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Deng S, Huang S, Yang A, Muir ER. Imaging ocular water inflow in the mouse with deuterium oxide MRI. Magn Reson Imaging 2023; 101:47-53. [PMID: 36965834 PMCID: PMC11104035 DOI: 10.1016/j.mri.2023.03.017] [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: 01/31/2023] [Accepted: 03/21/2023] [Indexed: 03/27/2023]
Abstract
Abnormal intraocular fluid flow or clearance is involved with a variety of eye diseases such as glaucoma and diabetic retinopathy, but measurement of water exchange dynamics in the vitreous and aqueous remain challenging. 2H MRI can be used to image deuterium oxide (D₂O) as a tracer, but the signal-to-noise ratio for deuterium is low due to its low concentration, which has hampered its application to imaging the eye. To overcome this challenge, we investigated the feasibility of direct D2O MRI to measure water dynamics in the mouse eye. The balanced steady-state free precession (bSSFP) sequence provided substantially higher signal-to-noise ratio for imaging D2O in fluid compared to standard gradient echo and spin echo sequences. bSSFP allowed dynamic imaging of intraocular water inflow in the mouse with 41 s temporal resolution. The inflow rate in the vitreous was found to be faster than in the aqueous. These studies demonstrate the feasibility of in vivo imaging of water inflow dynamics into the both the vitreous and aqueous in mice, which could be useful in studies of abnormal fluid exchange in rodent models of eye disease.
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Affiliation(s)
- Shengwen Deng
- Department of Radiology, University Hospitals Cleveland Medical Center and Case Western Reserve University, Cleveland, OH, United States; Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States
| | - Shiliang Huang
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States
| | - Alivia Yang
- Department of Radiology, School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Eric R Muir
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States; Department of Radiology, School of Medicine, Stony Brook University, Stony Brook, NY, United States.
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2
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Niendorf T, Beenakker JWM, Langner S, Erb-Eigner K, Bach Cuadra M, Beller E, Millward JM, Niendorf TM, Stachs O. Ophthalmic Magnetic Resonance Imaging: Where Are We (Heading To)? Curr Eye Res 2021; 46:1251-1270. [PMID: 33535828 DOI: 10.1080/02713683.2021.1874021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Magnetic resonance imaging of the eye and orbit (MReye) is a cross-domain research field, combining (bio)physics, (bio)engineering, physiology, data sciences and ophthalmology. A growing number of reports document technical innovations of MReye and promote their application in preclinical research and clinical science. Realizing the progress and promises, this review outlines current trends in MReye. Examples of MReye strategies and their clinical relevance are demonstrated. Frontier applications in ocular oncology, refractive surgery, ocular muscle disorders and orbital inflammation are presented and their implications for explorations into ophthalmic diseases are provided. Substantial progress in anatomically detailed, high-spatial resolution MReye of the eye, orbit and optic nerve is demonstrated. Recent developments in MReye of ocular tumors are explored, and its value for personalized eye models derived from machine learning in the treatment planning of uveal melanoma and evaluation of retinoblastoma is highlighted. The potential of MReye for monitoring drug distribution and for improving treatment management and the assessment of individual responses is discussed. To open a window into the eye and into (patho)physiological processes that in the past have been largely inaccessible, advances in MReye at ultrahigh magnetic field strengths are discussed. A concluding section ventures a glance beyond the horizon and explores future directions of MReye across multiple scales, including in vivo electrolyte mapping of sodium and other nuclei. This review underscores the need for the (bio)medical imaging and ophthalmic communities to expand efforts to find solutions to the remaining unsolved problems and technical obstacles of MReye, with the objective to transfer methodological advancements driven by MR physics into genuine clinical value.
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Affiliation(s)
- Thoralf Niendorf
- MRI.TOOLS GmbH, Berlin, Germany.,Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Jan-Willem M Beenakker
- Department of Ophthalmology and Department of Radiology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Sönke Langner
- Institute of Diagnostic and Interventional Radiology, Pediatric Radiology and Neuroradiology, Rostock University Medical Center, Rostock, Germany
| | - Katharina Erb-Eigner
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität Zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Meritxell Bach Cuadra
- Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.,Department of Radiology, Lausanne University and University Hospital, Lausanne, Switzerland
| | - Ebba Beller
- Institute of Diagnostic and Interventional Radiology, Pediatric Radiology and Neuroradiology, Rostock University Medical Center, Rostock, Germany
| | - Jason M Millward
- Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | | | - Oliver Stachs
- Department Life, Light & Matter, University Rostock, Rostock, Germany.,Department of Ophthalmology, Rostock University Medical Center, Rostock, Germany
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3
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Tecilazich F, Phan TA, Simeoni F, Scotti GM, Dagher Z, Lorenzi M. Patrolling Monocytes Are Recruited and Activated by Diabetes to Protect Retinal Microvessels. Diabetes 2020; 69:2709-2719. [PMID: 32907815 PMCID: PMC7679768 DOI: 10.2337/db19-1043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 08/28/2020] [Indexed: 11/13/2022]
Abstract
In diabetes there is a long latency between the onset of hyperglycemia and the appearance of structural microangiopathy. Because Ly6Clow patrolling monocytes (PMo) behave as housekeepers of the vasculature, we tested whether PMo protect microvessels against diabetes. We found that in wild-type mice, diabetes reduced PMo in the general circulation but increased by fourfold the absolute number of PMo adherent to retinal vessels (leukostasis). Conversely, in diabetic NR4A1-/- mice, a model of absence of PMo, there was no increase in leukostasis, and at 6 months of diabetes, the number of retinal acellular capillaries almost doubled compared with diabetic wild-type mice. Circulating PMo showed gene expression changes indicative of enhanced migratory, vasculoprotective, and housekeeping activities, as well as profound suppression of genes related to inflammation and apoptosis. Promigratory CXCR4 was no longer upregulated at longer duration when retinal acellular capillaries begin to increase. Thus, after a short diabetes duration, PMo are the cells preferentially recruited to the retinal vessels and protect vessels from diabetic damage. These observations support the need for reinterpretation of the functional meaning of leukostasis in diabetes and document within the natural history of diabetic retinopathy processes of protection and repair that can provide novel paradigms for prevention.
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Affiliation(s)
- Francesco Tecilazich
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA
- Department of Ophthalmology, Harvard Medical School, Boston, MA
- Istituto di Ricovero e Cura a Carattere Scientifico Burlo Garofalo, University of Trieste, Trieste, Italy
| | - Toan A Phan
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA
| | - Fabio Simeoni
- Center for Translational Genomics and Bioinformatics, Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele, Milan, Italy
| | - Giulia Maria Scotti
- Center for Translational Genomics and Bioinformatics, Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele, Milan, Italy
| | - Zeina Dagher
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA
- Department of Ophthalmology, Harvard Medical School, Boston, MA
| | - Mara Lorenzi
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, MA
- Department of Ophthalmology, Harvard Medical School, Boston, MA
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4
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Castro-Balado A, Mondelo-García C, González-Barcia M, Zarra-Ferro I, Otero-Espinar FJ, Ruibal-Morell Á, Aguiar-Fernández P, Fernández-Ferreiro A. Ocular Biodistribution Studies using Molecular Imaging. Pharmaceutics 2019; 11:pharmaceutics11050237. [PMID: 31100961 PMCID: PMC6572242 DOI: 10.3390/pharmaceutics11050237] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 05/05/2019] [Accepted: 05/07/2019] [Indexed: 02/07/2023] Open
Abstract
Classical methodologies used in ocular pharmacokinetics studies have difficulties to obtain information about topical and intraocular distribution and clearance of drugs and formulations. This is associated with multiple factors related to ophthalmic physiology, as well as the complexity and invasiveness intrinsic to the sampling. Molecular imaging is a new diagnostic discipline for in vivo imaging, which is emerging and spreading rapidly. Recent developments in molecular imaging techniques, such as positron emission tomography (PET), single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI), allow obtaining reliable pharmacokinetic data, which can be translated into improving the permanence of the ophthalmic drugs in its action site, leading to dosage optimisation. They can be used to study either topical or intraocular administration. With these techniques it is possible to obtain real-time visualisation, localisation, characterisation and quantification of the compounds after their administration, all in a reliable, safe and non-invasive way. None of these novel techniques presents simultaneously high sensitivity and specificity, but it is possible to study biological procedures with the information provided when the techniques are combined. With the results obtained, it is possible to assume that molecular imaging techniques are postulated as a resource with great potential for the research and development of new drugs and ophthalmic delivery systems.
