The Experts below are selected from a list of 91116 Experts worldwide ranked by ideXlab platform

Nagahisa Yoshimura - One of the best experts on this subject based on the ideXlab platform.

  • Three Dimensional Imaging of cystoid macular edema in retinal vein occlusion
    Ophthalmology, 2008
    Co-Authors: Noritatsu Yamaike, Akitaka Tsujikawa, Nagahisa Yoshimura, Atsushi Sakamoto, Yuriko Kotera, Mihori Kita, Kazuaki Miyamoto, Masanori Hangai
    Abstract:

    Objective To study the pathomorphologic features of cystoid macular edema (CME) associated with retinal vein occlusion by Three-Dimensional (3D) optical coherence tomography (OCT) and to study the relationship of the ocular findings to visual function. Design Observational case series. Participants Twenty eyes of 20 patients with retinal vein occlusion. Methods A prototype 3D OCT system based on Fourier-domain OCT technology was fabricated for patient examination in this study. This system uses a superluminescent diode, which has a center wavelength of 830 nm and a bandwidth of 50 nm, as the light source, resulting in 4.3-μm axial resolution in tissue. Data acquisition rates of approximately 18 700 axial scans per second and a sensitivity of 98 dB were achieved. Three-Dimensional Imaging was performed by volume rendering based on the 3D data set acquired with a raster scan of 256×256 axial scans. Main Outcome Measures Images of CME pathologic features obtained by 3D OCT and by Stratus OCT (Carl Zeiss, Dublin, CA). Results The 3D OCT Imaging system generates a realistic 3D image of CME with high resolution. In 16 eyes, 3D OCT showed large foveal cystoid spaces, most of which were accompanied by small cystoid spaces in the parafoveal region. Cystoid spaces were seen often in the inner nuclear layer and outer plexiform layer, but were detected to some extent in all retinal layers. The 3D OCT showed clearly a thin back-reflecting line corresponding to the external limiting membrane (ELM) in 18 eyes; of these, cystoid spaces were located on the inside of the ELM in 7 eyes and appeared to be in contact with the ELM in 9 eyes. In 2 eyes, the ELM line could not be seen clearly beneath the large foveal cystoid spaces. Integrity of the ELM in the foveal region had a direct correlation with visual acuity. Conclusions Observation of CME using 3D OCT enabled visualization of its spatial extent in each retinal layer and discernment of its relationship to the ELM. The use of 3D OCT thus may improve the monitoring of CME progression and its response to treatment.

  • Three Dimensional Imaging of the foveal photoreceptor layer in central serous chorioretinopathy using high speed optical coherence tomography
    Ophthalmology, 2007
    Co-Authors: Yumiko Ojima, Akitaka Tsujikawa, Masanori Hangai, Norimoto Gotoh, Ryo Inoue, Yoshiaki Yasuno, Shuichi Makita, Toyohiko Yatagai, Manabu Sasahara, Nagahisa Yoshimura
    Abstract:

    Objective To describe the 3-Dimensional (3-D) Imaging of the pathologic changes in the foveal photoreceptor layer in eyes with central serous chorioretinopathy (CSC) using high-speed optical coherence tomography (OCT). Design Prospective observational case series. Participants Twenty-seven eyes of 27 consecutive patients with various stages of CSC. Methods A prototype high-speed OCT system was fabricated for patient examinations based on Fourier domain OCT. The system had a sensitivity of 98 dB, a tissue axial resolution of 4.3 μm, and an acquisition rate of approximately 18700 axial scans per second. Three-Dimensional Imaging was performed based on a raster-scan protocol. Main Outcome Measures Anatomic features of CSC distinguished by 3-D OCT. Results A line corresponding to backreflection from the external limiting membrane (ELM) was visible in images from eyes with all stages of CSC, including 6 in the acute, 5 in the chronic, and 9 in the recurrent phase of retinal detachment and 11 examined in the quiescent phase (including 4 reexamined after reattachment). Backreflection from the photoreceptor inner and outer segment junction (IS/OS) was missing before but present after reattachment. The ELM line bordered the photoreceptor nuclear and inner segment layers, clearly showing that CSC primarily alters the outer segment (OS) layer. Punctate areas of intense reflectivity were observed more frequently in the OS layer of detached retinas in cases of chronic or recurrent versus acute CSC ( P P P P P Conclusions Three-Dimensional OCT Imaging delineates the microstructural changes that occur within the photoreceptor layers and demonstrates the spatial relationship between the laterally spreading or scattering microstructures and the fovea in eyes with CSC. Visualization of the 3-D relationship between the ELM and each photoreceptor layer before and after macular reattachment facilitates understanding of anatomic and vision changes that result from CSC.

