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Jiang Z, Chernoff D, Galenchik-Chan A, Tomorri D, Honkanen RA, Duong TQ, Muir ER. Improved MRI methods to quantify retinal and choroidal blood flow applied to a model of glaucoma. FRONTIERS IN OPHTHALMOLOGY 2024; 4:1385495. [PMID: 38984144 PMCID: PMC11182105 DOI: 10.3389/fopht.2024.1385495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 04/23/2024] [Indexed: 07/11/2024]
Abstract
Purpose Blood flow (BF) of the retinal and choroidal vasculatures can be quantitatively imaged using MRI. This study sought to improve methods of data acquisition and analysis for MRI of layer-specific retinal and choroidal BF and then applied this approach to detect reduced ocular BF in a well-established mouse model of glaucoma from both eyes. Methods Quantitative BF magnetic resonance imaging (MRI) was performed on glaucomatous DBA/2J and normal C57BL/6J mice. Arterial spin labeling MRI was applied to image retinal and choroidal BF using custom-made dual eye coils that could image both eyes during the same scan. Statistics using data from a single eye or two eyes were compared. BF values were calculated using two approaches. The BF rate per quantity of tissue was calculated as commonly done, and the peak BF values of the retinal and choroidal vasculatures were taken. Additionally, the BF rate per retinal surface area was calculated using a new analysis approach to attempt to reduce partial volume and variability by integrating BF over the retinal and choroidal depths. Results Ocular BF of both eyes could be imaged using the dual coil setup without effecting scan time. Intraocular pressure was significantly elevated in DBA/2J mice compared to C57BL/6J mice (P<0.01). Both retinal and choroidal BF were significantly decreased in DBA/2J mice in comparison to the age-matched normal C57BL/6J mice across all measurements (P < 0.01). From simulations, the values from the integrated BF analysis method had less partial volume effect, and from in vivo scans, this analysis approach also improved power. Conclusion The dual eye coil setup allows bilateral eye data acquisition, increasing the amount of data acquired without increasing acquisition times in vivo. The reduced ocular BF found using the improved acquisition and analysis approaches replicated the results of previous studies on DBA/2J mice. The ocular hypertensive stress-induced BF reduction found within these mice may represent changes associated with glaucomatous progression.
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Affiliation(s)
- Zhao Jiang
- Department of Radiology, Stony Brook University, Stony Brook, NY, United States
| | - Diane Chernoff
- Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, United States
| | - Andre Galenchik-Chan
- Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, United States
| | - David Tomorri
- School of Health Professions, Stony Brook University, Stony Brook, NY, United States
| | - Robert A. Honkanen
- Department of Ophthalmology, Stony Brook University, Stony Brook, NY, United States
| | - Timothy Q. Duong
- Department of Radiology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Eric R. Muir
- Department of Radiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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Rajendran Nair DS, Camarillo JCM, Lu G, Thomas BB. Measuring spatial visual loss in rats by retinotopic mapping of the superior colliculus using a novel multi-electrode array technique. J Neurosci Methods 2024; 405:110095. [PMID: 38403001 PMCID: PMC11363873 DOI: 10.1016/j.jneumeth.2024.110095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 02/06/2024] [Accepted: 02/22/2024] [Indexed: 02/27/2024]
Abstract
BACKGROUND The retinotopic map property of the superior colliculus (SC) is a reliable indicator of visual functional changes in rodents. Electrophysiological mapping of the SC using a single electrode has been employed for measuring visual function in rat and mouse disease models. Single electrode mapping is highly laborious requiring long-term exposure to the SC surface and prolonged anesthetic conditions that can adversely affect the mapping data. NEW METHOD To avoid the above-mentioned issues, we fabricated a fifty-six (56) electrode multi-electrode array (MEA) for rapid and reliable visual functional mapping of the SC. Since SC is a dome-shaped structure, the array was made of electrodes with dissimilar tip lengths to enable simultaneous and uniform penetration of the SC. RESULTS SC mapping using the new MEA was conducted in retinal degenerate (RD) Royal College of Surgeons (RCS) rats and rats with focal retinal damage induced by green diode laser. For SC mapping, the MEA was advanced into the SC surface and the visual activities were recorded during full-filed light stimulation of the eye. Based on the morphological examination, the MEA electrodes covered most of the exposed SC area and penetrated the SC surface at a relatively uniform depth. MEA mapping in RCS rats (n=9) demonstrated progressive development of a scotoma in the SC that corresponded to the degree of photoreceptor loss. MEA mapping in the laser damaged rats demonstrated the presence of a scotoma in the SC area that corresponded to the location of retinal laser injury. COMPARISON WITH EXISTING METHODS AND CONCLUSIONS The use of MEA for SC mapping is advantageous over single electrode recording by enabling faster recordings and reducing anesthesia time. This study establishes the feasibility of the MEA technique for rapid and efficient SC mapping, particularly advantageous for evaluating therapeutic effects in retinal degenerate rat disease models.
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Affiliation(s)
- Deepthi S Rajendran Nair
- Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, United States
| | - Juan Carlos-Martinez Camarillo
- Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, United States; USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, United States
| | - Gengxi Lu
- Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, United States
| | - Biju B Thomas
- Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, United States; USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, United States.
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Gersch J, Hufendiek K, Delarocque J, Framme C, Jacobsen C, Stöhr H, Kellner U, Hufendiek K. Investigation of Structural Alterations in Inherited Retinal Diseases: A Quantitative SD-OCT-Analysis of Retinal Layer Thicknesses in Light of Underlying Genetic Mutations. Int J Mol Sci 2022; 23:16007. [PMID: 36555650 PMCID: PMC9788460 DOI: 10.3390/ijms232416007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/08/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Inherited retinal diseases can result from various genetic defects and are one of the leading causes for blindness in the working-age population. The present study aims to provide a comprehensive description of changes in retinal structure associated with phenotypic disease entities and underlying genetic mutations. Full macular spectral domain optical coherence tomography scans were obtained and manually segmented in 16 patients with retinitis pigmentosa, 7 patients with cone−rod dystrophy, and 7 patients with Stargardt disease, as well as 23 age- and sex-matched controls without retinal disease, to assess retinal layer thicknesses. As indicated by generalized least squares models, all IRDs were associated with retinal thinning (p < 0.001), especially of the outer nuclear layer (ONL, p < 0.001). Except for the retinal nerve fiber layer, such thinning was associated with a reduced visual acuity (p < 0.001). These advances in our understanding of ultrastructural retinal changes are important for the development of gene-, cell-, and optogenetic therapy. Longitudinal studies are warranted to describe the temporal component of those changes.
