twenty datasets (inspiratory and expiratory exams including a range of disease states) demonstrates the tool's ability to generate results within five to seven minutes on average. We also describe a data representation scheme that involves compact encoding of label maps such that both "regions" (such as lung lobes) and "types" (such as emphysematous parenchyma) can be simultaneously represented at a given location in the HRCT.

  7. Dynamic imaging and quantitative analysis of cranial neural tube closure in the mouse embryo using optical coherence tomography.

    PubMed

    Wang, Shang; Garcia, Monica D; Lopez, Andrew L; Overbeek, Paul A; Larin, Kirill V; Larina, Irina V

    2017-01-01

    Neural tube closure is a critical feature of central nervous system morphogenesis during embryonic development. Failure of this process leads to neural tube defects, one of the most common forms of human congenital defects. Although molecular and genetic studies in model organisms have provided insights into the genes and proteins that are required for normal neural tube development, complications associated with live imaging of neural tube closure in mammals limit efficient morphological analyses. Here, we report the use of optical coherence tomography (OCT) for dynamic imaging and quantitative assessment of cranial neural tube closure in live mouse embryos in culture. Through time-lapse imaging, we captured two neural tube closure mechanisms in different cranial regions, zipper-like closure of the hindbrain region and button-like closure of the midbrain region. We also used OCT imaging for phenotypic characterization of a neural tube defect in a mouse mutant. These results suggest that the described approach is a useful tool for live dynamic analysis of normal neural tube closure and neural tube defects in the mouse model.

  8. Effect of Hydroxychloroquine on the Retinal Layers: A Quantitative Evaluation with Spectral-Domain Optical Coherence Tomography

    PubMed Central

    Gurler, Bulent; Yildirim, Aydin; Goker, Hasan; Pehlevan, Hatice Seval

    2016-01-01

    Purpose. To evaluate the effect of hydroxychloroquine on retinal pigment epithelium- (RPE-) Bruch's membrane complex, photoreceptor outer segment, and macular ganglion cell-inner plexiform layer (GCIPL) thicknesses using spectral-domain optical coherence tomography (SD-OCT). Methods. In this prospective case-control study, 51 eyes of 51 hydroxychloroquine patients and 30 eyes of 30 healthy subjects were included. High-quality images were obtained using a Cirrus HD-OCT with 5-line raster mode; the photoreceptor inner segment (IS) and outer segment (OS), sum of the segments (IS + OS), and RPE-Bruch's membrane complex were analyzed. Results. The thicknesses of the IS + OS and OS layers were significantly lower in the hydroxychloroquine subjects compared to the control subjects (P < 0.05). RPE-Bruch's membrane complex thicknesses were significantly higher in the hydroxychloroquine subjects than for those of the control subjects (P < 0.05). The minimum and temporal-inferior macular GCIPL thicknesses were significantly different between the patients with hydroxychloroquine use and the control subjects (P = 0.04 and P = 0.03, resp.). Conclusions. The foveal photoreceptor OS thinning, loss of GCIPL, and RPE-Bruch's membrane thickening were detected in patients with hydroxychloroquine therapy. This quantitative approach using SD-OCT images may have important implications to use as an early indicator of retinal toxicity without any visible signs of hydroxychloroquine retinopathy. PMID:27656292

  9. Dynamic imaging and quantitative analysis of cranial neural tube closure in the mouse embryo using optical coherence tomography

    PubMed Central

    Wang, Shang; Garcia, Monica D.; Lopez, Andrew L.; Overbeek, Paul A.; Larin, Kirill V.; Larina, Irina V.

    2016-01-01

    Neural tube closure is a critical feature of central nervous system morphogenesis during embryonic development. Failure of this process leads to neural tube defects, one of the most common forms of human congenital defects. Although molecular and genetic studies in model organisms have provided insights into the genes and proteins that are required for normal neural tube development, complications associated with live imaging of neural tube closure in mammals limit efficient morphological analyses. Here, we report the use of optical coherence tomography (OCT) for dynamic imaging and quantitative assessment of cranial neural tube closure in live mouse embryos in culture. Through time-lapse imaging, we captured two neural tube closure mechanisms in different cranial regions, zipper-like closure of the hindbrain region and button-like closure of the midbrain region. We also used OCT imaging for phenotypic characterization of a neural tube defect in a mouse mutant. These results suggest that the described approach is a useful tool for live dynamic analysis of normal neural tube closure and neural tube defects in the mouse model. PMID:28101427

  10. Quantitative imaging of cerebral blood flow velocity and intracellular motility using dynamic light scattering–optical coherence tomography

    PubMed Central

    Lee, Jonghwan; Radhakrishnan, Harsha; Wu, Weicheng; Daneshmand, Ali; Climov, Mihail; Ayata, Cenk; Boas, David A

    2013-01-01

    This paper describes a novel optical method for label-free quantitative imaging of cerebral blood flow (CBF) and intracellular motility (IM) in the rodent cerebral cortex. This method is based on a technique that integrates dynamic light scattering (DLS) and optical coherence tomography (OCT), named DLS–OCT. The technique measures both the axial and transverse velocities of CBF, whereas conventional Doppler OCT measures only the axial one. In addition, the technique produces a three-dimensional map of the diffusion coefficient quantifying nontranslational motions. In the DLS–OCT diffusion map, we observed high-diffusion spots, whose locations highly correspond to neuronal cell bodies and whose diffusion coefficient agreed with that of the motion of intracellular organelles reported in vitro in the literature. Therefore, the present method has enabled, for the first time to our knowledge, label-free imaging of the diffusion-like motion of intracellular organelles in vivo. As an example application, we used the method to monitor CBF and IM during a brief ischemic stroke, where we observed an induced persistent reduction in IM despite the recovery of CBF after stroke. This result supports that the IM measured in this study represent the cellular energy metabolism-related active motion of intracellular organelles rather than free diffusion of intracellular macromolecules. PMID:23403378

  11. Validation of high-resolution gamma-ray computed tomography for quantitative gas holdup measurements in centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Bieberle, André; Schäfer, Thomas; Neumann, Martin; Hampel, Uwe

    2015-09-01

    In this article, the capability of high-resolution gamma-ray computed tomography (HireCT) for quantitative gas-liquid phase distribution measurements in commercially available industrial pumps is experimentally investigated. The object of interest thereby operates under two-phase flow conditions. HireCT System comprises a collimated 137Cs isotopic source, a radiation detector arc with a multi-channel signal processing unit, and a rotary unit enabling CT scans of objects with diameters of up to 700 mm. The accuracy of gas holdup measurements was validated on a sophisticated modular test mockup replicating defined gas-liquid distributions, which are expected in impeller chambers of industrial centrifugal pumps under two-phase operation. Stationary as well as rotation-synchronized CT scanning techniques have been analyzed, which are both used to obtain sharply resolved gas phase distributions in rotating structures as well as non-rotating zones. A measuring accuracy of better than 1% absolute for variously distributed static gas holdups in the rotating frame has been verified with the modular test mockup using HireCT.

  12. [Cerebral blood flow and oxygen extraction in lacunar hemiplegia. Semi-quantitative study using oxygen 15 and emission tomography].

    PubMed

    Rougemont, D; Baron, J C; Lebrun-Grandie, P; Bousser, M G; Cabanis, E; Laplane, D

    1983-01-01

    The oxygen 15 non invasive continuous inhalation technique coupled with positron emission tomography (P.E.T.) allows the local study of cerebral blood flow and oxygen metabolism. Recent P.E.T. studies have demonstrated the frequent occurrence of widespread metabolic depression remote from the site of middle cerebral artery territory infarct per se, especially over the cortical mantle and thalamus ipsilaterally, and over the cerebellar hemisphere contralaterally. These phenomena have been taken as indicative of transneural depression (i.e. diaschisis). We thought it interesting to study the possible occurrence of such abnormalities in patients with lacunar syndromes. We have applied the (15)0 technique to six patients (2 with pure motor hemiplegia, 4 with ataxic hemiparesis) for whom no large causal ischemic lesion could be demonstrated on CT scans; in only one patient was a lacunar lesion, presumably responsible for the clinical deficit demonstrated. Compared to a set of 19 patients without brain disease, the semi-quantitative results (analyzed in terms of asymmetry indices between homologous brain regions) in our patients did not disclose any pathophysiologically significant abnormality. More specifically, no evidence of physiological dysfunction similar to that reported in internal carotid artery territory infarcts, was detected over the cerebral or cerebellar cortices. These findings are commented upon in view of the presumably small size and the uncertain topography of the causal lesion.

  13. Quantitative computed tomography and cranial burr holes: a model to evaluate the quality of cranial reconstruction in humans.

    PubMed

    Worm, Paulo Valdeci; Ferreira, Nelson Pires; Ferreira, Marcelo Paglioli; Kraemer, Jorge Luiz; Lenhardt, Rene; Alves, Ronnie Peterson Marcondes; Wunderlich, Ricardo Castilho; Collares, Marcus Vinicius Martins

    2012-05-01

    Current methods to evaluate the biologic development of bone grafts in human beings do not quantify results accurately. Cranial burr holes are standardized critical bone defects, and the differences between bone powder and bone grafts have been determined in numerous experimental studies. This study evaluated quantitative computed tomography (QCT) as a method to objectively measure cranial bone density after cranial reconstruction with autografts. In each of 8 patients, 2 of 4 surgical burr holes were reconstructed with autogenous wet bone powder collected during skull trephination, and the other 2 holes, with a circular cortical bone fragment removed from the inner table of the cranial bone flap. After 12 months, the reconstructed areas and a sample of normal bone were studied using three-dimensional QCT; bone density was measured in Hounsfield units (HU). Mean (SD) bone density was 1535.89 (141) HU for normal bone (P < 0.0001), 964 (176) HU for bone fragments, and 453 (241) HU for bone powder (P < 0.001). As expected, the density of the bone fragment graft was consistently greater than that of bone powder. Results confirm the accuracy and reproducibility of QCT, already demonstrated for bone in other locations, and suggest that it is an adequate tool to evaluate cranial reconstructions. The combination of QCT and cranial burr holes is an excellent model to accurately measure the quality of new bone in cranial reconstructions and also seems to be an appropriate choice of experimental model to clinically test any cranial bone or bone substitute reconstruction.

  14. Quantitative computed tomography (QCT) as a radiology reporting tool by using optical character recognition (OCR) and macro program.

    PubMed

    Lee, Young Han; Song, Ho-Taek; Suh, Jin-Suck

    2012-12-01

    The objectives are (1) to introduce a new concept of making a quantitative computed tomography (QCT) reporting system by using optical character recognition (OCR) and macro program and (2) to illustrate the practical usages of the QCT reporting system in radiology reading environment. This reporting system was created as a development tool by using an open-source OCR software and an open-source macro program. The main module was designed for OCR to report QCT images in radiology reading process. The principal processes are as follows: (1) to save a QCT report as a graphic file, (2) to recognize the characters from an image as a text, (3) to extract the T scores from the text, (4) to perform error correction, (5) to reformat the values into QCT radiology reporting template, and (6) to paste the reports into the electronic medical record (EMR) or picture archiving and communicating system (PACS). The accuracy test of OCR was performed on randomly selected QCTs. QCT as a radiology reporting tool successfully acted as OCR of QCT. The diagnosis of normal, osteopenia, or osteoporosis is also determined. Error correction of OCR is done with AutoHotkey-coded module. The results of T scores of femoral neck and lumbar vertebrae had an accuracy of 100 and 95.4 %, respectively. A convenient QCT reporting system could be established by utilizing open-source OCR software and open-source macro program. This method can be easily adapted for other QCT applications and PACS/EMR.

  15. Quantitatively Measured Anatomic Location and Volume of Optic Disc Drusen: An Enhanced Depth Imaging Optical Coherence Tomography Study.

    PubMed

    Malmqvist, Lasse; Lindberg, Anne-Sofie Wessel; Dahl, Vedrana Andersen; Jørgensen, Thomas Martini; Hamann, Steffen

    2017-05-01

    Optic disc drusen (ODD) are found in up to 2.4% of the population and are known to cause visual field defects. The purpose of the current study was to investigate how quantitatively estimated volume and anatomic location of ODD influence optic nerve function. Anatomic location, volume of ODD, and peripapillary retinal nerve fiber layer and macular ganglion cell layer thickness were assessed in 37 ODD patients using enhanced depth imaging optical coherence tomography. Volume of ODD was calculated by manual segmentation of ODD in 97 B-scans per eye. Anatomic characteristics were compared with optic nerve function using automated perimetric mean deviation (MD) and multifocal visual evoked potentials. Increased age (P = 0.015); larger ODD volume (P = 0.002); and more superficial anatomic ODD location (P = 0.007) were found in patients with ODD visible by ophthalmoscopy compared to patients with buried ODD. In a multivariate analysis, a worsening of MD was significantly associated with larger ODD volume (P < 0.0001). No association was found between MD and weighted anatomic location, age, and visibility by ophthalmoscopy. Decreased ganglion cell layer thickness was significantly associated with worse MD (P = 0.025) and had a higher effect on MD when compared to retinal nerve fiber layer thickness. Large ODD volume is associated with optic nerve dysfunction. The worse visual field defects associated with visible ODD should only be ascribed to larger ODD volume and not to a more superficial anatomic ODD location.

  16. Molecular Dynamics and Monte Carlo simulations in the microcanonical ensemble: Quantitative comparison and reweighting techniques.

    PubMed

    Schierz, Philipp; Zierenberg, Johannes; Janke, Wolfhard

    2015-10-07

    Molecular Dynamics (MD) and Monte Carlo (MC) simulations are the most popular simulation techniques for many-particle systems. Although they are often applied to similar systems, it is unclear to which extent one has to expect quantitative agreement of the two simulation techniques. In this work, we present a quantitative comparison of MD and MC simulations in the microcanonical ensemble. For three test examples, we study first- and second-order phase transitions with a focus on liquid-gas like transitions. We present MD analysis techniques to compensate for conservation law effects due to linear and angular momentum conservation. Additionally, we apply the weighted histogram analysis method to microcanonical histograms reweighted from MD simulations. By this means, we are able to estimate the density of states from many microcanonical simulations at various total energies. This further allows us to compute estimates of canonical expectation values.

  17. Simulation, hardware characterization, analysis, and assembly of the fiber trackers for the proton computed tomography scanner

    NASA Astrophysics Data System (ADS)

    Gearhart, Andrew James

    Proton computed tomography (pCT) is a new method of tomography that will allow for accurate patient imaging and reduced total patient radiation dose when compared to conventional X-ray CT. Proton therapy currently relies on the conversion of attenuation coefficients from X-ray CT scans to material density for use in the proton therapy treatment plan. With a pCT scan, the material density is directly measured, reducing the range errors from attenuation coefficient conversion. Therefore a pCT scan of a patient undergoing proton therapy will also aid in maximizing radiation dose to the target volume, while minimizing radiation dose to surrounding tissue. The pCT scanner is currently under construction, and completed components are being tested with a proton beam. This paper will focus on many of the studies done with the pCT scanner. Specifically, detector simulation, hardware characterization and analysis, and assembly of the fiber trackers used for the pCT scanner will be discussed.

  18. A quantitative analysis of cardiac myocyte relaxation: a simulation study.

    PubMed

    Niederer, S A; Hunter, P J; Smith, N P

    2006-03-01

    The determinants of relaxation in cardiac muscle are poorly understood, yet compromised relaxation accompanies various pathologies and impaired pump function. In this study, we develop a model of active contraction to elucidate the relative importance of the [Ca2+]i transient magnitude, the unbinding of Ca2+ from troponin C (TnC), and the length-dependence of tension and Ca2+ sensitivity on relaxation. Using the framework proposed by one of our researchers, we extensively reviewed experimental literature, to quantitatively characterize the binding of Ca2+ to TnC, the kinetics of tropomyosin, the availability of binding sites, and the kinetics of crossbridge binding after perturbations in sarcomere length. Model parameters were determined from multiple experimental results and modalities (skinned and intact preparations) and model results were validated against data from length step, caged Ca2+, isometric twitches, and the half-time to relaxation with increasing sarcomere length experiments. A factorial analysis found that the [Ca2+]i transient and the unbinding of Ca2+ from TnC were the primary determinants of relaxation, with a fivefold greater effect than that of length-dependent maximum tension and twice the effect of tension-dependent binding of Ca2+ to TnC and length-dependent Ca2+ sensitivity. The affects of the [Ca2+]i transient and the unbinding rate of Ca2+ from TnC were tightly coupled with the effect of increasing either factor, depending on the reference [Ca2+]i transient and unbinding rate.

  19. Early Assessment of Treatment Responses During Radiation Therapy for Lung Cancer Using Quantitative Analysis of Daily Computed Tomography.

