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Komyo Eto - One of the best experts on this subject based on the ideXlab platform.
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Hyperintensities of the Optic Radiation on T2-weighted MR images of elderly subjects
AJNR. American journal of neuroradiology, 1999Co-Authors: Mika Kitajima, Yukunori Korogi, T. Okuda, Shin Ya Shiraishi, Osamu Ikeda, Shoji Morishita, Mutsumasa Takahashi, Komyo EtoAbstract:Although abnormal hyperintensities are frequently observed at or around the Optic Radiation in elderly subjects, no previous reports have mentioned the clinical significance and pathologic changes of these hyperintensities. We evaluated the hyperintensity patterns of the Optic Radiation and its surrounding structures on T2-weighted MR images and compared these findings with pathologic observations and visual field measurements. High-resolution coronal T2-weighted MR images of 102 consecutive patients (51-84 years old) were evaluated retrospectively for the presence and morphology of hyperintensities of the Optic Radiation (204 sides) and its surrounding structures. Pathologic specimens were obtained from 25 other patients (60-91 years old) who had died of nonneurologic causes. The histopathologic changes of the Optic Radiation and its surrounding structures were evaluated and correlated with the MR findings. Finally, MR findings and visual field measurements were correlated in 46 elderly volunteers (70-91 years old). Hyperintensities of the Optic Radiation or its surrounding structures or both were observed on 125 sides (93%) of 67 patients (61%), and linear/laminar hyperintensity of the Optic Radiation and the tapetum was the characteristic finding. Eleven (44%) of 25 pathologic specimens exhibited pallor of three anatomic layers (the external sagittal stratum or the Optic Radiation, the internal sagittal stratum, and the tapetum). No subjects with hyperintensity of the Optic Radiation had visual field abnormalities. Linear/laminar hyperintensity of the Optic Radiation and tapetum on T2-weighted images is common in elderly subjects, and may reflect differences in the internal structures and in the water content of three anatomic structures. Hyperintensities of this region did not cause visual field abnormalities in a group of elderly volunteers.
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Hyperintensities of the Optic Radiation on T2-weighted MR images of elderly subjects
AJNR. American journal of neuroradiology, 1999Co-Authors: Mika Kitajima, Yukunori Korogi, T. Okuda, Shin Ya Shiraishi, Osamu Ikeda, Shoji Morishita, Mutsumasa Takahashi, Komyo EtoAbstract:BACKGROUND AND PURPOSE: Although abnormal hyperintensities are frequently observed at or around the Optic Radiation in elderly subjects, no previous reports have mentioned the clinical significance and pathologic changes of these hyperintensities. We evaluated the hyperintensity patterns of the Optic Radiation and its surrounding structures on T2-weighted MR images and compared these findings with pathologic observations and visual field measurements. METHODS: High-resolution coronal T2-weighted MR images of 102 consecutive patients (51–84 years old) were evaluated retrospectively for the presence and morphology of hyperintensities of the Optic Radiation (204 sides) and its surrounding structures. Pathologic specimens were obtained from 25 other patients (60–91 years old) who had died of nonneurologic causes. The histopathologic changes of the Optic Radiation and its surrounding structures were evaluated and correlated with the MR findings. Finally, MR findings and visual field measurements were correlated in 46 elderly volunteers (70–91 years old). RESULTS: Hyperintensities of the Optic Radiation or its surrounding structures or both were observed on 125 sides (93%) of 67 patients (61%), and linear/laminar hyperintensity of the Optic Radiation and the tapetum was the characteristic finding. Eleven (44%) of 25 pathologic specimens exhibited pallor of three anatomic layers (the external sagittal stratum or the Optic Radiation, the internal sagittal stratum, and the tapetum). No subjects with hyperintensity of the Optic Radiation had visual field abnormalities. CONCLUSION: Linear/laminar hyperintensity of the Optic Radiation and tapetum on T2-weighted images is common in elderly subjects, and may reflect differences in the internal structures and in the water content of three anatomic structures. Hyperintensities of this region did not cause visual field abnormalities in a group of elderly volunteers.
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MR signal intensity of the Optic Radiation.