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Affiliation(s)
- Julia Gersch
- University Eye Hospital, Hannover Medical School, 30625 Hannover, Germany
| | - Katerina Hufendiek
- University Eye Hospital, Hannover Medical School, 30625 Hannover, Germany
| | - Julien Delarocque
- Clinic for Horses, University Veterinary Medicine Hannover, Foundation, 30559 Hannover, Germany
| | - Carsten Framme
- University Eye Hospital, Hannover Medical School, 30625 Hannover, Germany
| | - Christina Jacobsen
- University Eye Hospital, Hannover Medical School, 30625 Hannover, Germany
| | - Heidi Stöhr
- Institute of Human Genetics, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Ulrich Kellner
- Center for Rare Retinal Diseases, AugenZentrum Siegburg, MVZ Augenärztliches Diagnostik- und Therapiecentrum Siegburg GmbH, Europaplatz 3, 53721 Siegburg, Germany
- RetinaScience, P.O. Box 301212, 53192 Bonn, Germany
| | - Karsten Hufendiek
- University Eye Hospital, Hannover Medical School, 30625 Hannover, Germany
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Mendoza M, Shotbolt M, Faiq MA, Parra C, Chan KC. Advanced Diffusion MRI of the Visual System in Glaucoma: From Experimental Animal Models to Humans. BIOLOGY 2022; 11:454. [PMID: 35336827 PMCID: PMC8945790 DOI: 10.3390/biology11030454] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 03/10/2022] [Indexed: 11/18/2022]
Abstract
Glaucoma is a group of ophthalmologic conditions characterized by progressive retinal ganglion cell death, optic nerve degeneration, and irreversible vision loss. While intraocular pressure is the only clinically modifiable risk factor, glaucoma may continue to progress at controlled intraocular pressure, indicating other major factors in contributing to the disease mechanisms. Recent studies demonstrated the feasibility of advanced diffusion magnetic resonance imaging (dMRI) in visualizing the microstructural integrity of the visual system, opening new possibilities for non-invasive characterization of glaucomatous brain changes for guiding earlier and targeted intervention besides intraocular pressure lowering. In this review, we discuss dMRI methods currently used in visual system investigations, focusing on the eye, optic nerve, optic tract, subcortical visual brain nuclei, optic radiations, and visual cortex. We evaluate how conventional diffusion tensor imaging, higher-order diffusion kurtosis imaging, and other extended dMRI techniques can assess the neuronal and glial integrity of the visual system in both humans and experimental animal models of glaucoma, among other optic neuropathies or neurodegenerative diseases. We also compare the pros and cons of these methods against other imaging modalities. A growing body of dMRI research indicates that this modality holds promise in characterizing early glaucomatous changes in the visual system, determining the disease severity, and identifying potential neurotherapeutic targets, offering more options to slow glaucoma progression and to reduce the prevalence of this world's leading cause of irreversible but preventable blindness.
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Affiliation(s)
- Monica Mendoza
- Department of Biomedical Engineering, Tandon School of Engineering, New York University, New York, NY 11201, USA; (M.M.); (M.S.)
| | - Max Shotbolt
- Department of Biomedical Engineering, Tandon School of Engineering, New York University, New York, NY 11201, USA; (M.M.); (M.S.)
| | - Muneeb A. Faiq
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY 10017, USA; (M.A.F.); (C.P.)
| | - Carlos Parra
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY 10017, USA; (M.A.F.); (C.P.)
| | - Kevin C. Chan
- Department of Biomedical Engineering, Tandon School of Engineering, New York University, New York, NY 11201, USA; (M.M.); (M.S.)
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY 10017, USA; (M.A.F.); (C.P.)
- Department of Radiology, Neuroscience Institute, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY 10016, USA
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Diabetic mice have retinal and choroidal blood flow deficits and electroretinogram deficits with impaired responses to hypercapnia. PLoS One 2021; 16:e0259505. [PMID: 34882677 PMCID: PMC8659412 DOI: 10.1371/journal.pone.0259505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 10/20/2021] [Indexed: 11/19/2022] Open
Abstract
Purpose The purpose of this study was to investigate neuronal and vascular functional deficits in the retina and their association in a diabetic mouse model. We measured electroretinography (ERG) responses and choroidal and retinal blood flow (ChBF, RBF) with magnetic resonance imaging (MRI) in healthy and diabetic mice under basal conditions and under hypercapnic challenge. Methods Ins2Akita diabetic (Diab, n = 8) and age-matched, wild-type C57BL/6J mice (Ctrl, n = 8) were studied under room air and moderate hypercapnia (5% CO2). Dark-adapted ERG a-wave, b-wave, and oscillatory potentials (OPs) were measured for a series of flashes. Regional ChBF and RBF under air and hypercapnia were measured using MRI in the same mice. Results Under room air, Diab mice had compromised ERG b-wave and OPs (e.g., b-wave amplitude was 422.2±10.7 μV in Diab vs. 600.1±13.9 μV in Ctrl, p < 0.001). Under hypercapnia, OPs and b-wave amplitudes were significantly reduced in Diab (OPs by 30.3±3.0% in Diab vs. -3.0±3.6% in Ctrl, b-wave by 17.9±1.4% in Diab vs. 1.3±0.5% in Ctrl). Both ChBF and RBF had significant differences in regional blood flow, with Diab mice having substantially lower blood flow in the nasal region (ChBF was 5.4±1.0 ml/g/min in Diab vs. 8.6±1.0 ml/g/min in Ctrl, RBF was 0.91±0.10 ml/g/min in Diab vs. 1.52±0.24 ml/g/min in Ctrl). Under hypercapnia, ChBF increased in both Ctrl and Diab without significant group difference (31±7% in Diab vs. 17±7% in Ctrl, p > 0.05), but an increase in RBF was not detected for either group. Conclusions Inner retinal neuronal function and both retinal and choroidal blood flow were impaired in Diab mice. Hypercapnia further compromised inner retinal neuronal function in diabetes, while the blood flow response was not affected, suggesting that the diabetic retina has difficulty adapting to metabolic challenges due to factors other than impaired blood flow regulation.
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Effect of Dual Endothelin Receptor Antagonist on a Retinal Degeneration Animal Model by Regulating Choroidal Microvascular Morphology. J Ophthalmol 2021; 2021:5688300. [PMID: 34840823 PMCID: PMC8626175 DOI: 10.1155/2021/5688300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 09/05/2021] [Accepted: 10/08/2021] [Indexed: 11/17/2022] Open
Abstract
Objective Clinical studies have found that increasing levels of plasma endothelin-1 (ET-1) might inhibit choroidal blood flow (BF) and promote choroidal vasoconstriction. This study was designed to investigate ET-1 levels and its effect on choroidal microvascular morphology in a retinitis pigmentosa (RP) animal model. Methods Mice with retinal degeneration (rd10) were intragastrically administered bosentan, a dual endothelin receptor antagonist. We detected plasma ET-1 levels using an enzyme-linked immunosorbent assay (ELISA) kit at P14, P21, and P28 and evaluated ET-1 expression in RPE/choroid/sclera complexes using western blot and whole mount immunofluorescence staining at P28. Retinal thickness was measured using hematoxylin and eosin (H&E) staining at P28. At the same time, we also estimated choroidal microvascular densities using vascular luminal casting with a scanning electron microscope (SEM). Results Plasma ET-1 levels were increased significantly in rd10 mice at P21 (65.48 ± 24.83 pg/ml) and P28 (85.89 ± 20.23 pg/ml) compared with C57BL/6J mice at P21 (33.52 ± 16.33 pg/ml) and P28 (42.38 ± 17.53 pg/ml); the expression of ET-1 was also upregulated in RPE/choroid/sclera complexes at P28. Bosentan inhibited ET-1 expression in plasma (P < 0.05) and RPE/choroid/sclera complexes at P28 in rd10 mice. Choroidal microvascular densities were decreased in rd10 mice, and bosentan could weaken these changes. Conclusion Plasma and local ET-1 was elevated in an animal model of RP, suggesting that it likely participates in the pathological progression of retinal degeneration and may thus provide a new intervention target. ET-1 blockade might exert its protective effect by elevating choroidal microvascular density via inhibition of ET-1.