  • Three Dimensional Imaging of macular holes with high speed optical coherence tomography
    Ophthalmology, 2007
    Co-Authors: Masanori Hangai, Mihori Kita, Yumiko Ojima, Norimoto Gotoh, Ryo Inoue, Yoshiaki Yasuno, Shuichi Makita, Masahiro Yamanari, Toyohiko Yatagai, Nagahisa Yoshimura
    Abstract:

    Objective To demonstrate the advantages of 3-Dimensional Imaging of macular hole pathology using new-generation high-speed optical coherence tomography (OCT). Design Prospective observational case series. Participants Twenty-one eyes from 20 consecutive patients diagnosed with a macular hole. Methods A prototype high-speed OCT system was built based on a Fourier-domain OCT (FD OCT) technology for patient examination. The system has achieved sensitivity of ∼98 decibels, axial resolution of ∼4.3 μm in tissue, and an acquisition rate of ∼18 700 axial scans per second. Three-Dimensional Imaging of macular hole pathology was performed based on a raster scan protocol consisting of 256×256 axial scans. All patients were imaged with 3-Dimensional OCT, Stratus OCT, and OCT Ophthalmoscope C7. Main Outcome Measures Images of macular hole pathologies obtained by 3-Dimensional OCT and standard OCT instruments. Results The 3-Dimensional OCT Imaging successfully generated realistic 3-Dimensional images of the vitreofoveal interface and intraretinal microstructures associated with a macular hole. The 3-Dimensional overview of the vitreofoveal interface was helpful in gaining an immediate understanding of the dynamic interactions of the vitreous and fovea. Observations of consecutive en face images in combination with conventional longitudinal images and of cross-sectional images in combination with sectioned volume images enabled identification of intraretinal microstructures and their 3-Dimensional extension associated with a macular hole, such as subfoveal structural changes after vitreous traction, connection of the flap to intraretinal structures, the external limiting membrane (ELM) and its disruption, and elevated photoreceptor inner and outer segments delineated by the ELM. The appearance of inner-wall images of a macular hole produced by photoreceptor inner and outer segment backreflection varied throughout macular hole stages. Conclusions Three-Dimensional Imaging of macular holes with high-speed OCT based on FD OCT technology offers 3-Dimensional overviews that facilitate understanding of the abnormalities in the vitreofoveal interface. It also provides consecutive orthogonal images that allow much more precise and minute observation of 3-Dimensionally extending intraretinal structural changes associated with a macular hole than conventional OCT Imaging, especially in the photoreceptor inner and outer segments.

Paul A Midgley - One of the best experts on this subject based on the ideXlab platform.

  • Three Dimensional Imaging of localized surface plasmon resonances of metal nanoparticles
    Nature, 2013
    Co-Authors: Olivia Nicoletti, Rowan K. Leary, Francisco Peña, Caterina Ducati, Daniel J Holland, Paul A Midgley
    Abstract:

    Localized surface plasmon resonances of an individual silver nanocube are reconstructed in Three dimensions using electron energy-loss spectrum Imaging, resulting in a better understanding of the optical response of noble-metal nanoparticles. Metal nanoparticles exhibit a range of striking and useful optical properties thanks to the excitation of localized surface plasmon resonances (LSPRs). But the precise relationship between the Three-Dimensional structure of the nanoparticles and the resulting LSPRs can be hard to determine. Paul Midgley and colleagues have developed a spectrally sensitive Imaging technique, based on electron energy-loss spectroscopy, that permits Three-Dimensional visualization of many of the key features associated with these LSPRs. With this technique, the interplay between the LSPRs, nanoparticle structure and substrate–nanoparticle interactions can be directly probed. This study focuses on silver nanocubes, but the method demonstrated is applicable to similar plasmonic phenomena across all metal nanoparticles. The remarkable optical properties of metal nanoparticles are governed by the excitation of localized surface plasmon resonances (LSPRs). The sensitivity of each LSPR mode, whose spatial distribution and resonant energy depend on the nanoparticle structure, composition and environment, has given rise to many potential photonic, optoelectronic, catalytic, photovoltaic, and gas- and bio-sensing applications1,2,3. However, the precise interplay between the Three-Dimensional (3D) nanoparticle structure and the LSPRs is not always fully understood and a spectrally sensitive 3D Imaging technique is needed to visualize the excitation on the nanometre scale. Here we show that 3D images related to LSPRs of an individual silver nanocube can be reconstructed through the application of electron energy-loss spectrum Imaging4, mapping the excitation across a range of orientations, with a novel combination of non-negative matrix factorization5,6, compressed sensing7,8 and electron tomography9. Our results extend the idea of substrate-mediated hybridization of dipolar and quadrupolar modes predicted by theory, simulations, and electron and optical spectroscopy10,11,12, and provide experimental evidence of higher-energy mode hybridization. This work represents an advance both in the understanding of the optical response of noble-metal nanoparticles and in the probing, analysis and visualization of LSPRs.

  • Three-Dimensional Imaging of localized surface plasmon resonances of metal nanoparticles
    Nature, 2013
    Co-Authors: Olivia Nicoletti, Rowan K. Leary, Francisco Peña, Caterina Ducati, Daniel J Holland, Paul A Midgley
    Abstract:

    The remarkable optical properties of metal nanoparticles are governed by the excitation of localized surface plasmon resonances (LSPRs). The sensitivity of each LSPR mode, whose spatial distribution and resonant energy depend on the nanoparticle structure, composition and environment, has given rise to many potential photonic, optoelectronic, catalytic, photovoltaic, and gas- and bio-sensing applications. However, the precise interplay between the Three-Dimensional (3D) nanoparticle structure and the LSPRs is not always fully understood and a spectrally sensitive 3D Imaging technique is needed to visualize the excitation on the nanometre scale. Here we show that 3D images related to LSPRs of an individual silver nanocube can be reconstructed through the application of electron energy-loss spectrum Imaging, mapping the excitation across a range of orientations, with a novel combination of non-negative matrix factorization, compressed sensing and electron tomography. Our results extend the idea of substrate-mediated hybridization of dipolar and quadrupolar modes predicted by theory, simulations, and electron and optical spectroscopy, and provide experimental evidence of higher-energy mode hybridization. This work represents an advance both in the understanding of the optical response of noble-metal nanoparticles and in the probing, analysis and visualization of LSPRs.

Masanori Hangai - One of the best experts on this subject based on the ideXlab platform.

  • Three Dimensional Imaging of cystoid macular edema in retinal vein occlusion
    Ophthalmology, 2008
    Co-Authors: Noritatsu Yamaike, Akitaka Tsujikawa, Nagahisa Yoshimura, Atsushi Sakamoto, Yuriko Kotera, Mihori Kita, Kazuaki Miyamoto, Masanori Hangai
    Abstract:

    Objective To study the pathomorphologic features of cystoid macular edema (CME) associated with retinal vein occlusion by Three-Dimensional (3D) optical coherence tomography (OCT) and to study the relationship of the ocular findings to visual function. Design Observational case series. Participants Twenty eyes of 20 patients with retinal vein occlusion. Methods A prototype 3D OCT system based on Fourier-domain OCT technology was fabricated for patient examination in this study. This system uses a superluminescent diode, which has a center wavelength of 830 nm and a bandwidth of 50 nm, as the light source, resulting in 4.3-μm axial resolution in tissue. Data acquisition rates of approximately 18 700 axial scans per second and a sensitivity of 98 dB were achieved. Three-Dimensional Imaging was performed by volume rendering based on the 3D data set acquired with a raster scan of 256×256 axial scans. Main Outcome Measures Images of CME pathologic features obtained by 3D OCT and by Stratus OCT (Carl Zeiss, Dublin, CA). Results The 3D OCT Imaging system generates a realistic 3D image of CME with high resolution. In 16 eyes, 3D OCT showed large foveal cystoid spaces, most of which were accompanied by small cystoid spaces in the parafoveal region. Cystoid spaces were seen often in the inner nuclear layer and outer plexiform layer, but were detected to some extent in all retinal layers. The 3D OCT showed clearly a thin back-reflecting line corresponding to the external limiting membrane (ELM) in 18 eyes; of these, cystoid spaces were located on the inside of the ELM in 7 eyes and appeared to be in contact with the ELM in 9 eyes. In 2 eyes, the ELM line could not be seen clearly beneath the large foveal cystoid spaces. Integrity of the ELM in the foveal region had a direct correlation with visual acuity. Conclusions Observation of CME using 3D OCT enabled visualization of its spatial extent in each retinal layer and discernment of its relationship to the ELM. The use of 3D OCT thus may improve the monitoring of CME progression and its response to treatment.

  • Three Dimensional Imaging of the foveal photoreceptor layer in central serous chorioretinopathy using high speed optical coherence tomography
    Ophthalmology, 2007
    Co-Authors: Yumiko Ojima, Akitaka Tsujikawa, Masanori Hangai, Norimoto Gotoh, Ryo Inoue, Yoshiaki Yasuno, Shuichi Makita, Toyohiko Yatagai, Manabu Sasahara, Nagahisa Yoshimura
    Abstract:

    Objective To describe the 3-Dimensional (3-D) Imaging of the pathologic changes in the foveal photoreceptor layer in eyes with central serous chorioretinopathy (CSC) using high-speed optical coherence tomography (OCT). Design Prospective observational case series. Participants Twenty-seven eyes of 27 consecutive patients with various stages of CSC. Methods A prototype high-speed OCT system was fabricated for patient examinations based on Fourier domain OCT. The system had a sensitivity of 98 dB, a tissue axial resolution of 4.3 μm, and an acquisition rate of approximately 18700 axial scans per second. Three-Dimensional Imaging was performed based on a raster-scan protocol. Main Outcome Measures Anatomic features of CSC distinguished by 3-D OCT. Results A line corresponding to backreflection from the external limiting membrane (ELM) was visible in images from eyes with all stages of CSC, including 6 in the acute, 5 in the chronic, and 9 in the recurrent phase of retinal detachment and 11 examined in the quiescent phase (including 4 reexamined after reattachment). Backreflection from the photoreceptor inner and outer segment junction (IS/OS) was missing before but present after reattachment. The ELM line bordered the photoreceptor nuclear and inner segment layers, clearly showing that CSC primarily alters the outer segment (OS) layer. Punctate areas of intense reflectivity were observed more frequently in the OS layer of detached retinas in cases of chronic or recurrent versus acute CSC ( P P P P P Conclusions Three-Dimensional OCT Imaging delineates the microstructural changes that occur within the photoreceptor layers and demonstrates the spatial relationship between the laterally spreading or scattering microstructures and the fovea in eyes with CSC. Visualization of the 3-D relationship between the ELM and each photoreceptor layer before and after macular reattachment facilitates understanding of anatomic and vision changes that result from CSC.

  • Three Dimensional Imaging of macular holes with high speed optical coherence tomography
    Ophthalmology, 2007
    Co-Authors: Masanori Hangai, Mihori Kita, Yumiko Ojima, Norimoto Gotoh, Ryo Inoue, Yoshiaki Yasuno, Shuichi Makita, Masahiro Yamanari, Toyohiko Yatagai, Nagahisa Yoshimura
    Abstract:

    Objective To demonstrate the advantages of 3-Dimensional Imaging of macular hole pathology using new-generation high-speed optical coherence tomography (OCT). Design Prospective observational case series. Participants Twenty-one eyes from 20 consecutive patients diagnosed with a macular hole. Methods A prototype high-speed OCT system was built based on a Fourier-domain OCT (FD OCT) technology for patient examination. The system has achieved sensitivity of ∼98 decibels, axial resolution of ∼4.3 μm in tissue, and an acquisition rate of ∼18 700 axial scans per second. Three-Dimensional Imaging of macular hole pathology was performed based on a raster scan protocol consisting of 256×256 axial scans. All patients were imaged with 3-Dimensional OCT, Stratus OCT, and OCT Ophthalmoscope C7. Main Outcome Measures Images of macular hole pathologies obtained by 3-Dimensional OCT and standard OCT instruments. Results The 3-Dimensional OCT Imaging successfully generated realistic 3-Dimensional images of the vitreofoveal interface and intraretinal microstructures associated with a macular hole. The 3-Dimensional overview of the vitreofoveal interface was helpful in gaining an immediate understanding of the dynamic interactions of the vitreous and fovea. Observations of consecutive en face images in combination with conventional longitudinal images and of cross-sectional images in combination with sectioned volume images enabled identification of intraretinal microstructures and their 3-Dimensional extension associated with a macular hole, such as subfoveal structural changes after vitreous traction, connection of the flap to intraretinal structures, the external limiting membrane (ELM) and its disruption, and elevated photoreceptor inner and outer segments delineated by the ELM. The appearance of inner-wall images of a macular hole produced by photoreceptor inner and outer segment backreflection varied throughout macular hole stages. Conclusions Three-Dimensional Imaging of macular holes with high-speed OCT based on FD OCT technology offers 3-Dimensional overviews that facilitate understanding of the abnormalities in the vitreofoveal interface. It also provides consecutive orthogonal images that allow much more precise and minute observation of 3-Dimensionally extending intraretinal structural changes associated with a macular hole than conventional OCT Imaging, especially in the photoreceptor inner and outer segments.

Olivia Nicoletti - One of the best experts on this subject based on the ideXlab platform.

  • Three Dimensional Imaging of localized surface plasmon resonances of metal nanoparticles
    Nature, 2013
    Co-Authors: Olivia Nicoletti, Rowan K. Leary, Francisco Peña, Caterina Ducati, Daniel J Holland, Paul A Midgley
    Abstract:

    Localized surface plasmon resonances of an individual silver nanocube are reconstructed in Three dimensions using electron energy-loss spectrum Imaging, resulting in a better understanding of the optical response of noble-metal nanoparticles. Metal nanoparticles exhibit a range of striking and useful optical properties thanks to the excitation of localized surface plasmon resonances (LSPRs). But the precise relationship between the Three-Dimensional structure of the nanoparticles and the resulting LSPRs can be hard to determine. Paul Midgley and colleagues have developed a spectrally sensitive Imaging technique, based on electron energy-loss spectroscopy, that permits Three-Dimensional visualization of many of the key features associated with these LSPRs. With this technique, the interplay between the LSPRs, nanoparticle structure and substrate–nanoparticle interactions can be directly probed. This study focuses on silver nanocubes, but the method demonstrated is applicable to similar plasmonic phenomena across all metal nanoparticles. The remarkable optical properties of metal nanoparticles are governed by the excitation of localized surface plasmon resonances (LSPRs). The sensitivity of each LSPR mode, whose spatial distribution and resonant energy depend on the nanoparticle structure, composition and environment, has given rise to many potential photonic, optoelectronic, catalytic, photovoltaic, and gas- and bio-sensing applications1,2,3. However, the precise interplay between the Three-Dimensional (3D) nanoparticle structure and the LSPRs is not always fully understood and a spectrally sensitive 3D Imaging technique is needed to visualize the excitation on the nanometre scale. Here we show that 3D images related to LSPRs of an individual silver nanocube can be reconstructed through the application of electron energy-loss spectrum Imaging4, mapping the excitation across a range of orientations, with a novel combination of non-negative matrix factorization5,6, compressed sensing7,8 and electron tomography9. Our results extend the idea of substrate-mediated hybridization of dipolar and quadrupolar modes predicted by theory, simulations, and electron and optical spectroscopy10,11,12, and provide experimental evidence of higher-energy mode hybridization. This work represents an advance both in the understanding of the optical response of noble-metal nanoparticles and in the probing, analysis and visualization of LSPRs.