AJNR. American journal of neuroradiology, 1996Co-Authors: Mika Kitajima, Yukunori Korogi, Mutsumasa Takahashi, Komyo EtoAbstract:PURPOSE To determine whether a hyperintense layer adjacent to the lateral ventricle on T2-weighted MR images represents the Optic Radiation. METHODS We reviewed 11 brain specimens from patients with nonneurologic diseases and MR images from 43 healthy volunteers. The MR images in a patient with cerebral infarction involving the lateral geniculate body were also reviewed to evaluate wallerian degeneration of the Optic Radiation. RESULTS The external sagittal stratum, composed of the Optic Radiation, showed a pale layer in specimens stained by Bodian's method. On high-power microscopic views of the specimens, the axons of the external sagittal stratum were large and separated by wide translucent spaces. In the volunteers, the external sagittal stratum appeared hyperintense on T2-weighted MR images and hypointense on T1-weighted images. The MR images in a patient with cerebral infarction showed hyperintensity within the layer corresponding to the external sagittal stratum. CONCLUSIONS The hyperintense layer on T2-weighted images represents the external sagittal stratum, or Optic Radiation. The signal intensity of the external sagittal stratum reflects histologic characteristics of low axonal density.
Takaaki Kirino - One of the best experts on this subject based on the ideXlab platform.
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functional monitoring for visual pathway using real time visual evoked potentials and Optic Radiation tractography
Neurosurgery, 2005Co-Authors: Kyousuke Kamada, Tomoki Todo, Yoshitaka Masutani, Akio Morita, Kensuke Kawai, S. Aoki, Takaaki KirinoAbstract:OBJECTIVE: It has been difficult to obtain anatomic and functional information about the visual pathway during neurosurgical operations. The aim of this study was to combine the information of the visual evoked potentials (VEPs) and the anatomic navigation of the Optic Radiation by diffusion tensor imaging-based tractography for functional monitoring of the visual pathway. METHODS: The subjects were two patients with brain lesions adjacent to the visual pathway. Diffusion tensor imaging-based tractography of the Optic Radiation was performed by selecting appropriate regions of interest and by fractional anisotropy. During surgery, cortical VEPs were recorded continuously under general anesthesia with sevoflurane. In Patient 2, the results of Optic Radiation tractography were imported to a neuronavigation system to better understand the spatial relationships between the lesions and the visual pathway (functional neuronavigation). RESULTS: In Patient 1, the lesion did not seem to be attached to the Optic Radiation, and VEP profiles remained stable during resection. In Patient 2, who had a lesion adjacent to the posterior horn of the lateral ventricle, VEPs suddenly diminished when resection reached the Optic Radiation as illustrated on the neuronavigation system. As a result, complete left hemianopia developed after surgery in Patient 2. CONCLUSION: We confirmed functional correlations of the results of diffusion tensor imaging-based tractography by monitoring intraoperative VEPs. The combination of continuous VEP and Optic-Radiation tractography is reliable to monitor the visual function and is helpful in performing neurosurgical planning near the visual pathway.
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Functional monitoring for visual pathway using real-time visual evoked potentials and Optic-Radiation tractography.
Neurosurgery, 2005Co-Authors: Kyousuke Kamada, Tomoki Todo, Yoshitaka Masutani, Akio Morita, Kensuke Kawai, S. Aoki, Kenji Ino, Takaaki KirinoAbstract:It has been difficult to obtain anatomic and functional information about the visual pathway during neurosurgical operations. The aim of this study was to combine the information of the visual evoked potentials (VEPs) and the anatomic navigation of the Optic Radiation by diffusion tensor imaging-based tractography for functional monitoring of the visual pathway. The subjects were two patients with brain lesions adjacent to the visual pathway. Diffusion tensor imaging-based tractography of the Optic Radiation was performed by selecting appropriate regions of interest and by fractional anisotropy. During surgery, cortical VEPs were recorded continuously under general anesthesia with sevoflurane. In Patient 2, the results of Optic Radiation tractography were imported to a neuronavigation system to better understand the spatial relationships between the lesions and the visual pathway (functional neuronavigation). In Patient 1, the lesion did not seem to be attached to the Optic Radiation, and VEP profiles remained stable during resection. In Patient 2, who had a lesion adjacent to the posterior horn of the lateral ventricle, VEPs suddenly diminished when resection reached the Optic Radiation as illustrated on the neuronavigation system. As a result, complete left hemianopia developed after surgery in Patient 2. We confirmed functional correlations of the results of diffusion tensor imaging-based tractography by monitoring intraoperative VEPs. The combination of continuous VEP and Optic-Radiation tractography is reliable to monitor the visual function and is helpful in performing neurosurgical planning near the visual pathway.
Saleem I. Abdulrauf - One of the best experts on this subject based on the ideXlab platform.
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An anteromedial approach to the temporal horn to avoid injury to the Optic Radiation fibers and uncinate fasciculus: anatomical and technical note.