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Thomas BB, Lin B, Martinez-Camarillo JC, Zhu D, McLelland BT, Nistor G, Keirstead HS, Humayun MS, Seiler MJ. Co-grafts of Human Embryonic Stem Cell Derived Retina Organoids and Retinal Pigment Epithelium for Retinal Reconstruction in Immunodeficient Retinal Degenerate Royal College of Surgeons Rats. Front Neurosci 2021; 15:752958. [PMID: 34764853 PMCID: PMC8576198 DOI: 10.3389/fnins.2021.752958] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/04/2021] [Indexed: 12/15/2022] Open
Abstract
End-stage age-related macular degeneration (AMD) and retinitis pigmentosa (RP) are two major retinal degenerative (RD) conditions that result in irreversible vision loss. Permanent eye damage can also occur in battlefields or due to accidents. This suggests there is an unmet need for developing effective strategies for treating permanent retinal damages. In previous studies, co-grafted sheets of fetal retina with its retinal pigment epithelium (RPE) have demonstrated vision improvement in rat retinal disease models and in patients, but this has not yet been attempted with stem-cell derived tissue. Here we demonstrate a cellular therapy for irreversible retinal eye injuries using a "total retina patch" consisting of retinal photoreceptor progenitor sheets and healthy RPE cells on an artificial Bruch's membrane (BM). For this, retina organoids (ROs) (cultured in suspension) and polarized RPE sheets (cultured on an ultrathin parylene substrate) were made into a co-graft using bio-adhesives [gelatin, growth factor-reduced matrigel, and medium viscosity (MVG) alginate]. In vivo transplantation experiments were conducted in immunodeficient Royal College of Surgeons (RCS) rats at advanced stages of retinal degeneration. Structural reconstruction of the severely damaged retina was observed based on histological assessments and optical coherence tomography (OCT) imaging. Visual functional assessments were conducted by optokinetic behavioral testing and superior colliculus electrophysiology. Long-term survival of the co-graft in the rat subretinal space and improvement in visual function were observed. Immunohistochemistry showed that co-grafts grew, generated new photoreceptors and developed neuronal processes that were integrated into the host retina. This novel approach can be considered as a new therapy for complete replacement of a degenerated retina.
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Affiliation(s)
- Biju B. Thomas
- Department of Ophthalmology, USC Roski Eye Institute, University of Southern California, Los Angeles, CA, United States
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA, United States
| | - Bin Lin
- Department of Physical Medicine and Rehabilitation, University of California, Irvine, Irvine, CA, United States
- Stem Cell Research Center, University of California, Irvine, Irvine, CA, United States
| | - Juan Carlos Martinez-Camarillo
- Department of Ophthalmology, USC Roski Eye Institute, University of Southern California, Los Angeles, CA, United States
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA, United States
| | - Danhong Zhu
- Department of Ophthalmology, USC Roski Eye Institute, University of Southern California, Los Angeles, CA, United States
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Bryce T. McLelland
- Department of Physical Medicine and Rehabilitation, University of California, Irvine, Irvine, CA, United States
- Stem Cell Research Center, University of California, Irvine, Irvine, CA, United States
| | | | | | - Mark S. Humayun
- Department of Ophthalmology, USC Roski Eye Institute, University of Southern California, Los Angeles, CA, United States
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA, United States
| | - Magdalene J. Seiler
- Department of Physical Medicine and Rehabilitation, University of California, Irvine, Irvine, CA, United States
- Stem Cell Research Center, University of California, Irvine, Irvine, CA, United States
- Department of Ophthalmology, University of California, Irvine, Irvine, CA, United States
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, CA, United States
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AttaAllah HR, Mohamed AAM, Hamid MA. Quantification of Macular Microvascular Changes in Retinitis Pigmentosa Using Optical Coherence Tomography Angiography. Clin Ophthalmol 2020; 14:1705-1713. [PMID: 32606586 PMCID: PMC7319527 DOI: 10.2147/opth.s254909] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/02/2020] [Indexed: 01/30/2023] Open
Abstract
Purpose To investigate macular structural and microvascular changes in retinitis pigmentosa (RP) eyes compared to age-matched controls using spectral domain optical coherence tomography (SD-OCT) and OCT angiography (OCTA). Methods This was a cross-sectional study. The foveal and parafoveal thickness and extent of ellipsoid zone (EZ) disruption were measured on OCT. The foveal avascular zone (FAZ) area and retinal vessel density (VD) were automatically calculated for superficial (SCP) and deep capillary plexuses (DCP) and choriocapillaris using OCTA-integrated software. VD was assessed for the whole 6 × 6 mm image, foveal and parafoveal regions. Quantitative measures were compared between healthy and diseased eyes. Results The study included 30 eyes of 30 RP patients and 24 eyes of 24 controls. Mean age was 26.9±6.4 years for RP patients and 27.4±4.9 years for controls (p=0.76). Mean LogMAR visual acuity (VA) was 0.9±0.5 for RP patients and 0.05±0.05 for controls (p <0.001). Foveal and parafoveal thicknesses were significantly lower in RP cases as compared to the control group. EZ disruption was observed in RP cases only (869±211 µm). Mean FAZ area was significantly larger in RP eyes in both SCP and DCP. VD was significantly reduced in RP eyes at the level of SCP, DCP and choriocapillaris. VA, deep parafoveal VD, foveal, parafoveal and whole image choriocapillaris VD were negatively correlated with the extent of EZ disruption. Conclusion We report OCTA findings in a relatively young cohort of RP patients. We demonstrated a reduction of retinal microvascular density in all studied layers on OCTA. We believe studying retinal vasculature in these patients is important, as a healthy blood supply is a prerequisite for the success of new cell-based therapies under trial for RP.