    PubMed

    Paul, Jijo; Yang, Cungeng; Wu, Hui; Tai, An; Dalah, Entesar; Zheng, Cheng; Johnstone, Candice; Kong, Feng-Ming; Gore, Elizabeth; Li, X Allen

    2017-06-01

    To investigate early tumor and normal tissue responses during the course of radiation therapy (RT) for lung cancer using quantitative analysis of daily computed tomography (CT) scans. Daily diagnostic-quality CT scans acquired using CT-on-rails during CT-guided RT for 20 lung cancer patients were quantitatively analyzed. On each daily CT set, the contours of the gross tumor volume (GTV) and lungs were generated and the radiation dose delivered was reconstructed. The changes in CT image intensity (Hounsfield unit [HU]) features in the GTV and the multiple normal lung tissue shells around the GTV were extracted from the daily CT scans. The associations between the changes in the mean HUs, GTV, accumulated dose during RT delivery, and patient survival rate were analyzed. During the RT course, radiation can induce substantial changes in the HU histogram features on the daily CT scans, with reductions in the GTV mean HUs (dH) observed in the range of 11 to 48 HU (median 30). The dH is statistically related to the accumulated GTV dose (R(2) > 0.99) and correlates weakly with the change in GTV (R(2) = 0.3481). Statistically significant increases in patient survival rates (P=.038) were observed for patients with a higher dH in the GTV. In the normal lung, the 4 regions proximal to the GTV showed statistically significant (P<.001) HU reductions from the first to last fraction. Quantitative analysis of the daily CT scans indicated that the mean HUs in lung tumor and surrounding normal tissue were reduced during RT delivery. This reduction was observed in the early phase of the treatment, is patient specific, and correlated with the delivered dose. A larger HU reduction in the GTV correlated significantly with greater patient survival. The changes in daily CT features, such as the mean HU, can be used for early assessment of the radiation response during RT delivery for lung cancer. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Organ doses for reference adult male and female undergoing computed tomography estimated by Monte Carlo simulations

    SciTech Connect

    Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel; Fisher, Ryan; Tien, Chris; Simon, Steven L.; Bouville, Andre; Bolch, Wesley E.

    2011-03-15

    Purpose: To develop a computed tomography (CT) organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantomsMethods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different

  1. Shallow Ocean Bottom BRDF Prediction, Modeling, and Inversion via Simulation with Surface/Volume Data Derived from X-ray Tomography

    DTIC Science & Technology

    2008-01-01

    Shallow Ocean Bottom BRDF Prediction, Modeling, and Inversion via Simulation with Surface/Volume Data Derived from X-ray Tomography G. C...Prediction, Modeling, and Inversion via Simulation with Surface/Volume Data Derived from X-ray Tomography 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...focus Xray Computerized Tomography (MXCT) instrument at NRL SSC. The MXCT instrument requires preparation of the sample by embedding it in an epoxy

  2. Simulating the influence of scatter and beam hardening in dimensional computed tomography

    NASA Astrophysics Data System (ADS)

    Lifton, J. J.; Carmignato, S.

    2017-10-01

    Cone-beam x-ray computed tomography (XCT) is a radiographic scanning technique that allows the non-destructive dimensional measurement of an object’s internal and external features. XCT measurements are influenced by a number of different factors that are poorly understood. This work investigates how non-linear x-ray attenuation caused by beam hardening and scatter influences XCT-based dimensional measurements through the use of simulated data. For the measurement task considered, both scatter and beam hardening are found to influence dimensional measurements when evaluated using the ISO50 surface determination method. On the other hand, only beam hardening is found to influence dimensional measurements when evaluated using an advanced surface determination method. Based on the results presented, recommendations on the use of beam hardening and scatter correction for dimensional XCT are given.

  3. Theoretical magnetograms based on quantitative simulation of a magnetospheric substorm

    NASA Technical Reports Server (NTRS)

    Chen, C.-K.; Wolf, R. A.; Karty, J. L.; Harel, M.

    1982-01-01

    Substorm currents derived from the Rice University computer simulation of the September 19, 1976 substorm event are used to compute theoretical magnetograms as a function of universal time for various stations, integrating the Biot-Savart law over a maze of about 2700 wires and bands that carry the ring, Birkeland and horizontal ionospheric currents. A comparison of theoretical results with corresponding observations leads to a claim of general agreement, especially for stations at high and middle magnetic latitudes. Model results suggest that the ground magnetic field perturbations arise from complicated combinations of different kinds of currents, and that magnetic field disturbances due to different but related currents cancel each other out despite the inapplicability of Fukushima's (1973) theorem. It is also found that the dawn-dusk asymmetry in the horizontal magnetic field disturbance component at low latitudes is due to a net downward Birkeland current at noon, a net upward current at midnight, and, generally, antisunward-flowing electrojets.

  4. Theoretical magnetograms based on quantitative simulation of a magnetospheric substorm

    NASA Technical Reports Server (NTRS)

    Chen, C.-K.; Wolf, R. A.; Karty, J. L.; Harel, M.

    1982-01-01

    Substorm currents derived from the Rice University computer simulation of the September 19, 1976 substorm event are used to compute theoretical magnetograms as a function of universal time for various stations, integrating the Biot-Savart law over a maze of about 2700 wires and bands that carry the ring, Birkeland and horizontal ionospheric currents. A comparison of theoretical results with corresponding observations leads to a claim of general agreement, especially for stations at high and middle magnetic latitudes. Model results suggest that the ground magnetic field perturbations arise from complicated combinations of different kinds of currents, and that magnetic field disturbances due to different but related currents cancel each other out despite the inapplicability of Fukushima's (1973) theorem. It is also found that the dawn-dusk asymmetry in the horizontal magnetic field disturbance component at low latitudes is due to a net downward Birkeland current at noon, a net upward current at midnight, and, generally, antisunward-flowing electrojets.

  5. Semi-quantitative myocardial perfusion measured by computed tomography in patients with refractory angina: a head-to-head comparison with quantitative rubidium-82 positron emission tomography as reference.

    PubMed

    Qayyum, Abbas Ali; Kühl, Jørgen Tobias; Kjaer, Andreas; Hasbak, Philip; Kofoed, Klaus Fuglsang; Kastrup, Jens

    2017-09-01

    Computed tomography (CT) is a novel method for assessment of myocardial perfusion and has not yet been compared to rubidium-82 positron emission tomography (PET). We aimed to compare CT measured semi-quantitative myocardial perfusion with absolute quantified myocardial perfusion using PET and to detect stenotic territories in patients with severe coronary artery disease. Eighteen patients with stenosis narrowing coronary arteries ≥70% demonstrated on invasive coronary angiography underwent rest and adenosine stress imaging obtained by 320-multidetector CT scanner and CT/PET 64-slice scanner. CT measured myocardial attenuation density (AD) and perfusion index (PI) were correlated to absolute PET myocardial perfusion values. Rest AD, rest and stress PI did not correlate to PET findings (r = 0·412, P = 0·113; r = 0·300, P = 0·259; and r = 0·508, P = 0·064, respectively). However, there was a significant correlation between stress AD and stress PET values (r = 0·670, P = 0·009) and between stress and rest differences for AD and PI with PET differences (r = 0·620, P = 0·006; and r = 0·639, P = 0·004, respectively). Furthermore, significant differences were observed between remote and stenotic territories for rest and stress AD (48 ± 14HU and 37 ± 16HU, P = 0·002; 76 ± 19HU and 58 ± 13HU, P<0·001, respectively), PI (9·6 ± 2·9 and 7·5 ± 3·1, P = 0·002; 21·6 ± 4·1 and 16·9 ± 3·9, P<0·001, respectively) and PET (0·96 ± 0·37 ml g(-1)  min(-1) and 0·86 ± 0·26 ml g(-1)  min(-1) , P = 0·036; 2·07 ± 0·76 ml g(-1)  min(-1) and 1·61 ± 0·76 ml g(-1)  min(-1) , P = 0·006, respectively). Semi-quantitative CT parameters may be useful in the detection of myocardium subtended by stenotic coronary arteries. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  6. Quantitative positron emission tomography imaging of angiogenesis in rats with forelimb ischemia using (68)Ga-NOTA-c(RGDyK).

    PubMed

    Kim, Joong Hyun; Kim, Young-Hwa; Kim, Young Joo; Yang, Bo Yeun; Jeong, Jae Min; Youn, Hyewon; Lee, Dong Soo; Lee, Jae Sung

    2013-10-01

    Gallium-68-labeled 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA)-cyclic Arg-Gly-Asp-D-Tyr-Lys (c(RGDyK)) was developed for αvβ3 targeting, and is a promising agent for imaging of cancer and disorders related to angiogenesis. In this study, we performed kinetic analysis of (68)Ga-NOTA-c(RGDyK) in rats with surgically induced forelimb ischemia, and immunohistochemical analysis was also performed to assess αvβ3 immuno-staining level. Animal models were created by excision of the left brachial vessels, and a sham operation was performed on the right brachial region under 2 % isoflurane anesthesia. Using an animal positron emission tomography/computed tomography (PET/CT) scanner, a list mode PET scan (120 min) was started with the injection of (68)Ga-NOTA-c(RGDyK) via the tail vein at 3, 5 and 7 days after ischemic surgery. Volumes of interest were drawn on the left ventricle, sham operation, control, and ischemic regions. Compartmental and two graphical analyses (Logan and RE plots) were performed for kinetic parameter estimation. The immunohistochemical analysis was also performed after the last PET scan, and cell components were scored on a six point scale for quantification of immuno-staining level (0-negative to 5-very high). A 3-compartment model with reversible binding best described the tissue time-activity curves. The distribution volume of the ischemic region was significantly higher than that of the sham operation (P < 10(-6)) and control region (P < 10(-9)). Both the Logan and RE plots showed high correlation with compartmental analysis (R(2) = 0.96 and 0.95 for Logan and RE, respectively). The temporal changes in distribution volume and binding potential were not significant. The immuno-staining level of the ischemic region was significantly higher than that of sham operation (P < 10(-4)) and control region (P < 10(-8)). Kinetic modeling studies with dynamic (68)Ga-NOTA-c(RGDyK) PET scan are feasible based on an image-derived input function in a

  7. Effect of specimen-specific anisotropic material properties in quantitative computed tomography-based finite element analysis of the vertebra.

    PubMed

    Unnikrishnan, Ginu U; Barest, Glenn D; Berry, David B; Hussein, Amira I; Morgan, Elise F

    2013-10-01

    Intra- and inter-specimen variations in trabecular anisotropy are often ignored in quantitative computed tomography (QCT)-based finite element (FE) models of the vertebra. The material properties are typically estimated solely from local variations in bone mineral density (BMD), and a fixed representation of elastic anisotropy ("generic anisotropy") is assumed. This study evaluated the effect of incorporating specimen-specific, trabecular anisotropy on QCT-based FE predictions of vertebral stiffness and deformation patterns. Orthotropic material properties estimated from microcomputed tomography data ("specimen-specific anisotropy"), were assigned to a large, columnar region of the L1 centrum (n = 12), and generic-anisotropic material properties were assigned to the remainder of the vertebral body. Results were compared to FE analyses in which generic-anisotropic properties were used throughout. FE analyses were also performed on only the columnar regions. For the columnar regions, the axial stiffnesses obtained from the two categories of material properties were uncorrelated with each other (p = 0.604), and the distributions of minimum principal strain were distinctly different (p ≤ 0.022). In contrast, for the whole vertebral bodies in both axial and flexural loading, the stiffnesses obtained using the two categories of material properties were highly correlated (R2 > 0.82, p < 0.001) with, and were no different (p > 0.359) from, each other. Only moderate variations in strain distributions were observed between the two categories of material properties. The contrasting results for the columns versus vertebrae indicate a large contribution of the peripheral regions of the vertebral body to the mechanical behavior of this bone. In companion analyses on the effect of the degree of anisotropy (DA), the axial stiffnesses of the trabecular column (p < 0.001) and vertebra (p = 0.007) increased with increasing DA. These findings

  8. Osteochondritis dissecans of the capitellum: lesion size and pattern analysis using quantitative 3-dimensional computed tomography and mapping technique.

    PubMed

    Bexkens, Rens; Oosterhoff, Jacobien H; Tsai, Tsung-Yuan; Doornberg, Job N; van den Bekerom, Michel P J; Eygendaal, Denise; Oh, Luke S

    2017-09-01

    The goals of this study were to evaluate the reliability of a quantitative 3-dimensional computed tomography (Q3DCT) technique for measurement of the capitellar osteochondritis dissecans (OCD) surface area, to analyze OCD distribution using a mapping technique, and to investigate associations between Q3DCT lesion quantification and demographic characteristics and/or clinical examination findings. We identified patients with capitellar OCD who presented to our orthopedic sports medicine practice between January 2001 and January 2016 and who had undergone a preoperative computed tomography scan (slice thickness ≤1.25 mm). A total of 17 patients with a median age of 15 years (range, 12-23 years) were included in this study. Three-dimensional polygon models were reconstructed after osseous structures were marked in 3 planes. Surface areas of the OCD lesion as well as the capitellum were measured. Observer agreement was assessed with the intraclass correlation coefficient (ICC). Heat maps were created to visualize OCD distribution. Measurements of the OCD surface area showed almost perfect intraobserver agreement (ICC, 0.99; confidence interval [CI], 0.98-0.99) and interobserver agreement (ICC, 0.93; CI, 0.86-0.97). Measurements of the capitellar surface area also showed almost perfect intraobserver agreement (ICC, 0.97;CI, 0.91-0.99) and interobserver agreement (ICC, 0.86; CI, 0.46-0.96). The median OCD surface area was 101 mm(2) (range, 49-217 mm(2)). On the basis of OCD heat mapping, the posterolateral zone of the capitellum was most frequently affected. OCDs in which the lateral wall was involved were associated with larger lesion size (P = .041), longer duration of symptoms (P = .030), and worse elbow extension (P = .013). The ability to quantify the capitellar OCD surface area and lesion location in a reliable manner using Q3DCT and a mapping technique should be considered when detailed knowledge of lesion size and location is desired

  9. Characterizing root system characteristics with Electrical resistivity Tomography: a virtual rhizotron simulation

    NASA Astrophysics Data System (ADS)

    Rao, Sathyanarayan; Ehosioke, Solomon; Lesparre, Nolwenn; Nguyen, Frédéric; Javaux, Mathieu

    2017-04-01

    Electrical Resistivity Tomography (ERT) is more and more used for monitoring soil water content in a cropped soil. Yet, the impact of roots on the signal is often neglected and a topic of controversy. In several studies related to soil-root system, it has been showed that the measured root mass density statistically correlates with the electrical conductivity (EC) data obtained from ERT. In addition, some studies suggest that some roots are more electrically conductive than soil for most water content. Thus, higher EC of roots suggest that it might have a measurable impact on ERT signals. In this work, virtual rhizotrons are simulated using the software package called R-SWMS that solves water and solute transport in plant root-soil system, including root growth. The distribution of water content obtained from R-SWMS simulation is converted into EC data using pedo-physical models. The electrical properties of roots and rhizosphere are explicitly included in the EC data to form a conductivity map (CM) with a very detailed spatial resolution. Forward ERT simulations is then carried out for CM generated for various root architectures and soil conditions to study the impact of roots on ERT forward (current and voltage patterns) and inverse solutions. It is demonstrated that under typical injection schemes with lateral electrodes, root system is hardly measurable. However, it is showed that adding electrodes and constraints on the ERT inversion based on root architecture help quantifying root system mass and extent.

  10. Hybrid simulation of scatter intensity in industrial cone-beam computed tomography

    NASA Astrophysics Data System (ADS)

    Thierry, R.; Miceli, A.; Hofmann, J.; Flisch, A.; Sennhauser, U.

    2009-01-01

    A cone-beam computed tomography (CT) system using a 450 kV X-ray tube has been developed to challenge the three-dimensional imaging of parts of the automotive industry in short acquisition time. Because the probability of detecting scattered photons is high regarding the energy range and the area of detection, a scattering correction becomes mandatory for generating reliable images with enhanced contrast detectability. In this paper, we present a hybrid simulator for the fast and accurate calculation of the scattering intensity distribution. The full acquisition chain, from the generation of a polyenergetic photon beam, its interaction with the scanned object and the energy deposit in the detector is simulated. Object phantoms can be spatially described in form of voxels, mathematical primitives or CAD models. Uncollided radiation is treated with a ray-tracing method and scattered radiation is split into single and multiple scattering. The single scattering is calculated with a deterministic approach accelerated with a forced detection method. The residual noisy signal is subsequently deconvoluted with the iterative Richardson-Lucy method. Finally the multiple scattering is addressed with a coarse Monte Carlo (MC) simulation. The proposed hybrid method has been validated on aluminium phantoms with varying size and object-to-detector distance, and found in good agreement with the MC code Geant4. The acceleration achieved by the hybrid method over the standard MC on a single projection is approximately of three orders of magnitude.

  11. Computed tomography with a low-intensity proton flux: results of a Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Schulte, Reinhard W.; Klock, Margio C. L.; Bashkirov, Vladimir; Evseev, Ivan G.; de Assis, Joaquim T.; Yevseyeva, Olga; Lopes, Ricardo T.; Li, Tianfang; Williams, David C.; Wroe, Andrew J.; Schelin, Hugo R.

    2004-10-01

    Conformal proton radiation therapy requires accurate prediction of the Bragg peak position. This problem may be solved by using protons rather than conventional x-rays to determine the relative electron density distribution via proton computed tomography (proton CT). However, proton CT has its own limitations, which need to be carefully studied before this technique can be introduced into routine clinical practice. In this work, we have used analytical relationships as well as the Monte Carlo simulation tool GEANT4 to study the principal resolution limits of proton CT. The GEANT4 simulations were validated by comparing them to predictions of the Bethe Bloch theory and Tschalar's theory of energy loss straggling, and were found to be in good agreement. The relationship between phantom thickness, initial energy, and the relative electron density uncertainty was systematically investigated to estimate the number of protons and dose needed to obtain a given density resolution. The predictions of this study were verified by simulating the performance of a hypothetical proton CT scanner when imaging a cylindrical water phantom with embedded density inhomogeneities. We show that a reasonable density resolution can be achieved with a relatively small number of protons, thus providing a possible dose advantage over x-ray CT.

