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Visualization of human optic nerve by diffusion tensor mapping and degree of neuropathy. PLoS One 2022; 17:e0278987. [PMID: 36508429 PMCID: PMC9744320 DOI: 10.1371/journal.pone.0278987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022] Open
Abstract
Diffusion-weighted magnetic resonance imaging of the human optic nerve and tract is technically difficult because of its small size, the inherent strong signal generated by the surrounding fat and the cerebrospinal fluid, and due to eddy current-induced distortions and subject movement artifacts. The effects of the bone canal through which the optic nerve passes, and the proximity of blood vessels, muscles and tendons are generally unknown. Also, the limited technical capabilities of the scanners and the minimization of acquisition times result in poor quality diffusion-weighted images. It is challenging for current tractography methods to accurately track optic pathway fibers that correspond to known anatomy. Despite these technical limitations and low image resolution, here we show how to visualize the optic nerve and tract and quantify nerve atrophy. Our visualization method based on the analysis of the diffusion tensor shows marked differences between a healthy male subject and a male subject with progressive optic nerve neuropathy. These differences coincide with diffusion scalar metrics and are not visible on standard morphological images. A quantification of the degree of optic nerve atrophy in a systematic way is provided and it is tested on 9 subjects from the Human Connectome Project.
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Duan F, Xiao Z, Wang Y, Sun X, Tang Z, Wang R, Guo L, Tang W, Liu T, Wang P, Zhan Y. Metabolic alterations in the visual pathway of retinitis pigmentosa rats: A longitudinal multimodal magnetic resonance imaging study with histopathological validation. NMR IN BIOMEDICINE 2022; 35:e4751. [PMID: 35478360 DOI: 10.1002/nbm.4751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 04/12/2022] [Accepted: 04/25/2022] [Indexed: 06/14/2023]
Abstract
Because retinitis pigmentosa (RP) has been shown to cause degenerative changes in the entire visual pathway, there is an urgent need to perform longitudinal assessments of RP-induced degeneration and identify imaging protocols to detect this degeneration as early as possible. In this study, we assessed a transgenic rat model of RP by using complementary noninvasive magnetic resonance imaging techniques, namely, proton magnetic resonance spectroscopy (1 H-MRS), to investigate the metabolic changes in RP. Our study demonstrated decreased concentrations and ratios to creatine (Cr) of N-acetylaspartate (NAA), glutamate (Glu), γ-aminobutyric acid (GABA), and taurine (Tau), whereas myo-inositol (Ins) and choline (Cho) were increased in the visual cortex of Royal College of Surgeons (RCS) rats compared with control rats (p < 0.05). Furthermore, with the progression of RP, the concentrations of NAA, Glu, GABA, and Tau, and the ratios of GABA/Cr and Tau/Cr significantly decreased over time, whereas the concentrations of Ins and Cho and the ratio of Ins/Cr significantly increased over time (p < 0.05). In addition, in RCS rats, NAA/Cr decreased significantly from 3 to 4 months postnatal (p < 0.001), and Cho/Cr increased significantly from 4 to 5 months postnatal (p = 0.005). Meanwhile, the 1 H-MRS indicators in 5-month postnatal RCS rats could be confirmed by immunohistochemical staining. In conclusion, with the progression of RP, the metabolic alterations in the visual cortex indicated progressive reprogramming with the decrease of neurons and axons, accompanied by the proliferation of gliocytes.