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Affiliation(s)
- Heba Radi AttaAllah
- Department of Ophthalmology, Faculty of Medicine, Minia University, Minia, Egypt
| | | | - Mohamed A Hamid
- Department of Ophthalmology, Faculty of Medicine, Minia University, Minia, Egypt
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Abstract
PURPOSE To evaluate the correlation between the flow density measured by optical coherence tomography angiography and functional parameters in patients with retinitis pigmentosa. METHODS Twenty eyes of 20 patients with retinitis pigmentosa and 21 eyes of 21 healthy subjects were prospectively included in this study. Optical coherence tomography angiography was performed using RTVue XR Avanti with AngioVue (Optovue Inc). The macula was imaged with a 6 × 6-mm scan, whereas for the optic nerve head a 4.5 × 4.5-mm scan was taken. Visual acuity, visual field parameters (mean deviation and visual field index), full-field electroretinography, and multifocal electroretinography were tested for correlation with flow density data. RESULTS The flow density (whole en face) in the superficial/deep retinal OCT angiograms and in the optical coherence tomography angiography of the optic nerve head was significantly lower in the retinitis pigmentosa group when compared with the control group (P < 0.001). The flow density in the superficial retinal OCT angiogram (fovea) correlated significantly with the visual acuity (rSpearman = -0.77, P < 0.001) and the visual field parameters (visual field index: rSpearman = 0.56, P = 0.01; mean deviation: rSpearman = 0.54, P = 0.01). CONCLUSION Patients with retinitis pigmentosa show a decreased macular and optic nerve head perfusion compared with healthy subjects. The flow density measured using optical coherence tomography angiography correlated with subjective and objective functional parameters.
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Liu R, Lu J, Liu Q, Wang Y, Cao D, Wang J, Wang X, Pan J, Ma L, Jin C, Sadda S, Luo Y, Lu L. Effect of Choroidal Vessel Density on the Ellipsoid Zone and Visual Function in Retinitis Pigmentosa Using Optical Coherence Tomography Angiography. Invest Ophthalmol Vis Sci 2020; 60:4328-4335. [PMID: 31622469 DOI: 10.1167/iovs.18-24921] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose We evaluate the effect of choroidal vessel density on the residual length of the ellipsoid zone (EZ) and visual function in patients with retinitis pigmentosa (RP) using optical coherence tomography angiography (OCTA). Methods Fifty-three patients with RP (n = 101 eyes) and 53 normal participants (n = 76 eyes) were enrolled in this study. Patients with RP were assigned to three groups according to their best-corrected visual acuity (BCVA). All patients underwent ophthalmologic examinations, including BCVA, fundus examination performed with a slit-lamp using an indirect 90 diopter (D) lens, OCTA, full-field electroretinogram (ERG), and visual field. The choroidal vessel density in the choriocapillaris-Sattler's layer (DC-S), Haller's layer (DH), horizontal length of the ellipsoid (HEL), and vertical length of the ellipsoid (VEL) were assessed using OCTA and Adobe Photoshop CS3 extended software. Results A significantly increasing impairment of choroidal vessel density (DC-S and DH) was characterized in the RP groups compared to those of the controls (P < 0.05 for all). The magnitude of the reduction in the DC-S and DH was much easier to identify for more severely impaired BCVA in the RP groups (P < 0.05 for all). The DC-S had the strongest correlation with the HEL, VEL, BCVA, visual field, and b-wave amplitude (r = 0.735, r = 0.753, r = -0.843, r = 0.579, and r = 0.671, respectively). Conclusions Using noninvasive OCTA, choroidal microcirculation, especially in the small/middle choroidal vessel layers, was a prominent factor affecting the EZ, visual acuity, visual field, and recordable ERG b-wave amplitude of patients with RP. This may provide new insights into the progress mechanism and treatment of RP.
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Affiliation(s)
- Ruyuan Liu
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Jing Lu
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Qiuhui Liu
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Yishen Wang
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Di Cao
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Jing Wang
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Xiao Wang
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Jianying Pan
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Li Ma
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Chenjin Jin
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - SriniVas Sadda
- Doheny Image Reading Center, Doheny Eye Institute, Los Angeles, California, United States
| | - Yan Luo
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Lin Lu
- State Key Laboratory of Ophthalmology, Image Reading Center, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, People's Republic of China
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Kim TH, Son T, Lu Y, Alam M, Yao X. Comparative Optical Coherence Tomography Angiography of Wild-Type and rd10 Mouse Retinas. Transl Vis Sci Technol 2018; 7:42. [PMID: 30619662 PMCID: PMC6314228 DOI: 10.1167/tvst.7.6.42] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 11/02/2018] [Indexed: 12/11/2022] Open
Abstract
Purpose To conduct longitudinal optical coherence tomography angiography (OCTA) to characterize dynamic changes of trilaminar vascular plexuses in wild-type (WT) and retinal degeneration 10 (rd10) mouse retinas. Methods Longitudinal in vivo OCT/OCTA measurements of WT and rd10 mouse retinas were conducted at postnatal day 14 (P14), P17, P21, P24, and P28. OCT images were used to quantify retinal thickness changes, while OCTA images were used to investigate vascular dynamics within the trilaminar vascular plexuses, that is, superficial vascular plexus (SVP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP). Blood vessel densities of all three plexus layers were quantitatively evaluated separately. The caliber of first-order blood vessel branches in the SVP layer was also measured. Results Vascular densities in all three plexuses continuously decreased with aging in both WT and rd10. However, abnormal density reduction in rd10 occurred at P17 in both ICP (P < 0.001) and DCP (P < 0.001). While the ICP of rd10 showed density recovery at P24, the DCP of rd10 showed significantly low density. Remarkable vascular narrowing in rd10 was also observed in the SVP, especially at P28. Conclusions The most severe vascular impairment happened in the DCP, while the ICP showed the transient recovery of vascular density after the onset of retinal degeneration. The SVP was most resistant to the retinal degeneration, but the first-order blood vessel branches within the SVP showed progressive narrowing. Translational Relevance Better understanding of the vascular changes correlated with retinal development, and retinal degeneration can provide insights in advanced development of treatment protocols of retinal degenerative diseases.
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Affiliation(s)
- Tae-Hoon Kim
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Taeyoon Son
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Yiming Lu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Minhaj Alam
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA.,Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
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7.1 T MRI and T2 mapping of the human and porcine vitreous body post mortem. Eur J Pharm Biopharm 2018; 131:82-91. [DOI: 10.1016/j.ejpb.2018.07.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 07/24/2018] [Accepted: 07/25/2018] [Indexed: 12/30/2022]
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13
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Quantitative progression of retinitis pigmentosa by optical coherence tomography angiography. Sci Rep 2018; 8:13130. [PMID: 30177829 PMCID: PMC6120860 DOI: 10.1038/s41598-018-31488-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 08/14/2018] [Indexed: 11/08/2022] Open
Abstract
Optical coherence tomography angiography (OCT-A) is a non-invasive alternative to fluorescein angiography that allows for the study of the retinal and choroidal vasculatures. In this retrospective cohort study of 28 patients with retinitis pigmentosa (RP), we used OCT-A to quantify changes in perfusion density, foveal avascular zone (FAZ) area, and choriocapillaris blood flow over time and correlated these variables with ellipsoid zone (EZ) line width and best-corrected visual acuity (BCVA). Perfusion density decreased by 2.42 ± 0.62% per year at the superior capillary plexus (SCP) (P = 0.001) and 2.41 ± 0.76% per year at the deep capillary plexus (DCP) (P = 0.004). FAZ area increased by 0.078 ± 0.021 mm2 per year (P = 0.001) at the SCP and 0.152 ± 0.039 mm2 per year (P = 0.001) at the DCP. No changes were observed in the choriocapillaris blood flow. EZ line width had the strongest correlation to perfusion density at the SCP (r = 0.660 and 0.635, first and second visit, respectively, P = 0.001), while BCVA most strongly correlated with FAZ area at the SCP (r = 0.679 and 0.548, P = 0.001 and 0.003). Our results suggest that OCT-A is a useful tool for monitoring RP disease progression and may be used to measure retinal vascular parameters as outcomes in clinical trials.