  12. Signal attenuation and localization in optical coherence tomography studied by Monte Carlo simulation.

    PubMed

    Smithies, D J; Lindmo, T; Chen, Z; Nelson, J S; Milner, T E

    1998-10-01

    A Monte Carlo model has been developed for optical coherence tomography (OCT). A geometrical optics implementation of the OCT probe with low-coherence interferometric detection was combined with three-dimensional stochastic Monte Carlo modelling of photon propagation in the homogeneous sample medium. Optical properties of the sample were selected to simulate intralipid and blood, representing moderately (g = 0.7) and highly (g = 0.99) anisotropic scattering respectively. For shallow optical depths in simulated intralipid (<3 scattering mean free path (mfp) units), the number of detected backscattered photons followed the extinction-single-backscatter model, and OCT was found to detect only minimally scattered photons. Within this depth range the backscatter positions of detected photons corresponded well with the nominal focus position of the probe. For propagation to deeper positions in intralipid, localization of backscattering was quickly lost due to detection of stray photons, and the number of detected photons remained constant with increasing depth in the non-absorbing medium. For strongly forward-directed scattering in simulated blood, the number of detected photons approached the extinction-single-backscatter model only for very shallow depths (<2 mfp units). However, backscattering positions for detected photons correlated well with the nominal focus position of the probe even for optical depths greater than 40 mfp units.

  13. Simulation of photoacoustic tomography (PAT) system in COMSOL and comparison of two popular reconstruction techniques

    NASA Astrophysics Data System (ADS)

    Sowmiya, C.; Thittai, Arun K.

    2017-03-01

    Photoacoustic imaging is a molecular cum functional imaging modality based on differential optical absorption of the incident laser pulse by the endogeneous tissue chromophores. Several numerical simulations and finite element models have been developed in the past to describe and study Photoacoustic (PA) signal generation principles and study the effect of variation in PA parameters. Most of these simulation work concentrate on analyzing extracted 1D PA signals and each of them mostly describe only few of the building blocks of a Photoacoustic Tomography (PAT) imaging system. Papers describing simulation of the entire PAT system in one simulation platform, along with reconstruction is seemingly rare. This study attempts to describe how a commercially available Finite Element software (COMSOL(R)), can serve as a single platform for simulating PAT that couples the electromagnetic, thermodynamic and acoustic pressure physics involved in PA phenomena. Further, an array of detector elements placed at the boundary in the FE model can provide acoustic pressure data that can be exported to Matlab(R) to perform tomographic image reconstruction. The performance of two most commonly used image reconstruction techniques; namely, Filtered Backprojection (FBP) and Synthetic Aperture (SA) beamforming are compared. Results obtained showed that the lateral resolution obtained using FBP vs. SA largely depends on the aperture parameters. FBP reconstruction was able to provide a slightly better lateral resolution for smaller aperture while SA worked better for larger aperture. This interesting effect is currently being investigated further. Computationally FBP was faster, but it had artifacts along the spherical shell on which the data is projected.

  14. Quantitative validation of carbon-fiber laminate low velocity impact simulations

    DOE PAGES

    English, Shawn A.; Briggs, Timothy M.; Nelson, Stacy M.

    2015-09-26

    Simulations of low velocity impact with a flat cylindrical indenter upon a carbon fiber fabric reinforced polymer laminate are rigorously validated. Comparison of the impact energy absorption between the model and experiment is used as the validation metric. Additionally, non-destructive evaluation, including ultrasonic scans and three-dimensional computed tomography, provide qualitative validation of the models. The simulations include delamination, matrix cracks and fiber breaks. An orthotropic damage and failure constitutive model, capable of predicting progressive damage and failure, is developed in conjunction and described. An ensemble of simulations incorporating model parameter uncertainties is used to predict a response distribution which ismore » then compared to experimental output using appropriate statistical methods. Lastly, the model form errors are exposed and corrected for use in an additional blind validation analysis. The result is a quantifiable confidence in material characterization and model physics when simulating low velocity impact in structures of interest.« less

  15. Quantitative validation of carbon-fiber laminate low velocity impact simulations

    SciTech Connect

    English, Shawn A.; Briggs, Timothy M.; Nelson, Stacy M.

    2015-09-26

    Simulations of low velocity impact with a flat cylindrical indenter upon a carbon fiber fabric reinforced polymer laminate are rigorously validated. Comparison of the impact energy absorption between the model and experiment is used as the validation metric. Additionally, non-destructive evaluation, including ultrasonic scans and three-dimensional computed tomography, provide qualitative validation of the models. The simulations include delamination, matrix cracks and fiber breaks. An orthotropic damage and failure constitutive model, capable of predicting progressive damage and failure, is developed in conjunction and described. An ensemble of simulations incorporating model parameter uncertainties is used to predict a response distribution which is then compared to experimental output using appropriate statistical methods. Lastly, the model form errors are exposed and corrected for use in an additional blind validation analysis. The result is a quantifiable confidence in material characterization and model physics when simulating low velocity impact in structures of interest.

  16. Quantitative evaluation of atlas-based high-density diffuse optical tomography for imaging of the human visual cortex

    PubMed Central

    Wu, Xue; Eggebrecht, Adam T.; Ferradal, Silvina L; Culver, Joseph P.; Dehghani, Hamid

    2014-01-01

    Image recovery in diffuse optical tomography (DOT) of the human brain often relies on accurate models of light propagation within the head. In the absence of subject specific models for image reconstruction, the use of atlas based models are showing strong promise. Although there exists some understanding in the use of some limited rigid model registrations in DOT, there has been a lack of a detailed analysis between errors in geometrical accuracy, light propagation in tissue and subsequent errors in dynamic imaging of recovered focal activations in the brain. In this work 11 different rigid registration algorithms, across 24 simulated subjects, are evaluated for DOT studies in the visual cortex. Although there exists a strong correlation (R2 = 0.97) between geometrical surface error and internal light propagation errors, the overall variation is minimal when analysing recovered focal activations in the visual cortex. While a subject specific mesh gives the best results with a 1.2 mm average location error, no single algorithm provides errors greater than 4.5 mm. This work demonstrates that the use of rigid algorithms for atlas based imaging is a promising route when subject specific models are not available. PMID:25426318

  17. Heart failure diagnostics based on ventilation/perfusion single photon emission computed tomography pattern and quantitative perfusion gradients.

    PubMed

    Jögi, Jonas; Palmer, John; Jonson, Björn; Bajc, Marika

    2008-08-01

    Left heart failure (LHF) is a common and frequently overlooked condition owing to insufficient diagnostic methods. This can potentially delay onset of treatment. Our clinical experience with ventilation/perfusion single photon emission computed tomography (V/P SPECT) indicates that perfusion shows an antigravitational distribution pattern in LHF. The aim of the study was to test the hypothesis that LHF diagnosis can be made on the basis of V/P SPECT, and to develop and perform a first evaluation of objective parameters for LHF diagnostics in terms of perfusion gradients. This retrospective study included 247 consecutive patients with clinical suspicion of pulmonary embolism (PE), who were examined with V/P SPECT. Perfusion gradients were developed and quantified in dorso-ventral and cranio-caudal directions. Quantitative results were compared with visual interpretation of patients with normal and heart failure patterns. Patients with LHF pattern were retrospectively followed up by review of medical records to confirm or discard heart failure diagnosis at the time of V/P SPECT examination. LHF pattern on V/P SPECT was identified in 36 patients (15%), normal ventilation/perfusion pattern was found in 67 patients (27%), and PE in 62 patients (25%). The follow-up confirmed heart failure diagnosis in 32 of the 36 cases with LHF pattern, leading to a positive predictive value of 88% for LHF diagnosis based on V/P SPECT. Dorso-ventral perfusion gradients discriminated normal from LHF patients. In patients with suspected PE, LHF is common. Appropriate V/P SPECT pattern recognition, supported by objectively determined dorso-ventral perfusion gradients, allows the diagnosis of LHF. A positive perfusion gradient in the dorso-ventral direction should lead to consideration of heart failure as a possible explanation for the symptoms in these patients.

  18. Comparison of frequency domain optical coherence tomography and quantitative coronary angiography for the assessment of coronary lesions

    NASA Astrophysics Data System (ADS)

    Zafar, Haroon; Sharif, Faisal; Leahy, Martin J.

    2014-03-01

    Quantitative coronary angiography (QCA) has been used as a standard technique for the evaluation of coronary artery disease for many years. Intracoronary optical coherence tomography (OCT) offers higher resolution, faster image acquisition speeds and greater sensitivity than the intravascular ultrasound (IVUS). Recently developed frequency domain OCT (FD-OCT) systems overcome many technical limitations of conventional time domain OCT systems (TDOCT). The main objective of this study was to compare the FD-OCT and QCA measurements for the assessment of coronary lesions. A total of 21 stenoses in 18 patients were analysed using QCA and FD-OCT. The average minimum lumen diameter (MLD) and percent lumen area stenosis (%AS) by QCA were 1.52+/-0.44 mm and 68+/-9% respectively. The average MLD and %AS by FD-OCT were 1.32+/-0.38 mm and 63+/-14% respectively. There was a moderate but significant correlation between QCA and FD-OCT measured MLD (r = 0.5, p < 0.01) and %AS (r = 0.56, p < 0.01). Bland-Altman analysis showed that the mean differences between the QCA and FD-OCT measurements were 0.18+/-0.81 (limits of agreement: -0.63 to 0.99) for MLD and 4.4+/-22.8 (limits of agreement: -18.4 to 27.2) for %AS. The root mean square error (RMSE) between the QCA and FD-OCT measured MLD and %AS was +/-0.44 mm and +/-12.1% respectively.

  19. Role of quantitative computed tomography texture analysis in the differentiation of primary lung cancer and granulomatous nodules

    PubMed Central

    Thornhill, Rebecca; Sethi-Virmani, Vineeta; Souza, Carolina A.; Bayanati, Hamid; Gupta, Ashish; Maziak, Donna

    2016-01-01

    Background Texture analysis is a computer tool that enables quantification of gray-level patterns, pixel interrelationships, and spectral properties of an image. It can enhance visual methods of image analysis. Primary lung cancer and granulomatous nodules have identical CT imaging features. The purpose of this study was to assess the sensitivity and specificity of CT texture analysis in differentiating lung cancer and granulomas. Methods This retrospective study evaluated 55 patients with primary lung cancer and granulomatous nodules who had contrast-enhanced (CE) and/or non-contrast-enhanced (NCE) CT within 3 months of biopsy. Textural features were extracted from 61 nodules. Mann-Whitney U tests were used to compare values for nodules. Receiver operating characteristic (ROC) curves were constructed and the area under the curve (AUC) calculated with histopathology as outcome. Combinations of features were entered as predictors in logistic regression models and optimal threshold criteria were used to estimate sensitivity and specificity. Results The model generated by sum of squares, sum difference, and sum entropy features for NCE CT yielded 88% sensitivity and 92% specificity (AUC =0.90±0.06, P<0.0001). For nodules with fluorodeoxyglucose positron emission tomography (FDG-PET)/CT, sensitivity for detection of lung cancer was 79.2% (CI: 57.8–92.9%), specificity was 38.5% (CI: 13.9–68.4%) and accuracy was 64.8%. Conclusions Quantitative CT texture analysis has the potential to differentiate primary lung cancer and granulomatous lesions. PMID:26981450

  20. Quality control for bone quality parameters affected by subject motion in high-resolution peripheral quantitative computed tomography.

    PubMed

    Pauchard, Yves; Liphardt, Anna-Maria; Macdonald, Heather M; Hanley, David A; Boyd, Steven K

    2012-06-01

    Subject motion during high-resolution peripheral quantitative computed tomography (HR-pQCT) causes image artifacts that affect morphological analysis of bone quality. The aim of our study was to determine effectiveness of techniques for quality control in the presence of motion in vivo including automated and manual approaches. First, repeatability of manual grading was determined within and between laboratories. Given proper training using a standardized scale and training images (provided by the manufacturer), we found that manual grading is suitable for repeatable image quality grading within and across sites (ICC>0.7). Both a new automated technique providing motion measures based on projection moments, and traditional manual grading (1=best, 5=worst) were subsequently used to assess subject data for motion in N=137 image pairs (scan/re-scan) from the Canadian Multicentre Osteoporosis Study (CaMos) Calgary cohort. High quality image pairs were selected and measurement precision was estimated by calculating the coefficient of variation (CV). Consistent with previous data, density parameters (e.g. total bone mineral density) are more robust than structural (e.g. trabecular number) or finite element parameters (e.g. failure load). To obtain acceptable measurement precision, images should not exceed a manual grading of 3 (on a scale from 1 to 5) or an automatic (ε(T)) grading of 1.2. Automatic and manual grading provide comparable quality control, but the advantage of the automated technique is its ability to provide a motion value at scan time (providing a basis for real time decision regarding re-scan requirements), and the assessment is objective. Notably, automatic motion measurement can be performed retrospectively based on original scan data, and is therefore well suited for multi-center studies as well as any research where objective quality control is paramount.

  1. Quantitative computed tomography of lung parenchyma in patients with emphysema: analysis of higher-density lung regions

    NASA Astrophysics Data System (ADS)

    Lederman, Dror; Leader, Joseph K.; Zheng, Bin; Sciurba, Frank C.; Tan, Jun; Gur, David

    2011-03-01

    Quantitative computed tomography (CT) has been widely used to detect and evaluate the presence (or absence) of emphysema applying the density masks at specific thresholds, e.g., -910 or -950 Hounsfield Unit (HU). However, it has also been observed that subjects with similar density-mask based emphysema scores could have varying lung function, possibly indicating differences of disease severity. To assess this possible discrepancy, we investigated whether density distribution of "viable" lung parenchyma regions with pixel values > -910 HU correlates with lung function. A dataset of 38 subjects, who underwent both pulmonary function testing and CT examinations in a COPD SCCOR study, was assembled. After the lung regions depicted on CT images were automatically segmented by a computerized scheme, we systematically divided the lung parenchyma into different density groups (bins) and computed a number of statistical features (i.e., mean, standard deviation (STD), skewness of the pixel value distributions) in these density bins. We then analyzed the correlations between each feature and lung function. The correlation between diffusion lung capacity (DLCO) and STD of pixel values in the bin of -910HU <= PV < -750HU was -0.43, as compared with a correlation of -0.49 obtained between the post-bronchodilator ratio (FEV1/FVC) measured by the forced expiratory volume in 1 second (FEV1) dividing the forced vital capacity (FVC) and the STD of pixel values in the bin of -1024HU <= PV < -910HU. The results showed an association between the distribution of pixel values in "viable" lung parenchyma and lung function, which indicates that similar to the conventional density mask method, the pixel value distribution features in "viable" lung parenchyma areas may also provide clinically useful information to improve assessments of lung disease severity as measured by lung functional tests.

  2. Dual energy X-ray absorptiometry of the knee in spinal cord injury: methodology and correlation with quantitative computed tomography.

    PubMed

    McPherson, J G; Edwards, W B; Prasad, A; Troy, K L; Griffith, J W; Schnitzer, T J

    2014-11-01

    Comparison of diagnostic tests; methodological validation. Primary: to investigate the precision and reliability of a knee bone mineral density (BMD) assessment protocol that uses an existing dual energy X-ray absorptiometry (DXA) forearm acquisition algorithm in individuals with spinal cord injury (SCI). Secondary: to correlate DXA-based knee areal BMD with volumetric BMD assessments derived from quantitative computed tomography (QCT). Academic medical center, Chicago, IL, USA. a convenience sample of 12 individuals with acute SCI recruited for an observational study of bone loss and 34 individuals with chronic SCI who were screened for a longitudinal study evaluating interventions to increase BMD. Root-mean-square standard deviation (RMS-SD) and intra/inter-rater reliability of areal BMD acquired at three knee regions using an existing DXA forearm acquisition algorithm; correlation of DXA-based areal BMD with QCT-derived volumetric BMD. The RMS-SD of areal BMD at the distal femoral epiphysis, distal femoral metaphysis and proximal tibial epiphysis averaged 0.021, 0.012 and 0.016 g cm(-2), respectively, in acute SCI and 0.018, 0.02 and 0.016 g cm(-2) in chronic SCI. All estimates of intra/inter-rater reliability exceeded 97% and DXA-based areal BMD was significantly correlated with QCT-derived volumetric BMD at all knee regions analyzed. Existing DXA forearm acquisition algorithms are sufficiently precise and reliable for short-term assessments of knee BMD in individuals with SCI. Future work is necessary to quantify the reliability of this approach in longitudinal investigations and to determine its ability to predict fractures and recovery potential. This work was funded by the Department of Defense, grant number DOD W81XWH-10-1-0951, with partial support from Merck & Co, Inc.