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Affiliation(s)
- Ana Castro-Balado
- Pharmacy Department, University Hospital of Santiago de Compostela (SERGAS), 15706 Santiago de Compostela, Spain.
- Pharmacology Group, Health Research Institute Santiago Compostela (IDIS), 15706 Santiago de Compostela, Spain.
| | - Cristina Mondelo-García
- Pharmacy Department, University Hospital of Santiago de Compostela (SERGAS), 15706 Santiago de Compostela, Spain.
- Pharmacology Group, Health Research Institute Santiago Compostela (IDIS), 15706 Santiago de Compostela, Spain.
| | - Miguel González-Barcia
- Pharmacy Department, University Hospital of Santiago de Compostela (SERGAS), 15706 Santiago de Compostela, Spain.
- Pharmacology Group, Health Research Institute Santiago Compostela (IDIS), 15706 Santiago de Compostela, Spain.
| | - Irene Zarra-Ferro
- Pharmacy Department, University Hospital of Santiago de Compostela (SERGAS), 15706 Santiago de Compostela, Spain.
- Pharmacology Group, Health Research Institute Santiago Compostela (IDIS), 15706 Santiago de Compostela, Spain.
| | - Francisco J Otero-Espinar
- Department of Pharmacology, Pharmacy and Pharmaceutical Technology and Industrial Pharmacy Institute, Faculty of Pharmacy, University of Santiago de Compostela (USC), 15706 Santiago de Compostela, Spain.
| | - Álvaro Ruibal-Morell
- Nuclear Medicine Department, University Hospital of Santiago de Compostela (SERGAS), University of Santiago de Compostela, 15706 Santiago de Compostela, Spain.
- Molecular Imaging Group. Health Research Institute Santiago Compostela (IDIS), 15706 Santiago de Compostela, Spain.
| | - Pablo Aguiar-Fernández
- Nuclear Medicine Department, University Hospital of Santiago de Compostela (SERGAS), University of Santiago de Compostela, 15706 Santiago de Compostela, Spain.
- Molecular Imaging Group. Health Research Institute Santiago Compostela (IDIS), 15706 Santiago de Compostela, Spain.
| | - Anxo Fernández-Ferreiro
- Pharmacy Department, University Hospital of Santiago de Compostela (SERGAS), 15706 Santiago de Compostela, Spain.
- Pharmacology Group, Health Research Institute Santiago Compostela (IDIS), 15706 Santiago de Compostela, Spain.
- Department of Pharmacology, Pharmacy and Pharmaceutical Technology and Industrial Pharmacy Institute, Faculty of Pharmacy, University of Santiago de Compostela (USC), 15706 Santiago de Compostela, Spain.
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5
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Crosbie DE, Keaney J, Tam LCS, Daniel Stamer W, Campbell M, Humphries P. Age-related changes in eye morphology and aqueous humor dynamics in DBA/2J mice using contrast-enhanced ocular MRI. Magn Reson Imaging 2019; 59:10-16. [PMID: 30660703 DOI: 10.1016/j.mri.2019.01.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/15/2019] [Accepted: 01/16/2019] [Indexed: 10/27/2022]
Abstract
PURPOSE Here, we are testing the hypothesis that dynamic contrast enhanced MRI (DCE-MRI) is a useful approach for non-invasively evaluating age-related changes in aqueous humor outflow and its contribution to elevated intraocular pressure in the DBA/2J model of pigmentary glaucoma. METHODS A rodent-specific 7 T MRI was used to assess eye anatomy (anterior chamber (AC) and vitreous body (VB) morphology, eye size, lens size) and aqueous humor dynamics (via intravenous administration of Gd-DTPA and Gd-BOPTA contrast agents) in C57BL/6 and DBA/2J mice at 3 and 9 months of age. RESULTS Gd-MRI was used to demonstrate an anterior solute pathway into the mouse AC. Topical latanoprost treatment in C57BL/6J mice reduced Gd-BOPTA accumulation in the AC. Age-related increases in AC area, AC depth and eye size were observed in DBA/2J mice compared to C57BL/6J mice. The rate of Gd-DTPA accumulation and peak Gd-DTPA intensity was lowest in 9-month old DBA/2J mice compared to 3-month old DBA/2J mice and C57BL/6J mice at both ages. Leakage of Gd-DTPA posteriorly into the VB was also observed in 9-month old DBA/2J mice. CONCLUSIONS These studies support the idea that age-related changes in aqueous humor outflow contribute to elevated intraocular pressure (IOP) in the DBA/2J model of pigmentary glaucoma. Gd-MRI is a valuable tool for better understanding of mechanisms and dynamics of aqueous humor circulation in normal and glaucomatous mouse eyes or following topical administration of medicines to reduce IOP.
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Affiliation(s)
- Darragh E Crosbie
- Ocular Genetics, Unit, Smurfit Institute of Genetics, Trinity College Dublin, Lincoln Place Gate, Dublin 2, Ireland
| | - James Keaney
- Ocular Genetics, Unit, Smurfit Institute of Genetics, Trinity College Dublin, Lincoln Place Gate, Dublin 2, Ireland; Ross University School of Veterinary Medicine, P. O. Box 334, Basseterre, St. Kitts, Saint Kitts and Nevis
| | - Lawrence C S Tam
- Ocular Genetics, Unit, Smurfit Institute of Genetics, Trinity College Dublin, Lincoln Place Gate, Dublin 2, Ireland
| | - W Daniel Stamer
- Departments of Ophthalmology and Biomedical Engineering, Duke University, Durham, NC, USA
| | - Matthew Campbell
- Ocular Genetics, Unit, Smurfit Institute of Genetics, Trinity College Dublin, Lincoln Place Gate, Dublin 2, Ireland.
| | - Peter Humphries
- Ocular Genetics, Unit, Smurfit Institute of Genetics, Trinity College Dublin, Lincoln Place Gate, Dublin 2, Ireland.
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6
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Li YM, Zhou HM, Xu XY, Shi HS. Research Progress in MRI of the Visual Pathway in Diabetic Retinopathy. Curr Med Sci 2018; 38:968-975. [DOI: 10.1007/s11596-018-1971-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 10/10/2018] [Indexed: 12/17/2022]
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7
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Tsiapa I, Tsilimbaris MK, Papadaki E, Bouziotis P, Pallikaris IG, Karantanas AH, Maris TG. High resolution MR eye protocol optimization: Comparison between 3D-CISS, 3D-PSIF and 3D-VIBE sequences. Phys Med 2015; 31:774-80. [DOI: 10.1016/j.ejmp.2015.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 03/03/2015] [Accepted: 03/19/2015] [Indexed: 10/23/2022] Open
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8
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Berkowitz BA, Bissig D, Roberts R. MRI of rod cell compartment-specific function in disease and treatment in vivo. Prog Retin Eye Res 2015; 51:90-106. [PMID: 26344734 DOI: 10.1016/j.preteyeres.2015.09.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/26/2015] [Accepted: 09/01/2015] [Indexed: 10/23/2022]
Abstract
Rod cell oxidative stress is a major pathogenic factor in retinal disease, such as diabetic retinopathy (DR) and retinitis pigmentosa (RP). Personalized, non-destructive, and targeted treatment for these diseases remains elusive since current imaging methods cannot analytically measure treatment efficacy against rod cell compartment-specific oxidative stress in vivo. Over the last decade, novel MRI-based approaches that address this technology gap have been developed. This review summarizes progress in the development of MRI since 2006 that enables earlier evaluation of the impact of disease on rod cell compartment-specific function and the efficacy of anti-oxidant treatment than is currently possible with other methods. Most of the new assays of rod cell compartment-specific function are based on endogenous contrast mechanisms, and this is expected to facilitate their translation into patients with DR and RP, and other oxidative stress-based retinal diseases.