  • Three-Dimensional Imaging of localized surface plasmon resonances of metal nanoparticles
    Nature, 2013
    Co-Authors: Olivia Nicoletti, Rowan K. Leary, Francisco Peña, Caterina Ducati, Daniel J Holland, Paul A Midgley
    Abstract:

    The remarkable optical properties of metal nanoparticles are governed by the excitation of localized surface plasmon resonances (LSPRs). The sensitivity of each LSPR mode, whose spatial distribution and resonant energy depend on the nanoparticle structure, composition and environment, has given rise to many potential photonic, optoelectronic, catalytic, photovoltaic, and gas- and bio-sensing applications. However, the precise interplay between the Three-Dimensional (3D) nanoparticle structure and the LSPRs is not always fully understood and a spectrally sensitive 3D Imaging technique is needed to visualize the excitation on the nanometre scale. Here we show that 3D images related to LSPRs of an individual silver nanocube can be reconstructed through the application of electron energy-loss spectrum Imaging, mapping the excitation across a range of orientations, with a novel combination of non-negative matrix factorization, compressed sensing and electron tomography. Our results extend the idea of substrate-mediated hybridization of dipolar and quadrupolar modes predicted by theory, simulations, and electron and optical spectroscopy, and provide experimental evidence of higher-energy mode hybridization. This work represents an advance both in the understanding of the optical response of noble-metal nanoparticles and in the probing, analysis and visualization of LSPRs.

Shigeru Suzuki - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of effective dose during abdominal Three Dimensional Imaging for Three flat panel detector angiography systems
    CardioVascular and Interventional Radiology, 2011
    Co-Authors: Shigeru Suzuki, Ichiro Yamaguchi, Takashi Kidouchi, Asako Yamamoto, Tomohiko Masumoto, Yutaka Ozaki
    Abstract:

    The purpose of this study was to evaluate the effective dose during abdominal Three-Dimensional (3D) Imaging on phantoms and estimate the dose-area product (DAP) for effective dose conversion factors for Three types of angiographic units. Three-Dimensional Imaging was performed for Three sizes (small, medium, large) of human-shaped phantoms using Three types of angiographic units (Allura Xper FD20/10, INNOVA 4100, AXIOM Artis dTA). We calculated 25 organ doses and effective doses using Monte Carlo technique for the Three phantoms with a program for a personal computer. As benchmark studies to back up the results by Monte Carlo technique, we measured the organ doses directly on the small phantom using radiophotoluminescent glass dosimeters. The DAP value increased as the phantom size increased. The organ doses and the effective doses during the 3D Imaging increased as the phantom size increased. The effective doses for the small phantom by Monte Carlo technique were 1.9, 2.2, and 2.1 mSv for the Allura Xper FD20/10, INNOVA 4100, and AXIOM Artis dTA, respectively, while those by direct measurement were 1.6, 2.0, and 2.6 mSv. The effective doses to DAP ratios by Monte Carlo technique were 0.37–0.45, 0.26–0.32, and 0.13–0.15 (mSv Gy−1 cm−2) for the Allura Xper FD20/10, INNOVA 4100, and AXIOM Artis dTA, respectively. In conclusion, the effective doses during 3D Imaging and the dose-to-DAP ratios differ among angiographic units, and the effective dose can be estimated using a proper conversion factor for each angiographic unit.

  • effective dose during abdominal Three Dimensional Imaging with a flat panel detector angiography system
    Radiology, 2009
    Co-Authors: Shigeru Suzuki, Shigeru Furui, Ichiro Yamaguchi, Masafumi Yamagishi, Akiko Watanabe, Toshi Abe, Ikuo Kobayashi
    Abstract:

    The purpose of this study was to measure the effective dose during abdominal Three-Dimensional Imaging obtained with an angiography unit with a digital flat-panel system on a phantom and to determine dose-area product (DAP)-to–effective dose conversion factors. DAPs and effective doses were evaluated for 163-cm-tall human-shaped phantoms with estimated body weights of 54, 64, and 77 kg, and the effective doses were 2.1, 3.2, and 4.2 mSv, respectively. The DAP-to–effective dose conversion factors were 0.28–0.29 mSv · Gy−1 · cm−2. In conclusion, the DAPs were useful for estimating the effective dose during abdominal Three-Dimensional angiographic Imaging. © RSNA, 2009