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Affiliation(s)
- Fei Duan
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Zebin Xiao
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Yuzhe Wang
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Xinghuai Sun
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University, Shanghai, China
- Key Laboratory of Myopia, NHFPC (Fudan University), Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Zuohua Tang
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Rong Wang
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
- Department of Radiology, Huashan Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Linying Guo
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Weijun Tang
- Department of Radiology, Huashan Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Tingting Liu
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Peng Wang
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Yang Zhan
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
- Shanghai Institute of Medical Imaging, Shanghai, China
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Sims JR, Chen AM, Sun Z, Deng W, Colwell NA, Colbert MK, Zhu J, Sainulabdeen A, Faiq MA, Bang JW, Chan KC. Role of Structural, Metabolic, and Functional MRI in Monitoring Visual System Impairment and Recovery. J Magn Reson Imaging 2021; 54:1706-1729. [PMID: 33009710 PMCID: PMC8099039 DOI: 10.1002/jmri.27367] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 08/24/2020] [Accepted: 08/27/2020] [Indexed: 12/13/2022] Open
Abstract
The visual system, consisting of the eyes and the visual pathways of the brain, receives and interprets light from the environment so that we can perceive the world around us. A wide variety of disorders can affect human vision, ranging from ocular to neurologic to systemic in nature. While other noninvasive imaging techniques such as optical coherence tomography and ultrasound can image particular sections of the visual system, magnetic resonance imaging (MRI) offers high resolution without depth limitations. MRI also gives superior soft-tissue contrast throughout the entire pathway compared to computed tomography. By leveraging different imaging sequences, MRI is uniquely capable of unveiling the intricate processes of ocular anatomy, tissue physiology, and neurological function in the human visual system from the microscopic to macroscopic levels. In this review we discuss how structural, metabolic, and functional MRI can be used in the clinical assessment of normal and pathologic states in the anatomic structures of the visual system, including the eyes, optic nerves, optic chiasm, optic tracts, visual brain nuclei, optic radiations, and visual cortical areas. We detail a selection of recent clinical applications of MRI at each position along the visual pathways, including the evaluation of pathology, plasticity, and the potential for restoration, as well as its limitations and key areas of ongoing exploration. Our discussion of the current and future developments in MR ocular and neuroimaging highlights its potential impact on our ability to understand visual function in new detail and to improve our protection and treatment of anatomic structures that are integral to this fundamental sensory system. LEVEL OF EVIDENCE 3: TECHNICAL EFFICACY STAGE 3: .
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Affiliation(s)
- Jeffrey R. Sims
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
| | - Anna M. Chen
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
- Sackler Institute of Graduate Biomedical Sciences, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
| | - Zhe Sun
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
- Sackler Institute of Graduate Biomedical Sciences, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
| | - Wenyu Deng
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
| | - Nicole A. Colwell
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
| | - Max K. Colbert
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
| | - Jingyuan Zhu
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
- Department of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Anoop Sainulabdeen
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
- Department of Surgery and Radiology, College of Veterinary and Animal Sciences, Kerala Veterinary and Animal Sciences University, Thrissur, India
| | - Muneeb A. Faiq
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
| | - Ji Won Bang
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
| | - Kevin C. Chan
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
- Sackler Institute of Graduate Biomedical Sciences, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
- Department of Radiology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
- Neuroscience Institute, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, USA
- Center for Neural Science, College of Arts and Science, New York University, New York, New York, USA
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Kominami T, Ueno S, Nishida K, Inooka D, Kominami A, Kondo M, Terasaki H. Electrically Evoked Potentials Are Reduced Compared to Axon Numbers in Rhodopsin P347L Transgenic Rabbits With Severe Photoreceptor Degeneration. Invest Ophthalmol Vis Sci 2019; 60:2543-2550. [PMID: 31206141 DOI: 10.1167/iovs.19-26972] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To determine the relationship between the amplitudes of the electrically evoked potentials (EEPs) and the number of optic nerve axons at a late stage of retinal degeneration in rhodopsin P347L transgenic (Tg) rabbits, a model of retinitis pigmentosa. Methods Six eyes of six wild-type (WT) (43.8 ± 7.5 months of age) and six eyes of six Tg (40.3 ± 2.6 months of age) rabbits were studied. The EEPs were elicited by 1 to 5 mA of transcorneal electrical stimulation. The first positive wave, the P1 component, was analyzed. After euthanasia, the number of axons in the optic nerve was counted. Results The threshold current to elicit a P1 was significantly higher in Tg rabbits than WT rabbits. The amplitude of P1 elicited by 5 mA in Tg rabbits was about 24% of that in WT rabbits (P < 0.01). The number of axons in the optic nerve of Tg rabbits was reduced to about 59% of that of WT rabbits (P < 0.01). The correlation between the axon number and the amplitude of the P1 in Tg and WT rabbits was not significant. The mean ratio of the P1 amplitude/axon in Tg rabbits was decreased to 53% of that in WT rabbits (P < 0.05). Conclusions The degree of reduction in the EEP in Tg rabbits is more severe than the reduction in the number of optic nerve axons. The use of transcorneal electrical stimulation to determine the suitable candidates for prosthesis at the end-stage of retinitis pigmentosa may underestimate the condition of the optic nerves.