  3. Population-Stratified Analysis of Bone Mineral Density Distribution in Cervical and Lumbar Vertebrae of Chinese from Quantitative Computed Tomography

    PubMed Central

    Zhang, Yong; Zhou, Zhuang; Wu, Cheng'ai; Zhao, Danhui; Wang, Chao; Cai, Wei; Wang, Ling; Duanmu, Yangyang; Zhang, Chenxin; Tian, Wei

    2016-01-01

    Objective To investigate the bone mineral density (BMD) of cervical vertebrae in a population-stratified manner and correlate with that of the lumbar vertebrae. Materials and Methods Five hundred and ninety-eight healthy volunteers (254 males, 344 females), ranging from 20 to 64 years of age, were recruited for volumetric BMD (vBMD) measurements by quantitative computed tomography. Basic information (age, height, weight, waistline, and hipline), and vBMD of the cervical and lumbar vertebrae (C2–7 and L2–4) were recorded. Comparisons among sex, age groups and different levels of vertebrae were analyzed using analysis of variance. Linear regression was performed for relevance of different vertebral levels. Results The vBMD of cervical and lumbar vertebrae was higher in females than males in each age group. The vBMD of the cervical and lumbar vertebrae in males and the vBMD of lumbar vertebrae in females decreased with aging. In each age group, the vBMD of the cervical vertebrae was higher than that of the lumbar vertebrae with gradual decreases from C2 to C7 except for C3; moreover, the vBMD of C6 and C7 was significantly different from that of C2–5. Correlations of vBMD among different cervical vertebrae (females: r = 0.62–0.94; males: r = 0.63–0.94) and lumbar vertebrae (males: r = 0.93–0.98; females: r = 0.82–0.97) were statistically significant at each age group. Conclusion The present study provided normative data of cervical vertebrae in an age- and sex-stratified manner. Sex differences in vBMD prominently vary with age, which can be helpful to design a more comprehensive pre-operative surgical plan. PMID:27587947

  4. Fusion of morphological data obtained by coronary computed tomography angiography with quantitative echocardiographic data on regional myocardial function.

    PubMed

    Lipiec, Piotr; Wejner-Mik, Paulina; Wdowiak-Okrojek, Katarzyna; Szymczyk, Ewa; Skurski, Adam; Napieralski, Andrzej; Kamiński, Marek; Szymczyk, Konrad; Kasprzak, Jarosław D

    2016-01-01

    Three-dimensional (3D) fusion of morphological data obtained by coronary computed tomography angiography (CCTA) with functional data from resting and stress echocardiography could potentially provide additional information compared to examination results analyzed separately and increase the diagnostic and prognostic value of non-invasive imaging in patients with suspected coronary artery disease (CAD). Using vendor-independent software developed in our institution, we aimed to assess the feasibility and reproducibility of 3D fusion of morphological CCTA data with echocardiographic data regarding regional myocardial function. Thirty patients with suspected CAD underwent CCTA and resting transthoracic echocardiography. From CCTA we obtained 3D reconstructions of coronary arteries and left ventricle (LV). Offline speckle-tracking analysis of the echocardiographic images provided parametric maps depicting myocardial longitudinal strain in 17 segments of the LV. Using our software, 3 independent investigators fused echocardiographic maps with CCTA reconstruc-tions in all patients. Based on the obtained fused models, each segment of the LV was assigned to one of the major coronary artery branches. Mean time necessary for data fusion was 65 ± 7 s. Complete agreement between independent investigators in assignment of LV segments to coronary branches was obtained in 94% of the segments. The average coefficient of agreement (kappa) between the investigators was 0.950 and the intra-class correlation coefficient was 0.9329 (95% CI 0.9227-0.9420). Three-dimensional fusion of morphological CCTA data with quantitative echocardiographic data on regional myocardial function is feasible and allows highly repro-ducible assignment of myocardial segments to coronary artery branches.

  5. Bilateral Asymmetry of Radius and Tibia Bone Macroarchitecture and Microarchitecture: A High-Resolution Peripheral Quantitative Computed Tomography Study.

    PubMed

    Hildebrandt, Erin M; Manske, Sarah L; Hanley, David A; Boyd, Steven K

    2016-01-01

    Studies assessing bone health often select the dominant or nondominant limb to scan, but not both, for efficiency reasons. New scanning technology allows 3-dimensional (3D) visualization of the microarchitecture in bone, but it is not well understood whether there are differences between the dominant and nondominant limbs. Using 3D high-resolution peripheral quantitative computed tomography (HR-pQCT), the aim of this study is to investigate the effect of limb dominance on bone macroarchitecture and microarchitecture. Healthy male and female participants (N=100; 59 female, 41 male), mean age 30.7±12.1 years, were scanned at both radii and tibiae using HR-pQCT. Hand and foot dominance were determined by the participant's self-report. Most participants were right hand dominant (94.0%) and right foot dominant (91.0%). In the pooled cohort, the dominant radius had significantly greater cortical area (2.11%; p=0.002) and failure load (3.00%; p=0.001). At the tibia, the dominant foot had significantly lower bone mineral density (-0.77%; p=0.042), cortical area (-1.05%; p=0.031), and thickness (-1.51%; p=0.017). For females, there were no differences at the radius, but at the tibia, the dominant side had greater cross-sectional area (1.03%; p=0.044). Our data suggest that dominance has a small yet significant effect on macroarchitecture at both the ultradistal radius and tibia but not microarchitecture. This work emphasizes that it is important to be consistent in the selection of either dominant or nondominant limbs for HR-pQCT cohort studies; however, in the case where the opposite limb needs to be scanned, there would be small differences in macroarchitecture and no significant differences in microarchitecture anticipated.

  6. Quantitative determination of the mineral distribution in different collagen zones of calcifying tendon using high voltage electron microscopic tomography

    NASA Technical Reports Server (NTRS)

    McEwen, B. F.; Song, M. J.; Landis, W. J.

    1991-01-01

    High voltage electron microscopic tomography was used to make the first quantitative determination of the distribution of mineral between different regions of collagen fibrils undergoing early calcification in normal leg tendons of the domestic turkey, Meleagris gallopavo. The tomographic 3-D reconstruction was computed from a tilt series of 61 different views spanning an angular range of +/- 60 degrees in 2 degrees intervals. Successive applications of an interactive computer operation were used to mask the collagen banding pattern of either hole or overlap zones into separate versions of the reconstruction. In such 3-D volumes, regions specified by the mask retained their original image density while the remaining volume was set to background levels. This approach was also applied to the mineral crystals present in the same volumes to yield versions of the 3-D reconstructions that were masked for both the crystal mass and the respective collagen zones. Density profiles from these volumes contained a distinct peak corresponding only to the crystal mass. A comparison of the integrated density of this peak from each profile established that 64% of the crystals observed were located in the collagen hole zones and 36% were found in the overlap zones. If no changes in crystal stability occur once crystals are formed, this result suggests the possibilities that nucleation of mineral is preferentially and initially associated with the hole zones, nucleation occurs more frequently in the hole zones, the rate of crystal growth is more rapid in the hole zones, or a combination of these alternatives. All lead to the conclusion that the overall accumulation of mineral mass is predominant in the collagen hole zones compared to overlap zones during early collagen fibril calcification.

  7. Quantitative determination of the mineral distribution in different collagen zones of calcifying tendon using high voltage electron microscopic tomography

    NASA Technical Reports Server (NTRS)

    McEwen, B. F.; Song, M. J.; Landis, W. J.

    1991-01-01

    High voltage electron microscopic tomography was used to make the first quantitative determination of the distribution of mineral between different regions of collagen fibrils undergoing early calcification in normal leg tendons of the domestic turkey, Meleagris gallopavo. The tomographic 3-D reconstruction was computed from a tilt series of 61 different views spanning an angular range of +/- 60 degrees in 2 degrees intervals. Successive applications of an interactive computer operation were used to mask the collagen banding pattern of either hole or overlap zones into separate versions of the reconstruction. In such 3-D volumes, regions specified by the mask retained their original image density while the remaining volume was set to background levels. This approach was also applied to the mineral crystals present in the same volumes to yield versions of the 3-D reconstructions that were masked for both the crystal mass and the respective collagen zones. Density profiles from these volumes contained a distinct peak corresponding only to the crystal mass. A comparison of the integrated density of this peak from each profile established that 64% of the crystals observed were located in the collagen hole zones and 36% were found in the overlap zones. If no changes in crystal stability occur once crystals are formed, this result suggests the possibilities that nucleation of mineral is preferentially and initially associated with the hole zones, nucleation occurs more frequently in the hole zones, the rate of crystal growth is more rapid in the hole zones, or a combination of these alternatives. All lead to the conclusion that the overall accumulation of mineral mass is predominant in the collagen hole zones compared to overlap zones during early collagen fibril calcification.

  8. Quantitative measurement of attenuation coefficients of bladder biopsies using optical coherence tomography for grading urothelial carcinoma of the bladder

    NASA Astrophysics Data System (ADS)

    Cauberg, Evelyne C. C.; de Bruin, Daniël M.; Faber, Dirk J.; de Reijke, Theo M.; Visser, Mike; de La Rosette, Jean J. M. C. H.; van Leeuwen, Ton G.

    2010-11-01

    Real-time grading of bladder urothelial carcinoma (UC) is clinically important, but the current standard for grading (histopathology) cannot provide this information. Based on optical coherence tomography (OCT)-measured optical attenuation (μt), the grade of bladder UC could potentially be assessed in real time. We evaluate ex vivo whether μt differs between different grades of UC and benign bladder tissue. Human bladder tissue specimens are examined ex vivo by 850-nm OCT using dynamic focusing. Three observers independently determine the μt from the OCT images, and three pathologists independently review the corresponding histology slides. For both methods, a consensus diagnosis is made. We include 76 OCT scans from 54 bladder samples obtained in 20 procedures on 18 patients. The median (interquartile range) μt of benign tissue is 5.75 mm-1 (4.77 to 6.14) versus 5.52 mm-1 (3.47 to 5.90), 4.85 mm-1 (4.25 to 6.50), and 5.62 mm-1 (5.01 to 6.29) for grade 1, 2, and 3 UC, respectively (p = 0.732). Interobserver agreement of histopathology is ``substantial'' [Kappa 0.62, 95% confidence interval (IC) 0.54 to 0.70] compared to ``almost perfect'' [interclass correlation coefficient (ICC) 0.87, 95% CI 0.80 to 0.92] for OCT. Quantitative OCT analysis (by μt) does not detect morphological UC changes. This may be due to factors typical for an ex-vivo experimental setting.

  9. Idiopathic juvenile osteoporosis: a cross-sectional single-centre experience with bone histomorphometry and quantitative computed tomography

    PubMed Central

    2013-01-01

    Background Idiopathic juvenile osteoporosis (IJO) is a rare condition of poorly understood etiology and pathophysiology that affects otherwise healthy children. This condition is characterized clinically by bone pain and vertebral fractures; spontaneous recovery is observed after puberty in the majority of cases. Although decreased trabecular bone turnover has been noted previously, cortical and trabecular bone characteristics as determined by quantitative computed tomography (QCT) and their relationship to bone histomorphometry are unknown. Methods All children with a clinical diagnosis of IJO who were followed in our center since 1995 and who had undergone at least one diagnostic bone biopsy were included in this cross-sectional analysis. Results Fifteen patients (11 males/4 females) with median ages of 5.8 and 10.2 years at first symptoms and at referral, respectively, were included in the analysis. Histomorphometric analysis demonstrated decreased trabecular bone turnover (BFR/BS) in the majority of patients with heterogeneous parameters of trabecular mineralization and volume. QCTresults demonstrated that bone mineral density (BMD) was reduced in both trabecular/lumbar and cortical/femoral bone: Z score: -2.1 (−3.6;–1.0) and −0.9 (−8.2;1.4)in the two compartments, respectively. In the eight patients who underwent both bone biopsy and QCT, cortical BMD was associated with trabecular separation and with trabecular bone formation rate (r = 0.898 and −0.881, respectively, both p < 0.05). Conclusions This series confirms that IJO is characterized by impaired trabecular architecture that can be detected by both bone biopsy and QCT. The association between bone biopsy and QCT results may have implications for diagnosis, treatment, and follow-up of these children. PMID:23418950

  10. Definition for Rheumatoid Arthritis Erosions Imaged with High Resolution Peripheral Quantitative Computed Tomography and Interreader Reliability for Detection and Measurement.

    PubMed

    Barnabe, Cheryl; Toepfer, Dominique; Marotte, Hubert; Hauge, Ellen-Margrethe; Scharmga, Andrea; Kocijan, Roland; Kraus, Sebastian; Boutroy, Stephanie; Schett, Georg; Keller, Kresten Krarup; de Jong, Joost; Stok, Kathryn S; Finzel, Stephanie

    2016-10-01

    High-resolution peripheral quantitative computed tomography (HR-pQCT) sensitively detects erosions in rheumatoid arthritis (RA); however, nonpathological cortical bone disruptions are potentially misclassified as erosive. Our objectives were to set and test a definition for pathologic cortical bone disruptions in RA and to standardize reference landmarks for measuring erosion size. HR-pQCT images of metacarpophalangeal joints of RA and control subjects were used in an iterative process to achieve consensus on the definition and reference landmarks. Independent readers (n = 11) applied the definition to score 58 joints and measure pathologic erosions in 2 perpendicular multiplanar reformations for their maximum width and depth. Interreader reliability for erosion detection and variability in measurements between readers [root mean square coefficient of variation (RMSCV), intraclass correlation (ICC)] were calculated. Pathologic erosions were defined as cortical breaks extending over a minimum of 2 consecutive slices in perpendicular planes, with underlying trabecular bone loss and a nonlinear shape. Interreader agreement for classifying pathologic erosions was 90.2%, whereas variability for width and depth erosion assessment was observed (RMSCV perpendicular width 12.3%, axial width 20.6%, perpendicular depth 24.0%, axial depth 22.2%; ICC perpendicular width 0.206, axial width 0.665, axial depth 0.871, perpendicular depth 0.783). Mean erosion width was 1.84 mm (range 0.16-8.90) and mean depth was 1.86 mm (range 0.30-8.00). We propose a new definition for erosions visualized with HR-pQCT imaging. Interreader reliability for erosion detection is good, but further refinement of selection of landmarks for erosion size measurement, or automated volumetric methods, will be pursued.

  11. Ex vivo visualization of human ciliated epithelium and quantitative analysis of induced flow dynamics by using optical coherence tomography.

    PubMed

    Ling, Yuye; Yao, Xinwen; Gamm, Ute A; Arteaga-Solis, Emilio; Emala, Charles W; Choma, Michael A; Hendon, Christine P

    2017-03-01

    Cilia-driven mucociliary clearance is an important self-defense mechanism of great clinical importance in pulmonary research. Conventional light microscopy possesses the capability to visualize individual cilia and its beating pattern but lacks the throughput to assess the global ciliary activities and flow dynamics. Optical coherence tomography (OCT), which provides depth-resolved cross-sectional images, was recently introduced to this area. Fourteen de-identified human tracheobronchial tissues are directly imaged by two OCT systems: one system centered at 1,300 nm with 6.5 μm axial resolution and 15 μm lateral resolution, and the other centered at 800 nm with 2.72 μm axial resolution and 5.52 μm lateral resolution. Speckle variance images are obtained in both cross-sectional and volumetric modes. After imaging, sample blocks are sliced along the registered OCT imaging plane and processed with hematoxylin and eosin (H&E) stain for comparison. Quantitative flow analysis is performed by tracking the path-lines of microspheres in a fixed cross-section. Both the flow rate and flow direction are characterized. The speckle variance images successfully segment the ciliated epithelial tissue from its cilia-denuded counterpart, and the results are validated by corresponding H&E stained sections. A further temporal frequency analysis is performed to extract the ciliary beat frequency (CBF) at cilia cites. By adding polyester microspheres as contrast agents, we demonstrate ex vivo imaging of the flow induced by cilia activities of human tracheobronchial samples. This manuscript presents an ex vivo study on human tracheobronchial ciliated epithelium and its induced mucous flow by using OCT. Within OCT images, intact ciliated epithelium is effectively distinguished from cilia-denuded counterpart, which serves as a negative control, by examining the speckle variance images. The cilia beat frequency is extracted by temporal frequency analysis. The flow rate, flow

  12. 23.4% saline decreases brain tissue volume in severe hepatic encephalopathy as assessed by a quantitative computed tomography marker

    PubMed Central

    Liotta, Eric M; Lizza, Bryan D; Romanova, Anna L; Guth, James C; Berman, Michael D; Carroll, Timothy J; Francis, Brandon; Ganger, Daniel; Ladner, Daniela P; Maas, Matthew B; Naidech, Andrew M

    2016-01-01

    Objective Cerebral edema is common in severe hepatic encephalopathy and may be life-threatening. Bolus 23.4% hypertonic saline (HTS) improves surveillance neuromonitoring scores, although its mechanism of action is not clearly established. We investigated the hypothesis that bolus HTS decreases cerebral edema in severe hepatic encephalopathy utilizing a quantitative technique to measure brain and CSF volume changes. Design Retrospective analysis of serial computed tomography (CT) scans and clinical data for a case-control series was performed. Setting Intensive care units of a tertiary care hospital. Patients Patients with severe hepatic encephalopathy treated with 23.4% HTS and control patients who did not receive 23.4% HTS. Methods We used clinically obtained CT scans to measure volumes of the ventricles, intracranial CSF, and brain using a previously validated semi-automated technique (Analyze Direct; Overland Park, KS). Volumes before and after 23.4% HTS were compared with Wilcoxon signed-rank test. Associations between total CSF volume, ventricular volume, serum sodium, and Glasgow Coma Scale Scores were assessed using Spearman correlation. Results Eleven patients with 18 administrations of 23.4% HTS met inclusion criteria. Total CSF (median 47.6 [35.1–69.4] to 61.9 [47.7–87.0] mL, p<0.001) and ventricular volumes (median 8.0 [6.9–9.5] to 9.2 [7.8–11.9] mL, p=0.002) increased and Glasgow Coma Scale Scores improved (median 4 [3–6] to 7 [6–9], p=0.008) after 23.4% HTS. In contrast, total CSF and ventricular volumes decreased in untreated control patients. Serum sodium increase was associated with increase in total CSF volume (r=0.83, p<0.001) and change in total CSF volume was associated with ventricular volume change (r=0.86, p<0.001). Conclusions Total CSF and ventricular volumes increased after 23.4% HTS, consistent with a reduction in brain tissue volume. Total CSF and ventricular volume change may be useful quantitative measures to assess