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Abstract
Magnetic resonance imaging has been utilized as a quantitative and noninvasive method to image blood flow. Arterial spin labeling (ASL) is an MRI technique that images blood flow using arterial blood water as an endogenous tracer. Herein we describe the use of ASL to measure cerebral blood flow completely noninvasively in rodents, including methods, analysis, and important considerations when utilizing this technique.
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Affiliation(s)
- Eric R Muir
- Department of Ophthalmology, Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
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15
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Lew YJ, Rinella N, Qin J, Chiang J, Moore AT, Porco TC, Roorda A, Duncan JL. High-resolution Imaging in Male Germ Cell-Associated Kinase (MAK)-related Retinal Degeneration. Am J Ophthalmol 2018; 185:32-42. [PMID: 29103961 PMCID: PMC5732075 DOI: 10.1016/j.ajo.2017.10.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/24/2017] [Accepted: 10/25/2017] [Indexed: 02/06/2023]
Abstract
PURPOSE To describe the characteristics of MAK-related retinal degeneration using optical coherence tomography angiography (OCTA) and adaptive optics scanning laser ophthalmoscopy (AOSLO). DESIGN Cross-sectional study. METHODS Six patients with rod-cone degeneration and disease-causing mutations in MAK were evaluated with visual acuity, spectral-domain OCT, confocal AOSLO, and OCTA. Foveal avascular zone (FAZ) area, vessel densities, and perfusion densities of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) in the central macula in all 6 patients were compared with 5 normal subjects. Cone spacing was measured in 4 patients from AOSLO images and compared with 37 normal subjects. RESULTS Patients ranged from 25 to 81 years of age (mean, 52 years). Visual acuity varied from 20/13 to 20/40+2, except in 1 patient with cystoid macular edema whose vision was 20/60- and 20/70+1. The SCP (P = .012) and DCP (P = .013) vessel density and perfusion density (P =.015 and .013, respectively) were significantly lower in patients compared to normal subjects in the parafoveal region 1.0-3.0 mm from the fovea, but were similar to normal subjects within 1.0 mm of the fovea. The FAZ area was not significantly different from normal (all P ≥ .24). Cone spacing was normal at almost all locations in 2 patients with early disease and increased in 2 patients with advanced disease. CONCLUSIONS Although retinal vascular densities are reduced and cone spacing is increased in advanced disease, central foveal structure is maintained until late stages of disease, which may contribute to preservation of foveal vision in eyes with MAK-related retinal degeneration.
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Affiliation(s)
- Young Ju Lew
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Nicholas Rinella
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Jia Qin
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Joanna Chiang
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Anthony T Moore
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Travis C Porco
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California; Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California; Proctor Foundation, University of California, San Francisco, San Francisco, California
| | - Austin Roorda
- School of Optometry and Vision Science Graduate Group, University of California, Berkeley, Berkeley, California
| | - Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California.
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Assessment of Safety and Functional Efficacy of Stem Cell-Based Therapeutic Approaches Using Retinal Degenerative Animal Models. Stem Cells Int 2017; 2017:9428176. [PMID: 28928775 PMCID: PMC5592015 DOI: 10.1155/2017/9428176] [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] [Received: 04/15/2017] [Accepted: 06/19/2017] [Indexed: 02/06/2023] Open
Abstract
Dysfunction and death of retinal pigment epithelium (RPE) and or photoreceptors can lead to irreversible vision loss. The eye represents an ideal microenvironment for stem cell-based therapy. It is considered an “immune privileged” site, and the number of cells needed for therapy is relatively low for the area of focused vision (macula). Further, surgical placement of stem cell-derived grafts (RPE, retinal progenitors, and photoreceptor precursors) into the vitreous cavity or subretinal space has been well established. For preclinical tests, assessments of stem cell-derived graft survival and functionality are conducted in animal models by various noninvasive approaches and imaging modalities. In vivo experiments conducted in animal models based on replacing photoreceptors and/or RPE cells have shown survival and functionality of the transplanted cells, rescue of the host retina, and improvement of visual function. Based on the positive results obtained from these animal experiments, human clinical trials are being initiated. Despite such progress in stem cell research, ethical, regulatory, safety, and technical difficulties still remain a challenge for the transformation of this technique into a standard clinical approach. In this review, the current status of preclinical safety and efficacy studies for retinal cell replacement therapies conducted in animal models will be discussed.
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Merkle CW, Leahy C, Srinivasan VJ. Dynamic contrast optical coherence tomography images transit time and quantifies microvascular plasma volume and flow in the retina and choriocapillaris. BIOMEDICAL OPTICS EXPRESS 2016; 7:4289-4312. [PMID: 27867732 PMCID: PMC5102529 DOI: 10.1364/boe.7.004289] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 08/19/2016] [Accepted: 09/16/2016] [Indexed: 05/18/2023]
Abstract
Despite the prevalence of optical imaging techniques to measure hemodynamics in large retinal vessels, quantitative measurements of retinal capillary and choroidal hemodynamics have traditionally been challenging. Here, a new imaging technique called dynamic contrast optical coherence tomography (DyC-OCT) is applied in the rat eye to study microvascular blood flow in individual retinal and choroidal layers in vivo. DyC-OCT is based on imaging the transit of an intravascular tracer dynamically as it passes through the field-of-view. Hemodynamic parameters can be determined through quantitative analysis of tracer kinetics. In addition to enabling depth-resolved transit time, volume, and flow measurements, the injected tracer also enhances OCT angiograms and enables clear visualization of the choriocapillaris, particularly when combined with a post-processing method for vessel enhancement. DyC-OCT complements conventional OCT angiography through quantification of tracer dynamics, similar to fluorescence angiography, but with the important added benefit of laminar resolution.