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Affiliation(s)
- Bruce A Berkowitz
- Dept. of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA; Dept. Of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, USA.
| | - David Bissig
- Dept. of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Robin Roberts
- Dept. Of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, USA
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9
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Ho LC, Sigal IA, Jan NJ, Squires A, Tse Z, Wu EX, Kim SG, Schuman JS, Chan KC. Magic angle-enhanced MRI of fibrous microstructures in sclera and cornea with and without intraocular pressure loading. Invest Ophthalmol Vis Sci 2014; 55:5662-72. [PMID: 25103267 DOI: 10.1167/iovs.14-14561] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The structure and biomechanics of the sclera and cornea are central to several eye diseases such as glaucoma and myopia. However, their roles remain unclear, partly because of limited noninvasive techniques to assess their fibrous microstructures globally, longitudinally, and quantitatively. We hypothesized that magic angle-enhanced magnetic resonance imaging (MRI) can reveal the structural details of the corneoscleral shell and their changes upon intraocular pressure (IOP) elevation. METHODS Seven ovine eyes were extracted and fixed at IOP = 50 mm Hg to mimic ocular hypertension, and another 11 eyes were unpressurized. The sclera and cornea were scanned at different angular orientations relative to the main magnetic field inside a 9.4-Tesla MRI scanner. Relative MRI signal intensities and intrinsic transverse relaxation times (T2 and T2*) were determined to quantify the magic angle effect on the corneoscleral shells. Three loaded and eight unloaded tendon samples were scanned as controls. RESULTS At magic angle, high-resolution MRI revealed distinct scleral and corneal lamellar fibers, and light/dark bands indicative of collagen fiber crimps in the sclera and tendon. Magic angle enhancement effect was the strongest in tendon and the least strong in cornea. Loaded sclera, cornea, and tendon possessed significantly higher T2 and T2* than unloaded tissues at magic angle. CONCLUSIONS Magic angle-enhanced MRI can detect ocular fibrous microstructures without contrast agents or coatings and can reveal their MR tissue property changes with IOP loading. This technique may open up new avenues for assessment of the biomechanical and biochemical properties of ocular tissues in aging and in diseases involving the corneoscleral shell.
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Affiliation(s)
- Leon C Ho
- NeuroImaging Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Ian A Sigal
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Ning-Jiun Jan
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Alexander Squires
- Medical Robotics Lab, College of Engineering, University of Georgia, Athens, Georgia, United States
| | - Zion Tse
- Medical Robotics Lab, College of Engineering, University of Georgia, Athens, Georgia, United States
| | - Ed X Wu
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Seong-Gi Kim
- NeuroImaging Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
| | - Joel S Schuman
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Kevin C Chan
- NeuroImaging Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, United States UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
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10
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Ho LC, Conner IP, Do CW, Kim SG, Wu EX, Wollstein G, Schuman JS, Chan KC. In vivo assessment of aqueous humor dynamics upon chronic ocular hypertension and hypotensive drug treatment using gadolinium-enhanced MRI. Invest Ophthalmol Vis Sci 2014; 55:3747-57. [PMID: 24764067 DOI: 10.1167/iovs.14-14263] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE Although glaucoma treatments alter aqueous humor (AH) dynamics to lower intraocular pressure, the regulatory mechanisms of AH circulation and their contributions to the pathogenesis of ocular hypertension and glaucoma remain unclear. We hypothesized that gadolinium-enhanced magnetic resonance imaging (Gd-MRI) can visualize and assess AH dynamics upon sustained intraocular pressure elevation and pharmacologic interventions. METHODS Gadolinium contrast agent was systemically administered to adult rats to mimic soluble AH components entering the anterior chamber (AC) via blood-aqueous barrier. Dynamic Gd-MRI was applied to examine the signal enhancement in AC and vitreous body upon microbead-induced ocular hypertension and unilateral topical applications of latanoprost, timolol maleate, and brimonidine tartrate to healthy eyes. RESULTS Gadolinium signal time courses in microbead-induced hypertensive eyes possessed faster initial gadolinium uptake and higher peak signals in AC than control eyes, reflective of reduced gadolinium clearance upon microbead occlusion. Opposite trends were observed in latanoprost- and timolol-treated eyes, indicative of their respective drug actions on increased uveoscleral outflow and reduced AH production. The slowest initial gadolinium uptake but strongest peak signals were found in AC of both brimonidine-treated and untreated fellow eyes. These findings drew attention to the systemic effects of topical hypotensive drug treatment. Gadolinium leaked into the vitreous of microbead-induced hypertensive eyes and brimonidine-treated and untreated fellow eyes, suggestive of a compromise of aqueous-vitreous or blood-ocular barrier integrity. CONCLUSIONS Gadolinium-enhanced MRI allows spatiotemporal and quantitative evaluation of altered AH dynamics and ocular tissue permeability for better understanding the physiological mechanisms of ocular hypertension and the efficacy of antiglaucoma drug treatments.
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Affiliation(s)
- Leon C Ho
- NeuroImaging Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Ian P Conner
- UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Chi-Wai Do
- School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Seong-Gi Kim
- NeuroImaging Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, United States UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Center for Neuroscience Imaging Research, Institute for Basic Science, Department of Biological Science, Sungkyunkwan University, Suwon, Korea Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
| | - Ed X Wu
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Gadi Wollstein
- UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Joel S Schuman
- UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Kevin C Chan
- NeuroImaging Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, United States UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, Pennsylvania, United States Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
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11
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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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12
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Ramos de Carvalho JE, Verbraak FD, Aalders MC, van Noorden CJ, Schlingemann RO. Recent advances in ophthalmic molecular imaging. Surv Ophthalmol 2013; 59:393-413. [PMID: 24529711 DOI: 10.1016/j.survophthal.2013.09.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 09/23/2013] [Accepted: 09/24/2013] [Indexed: 12/30/2022]
Abstract
The aim of molecular imaging techniques is the visualization of molecular processes and functional changes in living animals and human patients before morphological changes occur at the cellular and tissue level. Ophthalmic molecular imaging is still in its infancy and has mainly been used in small animals for pre-clinical research. The goal of most of these pre-clinical studies is their translation into ophthalmic molecular imaging techniques in clinical care. We discuss various molecular imaging techniques and their applications in ophthalmology.
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Affiliation(s)
- J Emanuel Ramos de Carvalho
- Ocular Angiogenesis Group, Departments of Ophthalmology and Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Frank D Verbraak
- Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Maurice C Aalders
- Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Cornelis J van Noorden
- Ocular Angiogenesis Group, Departments of Ophthalmology and Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Reinier O Schlingemann
- Ocular Angiogenesis Group, Departments of Ophthalmology and Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Netherlands Institute for Neuroscience, Royal Academy of Sciences, Amsterdam, The Netherlands.
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Chen J, Chiang CW, Zhang H, Song SK. Cell swelling contributes to thickening of low-dose N-methyl-D-aspartate-induced retinal edema. Invest Ophthalmol Vis Sci 2012; 53:2777-85. [PMID: 22467578 DOI: 10.1167/iovs.11-8827] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
PURPOSE The contribution of cell swelling versus vascular leakage in retinal edema remains largely undefined. The objective of this study was to use in vivo magnetic resonance imaging (MRI) to assess retinal cell swelling in the edematous mouse retina. METHODS Inner retinal edema was induced by intravitreal injection of 2.5 nmol N-methyl-D-aspartate (NMDA). To assess retinal cell swelling, diffusion MRI was performed at baseline, 3-hours, 1 day, 3 days, and 7 days (n ≥ 5 at each time point) after NMDA injection. To detect retinal vascular leakage, gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) enhanced MRI was performed at baseline, 3 hours and 1 day (n = 5 for each group) after NMDA injection. Upon the completion of MRI, mouse eyes were enucleated, cryosectioned, and stained for assessing retinal layer thickness and cell death. RESULTS Inner retinal cell swelling was hyperintense on diffusion-weighted images at 3 hours and 1 day after NMDA injection. The thickened inner retina was also seen in anatomic MRI and histology. Quantitatively, inner retinal apparent diffusion coefficient (ADC) decreased approximately 20% at 3 hours and 1 day after NMDA injection (P < 0.05 compared with baseline), suggesting cell swelling. Systematic injection of paramagnetic Gd-DTPA did not alter vitreous longitudinal relaxation time (T1) at baseline or at 3 hours after NMDA injection. In contrast, vitreous T1 in mice decreased 16 ± 6% (P < 0.05), reflecting retinal vascular leakage at 1 day after NMDA injection. CONCLUSIONS Noninvasive diffusion MRI was performed to detect retinal cell swelling in vivo. Our results demonstrated that retinal cell swelling could directly lead to retinal thickening independent of vascular leakage.