  13. Cryo-soft X-ray tomography as a quantitative three-dimensional tool to model nanoparticle:cell interaction.

    PubMed

    Chiappi, Michele; Conesa, José Javier; Pereiro, Eva; Sorzano, Carlos Oscar Sánchez; Rodríguez, María Josefa; Henzler, Katja; Schneider, Gerd; Chichón, Francisco Javier; Carrascosa, José L

    2016-03-03

    Recent advances in nanoparticle design have generated new possibilities for nano-biotechnology and nano-medicine. Here we used cryo-soft X-ray tomography (cryo-SXT) to collect comprehensive three-dimensional (3D) data to characterise the interaction of superparamagnetic iron oxide nanoparticles (SPION) with a breast cancer cell line. We incubated MCF-7 (a human breast cancer cell line) from 0 to 24 h with SPION (15 nm average diameter, coated with dimercaptosuccinic acid), a system that has been studied previously using various microscopy and bulk techniques. This system facilitates the validation and contextualization of the new 3D data acquired using the cryo-SXT-based approach. After vitrification, samples tested by correlative cryo-epifluorescent microscopy showed SPION accumulation in acidic vesicles related to the endocytic pathway. Microscopy grids bearing MCF-7 cells were then analysed by cryo-SXT to generate whole cell volume 3D maps. Cryo-SXT is an emerging technique that benefits from high X-ray penetration into the biological material to image close-to-native vitrified cells at nanometric resolution with no chemical fixation or staining agents. This unique possibility of obtaining 3D information from whole cells allows quantitative statistical analysis of SPION-containing vesicle (SCV) accumulation inside cells, including vesicle number and size, distances between vesicles, and their distance from the nucleus. Correlation between fluorescent microscopy, cryo-SXT and transmission electron microscopy allowed us to identify SCV and to generate 3D data for statistical analysis of SPION:cell interaction. This study supports continuous transfer of the internalized SPION from the plasma membrane to an accumulation area near the cell nucleus. Statistical analysis showed SCV increase in number and size concomitant with longer incubation times, and therefore an increase in their accumulated volume within the cell. This cumulative effect expands the accumulation

  14. SU-E-QI-16: Reproducibility of Computed Tomography Quantitative Structural Features Using the FDA Thoracic Phantom Image Database

    SciTech Connect

    Budzevich, M; Grove, O; Balagurunathan, Y; Gu, Y; Wang, H; Oliver, J; Latifi, K; Zhang, G; Dilling, T; Gillies, R; Moros, E; Lee, H.

    2014-06-15

    Purpose: To assess the reproducibility of quantitative structural features using images from the computed tomography thoracic FDA phantom database under different scanning conditions. Methods: Development of quantitative image features to describe lesion shape and size, beyond conventional RECIST measures, is an evolving area of research in need of benchmarking standards. Gavrielides et al. (2010) scanned a FDA-developed thoracic phantom with nodules of various Hounsfield units (HU) values, shapes and sizes close to vascular structures using several scanners and varying scanning conditions/parameters; these images are in the public domain. We tested six structural features, namely, Convexity, Perimeter, Major Axis, Minor Axis, Extent Mean and Eccentricity, to characterize lung nodules. Convexity measures lesion irregularity referenced to a convex surface. Previously, we showed it to have prognostic value in lung adenocarcinoma. The above metrics and RECIST measures were evaluated on three spiculated (8mm/-300HU, 12mm/+30HU and 15mm/+30HU) and two non-spiculated (8mm/+100HU and 10mm/+100HU) nodules (from layout 2) imaged at three different mAs values: 25, 100 and 200 mAs; on a Phillips scanner (16-slice Mx8000-IDT; 3mm slice thickness). The nodules were segmented semi-automatically using a commercial software tool; the same HU range was used for all nodules. Results: Analysis showed convexity having the lowest maximum coefficient of variation (MCV): 1.1% and 0.6% for spiculated and non-spiculated nodules, respectively, much lower compared to RECIST Major and Minor axes whose MCV were 10.1% and 13.4% for spiculated, and 1.9% and 2.3% for non-spiculated nodules, respectively, across the various mAs. MCVs were consistently larger for speculated nodules. In general, the dependence of structural features on mAs (noise) was low. Conclusion: The FDA phantom CT database may be used for benchmarking of structural features for various scanners and scanning conditions; we used

  15. Quantitative Classification of Eyes with and without Intermediate Age-related Macular Degeneration Using Optical Coherence Tomography

    PubMed Central

    Farsiu, Sina; Chiu, Stephanie J.; O'Connell, Rachelle V.; Folgar, Francisco A.; Yuan, Eric; Izatt, Joseph A.; Toth, Cynthia A.

    2013-01-01

    Objective To define quantitative indicators for the presence of intermediate age-related macular degeneration (AMD) via spectral-domain optical coherence tomography (SD-OCT) imaging of older adults. Design Evaluation of diagnostic test and technology. Participants and Controls One eye from 115 elderly subjects without AMD and 269 subjects with intermediate AMD from the Age-Related Eye Disease Study 2 (AREDS2) Ancillary SD-OCT Study. Methods We semiautomatically delineated the retinal pigment epithelium (RPE) and RPE drusen complex (RPEDC, the axial distance from the apex of the drusen and RPE layer to Bruch's membrane) and total retina (TR, the axial distance between the inner limiting and Bruch's membranes) boundaries. We registered and averaged the thickness maps from control subjects to generate a map of “normal” non-AMD thickness. We considered RPEDC thicknesses larger or smaller than 3 standard deviations from the mean as abnormal, indicating drusen or geographic atrophy (GA), respectively. We measured TR volumes, RPEDC volumes, and abnormal RPEDC thickening and thinning volumes for each subject. By using different combinations of these 4 disease indicators, we designed 5 automated classifiers for the presence of AMD on the basis of the generalized linear model regression framework. We trained and evaluated the performance of these classifiers using the leave-one-out method. Main Outcome Measures The range and topographic distribution of the RPEDC and TR thicknesses in a 5-mm diameter cylinder centered at the fovea. Results The most efficient method for separating AMD and control eyes required all 4 disease indicators. The area under the curve (AUC) of the receiver operating characteristic (ROC) for this classifier was >0.99. Overall neurosensory retinal thickening in eyes with AMD versus control eyes in our study contrasts with previous smaller studies. Conclusions We identified and validated efficient biometrics to distinguish AMD from normal eyes by

  16. Simulation based quantitative evaluation for display uniformity in a directional backlight auto-stereoscopic display

    NASA Astrophysics Data System (ADS)

    He, Jieyong; Liang, Haowen; Zhang, Quanquan; Feng, Shirui; Wang, Jiahui; Zhou, Jianying

    2016-03-01

    In this article, we propose a quantitative evaluation for the display uniformity in a directional backlight system. Display uniformity is divided into two research aspects - static uniformity and motional uniformity. Factors influencing uniformity deterioration are then discussed in our evaluation. Furthermore, a visualized simulation based on ray-tracing model is proposed to analyze this display uniformity in quantitative depth. Optical distribution on the screen is obtained in this simulation to provide visualized results compared with the experimental results. Our work helps to fill the vacancy for the evaluation of display uniformity on directional backlight type 3D display.

  17. Low resolution brain electromagnetic tomography in a realistic geometry head model: a simulation study

    NASA Astrophysics Data System (ADS)

    Ding, Lei; Lai, Yuan; He, Bin

    2005-01-01

    It is of importance to localize neural sources from scalp recorded EEG. Low resolution brain electromagnetic tomography (LORETA) has received considerable attention for localizing brain electrical sources. However, most such efforts have used spherical head models in representing the head volume conductor. Investigation of the performance of LORETA in a realistic geometry head model, as compared with the spherical model, will provide useful information guiding interpretation of data obtained by using the spherical head model. The performance of LORETA was evaluated by means of computer simulations. The boundary element method was used to solve the forward problem. A three-shell realistic geometry (RG) head model was constructed from MRI scans of a human subject. Dipole source configurations of a single dipole located at different regions of the brain with varying depth were used to assess the performance of LORETA in different regions of the brain. A three-sphere head model was also used to approximate the RG head model, and similar simulations performed, and results compared with the RG-LORETA with reference to the locations of the simulated sources. Multi-source localizations were discussed and examples given in the RG head model. Localization errors employing the spherical LORETA, with reference to the source locations within the realistic geometry head, were about 20-30 mm, for four brain regions evaluated: frontal, parietal, temporal and occipital regions. Localization errors employing the RG head model were about 10 mm over the same four brain regions. The present simulation results suggest that the use of the RG head model reduces the localization error of LORETA, and that the RG head model based LORETA is desirable if high localization accuracy is needed.

  18. Radiation doses in cone-beam breast computed tomography: A Monte Carlo simulation study

    SciTech Connect

    Yi Ying; Lai, Chao-Jen; Han Tao; Zhong Yuncheng; Shen Youtao; Liu Xinming; Ge Shuaiping; You Zhicheng; Wang Tianpeng; Shaw, Chris C.

    2011-02-15

    Purpose: In this article, we describe a method to estimate the spatial dose variation, average dose and mean glandular dose (MGD) for a real breast using Monte Carlo simulation based on cone beam breast computed tomography (CBBCT) images. We present and discuss the dose estimation results for 19 mastectomy breast specimens, 4 homogeneous breast models, 6 ellipsoidal phantoms, and 6 cylindrical phantoms. Methods: To validate the Monte Carlo method for dose estimation in CBBCT, we compared the Monte Carlo dose estimates with the thermoluminescent dosimeter measurements at various radial positions in two polycarbonate cylinders (11- and 15-cm in diameter). Cone-beam computed tomography (CBCT) images of 19 mastectomy breast specimens, obtained with a bench-top experimental scanner, were segmented and used to construct 19 structured breast models. Monte Carlo simulation of CBBCT with these models was performed and used to estimate the point doses, average doses, and mean glandular doses for unit open air exposure at the iso-center. Mass based glandularity values were computed and used to investigate their effects on the average doses as well as the mean glandular doses. Average doses for 4 homogeneous breast models were estimated and compared to those of the corresponding structured breast models to investigate the effect of tissue structures. Average doses for ellipsoidal and cylindrical digital phantoms of identical diameter and height were also estimated for various glandularity values and compared with those for the structured breast models. Results: The absorbed dose maps for structured breast models show that doses in the glandular tissue were higher than those in the nearby adipose tissue. Estimated average doses for the homogeneous breast models were almost identical to those for the structured breast models (p=1). Normalized average doses estimated for the ellipsoidal phantoms were similar to those for the structured breast models (root mean square (rms

  19. Wolter X-Ray Microscope Computed Tomography Ray-Trace Model with Preliminary Simulation Results

    SciTech Connect

    Jackson, J A

    2006-02-27

    It is proposed to build a Wolter X-ray Microscope Computed Tomography System in order to characterize objects to sub-micrometer resolution. Wolter Optics Systems use hyperbolic, elliptical, and/or parabolic mirrors to reflect x-rays in order to focus or magnify an image. Wolter Optics have been used as telescopes and as microscopes. As microscopes they have been used for a number of purposes such as measuring emission x-rays and x-ray fluoresce of thin biological samples. Standard Computed Tomography (CT) Systems use 2D radiographic images, from a series of rotational angles, acquired by passing x-rays through an object to reconstruct a 3D image of the object. The x-ray paths in a Wolter X-ray Microscope will be considerably different than those of a standard CT system. There is little information about the 2D radiographic images that can be expected from such a system. There are questions about the quality, resolution and focusing range of an image created with such a system. It is not known whether characterization information can be obtained from these images and whether these 2D images can be reconstructed to 3D images of the object. A code has been developed to model the 2D radiographic image created by an object in a Wolter X-ray Microscope. This code simply follows the x-ray through the object and optics. There is no modeling at this point of other effects, such as scattering, reflection losses etc. Any object, of appropriate size, can be used in the model code. A series of simulations using a number of different objects was run to study the effects of the optics. The next step will be to use this model to reconstruct an object from the simulated data. Funding for the project ended before this goal could be accomplished. The following documentation includes: (1) background information on current X-ray imaging systems, (2) background on Wolter Optics, (3) description of the Wolter System being used, (4) purpose, limitations and development of the modeling

  20. Injection blow moulding single stage process: Validation of the numerical simulation through tomography analysis

    NASA Astrophysics Data System (ADS)

    Biglione, Jordan; Béreaux, Yves; Charmeau, Jean-Yves

    2016-10-01

    The injection blow moulding single stage process has been made available on standard injection moulding machine. Both the injection moulding stage and the blow moulding stage are being taken care of in an injection mould. Thus the dimensions of this mould are those of a conventional injection moulding mould. The fact that the two stages are located in the same mould leads to a process more constrained than the conventional one. This process introduces temperature gradients, molecular orientation, high stretch rates and high cooling rates. These constraints lead to a small processing window. In practice, the preform has to remain sufficiently melted to be blown so that the process takes place between the melting temperature and the crystallization temperature. In our numerical approach, the polymer is supposed to be blown in its molten state. Hence we have identified the mechanical behaviour of the polymer in its molten state through dynamical rheology experiments. A viscous Cross model has been proved to be relevant to the problem. Thermal dependence is assumed by an Arrhenius law. The process is simulated through a finite element code (POLYFLOW software) in the Ansys Workbench framework. Thickness measurements using image analysis of tomography data are performed and comparisons with the simulation results show good agreements.

  1. Improved importance sampling for Monte Carlo simulation of time-domain optical coherence tomography

    PubMed Central

    Lima, Ivan T.; Kalra, Anshul; Sherif, Sherif S.

    2011-01-01

    We developed an importance sampling based method that significantly speeds up the calculation of the diffusive reflectance due to ballistic and to quasi-ballistic components of photons scattered in turbid media: Class I diffusive reflectance. These components of scattered photons make up the signal in optical coherence tomography (OCT) imaging. We show that the use of this method reduces the computation time of this diffusive reflectance in time-domain OCT by up to three orders of magnitude when compared with standard Monte Carlo simulation. Our method does not produce a systematic bias in the statistical result that is typically observed in existing methods to speed up Monte Carlo simulations of light transport in tissue. This fast Monte Carlo calculation of the Class I diffusive reflectance can be used as a tool to further study the physical process governing OCT signals, e.g., obtain the statistics of the depth-scan, including the effects of multiple scattering of light, in OCT. This is an important prerequisite to future research to increase penetration depth and to improve image extraction in OCT. PMID:21559120

  2. Application of orthogonal sampling to incomplete data interferometric tomography: numerical simulation and experimental analysis.

    PubMed

    Hongbing, Yao; Yongkang, Zhang; Xia, Ye; Anzhi, He

    2008-05-01

    Orthogonal projection sampling mode was proposed to reconstruct the incomplete-data flow field in optical computerized tomography (OCT). With numerical simulation technique, a two-peak plane symmetric flow field was reconstructed in different sampling modes and discussed in simulated results is the reconstructive accuracy with error indexes, such as mean square error (MSE) and peak error (PE). The corresponding experiments were researched with a Fabry-Perot rotary interferometer. The results indicated that the errors were drastically reduced and the precision was improved when orthogonal projection sampling mode was adopted in the reconstruction of the incomplete data field. The MSE obtained with orthogonal sampling mode was decreased 72.81% from that of the sequential projection sampling mode (the difference between the MSE obtained with the orthogonal sampling mode and that with the sequential sampling mode divided by the MSE of the sequential sampling mode) and the PE was decreased by 73.97%. The precision obtained from the experimental results reached 10%, which showed the orthogonal projection sampling could be a practicable sampling mode for the incomplete data field reconstruction in OCT and could provide some guidance for the flow-field measurement and apparatus design in the practical situation.

  3. FEM-based simulation of a fluorescence tomography experiment using anatomical MR images

    NASA Astrophysics Data System (ADS)

    Ren, Wuwei; Elmer, Andreas; Augath, Mark-Aurel; Rudin, Markus

    2016-03-01

    A hybrid system combining fluorescence molecular tomography (FMT) and magnetic resonance imaging (MRI) is attractive for preclinical imaging as it allows fusion of molecular information derived from FMT and anatomical reference data derived from MRI. We have previously developed such a system and demonstrated its performance in biological applications. For reconstruction slab geometry with homogeneous optical parameters was assumed, which led to undesirable artifacts. In order to exploit the power of the hybrid system, the use of MRI derived anatomical information, as a constraint for FMT reconstruction, appears logical. Heterogeneity of tissues and irregular surface derived from MRI can be accounted for by generating a mesh using the finite element method (FEM), and attributing optical parameters to individual mesh points. We have established a forward simulation tool based on TOAST++ to mimic an FMT experiment. MRI images were recorded on a 9.4T MR scanner using a T1-weighted pulse sequence. The voxelized dataset was processed by iso2mesh to yield a 3D-mesh. Four steps of FMT simulation were included: 1) Assignment of optical properties, 2) Specification of boundary conditions and generation of 3) excitation and 4) emission maps. FEM-derived results were compared with those obtained using the analytical solution of Green's function and with experimental data with a single fluorescent inclusion in a silicon phantom. Once, the forward modeling method is properly validated it will be used as a central element of a reconstruction algorithm for analyzing data derived from a hybrid FMT/MRI setup.

  4. [Flow simulation of normal pulmonary artery branches based on multiple detectors computed tomography].