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Affiliation(s)
- Taro Kominami
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shinji Ueno
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kentaro Nishida
- Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Daiki Inooka
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Azusa Kominami
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Mineo Kondo
- Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Hiroko Terasaki
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Dan H, Shen Y, Huang X, Zhou F, Xing Y. Arterial Spin Labeling Perfusion Magnetic Resonance Imaging Reveals Resting Cerebral Blood Flow Alterations Specific to Retinitis Pigmentosa Patients. Curr Eye Res 2019; 44:1353-1359. [PMID: 31352839 DOI: 10.1080/02713683.2019.1649702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Purpose: This study aimed to assess resting cerebral blood flow (CBF) changes in retinitis pigmentosa (RP) patients using a pseudo-continuous arterial spin labeling (pCASL) perfusion method.Methods: Forty-nine RP patients and 51 healthy controls (HCs) underwent T1-weighted structural and pCASL sequence magnetic resonance imaging (MRI) scans at rest. Two-sample t-tests were performed to compare CBF differences between groups. Pearson correlation was used to analyze relationships between CBF values and clinical variables in the RP group.Results: Compared with HCs, RP patients had significantly lower CBF values in the bilateral cuneus/lingual gyrus/precuneus/posterior cingulate/middle occipital gyrus. In the RP group, CBF values in the left middle occipital and inferior occipital gyrus were positively correlated with mean retinal nerve fiber layer thickness; furthermore, CBF values in several regions were correlated with duration of disease and age of onset.Conclusions: Our results highlighted that RP patients exhibited decreased CBF values in the visual cortices and vision-related cortices. The results suggest that altered CBF might contribute to trans-synaptic retrograde degeneration of the visual pathway in RP patients.
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Affiliation(s)
- Handong Dan
- Eye Center, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
| | - Yin Shen
- Eye Center, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
| | - Xin Huang
- Eye Center, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
| | - Fuqing Zhou
- Eye Center, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Department of Radiology, The First Affiliated Hospital of Nanchang University, Jiangxi Province Medical Imaging Research Institute, Nanchang, Jiangxi, China
| | - Yiqiao Xing
- Eye Center, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
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Abnormal intrinsic brain activity in individuals with peripheral vision loss because of retinitis pigmentosa using amplitude of low-frequency fluctuations. Neuroreport 2019; 29:1323-1332. [PMID: 30113921 DOI: 10.1097/wnr.0000000000001116] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The study aimed to determine alterations in intrinsic brain activity in retinitis pigmentosa (RP) individuals using the amplitude of low-frequency fluctuation (ALFF)/fractional amplitude of low-frequency fluctuation (fALFF) method. Sixteen RP individuals (10 men and six women) and 14 healthy controls (HCs) (six men and eight women) closely matched in age, sex, and education were enrolled in the study. The ALFF/fALFF method was applied to compare different intrinsic brain activities between the RP group and the HC group. The relationship between the mean ALFF/fALFF signal values of different brain regions and the visual measurements in RP group was analyzed by Pearson correlation. Compared with HCs, RP individuals had significantly lower ALFF values in the bilateral lingual gyrus (LIGG)/cerebellum posterior lobe [Brodmann area (BA) 17,18], but lower fALFF values in the bilateral LIGG/cerebellum anterior lobe (BA 17,18). Meanwhile, RP individuals had significantly higher ALFF in the bilateral precuneus cortex/middle cingulate cortex (BA 7,31), as well as higher fALFF values in the left superior/middle frontal gyrus (BA 9,10) and bilateral supplementary motor area (BA 6,8) (voxel-level P<0.01, cluster-level P<0.05). Moreover, the fALFF values of the bilateral LIGG/cerebellum anterior lobe showed positive relationships with the best-corrected visual acuity (BCVA)-oculus dexter (r=0.574, P=0.020) and BCVA-oculus sinister (r=0.570, P=0.021) in RP individuals; our results provide evidence that RP individuals may have impaired intrinsic brain activity in the primary visual area and the visuomotor coordination area that correlates with BCVA. Moreover, our findings indicate that reorganization of the dorsal visual stream and the parietoprefrontal pathway occurs in RP individuals.