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Affiliation(s)
- Junjie Chen
- Department of Medicine, Washington University, St. Louis, Missouri 63110, USA
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Li SK, Hao J, Liu H, Lee JH. MRI study of subconjunctival and intravitreal injections. J Pharm Sci 2012; 101:2353-63. [PMID: 22473517 DOI: 10.1002/jps.23127] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 02/21/2012] [Accepted: 03/01/2012] [Indexed: 11/06/2022]
Abstract
Previous magnetic resonance imaging (MRI) studies to investigate the routes of penetration and barriers in ocular delivery have provided insights into the mechanisms of transscleral and intraocular drug delivery. The objective of the present study was to investigate ocular penetration and clearance after subconjunctival and intravitreal injections using a contrast agent at concentrations higher than those in the previous studies. This high concentration approach was hypothesized to allow the visualization of the contrast agent in the eye that could not be achieved previously. Subconjunctival and intravitreal injections of contrast agent Magnevist, a model hydrophililc probe, were performed in rabbits, and the distribution and clearance of the probe after the injections were examined by MRI. After subconjunctival injection in vivo, significant contrast agent penetration into the anterior chamber was observed but not into the vitreous. A clearance pathway of the hydrophilic probe from the subconjunctival depot to the regions near the periocular fat behind the eye was found. After intravitreal injection in vivo, the contrast agent was observed in the anterior chamber, optic nerve, and tissues surrounding the eye during clearance. MRI continues to provide insights into the transport barriers and clearance pathways of hydrophilic molecules in ocular delivery.
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Affiliation(s)
- S Kevin Li
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, Ohio 45267, USA.
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15
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Maile LA, Gollahon K, Wai C, Byfield G, Hartnett ME, Clemmons D. Disruption of the association of integrin-associated protein (IAP) with tyrosine phosphatase non-receptor type substrate-1 (SHPS)-1 inhibits pathophysiological changes in retinal endothelial function in a rat model of diabetes. Diabetologia 2012; 55:835-44. [PMID: 22193512 PMCID: PMC3725181 DOI: 10.1007/s00125-011-2416-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 11/24/2011] [Indexed: 12/28/2022]
Abstract
AIMS/HYPOTHESIS We have previously shown that the association of integrin-associated protein (IAP) with tyrosine phosphatase non-receptor type substrate-1 (SHPS-1) regulates the response of cells, including osteoclasts, osteoblasts, smooth muscle and retinal endothelial cells, to IGF-I. Here we sought to: (1) determine whether the regulation of IGF-I responsiveness by the association of IAP with SHPS-1 is a generalised response of endothelial cells; (2) identify the mechanism by which this association contributes to changes in endothelial cell responses to IGF-I; and (3) determine whether inhibition of this association alters pathophysiological changes occurring in vivo. METHODS Endothelial cells were maintained in 5 mmol/l glucose and at hyperglycaemic levels, and exposed to an anti-IAP antibody that disrupts the association between IAP and SHPS-1. A rodent model of diabetes with endothelial cell dysfunction was used to investigate the role of the association of IAP with SHPS-1 in endothelial cell function in vivo. RESULTS Endothelial cells maintained in 5 mmol/l glucose showed constitutive cleavage of the extracellular domain of IAP (which contains the SHPS-1 binding site), with no association between IAP and SHPS-1 being detected. In contrast, hyperglycaemia inhibited IAP cleavage, allowing IAP to associate with SHPS-1 and IGF-I to stimulate SHPS-1 tyrosine phosphorylation. Exposure to the anti-IAP antibody inhibited IGF-I-stimulated tube formation and increased permeability. In the rodent model, basal IAP-SHPS-1 association was not detected in retinal extracts from normal rats, but was fully restored in rats with diabetes. The anti-IAP antibody inhibited the association of IAP with SHPS-1, and reduced retinal vascular permeability and leucocyte adherence to levels similar to those in non-diabetic rats. The antibody also significantly inhibited the aberrant neovascularisation induced by hypoxia. CONCLUSIONS/INTERPRETATION Our results demonstrate that the increased association of IAP with SHPS-1 contributes to the pathophysiological changes in the endothelium that are induced by hyperglycaemia and hypoxia.
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MESH Headings
- Animals
- Animals, Newborn
- CD47 Antigen/chemistry
- CD47 Antigen/metabolism
- Capillary Permeability
- Cell Adhesion
- Cells, Cultured
- Diabetic Retinopathy/metabolism
- Diabetic Retinopathy/pathology
- Diabetic Retinopathy/physiopathology
- Disease Models, Animal
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/pathology
- Endothelium, Vascular/physiopathology
- HL-60 Cells
- Human Umbilical Vein Endothelial Cells/metabolism
- Humans
- Infant, Newborn
- Insulin-Like Growth Factor I/metabolism
- Leukocytes/metabolism
- Male
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- Neovascularization, Pathologic/physiopathology
- Rats
- Rats, Sprague-Dawley
- Receptors, Immunologic/metabolism
- Retina/metabolism
- Retina/pathology
- Retinal Vessels/metabolism
- Retinal Vessels/pathology
- Retinal Vessels/physiopathology
- Retinopathy of Prematurity/metabolism
- Retinopathy of Prematurity/pathology
- Retinopathy of Prematurity/physiopathology
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Affiliation(s)
- L A Maile
- Departments of Medicine and Ophthalmology, School of Medicine, University of North Carolina at Chapel Hill, NC, USA.
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16
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Berkowitz BA, Bissig D, Ye Y, Valsadia P, Kern TS, Roberts R. Evidence for diffuse central retinal edema in vivo in diabetic male Sprague Dawley rats. PLoS One 2012; 7:e29619. [PMID: 22253747 PMCID: PMC3256169 DOI: 10.1371/journal.pone.0029619] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 12/01/2011] [Indexed: 12/27/2022] Open
Abstract
Background Investigations into the mechanism of diffuse retinal edema in diabetic subjects have been limited by a lack of animal models and techniques that co-localized retinal thickness and hydration in vivo. In this study we test the hypothesis that a previously reported supernormal central retinal thickness on MRI measured in experimental diabetic retinopathy in vivo represents a persistent and diffuse edema. Methodology/Principal Findings In diabetic and age-matched control rats, and in rats experiencing dilutional hyponatremia (as a positive edema control), whole central retinal thickness, intraretinal water content and apparent diffusion coefficients (ADC, ‘water mobility’) were measured in vivo using quantitative MRI methods. Glycated hemoglobin and retinal thickness ex vivo (histology) were also measured in control and diabetic groups. In the dilutional hyponatremia model, central retinal thickness and water content were supernormal by quantitative MRI, and intraretinal water mobility profiles changed in a manner consistent with intracellular edema. Groups of diabetic (2, 3, 4, 6, and 9 mo of diabetes), and age-matched controls were then investigated with MRI and all diabetic rats showed supernormal whole central retinal thickness. In a separate study in 4 mo diabetic rats (and controls), MRI retinal thickness and water content metrics were significantly greater than normal, and ADC was subnormal in the outer retina; the increase in retinal thickness was not detected histologically on sections of fixed and dehydrated retinas from these rats. Conclusions/Significance Diabetic male Sprague Dawley rats demonstrate a persistent and diffuse retinal edema in vivo, providing, for the first time, an important model for investigating its pathogenesis and treatment. These studies also validate MRI as a powerful approach for investigating mechanisms of diabetic retinal edema in future experimental and clinical investigations.
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Affiliation(s)
- Bruce A Berkowitz
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States of America.