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Affiliation(s)
- Conrad W. Merkle
- Department of Biomedical Engineering, University of California Davis, Davis, California, USA
| | - Conor Leahy
- Department of Biomedical Engineering, University of California Davis, Davis, California, USA
| | - Vivek J. Srinivasan
- Department of Biomedical Engineering, University of California Davis, Davis, California, USA
- Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, Sacramento, California, USA
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Sodi A, Mucciolo DP, Murro V, Zoppetti C, Terzuoli B, Mecocci A, Virgili G, Rizzo S. Computer-Assisted Evaluation of Retinal Vessel Diameter in Retinitis Pigmentosa. Ophthalmic Res 2016; 56:139-44. [DOI: 10.1159/000446843] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 05/12/2016] [Indexed: 11/19/2022]
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Battaglia Parodi M, Cicinelli MV, Rabiolo A, Pierro L, Gagliardi M, Bolognesi G, Bandello F. Vessel density analysis in patients with retinitis pigmentosa by means of optical coherence tomography angiography. Br J Ophthalmol 2016; 101:428-432. [DOI: 10.1136/bjophthalmol-2016-308925] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 05/30/2016] [Accepted: 06/08/2016] [Indexed: 11/03/2022]
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20
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Application of Arterial Spin Labelling in the Assessment of Ocular Tissues. BIOMED RESEARCH INTERNATIONAL 2016; 2016:6240504. [PMID: 27066501 PMCID: PMC4811053 DOI: 10.1155/2016/6240504] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 02/07/2016] [Indexed: 11/17/2022]
Abstract
Arterial spin labelling (ASL) is a noninvasive magnetic resonance imaging (MRI) modality, capable of measuring blood perfusion without the use of a contrast agent. While ASL implementation for imaging the brain and monitoring cerebral blood flow has been reviewed in depth, the technique is yet to be widely used for ocular tissue imaging. The human retina is a very thin but highly stratified structure and it is also situated close to the surface of the body which is not ideal for MR imaging. Hence, the application of MR imaging and ASL in particular has been very challenging for ocular tissues and retina. That is despite the fact that almost all of retinal pathologies are accompanied by blood perfusion irregularities. In this review article, we have focused on the technical aspects of the ASL and their implications for its optimum adaptation for retinal blood perfusion monitoring. Retinal blood perfusion has been assessed through qualitative or invasive quantitative methods but the prospect of imaging flow using ASL would increase monitoring and assessment of retinal pathologies. The review provides details of ASL application in human ocular blood flow assessment.
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Burmeister D, Bishwokarma B, AbouShwareb T, Olson J, Herco M, Tan J, Andersson KE, Christ G. The potential utility of non-invasive imaging to monitor restoration of bladder structure and function following subtotal cystectomy (STC). BMC Urol 2015; 15:103. [PMID: 26463481 PMCID: PMC4604729 DOI: 10.1186/s12894-015-0094-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/25/2015] [Indexed: 12/03/2022] Open
Abstract
Background Restoration of normal bladder volume and function (i.e., bioequivalent bladder) are observed within 8 weeks of performing subtotal cystectomy (STC; removal of ~70 % of the bladder) in 12-week old rats. For analysis of bladder function in rodents, terminal urodynamic approaches are largely utilized. In the current study, we investigated the potential for Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) scans to noninvasively track restoration of structure and function following STC. Methods Twelve week old female Fisher F344 rats underwent STC and were scanned via CT and/or MRI 2, 4, 8, and 12 weeks post-STC, followed by urodynamic testing. After euthanasia, bladders were excised for histological processing. Results MRI scans demonstrated an initial decline followed by a time-dependent increase to normal bladder wall thickness (BWT) by 8 weeks post-STC. Masson’s trichrome staining showed a lack of fibrosis post-STC, and also revealed that the percent of smooth muscle in the bladder wall at 2 and 4 weeks positively correlated with pre-operative baseline BWT. Moreover, increased BWT values before STC was predictive of improved bladder compliance at 2 and 4 weeks post-STC. Cystometric studies indicated that repeated MRI manipulation (i.e. bladder emptying) apparently had a negative impact on bladder capacity and compliance. A “window” of bladder volumes was identified 2 weeks post-STC via CT scanning that were commensurate with normal micturition pressures measured in the same animal 6 weeks later. Conclusions Taken together, the data indicate some limitations of “non-invasive” imaging to provide insight into bladder regeneration. Specifically, mechanical manipulation of the bladder during MRI appears to negatively impact the regenerative process per se, which highlights the importance of terminal cystometric studies.
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Affiliation(s)
- David Burmeister
- Wake Forest Institute for Regenerative Medicine, 391 Technology Way, Winston-Salem, NC, 27101, USA.
| | - Bimjhana Bishwokarma
- Wake Forest Institute for Regenerative Medicine, 391 Technology Way, Winston-Salem, NC, 27101, USA.
| | - Tamer AbouShwareb
- Wake Forest Institute for Regenerative Medicine, 391 Technology Way, Winston-Salem, NC, 27101, USA.
| | - John Olson
- Wake Forest Department of Biomolecular Imaging, Medical Center Blvd, Winston-Salem, NC, 27157, USA.
| | - Maja Herco
- Wake Forest Institute for Regenerative Medicine, 391 Technology Way, Winston-Salem, NC, 27101, USA.
| | - Josh Tan
- Wake Forest Department of Biomolecular Imaging, Medical Center Blvd, Winston-Salem, NC, 27157, USA.
| | - Karl-Erik Andersson
- Wake Forest Institute for Regenerative Medicine, 391 Technology Way, Winston-Salem, NC, 27101, USA.
| | - George Christ
- Wake Forest Institute for Regenerative Medicine, 391 Technology Way, Winston-Salem, NC, 27101, USA. .,Departments of Biomedical Engineering and Orthopaedic Surgery, and Laboratory of Regenerative Therapeutics, University of Virginia, 415 Lane Road, Charlottesville, VA, 22908, USA.
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Nakagawa S, Oishi A, Ogino K, Makiyama Y, Kurimoto M, Yoshimura N. Association of retinal vessel attenuation with visual function in eyes with retinitis pigmentosa. Clin Ophthalmol 2014; 8:1487-93. [PMID: 25143709 PMCID: PMC4136985 DOI: 10.2147/opth.s66326] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate the association between visual changes and retinal vessel attenuation in patients with retinitis pigmentosa (RP). Design A retrospective, longitudinal, observational cohort study. Methods We analyzed 45 eyes from 45 subjects who were followed-up for ≥3 years at our clinic. Using the computer-based Interactive Vessel Analysis program, central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) were determined. Age- and sex-matched controls from normal subjects were selected from our archived fundus photograph library. Visual acuity, visual field area (Goldmann perimetry, V4e white test light), mean deviation (Humphrey perimetry, central 10-2 program), and central macular thickness (optical coherence tomography) were analyzed for correlations with CRAE and CRVE. Results Both CRAE and CRVE were significantly decreased in RP eyes (94.9±13.5 μm and 155.6±20.0 μm, respectively) compared with control eyes (138.1±14.7 μm and 215.0±20.4 μm, respectively, both P<0.001). After 3 years of follow-up, visual field area was associated with both CRAE (r=0.584, P<0.01) and CRVE (r=0.500, P=0.008). A significant association was also observed between mean deviation and CRAE (r=0.298, P=0.047). In eyes with RP, a narrower vessel caliber at baseline was associated with a larger decline in visual acuity over the 3-year follow-up interval (CRAE: r=−0.344, P=0.021; CRVE: r=−0.314, P=0.035). Conclusion Retinal vessel caliber is associated with some visual functions in patients with RP.