    PubMed

    Wang, Li-Hua; Zhang, Wen-Pu; Jiang, Wei-Xiang; Qian, Yu-E; Guo, You-Min

    2007-09-25

    To simulate the flow condition in the main pulmonary artery and the branches of left and right pulmonary arteries by combining the images from CT pulmonary angiography (CTPA) by multiple detectors computed tomography (MDCT) and the flow condition data from ultrasonic cardiography. The normal enhanced chest CTPA images with ECG-gating from 25 persons undergoing physical examination, 21 males and 4 females, aged 39, underwent thin-slice multiple plane reconstruction in diastolic and systolic periods respectively. These images were stored in the InSpace software. On the base of coordinates GAMBIT software was used to generate the nodes and meshes. FLUENT software was used to simulate the blood flow speed and pressure field distribution. The pressure levels of the main pulmonary artery and the branches of left and right pulmonary arteries were higher during the systolic period. The blood flow velocity was faster during the systolic period too. The right lower lobe artery endured the most significant pressure during both systolic and diastolic periods. However, there were not significant differences in pressure and blood flow velocity between the systolic and diastolic periods in the segmental arteries. The right lower lobe artery is the first part to be affected when the pulmonary pressure rises. It is feasible to study the changes of the flow condition in the branches of pulmonary artery through combining CTPA images and relevant softwares.

  5. Simulation of broad spectral bandwidth emitters at 1060 nm for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Tooley, I. G.; Childs, D. T. D.; Stevens, B. J.; Groom, K. M.; Hogg, R. A.

    2016-03-01

    The simulation of broad spectral bandwidth light sources (semiconductor optical amplifiers (SOA) and superluminescent diodes (SLD)) for application in ophthalmic optical coherence tomography is reported. The device requirements and origin of key device parameters are outlined, and a range of single and double InGaAs/GaAs quantum well (QW) active elements are simulated with a view to application in different OCT embodiments. We confirm that utilising higher order optical transitions is beneficial for single QW SOAs, but may introduce deleterious spectral modulation in SLDs. We show how an addition QW may be introduced to eliminate this spectral modulation, but that this results in a reduction of the gain spectrum width. We go on to explore double QW structures where the roles of the two QWs are reversed, with the narrow QW providing long wavelength emission and gain. We show how this modification in the density of states results in a significant increase in gain-spectrum width for a given current.

  6. Celiac plexus block: an anatomical study and simulation using computed tomography*

    PubMed Central

    Pereira, Gabriela Augusta Mateus; Lopes, Paulo Tadeu Campos; dos Santos, Ana Maria Pujol Vieira; Pozzobon, Adriane; Duarte, Rodrigo Dias; Cima, Alexandre da Silveira; Massignan, Ângela

    2014-01-01

    Objective To analyze anatomical variations associated with celiac plexus complex by means of computed tomography simulation, assessing the risk for organ injury as the transcrural technique is utilized. Materials and Methods One hundred eight transaxial computed tomography images of abdomen were analyzed. The aortic-vertebral, celiac trunk (CeT)-vertebral, CeT-aortic and celiac-aortic-vertebral topographical relationships were recorded. Two needle insertion pathways were drawn on each of the images, at right and left, 9 cm and 4.5 cm away from the midline. Transfixed vital organs and gender-related associations were recorded. Results Aortic-vertebral - 45.37% at left and 54.62% in the middle; CeT-vertebral - T12, 36.11%; T12-L1, 32.4%; L1, 27.77%; T11-T12, 2.77%; CeT-aortic - 53.7% at left and 46.3% in the middle; celiac-aortic-vertebral - L-l, 22.22%; M-m, 23.15%; L-m, 31.48%; M-l, 23.15%. Neither correspondence on the right side nor significant gender-related associations were observed. Conclusion Considering the wide range of abdominal anatomical variations and the characteristics of needle insertion pathways, celiac plexus block should not be standardized. Imaging should be performed prior to the procedure in order to reduce the risks for injuries or for negative outcomes to patients. Gender-related anatomical variations involved in celiac plexus block should be more deeply investigated, since few studies have addressed the subject. PMID:25741102

  7. Pitch control margin at high angle of attack - Quantitative requirements (flight test correlation with simulation predictions)

    NASA Technical Reports Server (NTRS)

    Lackey, J.; Hadfield, C.

    1992-01-01

    Recent mishaps and incidents on Class IV aircraft have shown a need for establishing quantitative longitudinal high angle of attack (AOA) pitch control margin design guidelines for future aircraft. NASA Langley Research Center has conducted a series of simulation tests to define these design guidelines. Flight test results have confirmed the simulation studies in that pilot rating of high AOA nose-down recoveries were based on the short-term response interval in the forms of pitch acceleration and rate.

  8. Pitch control margin at high angle of attack - Quantitative requirements (flight test correlation with simulation predictions)

    NASA Technical Reports Server (NTRS)

    Lackey, J.; Hadfield, C.

    1992-01-01

    Recent mishaps and incidents on Class IV aircraft have shown a need for establishing quantitative longitudinal high angle of attack (AOA) pitch control margin design guidelines for future aircraft. NASA Langley Research Center has conducted a series of simulation tests to define these design guidelines. Flight test results have confirmed the simulation studies in that pilot rating of high AOA nose-down recoveries were based on the short-term response interval in the forms of pitch acceleration and rate.

  9. Simulation study of magnetic resonance imaging-guided cortically constrained diffuse optical tomography of human brain function

    NASA Astrophysics Data System (ADS)

    Boas, David A.; Dale, Anders M.

    2005-04-01

    Diffuse optical imaging can measure brain activity noninvasively in humans through the scalp and skull by measuring the light intensity modulation arising from localized-activity-induced absorption changes within the cortex. Spatial resolution and localization accuracy are currently limited by measurement geometry to approximately 3 cm in the plane parallel to the scalp. Depth resolution is a more significant challenge owing to the limited angle tomography permitted by reflectance-only measurements. We combine previously established concepts for improving image quality and demonstrate, through simulation studies, their application for improving the image quality of adult human brain function. We show in a three-dimensional human head model that localization accuracy is significantly improved by the addition of measurements that provide overlapping samples of brain tissue. However, the reconstructed absorption contrast is significantly underestimated because its depth is underestimated. We show that the absorption contrast amplitude accuracy can be significantly improved by providing a cortical spatial constraint in the image reconstruction to obtain a better depth localization. The cortical constraint makes physiological sense since the brain-activity-induced absorption changes are occurring in the cortex and not in the scalp, skull, and cerebral spinal fluid. This spatial constraint is provided by segmentation of coregistered structural magnetic resonance imaging (MRI). However, the absorption contrast deep within the cortex is reconstructed superficially, resulting in an underestimation of the absorption contrast. The synthesis of techniques described here indicates that multimodality imaging of brain function with diffuse optical imaging and MRI has the potential to provide more quantitative estimates of the total and deoxyhemoglobin response to brain activation, which is currently not provided by either method independently. However, issues of depth resolution

  10. Quantitative X-ray fluorescence computed tomography for low-Z samples using an iterative absorption correction algorithm

    NASA Astrophysics Data System (ADS)

    Huang, Rong; Limburg, Karin; Rohtla, Mehis

    2017-05-01

    X-ray fluorescence computed tomography is often used to measure trace element distributions within low-Z samples, using algorithms capable of X-ray absorption correction when sample self-absorption is not negligible. Its reconstruction is more complicated compared to transmission tomography, and therefore not widely used. We describe in this paper a very practical iterative method that uses widely available transmission tomography reconstruction software for fluorescence tomography. With this method, sample self-absorption can be corrected not only for the absorption within the measured layer but also for the absorption by material beyond that layer. By combining tomography with analysis for scanning X-ray fluorescence microscopy, absolute concentrations of trace elements can be obtained. By using widely shared software, we not only minimized the coding, took advantage of computing efficiency of fast Fourier transform in transmission tomography software, but also thereby accessed well-developed data processing tools coming with well-known and reliable software packages. The convergence of the iterations was also carefully studied for fluorescence of different attenuation lengths. As an example, fish eye lenses could provide valuable information about fish life-history and endured environmental conditions. Given the lens's spherical shape and sometimes the short distance from sample to detector for detecting low concentration trace elements, its tomography data are affected by absorption related to material beyond the measured layer but can be reconstructed well with our method. Fish eye lens tomography results are compared with sliced lens 2D fluorescence mapping with good agreement, and with tomography providing better spatial resolution.

  11. Influence of Cone-Beam Computed Tomography filters on diagnosis of simulated endodontic complications.

    PubMed

    Verner, F S; D'Addazio, P S; Campos, C N; Devito, K L; Almeida, S M; Junqueira, R B

    2017-11-01

    To evaluate the influence of cone-beam computed tomography (CBCT) filters on diagnosis of simulated endodontic complications. Sixteen human teeth, in three mandibles, were submitted to the following simulated endodontic complications: (G1) fractured file, (G2) perforations in the canal walls, (G3) deviated cast post, and (G4) external root resorption. The mandibles were submitted to CBCT examination (I-Cat(®) Next Generation). Five oral radiologists evaluated the images independently with and without XoranCat(®) software filters. Accuracy, sensitivity and specificity were determined. ROC curves were calculated for each group with the filters, and the areas under the curves were compared using anova (one-way) test. McNemar test was applied for pair-wise agreement between all images versus the gold standard and original images versus images with filters (P < 0.05). G1 was the most difficult endodontic complication to diagnosis, followed by G2, G4 and G3. There were no differences between areas under the ROC curves for the filters in all groups; however, Sharpen Super Mild filter had the best results for G1 (0.47), Angio Sharpen Low 3 × 3 for G2 (0.93), Angio Sharpen Low 3 × 3, S9, Shadow and Sharpen for G3 (1.00) and Sharpen 3 × 3 for G4 (1.00). The McNemar test revealed significant differences between all filters with the gold standard (P = 0.00 for all filters) and the originals images (P = 0.00 for all filters) only in G1 group. There were no differences in the other groups. The filters did not improve the diagnosis of the simulated endodontic complications evaluated. Their diagnosis remains a major challenge in clinical practice. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  12. A quantitative parameter-free prediction of simulated crystal nucleation times

    SciTech Connect

    Aga, Rachel S; Morris, James R; Hoyt, Jeffrey John; Mendelev, Mikhail I.

    2006-01-01

    We present direct comparisons between simulated crystal-nucleation times and theoretical predictions using a model of aluminum, and demonstrate that a quantitative prediction can be made. All relevant thermodynamic properties of the system are known, making the agreement of our simulation data with nucleation theories free of any adjustable parameters. The role of transient nucleation is included in the classical nucleation theory approach, and shown to be necessary to understand the observed nucleation times. The calculations provide an explanation on why nucleation is difficult to observe in simulations at moderate undercoolings. Even when the simulations are significantly larger than the critical nucleus, and when simulation times are sufficiently long, at moderate undercoolings the small concentration of critical nuclei makes the probability of the nucleation low in molecular dynamics simulations.

  13. Note on quantitatively correct simulations of the kinetic beam-plasma instability

    SciTech Connect

    Lotov, K. V.; Timofeev, I. V.; Mesyats, E. A.; Snytnikov, A. V.; Vshivkov, V. A.

    2015-02-15

    A large number of model particles are shown necessary for quantitatively correct simulations of the kinetic beam-plasma instability with the clouds-in-cells method. The required number of particles scales inversely with the expected growth rate, as only a narrow interval of beam velocities is resonant with the wave in the kinetic regime.

  14. The use of isodose levels to interpret radiation induced lung injury: a quantitative analysis of computed tomography changes

    PubMed Central

    Knoll, Miriam A.; Sheu, Ren Dih; Knoll, Abraham D.; Kerns, Sarah L.; Lo, Yeh-Chi; Rosenzweig, Kenneth E.

    2016-01-01

    Background Patients treated with stereotactic body radiation therapy (SBRT) for lung cancer are often found to have radiation-induced lung injury (RILI) surrounding the treated tumor. We investigated whether treatment isodose levels could predict RILI. Methods Thirty-seven lung lesions in 32 patients were treated with SBRT and received post-treatment follow up (FU) computed tomography (CT). Each CT was fused with the original simulation CT and treatment isodose levels were overlaid. The RILI surrounding the treated lesion was contoured. The RILI extension index [fibrosis extension index (FEI)] was defined as the volume of RILI extending outside a given isodose level relative to the total volume of RILI and was expressed as a percentage. Results Univariate analysis revealed that the planning target volume (PTV) was positively correlated with RILI volume at FU: correlation coefficient (CC) =0.628 and P<0.0001 at 1st FU; CE =0.401 and P=0.021 at 2nd FU; CE =0.265 and P=0.306 at 3rd FU. FEI −40 Gy at 1st FU was significantly positively correlated with FEI −40 Gy at subsequent FU’s (CC =0.689 and P=6.5×10−5 comparing 1st and 2nd FU; 0.901 and P=0.020 comparing 2nd and 3rd FU. Ninety-six percent of the RILI was found within the 20 Gy isodose line. Sixty-five percent of patients were found to have a decrease in RILI on the second 2nd CT. Conclusions We have shown that RILI evolves over time and 1st CT correlates well with subsequent CTs. Ninety-six percent of the RILI can be found to occur within the 20 Gy isodose lines, which may prove beneficial to radiologists attempting to distinguish recurrence vs. RILI. PMID:26981453

  15. Semi-quantitative and simulation analyses of effects of γ rays on determination of calibration factors of PET scanners with point-like (22)Na sources.

    PubMed

    Hasegawa, Tomoyuki; Sato, Yasushi; Oda, Keiichi; Wada, Yasuhiro; Murayama, Hideo; Yamada, Takahiro

    2011-09-21

    The uncertainty of radioactivity concentrations measured with positron emission tomography (PET) scanners ultimately depends on the uncertainty of the calibration factors. A new practical calibration scheme using point-like (22)Na radioactive sources has been developed. The purpose of this study is to theoretically investigate the effects of the associated 1.275 MeV γ rays on the calibration factors. The physical processes affecting the coincidence data were categorized in order to derive approximate semi-quantitative formulae. Assuming the design parameters of some typical commercial PET scanners, the effects of the γ rays as relative deviations in the calibration factors were evaluated by semi-quantitative formulae and a Monte Carlo simulation. The relative deviations in the calibration factors were less than 4%, depending on the details of the PET scanners. The event losses due to rejecting multiple coincidence events of scattered γ rays had the strongest effect. The results from the semi-quantitative formulae and the Monte Carlo simulation were consistent and were useful in understanding the underlying mechanisms. The deviations are considered small enough to correct on the basis of precise Monte Carlo simulation. This study thus offers an important theoretical basis for the validity of the calibration method using point-like (22)Na radioactive sources.

  16. Noninvasive imaging of hemoglobin concentration and oxygen saturation for detection of osteoarthritis in the finger joints using multispectral three-dimensional quantitative photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Sun, Yao; Sobel, Eric; Jiang, Huabei

    2013-05-01

    We present quantitative imaging of hemoglobin concentration and oxygen saturation in in vivo finger joints and evaluate the feasibility of detecting osteoarthritis (OA) in the hand using three-dimensional (3D) multispectral quantitative photoacoustic tomography (3D qPAT). The results show that both the anatomical structures and quantitative chromophore concentrations (oxy-hemoglobin and deoxy-hemoglobin) of different joint tissues (hard phalanges and soft cartilage/synovial fluid between phalanges) can be imaged in vivo with the multispectral 3D qPAT. Enhanced hemoglobin concentrations and dropped oxygen saturations in osteoarthritic phalanges and soft joint tissues in joint cavities have been observed. This study indicates that the multispectral 3D qPAT is a promising approach to detect the angiogenesis and hypoxia associated with OA disease and a potential clinical tool for early OA detection in the finger joints.

  17. Quantitative EEG abnormalities in persons with "pure" epileptic predisposition without epilepsy: a low resolution electromagnetic tomography (LORETA) study.

    PubMed

    Puskás, S; Bessenyei, M; Fekete, I; Hollódy, K; Clemens, B

    2010-09-01

    Epileptic predisposition means genetically determined, increased seizure susceptibility. Neurophysiological evaluation of this condition is still lacking. In order to investigate "pure epileptic predisposition" (without epilepsy) in this pilot study the authors prospectively recruited ten persons who displayed generalized tonic-clonic seizures precipitated by 24 or more hours of sleep deprivation but were healthy in any other respects. 21-channel EEGs were recorded in the morning, in the waking state, after a night of sufficient sleep in the interictal period. For each person, a total of 120s artifact-free EEG was processed to low resolution electromagnetic tomography (LORETA) analysis. LORETA activity (Ampers/meters squared) was computed for 2394 voxels, 19 active electrodes and 1Hz very narrow bands from 1 to 25Hz. The data were compressed into four frequency bands (delta: 0.5-4.0Hz, theta: 4.5-8.0Hz, alpha: 8.5-12.0Hz, beta: 12.5-25.0Hz) and projected onto the MRI figures of a digitized standard brain atlas. The band-related LORETA results were compared to those of ten, age- and sex-matched healthy persons using independent t-tests. p<0.01 differences were accepted as statistically significant. Statistically significant decrease of alpha activity was found in widespread, medial and lateral parts of the cortex above the level of the basal ganglia. Maximum alpha decrease and statistically significant beta decrease were found in the left precuneus. Statistically not significant differences were delta increase in the medial-basal frontal area and theta increase in the same area and in the basal temporal area. The significance of alpha decrease in the patient group remains enigmatic. beta decrease presumably reflects non-specific dysfunction of the cortex. Prefrontal delta and theta increase might have biological meaning despite the lack of statistical significance: these findings are topographically similar to those reported in idiopathic generalized epilepsy in

  18. Evaluation of bone microarchitecture by high-resolution peripheral quantitative computed tomography (HR-pQCT) in hemodialysis patients.