Neurosurgical focus, 2005Co-Authors: Jeroen R Coppens, Kelly B. Mahaney, Saleem I. AbdulraufAbstract:The aim of this study was to define an anteromedial approach to the temporal horn via a transsylvian approach to avoid injury to the Optic Radiation fibers as well as the uncinate fasciculus. This route was compared with standard surgical approaches to the temporal horn, and their relationship to the Optic Radiation and uncinate fasciculus was reviewed. Three cadaveric brain specimens were prepared with freezing and thawing cycles according to the Klingler technique. Dissection was performed in a lateral-to-medial fashion with the help of wooden spatulas. Photographs were taken through the operating microscope at every level of the dissection. The dissection was continued until the Optic Radiation was encountered. Particular attention was paid to the relationship of the uncinate fasciculus with the Optic Radiation. An anteromedial transsylvian approach was defined to enter the temporal horn without injuring the Optic Radiation or the uncinate fasciculus. A transsylvian anteromedial approach through the pyriform cortex at the level of the anterior and superior surface of the uncus enables a safe entry into the temporal horn without injury to the Optic Radiation fibers or the main part of the uncinate fasciculus.
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Three-dimensional relationships of the Optic Radiation. Commentary
Neurosurgery, 2005Co-Authors: Pablo Rubino, Evandro De Oliveira, Al Rhoton, Xiaoguang Tong, Saleem I. Abdulrauf, M. Gazi Yasargil, Patrick J. Kelly, Joseph M. PiepmeierAbstract:OBJECTIVE: This study examined the relationship of the Optic Radiation to the landmarks important in temporal lobe surgery. METHODS: The Optic Radiation was dissected by applying Klingler's fiber dissection technique to 20 formalin-fixed human hemispheres. The dissections were performed with the operating microscope and imaged in three-dimensional photographs. Several measures quantified the relationship of the Radiation to reliable surgical landmarks. RESULTS: In all specimens, the anterior loop of the Radiation extended to the anterior tip of the roof of the temporal horn. The anterior edge of the Optic Radiation was located an average of 25 mm (range, 22-30 mm) behind the temporal pole. The Optic Radiation extended an average of 5 mm (range, 3-6 mm) anterior to the hippocampus head and 22 mm (range, 20-25 mm) anterior to the anterior edge of the lateral geniculate body. The Optic Radiation also extended an average of 2 mm (range, 1-3 mm) anterior to the tip of the temporal horn. The relationships of the Optic Radiation to important surgical landmarks are discussed. CONCLUSION: The Optic Radiation reached the anterior tip of the temporal horn. Resections that extend through the roof of the temporal horn more than 3 cm behind the temporal pole cross the anterior loop of the Optic Radiation.
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An anteromedial approach to the temporal horn to avoid injury to the Optic Radiation fibers and uncinate fasciculus: anatomical and technical note.
Neurosurgical Focus, 2005Co-Authors: Jeroen Coppens, Kelly B. Mahaney, Saleem I. AbdulraufAbstract:Object. The aim of this study was to define an anteromedial approach to the temporal horn via a transsylvian approach to avoid injury to the Optic Radiation fibers as well as the uncinate fasciculus. This route was compared with standard surgical approaches to the temporal horn, and their relationship to the Optic Radiation and uncinate fasciculus was reviewed. Methods. Three cadaveric brain specimens were prepared with freezing and thawing cycles according to the Klingler technique. Dissection was performed in a lateral-to-medial fashion with the help of wooden spatulas. Photographs were taken through the operating microscope at every level of the dissection. The dissection was continued until the Optic Radiation was encountered. Particular attention was paid to the relationship of the uncinate fasciculus with the Optic Radiation. An anteromedial transsylvian approach was defined to enter the temporal horn without injuring the Optic Radiation or the uncinate fasciculus. Conclusions. A transsylvian anteromedial approach through the pyriform cortex at the level of the anterior and superior surface of the uncus enables a safe entry into the temporal horn without injury to the Optic Radiation fibers or the main part of the uncinate fasciculus.
Kyousuke Kamada - One of the best experts on this subject based on the ideXlab platform.
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Optic Radiation tractography integrated into simulated treatment planning for gamma knife surgery
Journal of Neurosurgery, 2007Co-Authors: Keisuke Maruyama, Yoshitaka Masutani, Kyousuke Kamada, Kenji Ino, Masahiro Shin, Daisuke Itoh, Masao Tago, Nobuhito SaitoAbstract:Object No definitive method of preventing visual field deficits after stereotactic radiosurgery for lesions near the Optic Radiation (OR) has been available so far. The authors report the results of integrating OR tractography based on diffusion tensor (DT) magnetic resonance imaging into simulated treatment planning for Gamma Knife surgery (GKS). Methods Data from imaging studies performed in 10 patients who underwent GKS for treatment of arteriovenous malformations (AVMs) located adjacent to the OR were used for the simulated treatment planning. Diffusion tensor images performed without the patient's head being secured by a stereotactic frame were used for DT tractography, and the OR was visualized by means of software developed by the authors. Data from stereotactic 3D imaging studies performed after frame fixation were coregistered with the data from DT tractography. The combined images were transferred to a GKS treatment-planning workstation. Delivered doses and distances between the treated lesions ...