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17
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Shih YYI, Li G, Muir ER, De La Garza BH, Kiel JW, Duong TQ. Pharmacological MRI of the choroid and retina: blood flow and BOLD responses during nitroprusside infusion. Magn Reson Med 2011; 68:1273-8. [PMID: 22183830 DOI: 10.1002/mrm.24112] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 10/06/2011] [Accepted: 11/18/2011] [Indexed: 11/10/2022]
Abstract
Nitroprusside, a vasodilatory nitric oxide donor, is clinically used during vascular surgery and to lower blood pressure in acute hypertension. This article reports a novel application of blood flow (BF) and blood oxygenation level dependent (BOLD) MRI on an 11.7T scanner to image the rat chorioretinal BF and BOLD changes associated with graded nitroprusside infusion. At low doses (1 or 2 μg/kg/min), nitroprusside increased BF as expected but decreased BOLD signals, showing an intriguing BF-BOLD uncoupling. At high doses (3-5 μg/kg/min), nitroprusside decreased BF and markedly decreased BOLD signals. To our knowledge, this is the first pharmacological MRI application of the retina. This approach has potential to open up new avenues to study the drug-related hemodynamic functions and to evaluate the effects of novel therapeutic interventions on BOLD and BF in the normal and diseased retinas.
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Affiliation(s)
- Yen-Yu I Shih
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas 78229, USA.
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18
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Kashiwagi Y, Nodaira M, Amitani M, Murase K, Abe K. Assessment of peripheral tissue perfusion disorder in streptozotocin-induced diabetic rats using dynamic contrast-enhanced MRI. Magn Reson Imaging 2011; 30:254-60. [PMID: 22055847 DOI: 10.1016/j.mri.2011.09.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 09/01/2011] [Accepted: 09/18/2011] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess peripheral tissue perfusion disorder in streptozotocin (STZ)-induced diabetic rats by using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). MATERIALS AND METHODS A rat diabetes model was produced by intravenous injection of STZ. Diabetic rats were sustainably treated with either saline or insulin using an Alzet osmotic pump. Hind paw tissue perfusion was measured by signal intensity (SI) enhancement after gadolinium diethylenetriaminepentaacetic acid injection in DCE-MRI study and quantified using the initial area under the SI-time curve (IAUC). Peripheral tissue uptake of [(14)C]iodoantipyrine (IAP) was also determined as a marker of tissue blood flow for comparison with the IAUC value indicating tissue perfusion. RESULTS STZ caused hyperglycemia at 1 and 2 weeks after injection. Treatment with insulin significantly alleviated hyperglycemia. At 2 weeks after STZ injection, peripheral tissue perfusion was clearly reduced in the diabetic rats and its reduction was significantly improved in the insulin-treated diabetic rats. Tissue perfusion evaluated by DCE-MRI was similar to the tissue blood flow measured by [(14)C]IAP uptake. CONCLUSION Our findings demonstrated that DCE-MRI can assess peripheral tissue perfusion disorder in diabetes. DCE-MRI could be suitable for noninvasive evaluation of peripheral tissue perfusion in both preclinical and clinical studies. It may also be useful for developing novel drugs to protect against diabetic vascular complications.
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Affiliation(s)
- Yuto Kashiwagi
- Department of Innovative Drug Discovery Technologies, Innovative Drug Discovery Research Laboratories, Shionogi & Co., Ltd., Osaka, Japan.
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19
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Zhang Y, Nateras OSE, Peng Q, Kuranov RV, Harrison JM, Milner TE, Duong TQ. Lamina-specific anatomic magnetic resonance imaging of the human retina. Invest Ophthalmol Vis Sci 2011; 52:7232-7. [PMID: 21828153 DOI: 10.1167/iovs.11-7623] [Citation(s) in RCA: 33] [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 Magnetic resonance imaging (MRI) of the human retina faces two major challenges: eye movement and hardware limitation that could preclude human retinal MRI with adequate spatiotemporal resolution. This study investigated eye-fixation stability and high-resolution anatomic MRI of the human retina on a 3-Tesla (T) MRI scanner. Comparison was made with optical coherence tomography (OCT) on the same subjects. METHODS Eye-fixation stability of protocols used in MRI was evaluated on four normal volunteers using an eye tracker. High-resolution MRI (100 × 200 × 2000 μm) protocol was developed on a 3-T scanner. Subjects were instructed to maintain stable eye fixation on a target with cued blinks every 8 seconds during MRI. OCT imaging of the retina was performed. Retinal layer thicknesses measured with MRI and OCT were analyzed for matching regions of the same eyes close to the optic nerve head. RESULTS The temporal SDs of the horizontal and vertical displacements were 78 ± 51 and 130 ± 51 μm (±SD, n = 4), respectively. MRI detected three layers within the human retina, consistent with MRI findings in rodent, feline, and baboon retinas. The hyperintense layer 1 closest to the vitreous likely consisted of nerve fiber, ganglion cell, and inner nuclear layer; the hypointense layer 2, the outer nuclear layer and the inner and outer segments; and the hyperintense layer 3, the choroid. The MRI retina/choroid thickness was 711 ± 37 μm, 19% (P < 0.05) thicker than OCT thickness (579 ± 34 μm). CONCLUSIONS This study reports high-resolution MRI of lamina-specific structures in the human retina. These initial results are encouraging. Further improvement in spatiotemporal resolution is warranted.
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Affiliation(s)
- Yi Zhang
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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20
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Duong TQ. Magnetic resonance imaging of the retina: A brief historical and future perspective. Saudi J Ophthalmol 2011; 25:137-43. [PMID: 23960915 PMCID: PMC3729810 DOI: 10.1016/j.sjopt.2011.01.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 01/21/2011] [Indexed: 11/30/2022] Open
Abstract
This invited review starts with a brief introduction of retinal anatomy and magnetic resonance imaging techniques with contrast to optics, followed by a history and future perspective on MRI applications to investigate the retinas of rodents, non-human primates and humans.
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Affiliation(s)
- Timothy Q. Duong
- Address: University of Texas Health Science Center at San Antonio, Research Imaging Institute, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA. Tel.: +1 567 8100; fax: +1 210 567 8152.
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21
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Zhang Y, Wey HY, San Emeterio Nateras O, Peng Q, De La Garza BH, Duong TQ. Anatomical, blood oxygenation level-dependent, and blood flow MRI of nonhuman primate (baboon) retina. Magn Reson Med 2011; 66:546-54. [PMID: 21360746 DOI: 10.1002/mrm.22853] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 12/04/2010] [Accepted: 01/05/2011] [Indexed: 11/10/2022]
Abstract
The goal of this study was to demonstrate high-resolution anatomical, blood oxygenation level-dependent, and blood flow MRI on large nonhuman primate retinas using a 3-Tesla clinical scanner as a first step toward translation. Baboon was chosen because of its evolutionary similarity to human. Anesthetized preparation, free of eye-movement artifacts, was used to evaluate clinical scanner hardware feasibility and optimize multimodal protocols for retinal MRI. Anatomical MRI (0.1×0.2×2.0 mm3) before contrast-agent injection detected three alternating bright-dark-bright layers. The hyperintense inner strip nearest to the vitreous was enhanced by an intravascular contrast agent, which likely included the ganglion and bipolar cell layer and the embedded retinal vessels. The hypointense middle strip showed no contrast enhancement, which likely included the avascular outer unclear layer and photoreceptor segments. The hyperintense outer strip showed contrast enhancement, which likely corresponded to the choroid vascular layer. In the posterior retina, the total thickness including the choroid was 617±101 μm (±standard deviation, n=7). Blood oxygenation level-dependent functional MRI (0.3×0.6×2.0 mm3) of oxygen inhalation relative to air increased the signals by 6.5±1.4%. Basal blood flow (2×2×2 mm3) was 83±30 mL/100 g/min (air), and hypercapnia increased blood flow by 25±9% (P<0.05). This study demonstrates multimodal MRI to image anatomy, physiology, and function on large nonhuman primate retinas using a clinical scanner, offering encouraging data to explore human applications.