    PubMed

    Negri, A L; Del Valle, E E; Zanchetta, M B; Nobaru, M; Silveira, F; Puddu, M; Barone, R; Bogado, C E; Zanchetta, J R

    2012-10-01

    Hemodialyzed patients have decreased bone strength not completely characterized. We evaluated bone microarchitecture in hemodialysis patients and compared it to that of subjects without renal disease by high-resolution peripheral quantitative computed tomography (HR-pQCT). Hemodialysis patients have a marked decreased in cortical density, thickness, and area with significant reduction in trabecular parameters that correlated with the severity of secondary hyperparathyroidism only in women. Although fracture risk is greatly increased in dialysis patients, the corresponding decreased in bone strength has not been completely characterized. We evaluated volumetric bone mineral density (vBMD) and bone microstructure by HR-pQCT at the distal radius and tibia in 50 hemodialyzed (HD) patients (30 females, mean age 53.2 ± 6 years and 20 males, mean age 59.1 ± 11 years) and 50 sex- and age-matched controls. At the distal radius HD, women showed a 29% reduction in total and trabecular density and trabecular bone volume fraction (p < 0.0001) compared to controls. Trabecular number was reduced by 25% (p < 0.0001), while trabecular separation was increased by 51%. Cortical thickness (-40%, p < 0.0001) and cortical area (-42%, p < 0.0001) were the parameters most reduced, while compact density was the parameter least reduced (-15%, p < 0.0001). Similar findings were found at the tibia. In HD men, HR-pQCT at the distal radius and tibia showed a reduction in volumetric density and microstructure parameters to a lesser extent than in women. In the hemodialyzed group, cortical thickness at the radius was negatively correlated with age both in women and men. At the distal radius and tibia, we found significant negative correlations between Log iPTH and total alkaline phosphatase with cortical vBMD(r = -0.48, p < 0.01; r = -0.69, p < 0.001), thickness (-0.37, p < 0.05; r = -0.60, p < 0.001), and area ((r = -0.43, p = 0

  19. A New Material Mapping Procedure for Quantitative Computed Tomography-Based, Continuum Finite Element Analyses of the Vertebra

    PubMed Central

    Unnikrishnan, Ginu U.; Morgan, Elise F.

    2011-01-01

    Inaccuracies in the estimation of material properties and errors in the assignment of these properties into finite element models limit the reliability, accuracy, and precision of quantitative computed tomography (QCT)-based finite element analyses of the vertebra. In this work, a new mesh-independent, material mapping procedure was developed to improve the quality of predictions of vertebral mechanical behavior from QCT-based finite element models. In this procedure, an intermediate step, called the material block model, was introduced to determine the distribution of material properties based on bone mineral density, and these properties were then mapped onto the finite element mesh. A sensitivity study was first conducted on a calibration phantom to understand the influence of the size of the material blocks on the computed bone mineral density. It was observed that varying the material block size produced only marginal changes in the predictions of mineral density. Finite element (FE) analyses were then conducted on a square column-shaped region of the vertebra and also on the entire vertebra in order to study the effect of material block size on the FE-derived outcomes. The predicted values of stiffness for the column and the vertebra decreased with decreasing block size. When these results were compared to those of a mesh convergence analysis, it was found that the influence of element size on vertebral stiffness was less than that of the material block size. This mapping procedure allows the material properties in a finite element study to be determined based on the block size required for an accurate representation of the material field, while the size of the finite elements can be selected independently and based on the required numerical accuracy of the finite element solution. The mesh-independent, material mapping procedure developed in this study could be particularly helpful in improving the accuracy of finite element analyses of

  20. Quantitative evaluation of bone development of the distal phalanx of the cow hind limb using computed tomography.

    PubMed

    Tsuka, T; Ooshita, K; Sugiyama, A; Osaki, T; Okamoto, Y; Minami, S; Imagawa, T

    2012-01-01

    Computed tomography (CT) was performed on 400 claws (200 inner and 200 outer claws) of 100 pairs of bovine hind limbs to investigate the etiological theory that an exacerbating factor for ulceration is exostosis of the tuberculum flexorium within the distal phalanx. A variety of morphological changes of the tuberculum flexorium of bovine hind limb claws was visualized by 3-dimensional CT, and the geometry of these claws suggested a growth pattern of bone development with respect to the assumed daily loading patterns. This growth occurs initially at the abaxial caudal aspect of the distal phalanx and is followed by horizontal progression toward the axial aspect. The length of downward bone development on the solar face of the distal phalanx was 2.73±1.32 mm in the outer claws, significantly greater than in the inner claws (2.38±0.96 mm). Ratios of downward (vertical) bone development to the thickness of the subcutis and the corium (VerBD ratios) did not differ between the outer and inner claws (36.7 vs. 38.3%, respectively). Ratios of horizontal bone development to the axial-to-abaxial line of the tuberculum flexorium (HorBD ratios) were approximately 60% for both outer and inner claws. These quantitative measures regarding horizontal and vertical bone development within the distal phalanx were positively correlated with age and VerBD ratios (r=0.53 and r=0.36 for the inner and outer claws, respectively). Correlations between claw width of the outer claw and length of vertical bone development (r=0.43), the HorBD ratio (r=0.51), and the VerBD ratio (r=0.42) suggested that the relative size difference between the inner and outer claws enhances bone development in the outer claw. Correlation coefficients between VerBD and HorBD ratios (r=0.52 and 0.63 for the inner and outer claws, respectively) suggested that horizontal and vertical bone development occurs as a synchronized process within the tuberculum flexorium. This age-related progress of bone development

  1. Can high-resolution peripheral quantitative computed tomography imaging of subchondral and cortical bone predict condylar fracture in Thoroughbred racehorses?

    PubMed

    Trope, G D; Ghasem-Zadeh, A; Anderson, G A; Mackie, E J; Whitton, R C

    2015-07-01

    High-resolution 3D imaging may improve the prediction and/or early identification of condylar fractures of the distal metacarpus/tarsus and reduce the frequency of breakdown injury in racehorses. To test the hypotheses that horses suffering condylar fractures have higher bone volume fraction (BV/TV) of the distal metacarpal epiphysis, greater subchondral bone thickness at the fracture site and higher second moment of inertia in the metacarpal midshaft as identified with high-resolution 3D imaging. Cross-sectional study using cadaver material. Thoroughbreds that died on racetracks were grouped as: 1) horses with third metacarpal (McIII) fractures with a condylar component (cases, n = 13); 2) horses with no limb fracture (controls, n = 8); 3) horses with fractures in other bones or suspensory apparatus disruption (other fatal injuries, n = 16). The palmar condyles of McIII and the midshaft were examined with high resolution peripheral quantitative computed tomography (HR-pQCT). Statistical analysis included logistic regression and Spearman's correlation. There were no significant differences in BV/TV of distal McIII and second moment of inertia of the midshaft between cases and controls. Epiphyseal bone BV/TV was greater in injured limbs of horses with any fatal limb injury (Groups 1 and 3 combined) compared with controls (odds ratio = 1.20, 95% confidence interval 1.01-1.42, P = 0.034). An epiphyseal BV/TV>0.742 resulted in a sensitivity of 82.8% and specificity of 62.5% in identifying horses with fatal limb injury. In horses without condylar fracture, increased subchondral bone thickness was associated with palmar osteochondral disease lesions in the adjacent condyle (rs = 0.65, P<0.001). Increased BV/TV of the distal metacarpus may have some value for identifying horses at risk of any fatal breakdown injury but not metacarpal condylar fractures. Measurement of parasagittal groove subchondral bone thickness is complicated by adjacent palmar osteochondral disease

  2. A new material mapping procedure for quantitative computed tomography-based, continuum finite element analyses of the vertebra.

    PubMed

    Unnikrishnan, Ginu U; Morgan, Elise F

    2011-07-01

    Inaccuracies in the estimation of material properties and errors in the assignment of these properties into finite element models limit the reliability, accuracy, and precision of quantitative computed tomography (QCT)-based finite element analyses of the vertebra. In this work, a new mesh-independent, material mapping procedure was developed to improve the quality of predictions of vertebral mechanical behavior from QCT-based finite element models. In this procedure, an intermediate step, called the material block model, was introduced to determine the distribution of material properties based on bone mineral density, and these properties were then mapped onto the finite element mesh. A sensitivity study was first conducted on a calibration phantom to understand the influence of the size of the material blocks on the computed bone mineral density. It was observed that varying the material block size produced only marginal changes in the predictions of mineral density. Finite element (FE) analyses were then conducted on a square column-shaped region of the vertebra and also on the entire vertebra in order to study the effect of material block size on the FE-derived outcomes. The predicted values of stiffness for the column and the vertebra decreased with decreasing block size. When these results were compared to those of a mesh convergence analysis, it was found that the influence of element size on vertebral stiffness was less than that of the material block size. This mapping procedure allows the material properties in a finite element study to be determined based on the block size required for an accurate representation of the material field, while the size of the finite elements can be selected independently and based on the required numerical accuracy of the finite element solution. The mesh-independent, material mapping procedure developed in this study could be particularly helpful in improving the accuracy of finite element analyses of vertebroplasty and

  3. Bone mineral density obtained by peripheral quantitative computed tomography (pQCT) in middle-aged and elderly Japanese.

    PubMed

    Tsuzuku, S; Niino, N; Ando, F; Shimokata, H

    2000-04-01

    To clarify age-related changes in bone mineral density (BMD) by peripheral quantitative computed tomography (pQCT), 1,124 Japanese middle-aged and elderly community-dwelling people were examined. The BMD of the trabecular bone was assessed at the distal part of the radius (D50), and the BMD of the cortical bone was assessed at the diaphysis of the radius (P100). P100 during age 40 to 49 was significantly higher in females (1359.6 +/- 10.7 mg/cm3, mean +/- SE) than in males (1253.5 +/- 9.5 mg/cm3), while there was no difference in D50, 245.3 +/- 5.1 mg/cm3 in females and 293.0 +/- 5.5 mg/cm3 in males. Females and males aged 50 to 59 lost 8.09 +/- 2.08 (mean +/- SE) mg/cm3 and 3.80 +/- 1.77 mg/cm3 of D50 every year, respectively. As for P100, females lost 25.1 +/- 4.48 mg/cm3, and males lost 6.37 +/- 3.89 mg/cm3 every year. Because of these gender differences, both D50 and P100 were significantly higher in males than in females aged 50 and over. Assuming that the average BMD between ages 40 and 44 was the maximum bone mineral density (BMD max), the percentage change from the BMD max with age was examined. Females aged 60 to 69 whose BMD were under 70% of the BMD max made up 73.9% in D50 and 23.2% in P100. Only 21.1% of males aged 60 to 69 showed less than 70% of the BMD max in D50 and only 3.8% in P100. The percentage decrease in BMD by age was larger in D50 than in P100 in both males and females. The individual difference in BMD was larger in D50 than in P100. These results suggest that pQCT may be useful to independently assess aging effects on cortical and trabecular bone density.

  4. Administration of romosozumab improves vertebral trabecular and cortical bone as assessed with quantitative computed tomography and finite element analysis.

    PubMed

    Graeff, Christian; Campbell, Graeme M; Peña, Jaime; Borggrefe, Jan; Padhi, Desmond; Kaufman, Allegra; Chang, Sung; Libanati, Cesar; Glüer, Claus-Christian

    2015-12-01

    Romosozumab inhibits sclerostin, thereby increasing bone formation and decreasing bone resorption. This dual effect of romosozumab leads to rapid and substantial increases in areal bone mineral density (aBMD) as measured by dual-energy X-ray absorptiometry (DXA). In a phase 1b, randomized, double-blind, placebo-controlled study, romosozumab or placebo was administered to 32 women and 16 men with low aBMD for 3 months, with a further 3-month follow-up: women received six doses of 1 or 2mg/kg every 2 weeks (Q2W) or three doses of 2 or 3mg/kg every 4 weeks (Q4W); men received 1mg/kg Q2W or 3mg/kg Q4W. Quantitative computed tomography (QCT) scans at lumbar (L1-2) vertebrae and high-resolution QCT (HR-QCT) scans at thoracic vertebra (T12) were analyzed in a subset of subjects at baseline, month 3, and month 6. The QCT subset included 24 romosozumab and 9 placebo subjects and the HR-QCT subset included 11 romosozumab and 3 placebo subjects. The analyses pooled the romosozumab doses. Linear finite element modeling of bone stiffness was performed. Compared with placebo, the romosozumab group showed improvements at month 3 for trabecular BMD by QCT and HR-QCT, HR-QCT trabecular bone volume fraction (BV/TV) and separation, density-weighted cortical thickness, and QCT stiffness (all p<0.05). At month 6, improvements from baseline were observed in QCT trabecular BMD and stiffness, and in HR-QCT BMD, trabecular BV/TV and separation, density-weighted cortical thickness, and stiffness in the romosozumab group (all p<0.05 compared with placebo). The mean (SE) increase in HR-QCT stiffness with romosozumab from baseline was 26.9% ± 6.8% and 35.0% ±6.8% at months 3 and 6, respectively; subjects administered placebo had changes of -2.7% ± 13.4% and -6.4% ± 13.4%, respectively. In conclusion, romosozumab administered for 3 months resulted in rapid and large improvements in trabecular and cortical bone mass and structure as well as whole bone stiffness, which continued 3 months

  5. Monte Carlo simulation of an x-ray luminescence optical tomography scanner prototype

    SciTech Connect

    Rosas-González, S. E-mail: arnulfo@fisica.unam.mx; Martínez-Dávalos, A. E-mail: arnulfo@fisica.unam.mx; Rodríguez-Villafuerte, M. E-mail: arnulfo@fisica.unam.mx; Murrieta-Rodríguez, T. E-mail: arnulfo@fisica.unam.mx

    2014-11-07

    In this work we report the calculation of the deposited energy distribution produced by an x-ray luminescence optical tomography (XLOT) system in a phantom containing different concentrations of Gd{sub 2}O{sub 2}S:Eu nanoparticles. The calculations were performed via Monte Carlo simulation considering spectra from a W target x-ray tube operating between 30 and 90 kVp, with 1.0 mm Al added filtration. CT and XLOT tomographic images were reconstructed from the same data. The results show that XLOT has better detectability than CT alone, that the dose scales linearly with kVp for a fixed concentration of Gd{sub 2}O{sub 2}S:Eu and air-kerma rate, the scattered radiation contribution to the total dose and signal is about 20% and that the dose ratio for a 3 mm diameter insert containing 10 mg/ml Gd{sub 2}O{sub 2}S embedded in a 30 mm diameter water phantom is 6:1. This ratio drops to less than 2:1 for a 1 mg/ml concentration. Finally we show that the method of conjugate images can be used to correct for artifacts due to attenuation effects in XLOT images.

  6. EVALUATION OF SIMULATED BONE LESION IN THE HEAD OF THE MANDIBLE BY USING MULTISLICE COMPUTED TOMOGRAPHY

    PubMed Central

    Utumi, Estevam Rubens; Perrella, Andréia; Albuquerque, Marco Antonio Portela; Adde, Carlos Alberto; Rocha, Rodney Garcia; Cavalcanti, Marcelo Gusmão Paraíso

    2009-01-01

    Conventional radiography has shown limitation in acquiring image of the ATM region, thus, computed tomography (CT) scanning has been the best option to the present date for diagnosis, surgical planning and treatment of bone lesions, owing to its specific properties. Objective: The aim of the study was to evaluate images of simulated bone lesions at the head of the mandible by multislice CT. Material and methods: Spherical lesions were made with dental spherical drills (sizes 1, 3, and 6) and were evaluated by using multislice CT (64 rows), by two observers in two different occasions, deploying two protocols: axial, coronal, and sagittal images, and parasagittal images for pole visualization (anterior, lateral, posterior, medial and superior). Acquired images were then compared with those lesions in the dry mandible (gold standard) to evaluate the specificity and sensibility of both protocols. Statistical methods included: Kappa statistics, validity test and chi-square test. Results demonstrated the advantage of associating axial, coronal, and sagittal slices with parasagittal slices for lesion detection at the head of the mandible. Results: There was no statistically significant difference between the types of protocols regarding a particular localization of lesions at the poles. Conclusions: Protocols for the assessment of the head of the mandible were established to improve the visualization of alterations of each of the poles of the mandible's head. The anterior and posterior poles were better visualized in lateral-medial planes while lateral, medial and superior poles were better visualized in the anterior-posterior plane. PMID:19936536

  7. Microwave tomography of extremities: 2. Functional fused imaging of flow reduction and simulated compartment syndrome.

    PubMed

    Semenov, Serguei; Kellam, James; Nair, Bindu; Williams, Thomas; Quinn, Michael; Sizov, Yuri; Nazarov, Alexei; Pavlovsky, Andrey

    2011-04-07

    Medical imaging has recently expanded into the dual- or multi-modality fusion of anatomical and functional imaging modalities. This significantly improves the diagnostic power while simultaneously increasing the cost of already expensive medical devices or investigations and decreasing their mobility. We are introducing a novel imaging concept of four-dimensional (4D) microwave tomographic (MWT) functional imaging: three dimensional (3D) in the spatial domain plus one dimensional (1D) in the time, functional dynamic domain. Instead of a fusion of images obtained by different imaging modalities, 4D MWT fuses absolute anatomical images with dynamic, differential images of the same imaging technology. The approach was successively validated in animal experiments with short-term arterial flow reduction and a simulated compartment syndrome in an initial simplified experimental setting using a dedicated MWT system. The presented fused images are not perfect as MWT is a novel imaging modality at its early stage of the development and ways of reading reconstructed MWT images need to be further studied and understood. However, the reconstructed fused images present clear evidence that microwave tomography is an emerging imaging modality with great potentials for functional imaging.