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Affiliation(s)
- Satoko Nakagawa
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Akio Oishi
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Ken Ogino
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yukiko Makiyama
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Masafumi Kurimoto
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Nagahisa Yoshimura
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
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Duong TQ. Magnetic resonance imaging of the retina: from mice to men. Magn Reson Med 2014; 71:1526-30. [PMID: 23716429 PMCID: PMC3783549 DOI: 10.1002/mrm.24797] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 03/25/2013] [Accepted: 04/15/2013] [Indexed: 11/09/2022]
Abstract
This mini-review provides an overview of magnetic resonance imaging (MRI) applications to study rodent, cat, non-human primate, and human retinas. These techniques include T(1) - and T(2) -weighted anatomical, diffusion, blood flow, blood volume, blood-oxygenation level dependent, manganese-enhanced, physiological, and functional MRI. Applications to study the retinas in diabetic retinopathy, glaucoma, and retinal degeneration are also reviewed. MRI offers some unique advantages compared with existing imaging techniques and has the potential to further our understanding of physiology and function in healthy and diseased retinas.
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Affiliation(s)
- Timothy Q Duong
- South Texas Veterans Health Care System, Research Imaging Institute, Department of Ophthalmology, University of Texas Health Science Center, San Antonio, Texas, USA
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24
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Emeterio Nateras OS, Harrison JM, Muir ER, Zhang Y, Peng Q, Chalfin S, Gutierrez JE, Johnson DA, Kiel JW, Duong TQ. Choroidal blood flow decreases with age: an MRI study. Curr Eye Res 2014; 39:1059-67. [PMID: 24655028 DOI: 10.3109/02713683.2014.892997] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To verify that a visual fixation protocol with cued eye blinks achieves sufficient stability for magnetic resonance imaging (MRI) blood-flow measurements and to determine if choroidal blood flow (ChBF) changes with age in humans. METHODS The visual fixation stability achievable during an MRI scan was measured in five normal subjects using an eye-tracking camera outside the MRI scanner. Subjects were instructed to blink immediately after recorded MRI sound cues but to otherwise maintain stable visual fixation on a small target. Using this fixation protocol, ChBF was measured with MRI using a 3 Tesla clinical scanner in 17 normal subjects (24-68 years old). Arterial and intraocular pressures (IOP) were measured to calculate perfusion pressure in the same subjects. RESULTS The mean temporal fluctuations (standard deviation) of the horizontal and vertical displacements were 29 ± 9 μm and 38 ± 11 μm within individual fixation periods, and 50 ± 34 μm and 48 ± 19 μm across different fixation periods. The absolute displacements were 67 ± 31 μm and 81 ± 26 μm. ChBF was negatively correlated with age (R = -0.7, p = 0.003), declining 2.7 ml/100 ml/min per year. There were no significant correlations between ChBF versus perfusion pressure, arterial pressure, or IOP. There were also no significant correlations between age versus perfusion pressure, arterial pressure, or IOP. Multiple regression analysis indicated that age was the only measured independent variable that was significantly correlated with ChBF (p = 0.03). CONCLUSIONS The visual fixation protocol with cued eye blinks was effective in achieving sufficient stability for MRI measurements. ChBF had a significant negative correlation with age.
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Harris NR, Watts MN, Leskova W. Intravital video microscopy measurements of retinal blood flow in mice. J Vis Exp 2013:51110. [PMID: 24429840 DOI: 10.3791/51110] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Alterations in retinal blood flow can contribute to, or be a consequence of, ocular disease and visual dysfunction. Therefore, quantitation of altered perfusion can aid research into the mechanisms of retinal pathologies. Intravital video microscopy of fluorescent tracers can be used to measure vascular diameters and bloodstream velocities of the retinal vasculature, specifically the arterioles branching from the central retinal artery and of the venules leading into the central retinal vein. Blood flow rates can be calculated from the diameters and velocities, with the summation of arteriolar flow, and separately venular flow, providing values of total retinal blood flow. This paper and associated video describe the methods for applying this technique to mice, which includes 1) the preparation of the eye for intravital microscopy of the anesthetized animal, 2) the intravenous infusion of fluorescent microspheres to measure bloodstream velocity, 3) the intravenous infusion of a high molecular weight fluorescent dextran, to aid the microscopic visualization of the retinal microvasculature, 4) the use of a digital microscope camera to obtain videos of the perfused retina, and 5) the use of image processing software to analyze the video. The same techniques can be used for measuring retinal blood flow rates in rats.
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Affiliation(s)
- Norman R Harris
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center
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Shih YYI, De La Garza BH, Huang S, Li G, Wang L, Duong TQ. Comparison of retinal and cerebral blood flow between continuous arterial spin labeling MRI and fluorescent microsphere techniques. J Magn Reson Imaging 2013; 40:609-15. [PMID: 24227681 DOI: 10.1002/jmri.24407] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 08/05/2013] [Indexed: 01/09/2023] Open
Abstract
PURPOSE To compare basal retinal and cerebral blood flow (BF) values using continuous arterial spin labeling (CASL) MRI and fluorescent microspheres. MATERIALS AND METHODS A total of 41 animals were used. BF was measured using an established microsphere technique (a mixture of 2.5 million 8 μm green and 0.5 million 10 μm blue fluorescent microspheres) and CASL MRI blood flow measurement in the rat retina and brain at 7 Tesla (T) and 11.7T, respectively. RESULTS Retinal BF by MRI was 1.18 ± 0.57 mL/g/min and choroidal BF was 8.14 ± 1.8 mL/g/min (n = 6). Microsphere retinal BF was 9.12 ± 2.8 μL/min per tissue and choroidal BF was 73.38 ± 44 μL/min per tissue (n = 18), corresponding to a retinal BF value of 1.22 ± 0.36 mL/g/min by means of a wet weight conversion. The wet-weight of the choroid could not be determined. To corroborate our findings, cerebral BF (CBF) by MRI was also analyzed. In the cerebral cortices, CBF was 0.91 ± 0.29 mL/g/min (n = 14) by CASL MRI and 1.09 ± 0.37 mL/g/min (n = 6) by microspheres. There were no significant differences found between MRI and microsphere blood flow in the retina and brain. CONCLUSION BF values in the rat retina and cerebral cortex by MRI are in agreement with those obtained by the microsphere technique.
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Affiliation(s)
- Yen-Yu I Shih
- Departments of Neurology, Biomedical Research Imaging Center, and Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina, USA; Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
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Li G, Kiel JW, Cardenas DP, De La Garza BH, Duong TQ. Postocclusive reactive hyperemia occurs in the rat retinal circulation but not in the choroid. Invest Ophthalmol Vis Sci 2013; 54:5123-31. [PMID: 23821190 DOI: 10.1167/iovs.13-12404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We tested the hypothesis that retinal blood flow has a postocclusive reactive hyperemia response modulated by occlusion duration and metabolic activity, and that choroidal blood flow does not. METHODS Anesthetized and paralyzed rats (n = 34) were studied. Retinal and choroidal blood flow was measured by laser speckle imaging and laser Doppler flowmetry, respectively. Blood oxygenation level-dependent functional magnetic resonance imaging (BOLD fMRI) was used to measure changes in relative blood oxygenation of the retinal and choroidal circulations. Transient carotid occlusion was elicited with a hydraulic occluder on the common carotid artery. Several occlusion durations were tested during dark, constant light, and flicker light conditions to modulate metabolic demand. The hyperemia response magnitude was quantified by integrating the area above the blood flow baseline for the 3 minutes after release of the occlusion. RESULTS Systemic arterial pressure (108.2 ± 1.4 mm Hg) was unaffected by the carotid occlusions, and was similar among animals and conditions. Retinal blood flow had a reactive hyperemia, but choroidal blood flow did not (e.g., 14 ± 2%.sec versus 0.5 ± 4%. sec after 60-second occlusion). The hyperemia magnitude increased as a nonlinear function of occlusion duration and reached a plateau at occlusion durations < 60 second. The hyperemia magnitude was not altered by different lighting conditions at occlusion durations of 15 and 60 seconds. BOLD fMRI results were similar to the laser-based blood flow measurements. CONCLUSIONS The results indicate that metabolic local control has a negligible role in choroidal blood flow regulation and only partially accounts for the blood flow behavior in the retinal circulation.