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Affiliation(s)
- Yi Zhang
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA; Department of Radiology, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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Wang Q, Song SK, Zhang H, Berkowitz BA, Chen S, Wickline SA, Chen J. Photoreceptor degeneration changes magnetic resonance imaging features in a mouse model of retinitis pigmentosa. Magn Reson Med 2011; 65:1793-8. [PMID: 21590807 DOI: 10.1002/mrm.22751] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 09/29/2010] [Accepted: 11/17/2010] [Indexed: 11/07/2022]
Abstract
Retinal degeneration-1 (rd1) mice are animal models of retinitis pigmentosa, a blinding disease caused by photoreceptor cell degeneration. This study aims to determine magnetic resonance imaging (MRI) changes in retinas of 1- and 3-month-old rd1 mice. Apparent diffusion coefficient in retina was measured using diffusion MRI. The blood-retinal barrier leakage was evaluated using gadolinium-diethylenetriaminepentaacetic acid-enhanced T(1)-weighted MRI before and after systemic gadolinium-diethylenetriaminepentaacetic acid injection. Photoreceptor degeneration in rd1 retina was apparent by decreased retinal thickness and loss of water diffusion anisotropy in both 1- and 3-month-old rd1 mice. Furthermore, statistically significant increase of mean retinal apparent diffusion coefficient and gadolinium-diethylenetriaminepentaacetic acid-enhanced T(1)-weighted MRI signals were observed in 3-month-old rd1 mice comparing with age-matched wild-type mice. Together, these data suggest that MRI parameter changes can signature common pathological changes in photoreceptor-degenerated eyes, particularly blood-retinal barrier leakage-induced retinal edema.
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Affiliation(s)
- Qing Wang
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, Missouri, USA
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CHAN KEVINC, CHEUNG MATTHEWM, WU EDX. IN VIVOMULTIPARAMETRIC MAGNETIC RESONANCE IMAGING AND SPECTROSCOPY OF RODENT VISUAL SYSTEM. J Integr Neurosci 2010; 9:477-508. [DOI: 10.1142/s0219635210002524] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 11/04/2010] [Indexed: 01/27/2023] Open
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Blood-brain barrier and cerebral small vessel disease. J Neurol Sci 2010; 299:66-71. [PMID: 20850797 DOI: 10.1016/j.jns.2010.08.042] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2010] [Revised: 07/04/2010] [Accepted: 08/24/2010] [Indexed: 01/08/2023]
Abstract
Increasing evidence from neuro and retinal imaging, neuropathology, epidemiology and experimental models suggests that the primary underlying initiating cause of cerebral small vessel disease is the derangement of the blood-brain barrier. This may start some years before the first symptoms, leads to the small vessel structural changes (vessel wall thickening, disorganisation and eventual breakdown) and perivascular changes (oedema, enlarged perivascular spaces, tissue damage interpreted as "infarcts") and is fundamentally different to traditional "ischaemic" mechanisms, although small vessel occlusion due to thrombus formation on damaged vessel walls may be a late secondary phenomenon. Space limits a detailed discussion of the epidemiology and experimental evidence, so this brief review will focus on neuroimaging evidence and summarise the appearances, risk factors and associations of different components of cerebral small vessel disease as identified on imaging, discuss potential causes and, in particular, the evidence that disordered blood-brain barrier precipitates or worsens progression of cerebral small vessel disease. This mechanism may also play a role in other common disorders of ageing such as Alzheimer's disease.
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Wang H, Miao Y, Zhou K, Yu Y, Bao S, He Q, Dai Y, Xuan SY, Tarabishy B, Ye Y, Hu J. Feasibility of high temporal resolution breast DCE-MRI using compressed sensing theory. Med Phys 2010; 37:4971-81. [PMID: 20964216 PMCID: PMC2945738 DOI: 10.1118/1.3483094] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 07/15/2010] [Accepted: 08/05/2010] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To investigate the feasibility of high temporal resolution breast DCE-MRI using compressed sensing theory. METHODS Two experiments were designed to investigate the feasibility of using reference image based compressed sensing (RICS) technique in DCE-MRI of the breast. The first experiment examined the capability of RICS to faithfully reconstruct uptake curves using undersampled data sets extracted from fully sampled clinical breast DCE-MRI data. An average approach and an approach using motion estimation and motion compensation (ME/MC) were implemented to obtain reference images and to evaluate their efficacy in reducing motion related effects. The second experiment, an in vitro phantom study, tested the feasibility of RICS for improving temporal resolution without degrading the spatial resolution. RESULTS For the uptake-curve reconstruction experiment, there was a high correlation between uptake curves reconstructed from fully sampled data by Fourier transform and from undersampled data by RICS, indicating high similarity between them. The mean Pearson correlation coefficients for RICS with the ME/MC approach and RICS with the average approach were 0.977 +/- 0.023 and 0.953 +/- 0.031, respectively. The comparisons of final reconstruction results between RICS with the average approach and RICS with the ME/MC approach suggested that the latter was superior to the former in reducing motion related effects. For the in vitro experiment, compared to the fully sampled method, RICS improved the temporal resolution by an acceleration factor of 10 without degrading the spatial resolution. CONCLUSIONS The preliminary study demonstrates the feasibility of RICS for faithfully reconstructing uptake curves and improving temporal resolution of breast DCE-MRI without degrading the spatial resolution.
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Affiliation(s)
- Haoyu Wang
- Beijing City Key Laboratory of Medical Physics and Engineering, Peking University, Beijing 100871, China
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Ocular pharmacokinetic study of a corticosteroid by 19F MR. Exp Eye Res 2010; 91:347-52. [PMID: 20537996 DOI: 10.1016/j.exer.2010.05.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 04/22/2010] [Accepted: 05/26/2010] [Indexed: 11/21/2022]
Abstract
Traditional ocular pharmacokinetic studies are invasive and cannot be easily applied to humans in vivo. To acquire in vivo ocular pharmacokinetic data noninvasively, (19)F MR on a 3T clinical scanner was used to follow the real time dynamics of a corticosteroid in the eye. (1)H MR was also performed to locate the site of administration. Triamcinolone acetonide phosphate (TAP) was the model drug, administered by intravitreal and subconjunctival injections. TAP pharmacokinetics were monitored by changes in the (19)F spectrum of the intraocular drug in real time. The elimination half-lives of TAP in the eye after intravitreal and subconjunctival injections were 8 and 0.5 h in vivo and 17 and 6.0 h postmortem, respectively. The half-lives associated with clearance were 14 h for intravitreal injection and 0.5 h for subconjunctival injection.
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Wisard J, Chrenek MA, Wright C, Dalal N, Pardue MT, Boatright JH, Nickerson JM. Non-contact measurement of linear external dimensions of the mouse eye. J Neurosci Methods 2010; 187:156-66. [PMID: 20067806 PMCID: PMC2832717 DOI: 10.1016/j.jneumeth.2010.01.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 01/04/2010] [Accepted: 01/05/2010] [Indexed: 11/25/2022]
Abstract
Biometric analyses of quantitative traits in eyes of mice can reveal abnormalities related to refractive or ocular development. Due to the small size of the mouse eye, highly accurate and precise measurements are needed to detect meaningful differences. We sought a non-contact measuring technique to obtain highly accurate and precise linear dimensions of the mouse eye. Laser micrometry was validated with gauge block standards. Simple procedures to measure eye dimensions on three axes were devised. Mouse eyes from C57BL/6J and rd10 on a C57BL/6J background were dissected and extraocular muscle and fat removed. External eye dimensions of axial length (anterior-posterior (A-P) axis) and equatorial diameter (superior-inferior (S-I) and nasal-temporal (N-T) axes) were obtained with a laser micrometer. Several approaches to prevent or ameliorate evaporation due to room air were employed. The resolution of the laser micrometer was less than 0.77 microm, and it provided accurate and precise non-contact measurements of eye dimensions on three axes. External dimensions of the eye strongly correlated with eye weight. The N-T and S-I dimensions of the eye correlated with each other most closely from among the 28 pair-wise combinations of the several parameters that were collected. The equatorial axis measurements correlated well from the right and left eye of each mouse. The A-P measurements did not correlate or correlated poorly in each pair of eyes. The instrument is well suited for the measurement of enucleated eyes and other structures from most commonly used species in experimental vision research and ophthalmology.