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functional monitoring for visual pathway using real time visual evoked potentials and Optic Radiation tractography
Neurosurgery, 2005Co-Authors: Kyousuke Kamada, Tomoki Todo, Yoshitaka Masutani, Akio Morita, Kensuke Kawai, S. Aoki, Takaaki KirinoAbstract:OBJECTIVE: It has been difficult to obtain anatomic and functional information about the visual pathway during neurosurgical operations. The aim of this study was to combine the information of the visual evoked potentials (VEPs) and the anatomic navigation of the Optic Radiation by diffusion tensor imaging-based tractography for functional monitoring of the visual pathway. METHODS: The subjects were two patients with brain lesions adjacent to the visual pathway. Diffusion tensor imaging-based tractography of the Optic Radiation was performed by selecting appropriate regions of interest and by fractional anisotropy. During surgery, cortical VEPs were recorded continuously under general anesthesia with sevoflurane. In Patient 2, the results of Optic Radiation tractography were imported to a neuronavigation system to better understand the spatial relationships between the lesions and the visual pathway (functional neuronavigation). RESULTS: In Patient 1, the lesion did not seem to be attached to the Optic Radiation, and VEP profiles remained stable during resection. In Patient 2, who had a lesion adjacent to the posterior horn of the lateral ventricle, VEPs suddenly diminished when resection reached the Optic Radiation as illustrated on the neuronavigation system. As a result, complete left hemianopia developed after surgery in Patient 2. CONCLUSION: We confirmed functional correlations of the results of diffusion tensor imaging-based tractography by monitoring intraoperative VEPs. The combination of continuous VEP and Optic-Radiation tractography is reliable to monitor the visual function and is helpful in performing neurosurgical planning near the visual pathway.
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Functional monitoring for visual pathway using real-time visual evoked potentials and Optic-Radiation tractography.
Neurosurgery, 2005Co-Authors: Kyousuke Kamada, Tomoki Todo, Yoshitaka Masutani, Akio Morita, Kensuke Kawai, S. Aoki, Kenji Ino, Takaaki KirinoAbstract:It has been difficult to obtain anatomic and functional information about the visual pathway during neurosurgical operations. The aim of this study was to combine the information of the visual evoked potentials (VEPs) and the anatomic navigation of the Optic Radiation by diffusion tensor imaging-based tractography for functional monitoring of the visual pathway. The subjects were two patients with brain lesions adjacent to the visual pathway. Diffusion tensor imaging-based tractography of the Optic Radiation was performed by selecting appropriate regions of interest and by fractional anisotropy. During surgery, cortical VEPs were recorded continuously under general anesthesia with sevoflurane. In Patient 2, the results of Optic Radiation tractography were imported to a neuronavigation system to better understand the spatial relationships between the lesions and the visual pathway (functional neuronavigation). In Patient 1, the lesion did not seem to be attached to the Optic Radiation, and VEP profiles remained stable during resection. In Patient 2, who had a lesion adjacent to the posterior horn of the lateral ventricle, VEPs suddenly diminished when resection reached the Optic Radiation as illustrated on the neuronavigation system. As a result, complete left hemianopia developed after surgery in Patient 2. We confirmed functional correlations of the results of diffusion tensor imaging-based tractography by monitoring intraoperative VEPs. The combination of continuous VEP and Optic-Radiation tractography is reliable to monitor the visual function and is helpful in performing neurosurgical planning near the visual pathway.
Mika Kitajima - One of the best experts on this subject based on the ideXlab platform.