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7
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Dan HD, Zhou FQ, Huang X, Xing YQ, Shen Y. Altered intra- and inter-regional functional connectivity of the visual cortex in individuals with peripheral vision loss due to retinitis pigmentosa. Vision Res 2019; 159:68-75. [PMID: 30904614 DOI: 10.1016/j.visres.2019.02.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 02/04/2019] [Accepted: 02/27/2019] [Indexed: 01/05/2023]
Abstract
This study investigated changes in intra- and inter-regional functional connectivity (FC) in individuals with retinitis pigmentosa (RP) by using regional homogeneity (ReHo) and FC methods. Sixteen RP individuals and 14 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging scans (fMRI). A combined ReHo and FC method was conducted to evaluate synchronization of brain activity. Compared with HCs, RP individuals had significantly lower ReHo values in the bilateral lingual gyrus/cerebellum posterior lobe (LGG/CPL). In FC analysis, the RP group showed decreased positive FC relative to the HC group, from bilateral LGG/CPL to bilateral LGG/cuneus (CUN) and to left postcentral gyrus (PosCG). In contrast, the RP group showed increased negative FC relative to the HC group, from bilateral LGG/CPL to bilateral thalamus, and decreased negative FC from bilateral LGG/CPL to right middle frontal gyrus (MFG), and to left inferior parietal lobule (IPL). Moreover, ReHo values of the bilateral LGG/CPL showed negative correlations with the duration of RP. FC values of the bilateral LGG/CPL-left IPL showed negative correlations with best-corrected visual acuity (BCVA) of the right eye and left eye in RP individuals. Our results reveal reduced synchronicity of neural activity changes in the primary visual area in RP individuals. Moreover, RP individuals showed intrinsic visual network disconnection and reorganization of the retino-thalamocortical pathway and dorsal visual stream, suggesting impaired visuospatial and stereoscopic vision.
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Affiliation(s)
- Han-Dong Dan
- Eye Center, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei, China
| | - Fu-Qing Zhou
- Department of Radiology, The First Affiliated Hospital of Nanchang University, Jiangxi Province Medical Imaging Research Institute, Nanchang 330006, Jiangxi, China
| | - Xin Huang
- Eye Center, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei, China
| | - Yi-Qiao Xing
- Eye Center, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei, China
| | - Yin Shen
- Eye Center, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei, China.
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Liang J, Zhao S, Di L, Wang J, Sun P, Chai X, Li H. Eddy-current-induced distortion correction using maximum reconciled mutual information in diffusion MR imaging. Int J Comput Assist Radiol Surg 2019; 14:463-472. [PMID: 30684107 DOI: 10.1007/s11548-018-01901-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 12/14/2018] [Indexed: 11/30/2022]
Abstract
PURPOSE In diffusion tensor imaging, a large number of diffusion-weighted (DW) images with different diffusion gradient directions are attained during scanning. However, subjects' involuntary head movements and eddy current effect related to large diffusion-sensitizing gradients will cause distortions of DW images. Therefore, for tracking accurately white matter structures and tractography, the distortions have to be realigned before model fitting. Currently, traditional methods use maximum mutual information (MMI) or normalized mutual information (NMI) as similarity measure for DW images registration. These information measures are defined by Shannon entropy. The image entropy is able to embody the global information complexity but ignore the local information complexity caused by heterogeneous intensity contrasts in DW images, making registration algorithm early converge. METHOD To overcome the above problem, we present maximum reconciled mutual information (MRMI) combining both global information and local information as the similarity measure of the registration algorithm framework. RESULT (i) In comparison with traditional methods, under our proposed MRMI method, the border of DW image is more anastomotic with the b0 image, and the fitted fractional anisotropy (FA) map after registration is closer to the true brain boundary. (ii) By quantitative analysis of registration results, our method has a significant advantage over others in terms of NMI between b0 image and the aligned DW images. CONCLUSION The results suggest that there is a high-level matching in space between the b0 image and the DW images aligned by the MRMI method, raising the registration robustness and accuracy compared to the traditional DW registration methods. It may provide a better option for the existing diffusion image registration tools (e.g., FMRIB Software Library) and commonly multimodal medical image registration.