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Affiliation(s)
- Jeffrey Wisard
- Department of Ophthalmology, Emory University, Atlanta, GA
| | | | - Charles Wright
- Department of Ophthalmology, Emory University, Atlanta, GA
| | - Nupur Dalal
- Department of Ophthalmology, Emory University, Atlanta, GA
| | - Machelle T. Pardue
- Department of Ophthalmology, Emory University, Atlanta, GA
- Rehabilitation Research and Development Center of Excellence, Atlanta VA Hospital, Decatur, GA
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Evidence for a critical role of panretinal pathophysiology in experimental ROP. Doc Ophthalmol 2009; 120:13-24. [PMID: 19506927 DOI: 10.1007/s10633-009-9175-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 05/22/2009] [Indexed: 10/20/2022]
Abstract
In this review, we summarize our in vivo studies of retinal pathophysiology in experimental models of retinopathy of prematurity, which were largely focused on the temporal and spatial links between retinal neovascularization (NV), vascular oxygenation, and intraretinal ion regulation. These studies were made possible through the use of magnetic resonance methods. Prior to the phenotype change from normal vessel development to NV, we found little support for a pathogenic role of focal retinal hypoxia at the border of vascular and avascular retina. However, key links were found between retinal NV and functional panretinal defects in both oxygenation to a provocation and intraretinal ion regulation. Through a treatment which reduced NV incidence but not panretinal pathophysiology, proliferative disease was found to last longer than that in the untreated group. These considerations provide compelling evidence that clinical attention directed toward reducing retinal NV should include approaches that reduce functional panretinal pathophysiology.
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Wardlaw JM, Doubal F, Armitage P, Chappell F, Carpenter T, Muñoz Maniega S, Farrall A, Sudlow C, Dennis M, Dhillon B. Lacunar stroke is associated with diffuse blood-brain barrier dysfunction. Ann Neurol 2009; 65:194-202. [PMID: 19260033 DOI: 10.1002/ana.21549] [Citation(s) in RCA: 243] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Lacunar stroke is common (25% of ischemic strokes) and mostly because of an intrinsic cerebral microvascular disease of unknown cause. Although considered primarily to be an ischemic process, the vessel and tissue damage could also be explained by dysfunctional endothelium or blood-brain barrier (BBB) leak, not just ischemia. We tested for subtle generalized BBB leakiness in patients with lacunar stroke and control patients with cortical ischemic stroke. METHODS We recruited patients with lacunar and mild cortical stroke. We assessed BBB leak in gray matter, white matter, and cerebrospinal fluid, at least 1 month after stroke, using magnetic resonance imaging before and after intravenous gadolinium. We measured tissue enhancement for 30 minutes after intravenous gadolinium by two image analysis approaches (regions of interest and tissue segmentation). We compared the enhancement (leak) between lacunar and cortical patients, and associations with key variables, using general linear modeling. RESULTS We recruited 51 lacunar and 46 cortical stroke patients. Signal enhancement after gadolinium was higher in lacunar than cortical stroke patients in white matter (p < 0.001) and cerebrospinal fluid (p < 0.003) by both analysis methods, independent of other variables. Signal enhancement after gadolinium was also associated with increasing age and enlarged perivascular spaces, but these did not explain the lacunar-cortical difference. INTERPRETATION Patients with lacunar stroke have subtle, diffuse BBB dysfunction in white matter. Further studies are required to determine the relative contributions of BBB dysfunction and/or ischemia to the microvascular and brain abnormalities in lacunar stroke.
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Chan KC, Fu QL, So KF, Wu EX. Dynamic contrast-enhanced MRI of ocular biotransport in normal and hypertensive eyes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2008:835-8. [PMID: 19162786 DOI: 10.1109/iembs.2008.4649283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This study aims to employ in vivo dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to evaluate the ocular transport following an induction of ocular hypertension in a rat model of chronic glaucoma. Upon systemic administration of Gd-DTPA solution, T1-weighted signal increase was observed in the vitreous body of the glaucomatous eye but not the control eye. This increase occurred earlier in the anterior vitreous body than the preretinal vitreous. Further, there was an earlier Gd-DTPA transport into the anterior chamber in the majority of glaucomatous eyes. Our DCE-MRI findings revealed the leakage of Gd-DTPA at the aqueous-vitreous interface, which was likely resulted from increased permeability of blood-aqueous or aqueous-vitreous barrier. These may explain the sources of changing biochemical compositions in the chamber components, which may implicate the neurodegenerative processes in the glaucomatous visual components.
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Affiliation(s)
- Kevin C Chan
- Laboratory of Biomedical Imaging and Signal Processing, Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong.
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Trick GL, Edwards PA, Desai U, Morton PE, Latif Z, Berkowitz BA. MRI retinovascular studies in humans: research in patients with diabetes. NMR IN BIOMEDICINE 2008; 21:1003-1012. [PMID: 18821575 DOI: 10.1002/nbm.1314] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
PURPOSE To review existing applications of MRI for detecting blood-retinal barrier (BRB) damage and retinal oxygenation response abnormalities in patients with diabetes and highlight new information available from such applications. METHODS BRB studies were accomplished using dynamic contrast-enhanced MRI, and the retinal oxygenation response studies were accomplished by monitoring changes in the MRI signal associated with hyperoxic provocation. Participants were patients with diabetes and macular edema, with either no detectable or mild to moderate background retinopathy, as well as non-diabetic individuals of similar age (controls). Single-slice FLASH images were obtained using a Siemens Sonata, 1.5 T together with a Siemens 'Loop Small' surface coil fixed in place over the eye. Time-dependent changes in image contrast in the pre-retinal vitreous were quantified, and differences between patients and controls were assessed statistically. RESULTS The BRB breakdown studies showed a significant difference in the temporal evolution of the MRI signal enhancement post-contrast injection between the controls and the patients with diabetic macular edema. The retinal oxygenation studies revealed a supernormal oxygenation response in the pre-retinal vitreous in patients with diabetes who had no evidence of retinopathy, as well as in patients with background diabetic retinopathy. A nasal-temporal asymmetry in the evolution of retinal oxygenation response was found in patients with diabetes that was not present in healthy subjects. CONCLUSIONS These studies show that subtle differences in retinovascular function between patients with diabetes and non-diabetic individuals, including changes that occur in advance of the clinical appearance of diabetic retinopathy, can be detected with MRI. These results, together with previous extensive preclinical data, establish MRI as a powerful non-invasive method for measuring spatial and temporal changes in the same key retinovascular metrics in both animals and humans. Wide application of these techniques for diagnosis and evaluation of treatment efficacy in a variety of human retinopathies, including diabetic retinopathy, is expected.
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Affiliation(s)
- Gary L Trick
- Department of Ophthalmology, Henry Ford Health System, Detroit, MI 48202, USA.
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Berkowitz BA, Roberts R. Prognostic MRI biomarkers of treatment efficacy for retinopathy. NMR IN BIOMEDICINE 2008; 21:957-967. [PMID: 18729237 DOI: 10.1002/nbm.1303] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
There is a pressing need for retina-specific imaging biomarkers that robustly measure early (subclinical) changes in physiology, are linked to the histopathology responsible for vision loss, and, importantly, predict treatment efficacy. This review focuses on the following four MRI markers that we have developed and applied in preclinical and clinical settings: preretinal vitreous oxygen level (a steady-state biomarker of inner retinal oxygen tension); leakage of contrast agent into the vitreous (a steady-state biomarker of blood-retinal barrier permeability surface area product); change in preretinal vitreous oxygen tension during a hyperoxic provocation (a functional biomarker of vascular autoregulation); and retinal uptake of systemically administered manganese during a visual task (a functional biomarker of intraretinal ion regulation). We conclude that functional biomarkers are most promising for prognostic evaluation of treatment efficacy earlier in the course of retinopathy than is currently possible.
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Affiliation(s)
- Bruce A Berkowitz
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, MI 48201, USA.
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Abstract
Conventional pharmacokinetic methods for studying ocular drug delivery are invasive and cannot be conveniently applied to humans. The advancement of MRI technology has provided new opportunities in ocular drug-delivery research. MRI provides a means to non-invasively and continuously monitor ocular drug-delivery systems with a contrast agent or compound labeled with a contrast agent. It is a useful technique in pharmacokinetic studies, evaluation of drug-delivery methods, and drug-delivery device testing. Although the current status of the technology presents some major challenges to pharmaceutical research using MRI, it has a lot of potential. In the past decade, MRI has been used to examine ocular drug delivery via the subconjunctival route, intravitreal injection, intrascleral injection to the suprachoroidal space, episcleral and intravitreal implants, periocular injections, and ocular iontophoresis. In this review, the advantages and limitations of MRI in the study of ocular drug delivery are discussed. Different MR contrast agents and MRI techniques for ocular drug-delivery research are compared. Ocular drug-delivery studies using MRI are reviewed.
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Affiliation(s)
- S Kevin Li
- Division of Pharmaceutical Sciences, College of Pharmacy, University of Cincinnati, Cincinnati, OH 45267, USA.