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Affiliation(s)
- Guang Li
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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Park SH, Wang DJJ, Duong TQ. Balanced steady state free precession for arterial spin labeling MRI: Initial experience for blood flow mapping in human brain, retina, and kidney. Magn Reson Imaging 2013; 31:1044-50. [PMID: 23664680 DOI: 10.1016/j.mri.2013.03.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 03/26/2013] [Accepted: 03/26/2013] [Indexed: 11/26/2022]
Abstract
We implemented pseudo-continuous ASL (pCASL) with 2D and 3D balanced steady state free precession (bSSFP) readout for mapping blood flow in the human brain, retina, and kidney, free of distortion and signal dropout, which are typically observed in the most commonly used echo-planar imaging acquisition. High resolution functional brain imaging in the human visual cortex was feasible with 3D bSSFP pCASL. Blood flow of the human retina could be imaged with pCASL and bSSFP in conjunction with a phase cycling approach to suppress the banding artifacts associated with bSSFP. Furthermore, bSSFP based pCASL enabled us to map renal blood flow within a single breath hold. Control and test-retest experiments suggested that the measured blood flow values in retina and kidney were reliable. Because there is no specific imaging tool for mapping human retina blood flow and the standard contrast agent technique for mapping renal blood flow can cause problems for patients with kidney dysfunction, bSSFP based pCASL may provide a useful tool for the diagnosis of retinal and renal diseases and can complement existing imaging techniques.
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Affiliation(s)
- Sung-Hong Park
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
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29
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Li G, Shih YYI, Kiel JW, De La Garza BH, Du F, Duong TQ. MRI study of cerebral, retinal and choroidal blood flow responses to acute hypertension. Exp Eye Res 2013; 112:118-24. [PMID: 23623996 DOI: 10.1016/j.exer.2013.04.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 04/03/2013] [Accepted: 04/05/2013] [Indexed: 11/17/2022]
Abstract
Blood flow (BF) in many tissues is stable during significant fluctuations in systemic arterial blood pressure or perfusion pressure under normal conditions. The regulatory mechanisms responsible for this non-passive BF behavior include both local and neural control mechanisms. This study evaluated cerebral BF (CBF), retinal BF (RBF) and choroidal BF (ChBF) responses to acute blood pressure increases in rats using magnetic resonance imaging (MRI). A transient increase in blood pressure inside the MRI scanner was achieved by mechanically inflating a balloon catheter to occlude the descending aorta near the diaphragm. We verified the rat model of mechanical occlusion and MRI approach by first measuring blood-flow regulatory responses to changing BP in the brain under normoxia and hypercapnia where the phenomenon is well documented. Retinal and choroidal blood-flow responses to transient increased arterial pressure were then investigated. In response to an acute increase in blood pressure, RBF exhibited autoregulatory behavior and ChBF exhibited baroregulation similar to that seen in the cerebral circulation. This approach may prove useful to investigate retinal and choroidal vascular dysregulation in rat models of retinal diseases with suspected vascular etiology.
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Affiliation(s)
- Guang Li
- Research Imaging Institute, University of Texas Health Science Center, USA
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30
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Zhang Y, Harrison JM, Nateras OSE, Chalfin S, Duong TQ. Decreased retinal-choroidal blood flow in retinitis pigmentosa as measured by MRI. Doc Ophthalmol 2013; 126:187-97. [PMID: 23408312 DOI: 10.1007/s10633-013-9374-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 01/28/2013] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate retinal and choroidal blood flow (BF) using high-resolution magnetic resonance imaging (MRI) as well as visual function measured by the electroretinogram (ERG) in patients with retinitis pigmentosa (RP). METHODS MRI studies were performed in 6 RP patients (29-67 years) and 5 healthy volunteers (29-64 years) on a 3-Tesla scanner with a custom-made surface coil. Quantitative BF was measured using the pseudo-continuous arterial spin-labeling technique at 0.5 × 0.8 × 6.0 mm. Full-field ERGs of all patients were recorded. Amplitudes and implicit times of standard ERGs were analyzed. RESULTS Basal BF in the posterior retinal-choroid was 142 ± 16 ml/100ml/min (or 1.14 ± 0.13 μl/mm(2)/min) in the control group and was 70 ±19 ml/100ml/min (or 0.56 ± 0.15 μl/mm(2)/min) in the RP group. Retinal-choroidal BF was significantly reduced by 52 ± 8 % in RP patients compared to controls (P<0.05). ERG a- and b-wave amplitudes of RP patients were reduced, and b-wave implicit times were delayed. There were statistically significant correlations between a-wave amplitude and BF value (r=0.9, P<0.05) but not between b-wave amplitude and BF value (r =0.7, P=0.2). CONCLUSIONS This study demonstrates a novel non-invasive MRI approach to measure quantitative retinal and choroidal BF in RP patients. We found that retinal-choroidal BF was markedly reduced and significantly correlated with reduced amplitudes of the a-wave of the standard combined ERG.
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Affiliation(s)
- Yi Zhang
- Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA
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31
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Fanea L, Fagan AJ. Review: magnetic resonance imaging techniques in ophthalmology. Mol Vis 2012; 18:2538-60. [PMID: 23112569 PMCID: PMC3482169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 10/10/2012] [Indexed: 11/19/2022] Open
Abstract
Imaging the eye with magnetic resonance imaging (MRI) has proved difficult due to the eye's propensity to move involuntarily over typical imaging timescales, obscuring the fine structure in the eye due to the resulting motion artifacts. However, advances in MRI technology help to mitigate such drawbacks, enabling the acquisition of high spatiotemporal resolution images with a variety of contrast mechanisms. This review aims to classify the MRI techniques used to date in clinical and preclinical ophthalmologic studies, describing the qualitative and quantitative information that may be extracted and how this may inform on ocular pathophysiology.
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Affiliation(s)
- Laura Fanea
- Department of Biomedical Physics, Physics Faculty, Babes-Bolyai University, Cluj-Napoca, Romania,Department of Radiology, Cluj County Emergency Hospital, Cluj-Napoca, Romania
| | - Andrew J. Fagan
- Centre for Advanced Medical Imaging, St. James’s Hospital Dublin / University of Dublin Trinity College, Ireland
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