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Hyperintensities of the Optic Radiation on T2-weighted MR images of elderly subjects
AJNR. American journal of neuroradiology, 1999Co-Authors: Mika Kitajima, Yukunori Korogi, T. Okuda, Shin Ya Shiraishi, Osamu Ikeda, Shoji Morishita, Mutsumasa Takahashi, Komyo EtoAbstract:Although abnormal hyperintensities are frequently observed at or around the Optic Radiation in elderly subjects, no previous reports have mentioned the clinical significance and pathologic changes of these hyperintensities. We evaluated the hyperintensity patterns of the Optic Radiation and its surrounding structures on T2-weighted MR images and compared these findings with pathologic observations and visual field measurements. High-resolution coronal T2-weighted MR images of 102 consecutive patients (51-84 years old) were evaluated retrospectively for the presence and morphology of hyperintensities of the Optic Radiation (204 sides) and its surrounding structures. Pathologic specimens were obtained from 25 other patients (60-91 years old) who had died of nonneurologic causes. The histopathologic changes of the Optic Radiation and its surrounding structures were evaluated and correlated with the MR findings. Finally, MR findings and visual field measurements were correlated in 46 elderly volunteers (70-91 years old). Hyperintensities of the Optic Radiation or its surrounding structures or both were observed on 125 sides (93%) of 67 patients (61%), and linear/laminar hyperintensity of the Optic Radiation and the tapetum was the characteristic finding. Eleven (44%) of 25 pathologic specimens exhibited pallor of three anatomic layers (the external sagittal stratum or the Optic Radiation, the internal sagittal stratum, and the tapetum). No subjects with hyperintensity of the Optic Radiation had visual field abnormalities. Linear/laminar hyperintensity of the Optic Radiation and tapetum on T2-weighted images is common in elderly subjects, and may reflect differences in the internal structures and in the water content of three anatomic structures. Hyperintensities of this region did not cause visual field abnormalities in a group of elderly volunteers.
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Hyperintensities of the Optic Radiation on T2-weighted MR images of elderly subjects
AJNR. American journal of neuroradiology, 1999Co-Authors: Mika Kitajima, Yukunori Korogi, T. Okuda, Shin Ya Shiraishi, Osamu Ikeda, Shoji Morishita, Mutsumasa Takahashi, Komyo EtoAbstract:BACKGROUND AND PURPOSE: Although abnormal hyperintensities are frequently observed at or around the Optic Radiation in elderly subjects, no previous reports have mentioned the clinical significance and pathologic changes of these hyperintensities. We evaluated the hyperintensity patterns of the Optic Radiation and its surrounding structures on T2-weighted MR images and compared these findings with pathologic observations and visual field measurements. METHODS: High-resolution coronal T2-weighted MR images of 102 consecutive patients (51–84 years old) were evaluated retrospectively for the presence and morphology of hyperintensities of the Optic Radiation (204 sides) and its surrounding structures. Pathologic specimens were obtained from 25 other patients (60–91 years old) who had died of nonneurologic causes. The histopathologic changes of the Optic Radiation and its surrounding structures were evaluated and correlated with the MR findings. Finally, MR findings and visual field measurements were correlated in 46 elderly volunteers (70–91 years old). RESULTS: Hyperintensities of the Optic Radiation or its surrounding structures or both were observed on 125 sides (93%) of 67 patients (61%), and linear/laminar hyperintensity of the Optic Radiation and the tapetum was the characteristic finding. Eleven (44%) of 25 pathologic specimens exhibited pallor of three anatomic layers (the external sagittal stratum or the Optic Radiation, the internal sagittal stratum, and the tapetum). No subjects with hyperintensity of the Optic Radiation had visual field abnormalities. CONCLUSION: Linear/laminar hyperintensity of the Optic Radiation and tapetum on T2-weighted images is common in elderly subjects, and may reflect differences in the internal structures and in the water content of three anatomic structures. Hyperintensities of this region did not cause visual field abnormalities in a group of elderly volunteers.
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MR signal intensity of the Optic Radiation.
AJNR. American journal of neuroradiology, 1996Co-Authors: Mika Kitajima, Yukunori Korogi, Mutsumasa Takahashi, Komyo EtoAbstract:PURPOSE To determine whether a hyperintense layer adjacent to the lateral ventricle on T2-weighted MR images represents the Optic Radiation. METHODS We reviewed 11 brain specimens from patients with nonneurologic diseases and MR images from 43 healthy volunteers. The MR images in a patient with cerebral infarction involving the lateral geniculate body were also reviewed to evaluate wallerian degeneration of the Optic Radiation. RESULTS The external sagittal stratum, composed of the Optic Radiation, showed a pale layer in specimens stained by Bodian's method. On high-power microscopic views of the specimens, the axons of the external sagittal stratum were large and separated by wide translucent spaces. In the volunteers, the external sagittal stratum appeared hyperintense on T2-weighted MR images and hypointense on T1-weighted images. The MR images in a patient with cerebral infarction showed hyperintensity within the layer corresponding to the external sagittal stratum. CONCLUSIONS The hyperintense layer on T2-weighted images represents the external sagittal stratum, or Optic Radiation. The signal intensity of the external sagittal stratum reflects histologic characteristics of low axonal density.