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Affiliation(s)
- Junling Liang
- College of Physical Engineering, Zhengzhou University, Zhengzhou, 450001, China.,School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Shujun Zhao
- College of Physical Engineering, Zhengzhou University, Zhengzhou, 450001, China
| | - Liqing Di
- School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jingjuan Wang
- Xuanwu Hospital of Capital Medical University, Beijing, 100053, China
| | - Pengcheng Sun
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xinyu Chai
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Heng Li
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
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Hu J, Li M, Dai Y, Geng C, Tong B, Zhou Z, Liang X, Yang W, Zhang B. Combining SENSE and reduced field-of-view for high-resolution diffusion weighted magnetic resonance imaging. Biomed Eng Online 2018; 17:77. [PMID: 29903023 PMCID: PMC6003092 DOI: 10.1186/s12938-018-0511-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 06/05/2018] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND In diffusion-weighted magnetic resonance imaging (DWI) using single-shot echo planar imaging (ss-EPI), both reduced field-of-view (FOV) excitation and sensitivity encoding (SENSE) alone can increase in-plane resolution to some degree. However, when the two techniques are combined to further increase resolution without pronounced geometric distortion, the resulted images are often corrupted by high level of noise and artifact due to the numerical restriction in SENSE. Hence, this study is aimed to provide a reconstruction method to deal with this problem. METHODS The proposed reconstruction method was developed and implemented to deal with the high level of noise and artifact in the combination of reduced FOV imaging and traditional SENSE, in which all the imaging data were considered jointly by incorporating the motion induced phase variations among excitations. The in vivo human spine diffusion images from ten subjects were acquired at 1.5 T and reconstructed using the proposed method, and compared with SENSE magnitude average results for a range of reduction factors in reduced FOV. These images were evaluated by two radiologists using visual scores (considering distortion, noise and artifact levels) from 1 to 10. RESULTS The proposed method was able to reconstruct images with greatly reduced noise and artifact compared to SENSE magnitude average. The mean g-factors were maintained close to 1 along with enhanced signal-to-noise ratio efficiency. The image quality scores of the proposed method were significantly higher (P < 0.01) than SENSE magnitude average for all the evaluated reduction factors. CONCLUSION The proposed method can improve the combination of SENSE and reduced FOV for high-resolution ss-EPI DWI with reduced noise and artifact.
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Affiliation(s)
- Jisu Hu
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Ming Li
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, China
| | - Yakang Dai
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Chen Geng
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Baotong Tong
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Zhiyong Zhou
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Xue Liang
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, China
| | - Wen Yang
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, China
| | - Bing Zhang
- Department of Radiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, China.
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10
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Structure-function correlations in Retinitis Pigmentosa patients with partially preserved vision: a voxel-based morphometry study. Sci Rep 2017; 7:11411. [PMID: 28900214 PMCID: PMC5596003 DOI: 10.1038/s41598-017-11317-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 08/22/2017] [Indexed: 11/08/2022] Open
Abstract
Retinitis Pigmentosa is a group of hereditary retinal dystrophy disorders associated with progressive peripheral visual field loss. The impact of this retinal loss in cortical gray matter volume has not been addressed before in Retinitis Pigmentosa patients with low vision. Voxel-based morphometry was applied to study whole brain gray matter volume changes in 27 Retinitis Pigmentosa patients with partially preserved vision and 38 age- and gender-matched normally sighted controls to determine whether peripheral visual loss can lead to changes in gray matter volume. We found significant reductions in gray matter volume that were restricted to the occipital cortex of patients. The anteromedial pattern of reduced gray matter volume in visual primary and association cortices was significantly correlated with the extent of the peripheral visual field deficit in this cohort. Moreover, this pattern was found to be associated with the extent of visual field loss. In summary, we found specific visual cortical gray matter loss in Retinitis Pigmentosa patients associated with their visual function profile. The spatial pattern of gray matter loss is consistent with disuse-driven neuronal atrophy which may have clinical implications for disease management, including prosthetic restoration strategies.