  8. Optical clearing of paper studied by optical coherence tomography: Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Kirillin, Mikhail; Priezzhev, Alexander V.; Hast, Jukka; Myllylä, Risto

    2006-02-01

    The problem of fast investigation of the structural properties of paper samples is of great interest nowadays. The existing methods for structural imaging of paper require long time for obtaining the final result or need changing the structure of the studied sample. One of modem high-promising non-invasive techniques for faster examination of paper structure is optical coherence tomography (OCT), based on the principles of low-coherence interferometry of light backscattered from the investigated object. In present paper we simulate OCT signals from different paper samples with planar and non-planar geometry of air-fiber boundaries implementing Monte Carlo method. OCT provides quality images of in-depth scanning for optically transparent low-scattering objects, however for high-scattering media the maximal scanning depth is quite small. In order to increase the scanning depth for such media different clearing agents are used. We consider ethanol, 1-pentanol, glycerol and benzyl alcohol as such agents applied to a paper sample. Obtained results show, that all agents under consideration provide better visualization of rear border of the studied sample, which is very important for precise paper thickness measurement. However, the agents, showing the best results for rear border visualization provide worse visualization of the inner structure of the sample.

  9. Microwave tomography of extremities: 2. Functional fused imaging of flow reduction and simulated compartment syndrome

    NASA Astrophysics Data System (ADS)

    Semenov, Serguei; Kellam, James; Nair, Bindu; Williams, Thomas; Quinn, Michael; Sizov, Yuri; Nazarov, Alexei; Pavlovsky, Andrey

    2011-04-01

    Medical imaging has recently expanded into the dual- or multi-modality fusion of anatomical and functional imaging modalities. This significantly improves the diagnostic power while simultaneously increasing the cost of already expensive medical devices or investigations and decreasing their mobility. We are introducing a novel imaging concept of four-dimensional (4D) microwave tomographic (MWT) functional imaging: three dimensional (3D) in the spatial domain plus one dimensional (1D) in the time, functional dynamic domain. Instead of a fusion of images obtained by different imaging modalities, 4D MWT fuses absolute anatomical images with dynamic, differential images of the same imaging technology. The approach was successively validated in animal experiments with short-term arterial flow reduction and a simulated compartment syndrome in an initial simplified experimental setting using a dedicated MWT system. The presented fused images are not perfect as MWT is a novel imaging modality at its early stage of the development and ways of reading reconstructed MWT images need to be further studied and understood. However, the reconstructed fused images present clear evidence that microwave tomography is an emerging imaging modality with great potentials for functional imaging.

  10. Determining Favorable Maxillary Implant Locations Using Three-Dimensional Simulation Software and Computed Tomography Data.

    PubMed

    Gonda, Tomoya; Kamei, Koichiro; Maeda, Yoshinobu

    Success rates for maxillary implant treatment are lower than for mandibular treatment because of the presence of poorer bone quality or quantity in the maxilla. The purpose of this study was to determine favorable implant positions in the maxilla using implant simulation software and clinical anatomical morphology together with bone quality data obtained by computed tomography (CT). A convenience research sample of 10 edentulous subjects was recruited, and research information from right and left edentulous sites was obtained from each subject. The height, width, angulation, and Hounsfield unit value of the maxillary alveolar bone were measured using CT data obtained from the subjects. Bone height in the incisor area was significantly greater than in the molar area, and bone width in the incisor area was significantly narrower than in the molar area. The average bone quality in the maxillary molar area was significantly higher when compared with the premolar and incisor areas. The angle between the occlusal plane and the bisector of the alveolar bone in the incisor area was reduced when compared with the molar area. The premolar region appears to be the most favorable area in the maxillary arch for implant placement with regard to bone height, width, angulation, and quality.

  11. Quantitative analysis of doped/undoped ZnO nanomaterials using laser assisted atom probe tomography: Influence of the analysis parameters

    SciTech Connect

    Amirifar, Nooshin; Lardé, Rodrigue Talbot, Etienne; Pareige, Philippe; Rigutti, Lorenzo; Mancini, Lorenzo; Houard, Jonathan; Castro, Celia; Sallet, Vincent; Zehani, Emir; Hassani, Said; Sartel, Corine; Ziani, Ahmed; Portier, Xavier

    2015-12-07

    In the last decade, atom probe tomography has become a powerful tool to investigate semiconductor and insulator nanomaterials in microelectronics, spintronics, and optoelectronics. In this paper, we report an investigation of zinc oxide nanostructures using atom probe tomography. We observed that the chemical composition of zinc oxide is strongly dependent on the analysis parameters used for atom probe experiments. It was observed that at high laser pulse energies, the electric field at the specimen surface is strongly dependent on the crystallographic directions. This dependence leads to an inhomogeneous field evaporation of the surface atoms, resulting in unreliable measurements. We show that the laser pulse energy has to be well tuned to obtain reliable quantitative chemical composition measurements of undoped and doped ZnO nanomaterials.

  12. Differentiating malignant from benign gastric mucosal lesions with quantitative analysis in dual energy spectral computed tomography: Initial experience.

    PubMed

    Meng, Xiaoyan; Ni, Cheng; Shen, Yaqi; Hu, Xuemei; Chen, Xiao; Li, Zhen; Hu, Daoyu

    2017-01-01

    To investigate the value of quantitative analysis in dual energy spectral computed tomography (DESCT) for differentiating malignant gastric mucosal lesions from benign gastric mucosal lesions (including gastric inflammation [GI] and normal gastric mucosa [NGM]). This study was approved by the ethics committee, and all patients provided written informed consent. A total of 161 consecutive patients (63 with gastric cancer [GC], 48 with GI, and 50 with NGM) who underwent dual-phase contrast enhanced DESCT scans in the arterial phase (AP) and portal venous phase (PVP) were included in this study. Iodine concentration (IC) in lesions was derived from the iodine-based material-decomposition images and normalized to that in the aorta to obtain normalized IC (nIC). The ratios of IC and nIC between the AP and PVP were calculated. Diagnostic confidence for GC and GI was evaluated with reviewing the features including gastric wall thickness, focal, and eccentric on the conventional polychromatic images. All statistical analyses were performed by using statistical software SPSS 17.0 (SPSS, Chicago, IL). IC and nIC in GC differed significantly from those in GI and NGM, except for nICAP in comparing GC with GI. Mean nIC values of GC (0.18 ± 0.06 in AP and 0.62 ± 0.16 in PVP) were significantly higher than that of NGM (0.12 ± 0.03 in AP and 0.37 ± 0.08 in PVP) (all P < 0.05). There was also significant difference for IC values in GC, GI, and NGM (24.19 ± 8.27, 19.07 ± 5.82, and 13.61 ± 2.52 mg/mL, respectively, in AP and 28.00 ± 7.01, 24.66 ± 6.55, and 16.94 ± 3.06 mg/mL, respectively, in PVP). Based on Receiver Operating Characteristic Curve analysis, nIC and IC in PVP had high sensitivities of 88.89% and 90.48%, respectively, in differentiating GC from NGM, while the sensitivities were 71.43% and 88.89% during AP. Ratios IC and nIC ratios did not provide adequate diagnostic accuracy with their area under curves less than

  13. Comparison of Visual and Quantitative Florbetapir F 18 Positron Emission Tomography Analysis in Predicting Mild Cognitive Impairment Outcomes.

    PubMed

    Schreiber, Stefanie; Landau, Susan M; Fero, Allison; Schreiber, Frank; Jagust, William J

    2015-10-01

    The applicability of β-amyloid peptide (Aβ) positron emission tomography (PET) as a biomarker in clinical settings to aid in selection of individuals at preclinical and prodromal Alzheimer disease (AD) will depend on the practicality of PET image analysis. In this context, visual-based Aβ PET assessment seems to be the most feasible approach. To determine the agreement between visual and quantitative Aβ PET analysis and to assess the ability of both techniques to predict conversion from mild cognitive impairment (MCI) to AD. A longitudinal study was conducted among the Alzheimer's Disease Neuroimaging Initiative (ADNI) sites in the United States and Canada during a 1.6-year mean follow-up period. The study was performed from September 21, 2010, to August 11, 2014; data analysis was conducted from September 21, 2014, to May 26, 2015. Participants included 401 individuals with MCI receiving care at a specialty clinic (219 [54.6%] men; mean [SD] age, 71.6 [7.5] years; 16.2 [2.7] years of education). All participants were studied with florbetapir F 18 [18F] PET. The standardized uptake value ratio (SUVR) positivity threshold was 1.11, and one reader rated all images, with a subset of 125 scans rated by a second reader. Sensitivity and specificity of positive and negative [18F] florbetapir PET categorization, which was estimated with cerebrospinal fluid Aβ1-42 as the reference standard. Risk for conversion to AD was assessed using Cox proportional hazards regression models. The frequency of Aβ positivity was 48.9% (196 patients; visual analysis), 55.1% (221 patients; SUVR), and 64.8% (166 patients; cerebrospinal fluid), yielding substantial agreement between visual and SUVR data (κ = 0.74) and between all methods (Fleiss κ = 0.71). For approximately 10% of the 401 participants in whom visual and SUVR data disagreed, interrater reliability was moderate (κ = 0.44), but it was very high if visual and quantitative results agreed (κ = 0.92). Visual

  14. Quantitative coronary plaque analysis predicts high-risk plaque morphology on coronary computed tomography angiography: results from the ROMICAT II trial.

    PubMed

    Liu, Ting; Maurovich-Horvat, Pál; Mayrhofer, Thomas; Puchner, Stefan B; Lu, Michael T; Ghemigian, Khristine; Kitslaar, Pieter H; Broersen, Alexander; Pursnani, Amit; Hoffmann, Udo; Ferencik, Maros

    2017-08-12

    Semi-automated software can provide quantitative assessment of atherosclerotic plaques on coronary CT angiography (CTA). The relationship between established qualitative high-risk plaque features and quantitative plaque measurements has not been studied. We analyzed the association between quantitative plaque measurements and qualitative high-risk plaque features on coronary CTA. We included 260 patients with plaque who underwent coronary CTA in the Rule Out Myocardial Infarction/Ischemia Using Computer Assisted Tomography (ROMICAT) II trial. Quantitative plaque assessment and qualitative plaque characterization were performed on a per coronary segment basis. Quantitative coronary plaque measurements included plaque volume, plaque burden, remodeling index, and diameter stenosis. In qualitative analysis, high-risk plaque was present if positive remodeling, low CT attenuation plaque, napkin-ring sign or spotty calcium were detected. Univariable and multivariable logistic regression analyses were performed to assess the association between quantitative and qualitative high-risk plaque assessment. Among 888 segments with coronary plaque, high-risk plaque was present in 391 (44.0%) segments by qualitative analysis. In quantitative analysis, segments with high-risk plaque had higher total plaque volume, low CT attenuation plaque volume, plaque burden and remodeling index. Quantitatively assessed low CT attenuation plaque volume (odds ratio 1.12 per 1 mm(3), 95% CI 1.04-1.21), positive remodeling (odds ratio 1.25 per 0.1, 95% CI 1.10-1.41) and plaque burden (odds ratio 1.53 per 0.1, 95% CI 1.08-2.16) were associated with high-risk plaque. Quantitative coronary plaque characteristics (low CT attenuation plaque volume, positive remodeling and plaque burden) measured by semi-automated software correlated with qualitative assessment of high-risk plaque features.

  15. Conceptual detector development and Monte Carlo simulation of a novel 3D breast computed tomography system

    NASA Astrophysics Data System (ADS)

    Ziegle, Jens; Müller, Bernhard H.; Neumann, Bernd; Hoeschen, Christoph

    2016-03-01

    A new 3D breast computed tomography (CT) system is under development enabling imaging of microcalcifications in a fully uncompressed breast including posterior chest wall tissue. The system setup uses a steered electron beam impinging on small tungsten targets surrounding the breast to emit X-rays. A realization of the corresponding detector concept is presented in this work and it is modeled through Monte Carlo simulations in order to quantify first characteristics of transmission and secondary photons. The modeled system comprises a vertical alignment of linear detectors hold by a case that also hosts the breast. Detectors are separated by gaps to allow the passage of X-rays towards the breast volume. The detectors located directly on the opposite side of the gaps detect incident X-rays. Mechanically moving parts in an imaging system increase the duration of image acquisition and thus can cause motion artifacts. So, a major advantage of the presented system design is the combination of the fixed detectors and the fast steering electron beam which enable a greatly reduced scan time. Thereby potential motion artifacts are reduced so that the visualization of small structures such as microcalcifications is improved. The result of the simulation of a single projection shows high attenuation by parts of the detector electronics causing low count levels at the opposing detectors which would require a flat field correction, but it also shows a secondary to transmission ratio of all counted X-rays of less than 1 percent. Additionally, a single slice with details of various sizes was reconstructed using filtered backprojection. The smallest detail which was still visible in the reconstructed image has a size of 0.2mm.

  16. Qualitative and quantitative simulation of androgen receptor antagonists: A case study of polybrominated diphenyl ethers.

    PubMed

    Wu, Yang; Shi, Wei; Xia, Pu; Zhang, Xiaowei; Yu, Hongxia

    2017-12-15

    Recently, great attention has been paid to the identification and prediction of the androgen disrupting potencies of polybrominated diphenyl ethers (PBDEs). However, few existing models can discriminate active and inactive compounds, which make the quantitative prediction process including the quantitative structure-activity relationship (QSAR) technique unreliable. In this study, different grouping methods were investigated and compared for qualitative identification, including molecular docking and molecular dynamics simulations (MD). The results showed that qualitative identification based on MD, which is lab-independent, accurate and closer to the real transcriptional activation process, could separate 90.5% of active and inactive chemicals and was preferred. The 3D-QSAR models built as the quantitative simulation method showed r(2) and q(2) values of 0.513 and 0.980, respectively. Together, a novel workflow combining qualitative identification and quantitative simulations was generated with processes including activeness discrimination and activity prediction. This workflow, for analyzing the antagonism of androgen receptor (AR) of PBDEs is not only allowing researchers to reduce their intense laboratory experiments but also assisting them in inspecting and adjusting their laboratory systems and results. Copyright © 2017. Published by Elsevier B.V.

  17. Tomographic reconstruction of melanin structures of optical coherence tomography via the finite-difference time-domain simulation

    NASA Astrophysics Data System (ADS)

    Huang, Shi-Hao; Wang, Shiang-Jiu; Tseng, Snow H.

    2015-03-01

    Optical coherence tomography (OCT) provides high resolution, cross-sectional image of internal microstructure of biological tissue. We use the Finite-Difference Time-Domain method (FDTD) to analyze the data acquired by OCT, which can help us reconstruct the refractive index of the biological tissue. We calculate the refractive index tomography and try to match the simulation with the data acquired by OCT. Specifically, we try to reconstruct the structure of melanin, which has complex refractive indices and is the key component of human pigment system. The results indicate that better reconstruction can be achieved for homogenous sample, whereas the reconstruction is degraded for samples with fine structure or with complex interface. Simulation reconstruction shows structures of the Melanin that may be useful for biomedical optics applications.

  18. Biomedical implications of dental-ceramic defects investigated by numerical simulation, radiographic, microcomputer tomography, and time-domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Sinescu, Cosmin; Negrutiu, Meda Lavinia; Ionita, Ciprian; Marsavina, Liviu; Negru, Radu; Topala, Florin; Petrescu, Emanuela; Rominu, Roxana; Fabriky, Mihai; Bradu, Adrian; Rominu, Mihai; Podoleanu, Adrian Gh.

    2011-10-01

    Imagistic investigation of the metal-ceramic crowns and fixed partial prostheses represent a very important issue in nowadays dentistry. At this time, in dental office, it is difficult or even impossible to evaluate a metal ceramic crown or bridge before setting it in the oral cavity. The possibilities of ceramic fractures are due to small fracture lines or material defects inside the esthetic layers. Material and methods: In this study 25 metal ceramic crowns and fixed partial prostheses were investigated by radiographic method (Rx), micro computer tomography (MicroCT) and optical coherence tomography (OCT) working in Time Domain, at 1300 nm. The OCT system contains two interferometers and one scanner. For each incident analysis a stuck made of 100 slices was obtain. These slices were used in order to obtain a 3D model of the ceramic interface. After detecting the presence and the positions of the ceramic defects the numerical simulation method was used to estimate the biomechanical effect of the masticatory forces on fractures propagations in ceramic materials. Results: For all the dental ceramic defects numerical simulation analysis was performed. The simulation of crack propagation shows that the crack could initiate from the upper, lower or both parts of the defect and propagates through the ceramic material where tensile stress field is present. RX and MicroCT are very powerful instruments that provide a good characterization of the dental construct. It is important to observe the reflections due to the metal infrastructure that could affect the evaluation of the metal ceramic crowns and bridges. The OCT investigations could complete the imagistic evaluation of the dental construct by offering important information when it is need it.

  19. 3D dynamic rupture simulation and local tomography studies following the 2010 Haiti earthquake

    NA