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11
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Quantitative assessment of optic nerve in patients with Leber’s hereditary optic neuropathy using reduced field-of-view diffusion tensor imaging. Eur J Radiol 2017; 93:24-29. [DOI: 10.1016/j.ejrad.2017.05.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/21/2017] [Indexed: 11/22/2022]
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12
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MRI-derived diffusion parameters in the human optic nerve and its surrounding sheath during head-down tilt. NPJ Microgravity 2017. [PMID: 28649640 PMCID: PMC5479856 DOI: 10.1038/s41526-017-0023-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
More than half of astronauts present with significant neuro-ophthalmic findings during 6-month missions onboard the International Space Station. Although the underlying cause of this Microgravity Ocular Syndrome is currently unknown, alterations in cerebrospinal fluid dynamics within the optic nerve sheath may play a role. In the presented study, diffusion tensor imaging was used to assess changes in diffusivity of the optic nerve and its surrounding sheath during head-down tilt, a ground-based model of microgravity. Nine healthy male subjects (mean age ± SD: 25 ± 2.4 years; mean body mass index ± SD: 24.1 ± 2.4 kg/m2) underwent 5 head-down tilt conditions: −6°,−12°, −18°,−12° and 1% CO2, and −12° and lower body negative pressure. Mean diffusivity, fractional anisotropy, axial diffusivity, radial diffusivity were quantified in the left and right optic nerves and surrounding sheaths at supine baseline and after 4.5 h head-down tilt for each condition. In the optic nerve sheath, mean diffusivity was increased with all head-down tilt conditions by (Best Linear Unbiased Predictors) 0.147 (SE: 0.04) × 10−3 mm2/s (P < 0.001), axial diffusivity by 0.188 (SE: 0.064) × 10−3 mm2/s (P < 0.001), and radial diffusivity by 0.126 (SE: 0.04) × 10−3 mm2/s (P = 0.0019). Within the optic nerve itself, fractional anisotropy was increased by 0.133 (SE: 0.047) (P = 0.0051) and axial diffusivity increased by 0.135 (SE: 0.08) × 10−3 mm2/s (P = 0.014) during head-down tilt, whilst mean diffusivity and radial diffusivity were unaffected (P > 0.3). These findings could be due to increased perioptic cerebral spinal fluid hydrodynamics during head-down tilt, as well as increased cerebral spinal fluid volume and movement within the optic nerve sheath. Changes to the optic nerve and surrounding sheath during microgravity could explain why space flight is harmful to an astronaut’s vision. Darius Gerlach from the German Aerospace Center in Cologne and colleagues studied the tissue architecture of the optic nerve and its surrounding sheath in nine healthy men who experienced head-down tilt, a commonly used ground-based model of weightlessness. Using a neuroimaging technique called diffusion tensor imaging, the researchers documented fluid dynamic changes wrought by the microgravity-like conditions that could be due to alterations in the volume and movement of cerebrospinal fluid within and around the optic nerve. The findings may help explain why many astronauts experience poorer vision after long-duration space flights, although more work is needed to explore the effects of true microgravity on the visual system.
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Lu P, Sha Y, Wan H, Wang F, Tian G, Tang W. Assessment of nonarteritic anterior ischemic optic neuropathy with intravoxel incoherent motion diffusion-weighted imaging using readout-segmented echo-planar imaging, parallel imaging, and 2D navigator-based reacquisition. J Magn Reson Imaging 2017; 46:1760-1766. [PMID: 28513892 DOI: 10.1002/jmri.25760] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 04/18/2017] [Indexed: 12/31/2022] Open
Affiliation(s)
- Ping Lu
- Shanghai Institution of Medical Imaging; Zhongshan Hospital, Fudan University; Shanghai P.R. China
- Department of Radiology; Eye & ENT Hospital of Fudan University; Shanghai P.R. China
| | - Yan Sha
- Department of Radiology; Eye & ENT Hospital of Fudan University; Shanghai P.R. China
| | - Hailin Wan
- Department of Radiology; Eye & ENT Hospital of Fudan University; Shanghai P.R. China
| | - Feng Wang
- Department of Radiology; Eye & ENT Hospital of Fudan University; Shanghai P.R. China
| | - Guohong Tian
- Department of Ophthalmology; Eye & ENT Hospital of Fudan University; Shanghai P.R. China
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