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GD-DTPA enhanced MRI of ocular transport in a rat model of chronic glaucoma. Exp Eye Res 2008; 87:334-41. [DOI: 10.1016/j.exer.2008.06.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 06/10/2008] [Accepted: 06/23/2008] [Indexed: 11/21/2022]
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Chen J, Wang Q, Zhang H, Yang X, Wang J, Berkowitz BA, Wickline SA, Song SK. In vivo quantification of T1, T2, and apparent diffusion coefficient in the mouse retina at 11.74T. Magn Reson Med 2008; 59:731-8. [PMID: 18383302 DOI: 10.1002/mrm.21570] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
MRI has recently been used for noninvasive examination of retinal structure and function in rats and cats. However, the advantages of quantitative high-resolution MRI of retina from mice have not yet been explored. In the present study, T(1) and T(2) relaxation time constants and the directional apparent diffusion coefficient (ADC) in the retina of C57/BL6 mice were measured. Three MR-detected retina layers and a MR-detected choroid layer were observed on both T(1)- and T(2)-weighted images at an image resolution of 47 x 47 x 400 microm(3). The significantly higher ADC parallel to than that perpendicular to the optic nerve in the MR-detected outer retina layer at the central retina reflects the known cellular organization of the photoreceptor cells. This study establishes, for the first time, normative metrics of T(1), T(2), and ADC of the mouse retina. These MR parameters are expected to be useful in future evaluation of developmental and pathological alterations of retinal cell layers in mice.
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Affiliation(s)
- Junjie Chen
- Department of Medicine, Washington University, St. Louis, Missouri, USA
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Contributions of inflammatory processes to the development of the early stages of diabetic retinopathy. EXPERIMENTAL DIABETES RESEARCH 2008; 2007:95103. [PMID: 18274606 PMCID: PMC2216058 DOI: 10.1155/2007/95103] [Citation(s) in RCA: 450] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Accepted: 05/27/2007] [Indexed: 12/11/2022]
Abstract
Diabetes causes metabolic and physiologic abnormalities in the retina, and these changes suggest a role for inflammation in the development of diabetic retinopathy. These changes include upregulation of iNOS, COX-2, ICAM-1, caspase 1, VEGF, and NF-κB, increased production of nitric oxide, prostaglandin E2, IL-1β, and cytokines, as well as increased permeability and leukostasis. Using selective pharmacologic inhibitors or genetically modified animals, an increasing number of therapeutic approaches have been identified that significantly inhibit development of at least the early stages of diabetic retinopathy, especially occlusion and degeneration of retinal capillaries. A common feature of a number of these therapies is that they inhibit production of inflammatory mediators. The concept that localized inflammatory processes play a role in the development of diabetic retinopathy is relatively new, but evidence that supports the hypothesis is accumulating rapidly. This new hypothesis offers new insight into the pathogenesis of diabetic retinopathy, and offers novel targets to inhibit the ocular disease.
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Wardlaw JM, Farrall A, Armitage PA, Carpenter T, Chappell F, Doubal F, Chowdhury D, Cvoro V, Dennis MS. Changes in background blood-brain barrier integrity between lacunar and cortical ischemic stroke subtypes. Stroke 2008; 39:1327-32. [PMID: 18309161 DOI: 10.1161/strokeaha.107.500124] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Lacunar stroke is associated with endothelial dysfunction and histologically with intrinsic cerebral microvascular disease of unknown cause. Endothelial dysfunction could impair blood-brain barrier integrity. We assessed background blood-brain barrier leakage in patients with lacunar ischemic stroke compared with cortical stroke controls. METHODS We recruited patients with lacunar or mild cortical ischemic stroke and assessed generalized cerebral blood-brain barrier leak with MRI and intravenous gadolinium at least 1 month after stroke. We used detailed image processing to compare signal change before and for 30 minutes postcontrast throughout gray matter, white matter, and cerebrospinal fluid with summary analyses and general linear modeling. RESULTS Among 48 patients (29 lacunar, 19 cortical), postcontrast enhancement was significantly higher in cerebrospinal fluid (P=0.04, Mann-Whitney U), and nonsignificantly higher in white matter, in lacunar than in cortical strokes, with no difference in gray matter. General linear modeling confirmed significantly greater postcontrast enhancement in cerebrospinal fluid in lacunar patients than in cortical controls (t=3.37, P<0.0008). CONCLUSIONS These preliminary data suggest that the blood-brain barrier may be dysfunctional throughout subcortical white matter (white matter drains via interstitial spaces to cerebrospinal fluid) in patients with lacunar stroke. Further studies are required to confirm these findings and determine whether abnormal blood-brain barrier might predate development of lacunar disease. Blood-brain barrier dysfunction may be an important mechanism for brain damage in cerebral microvascular disease.
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Berkowitz BA, Roberts R, Luan H, Bissig D, Bui BV, Gradianu M, Calkins DJ, Vingrys AJ. Manganese-enhanced MRI studies of alterations of intraretinal ion demand in models of ocular injury. Invest Ophthalmol Vis Sci 2007; 48:3796-804. [PMID: 17652754 PMCID: PMC2041849 DOI: 10.1167/iovs.06-1278] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To provide proof-of-concept that the extent of intraretinal manganese uptake after systemic MnCl(2) injection, detected with manganese-enhanced MRI (MEMRI), assesses alterations in intraretinal ion demand in models of ocular insult. METHODS In Sprague-Dawley rats, retinal ion demand and thickness were measured from MEMRI data collected before, 4 hours after, or 1, 3, and 7 days after intraperitoneal injection of MnCl(2). Choroidal contribution or blood-retinal barrier permeability surface area product (BRB PS') was determined using MRI after Gd-DTPA injection. Ocular injury was evaluated 24 hours after intravitreal injection of phosphate-buffered saline (PBS, vehicle) or PBS + ouabain, or after intraperitoneal injection of sodium iodate. Manganese retinal toxicity was assessed by comparing full-field, white-flash electroretinographic (ERG) data obtained before and after systemic MnCl(2) administration. Rat choroidal thickness was measured from cross-sections prepared from paraformaldehyde-perfused adult rats. RESULTS Comparing pre- and post-Gd-DTPA images demonstrated minimal choroidal contribution to intraretinal analysis. Intraretinal signal intensity returned to baseline by 7 days after MnCl(2) injection. After ouabain injection, receptor and postreceptor uptake of manganese were subnormal (P < 0.05). After sodium iodate exposure, intraretinal manganese uptake was supernormal (P < 0.05) and did not increase with increasing BRB PS'. ERG data did not show any effect of MnCl(2) on photoreceptor a-wave and postreceptor b-wave relative to baseline at either observation time. CONCLUSIONS MEMRI measurements of uptake of systemically administered and nontoxic doses of manganese appear to be a powerful approach for measuring alteration in intraretinal ion demand in models of ocular injury.
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Affiliation(s)
- Bruce A. Berkowitz
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan
- Department of Ophthalmology, Wayne State University, Detroit, Michigan
| | - Robin Roberts
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan
| | - Hongmei Luan
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan
| | - David Bissig
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan
| | - Bang V. Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Victoria, Australia
| | - Marius Gradianu
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan
| | - David J. Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, Tennessee
| | - Algis J. Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne, Victoria, Australia
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Kim SH, Csaky KG, Wang NS, Lutz RJ. Drug elimination kinetics following subconjunctival injection using dynamic contrast-enhanced magnetic resonance imaging. Pharm Res 2007; 25:512-20. [PMID: 17674155 DOI: 10.1007/s11095-007-9408-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Accepted: 07/06/2007] [Indexed: 10/23/2022]
Abstract
PURPOSE To determine the elimination rates of subconjunctivally injected model drugs using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). METHODS Gadolinium-diethylenetriaminopentaacetic acid (Gd-DTPA) and gadolinium-albumin (Gd-albumin) were injected in rabbits. Experiments were performed in vivo and post mortem and injection volumes of 200 and 600 microl were administered. Signal intensity values from MR images were converted to concentration of contrast agent to determine the mass clearance rates from subconjunctival space. RESULTS Injection volume did not have a significant effect on clearance rate for both Gd-DTPA and Gd-albumin. The clearance rate of Gd-DTPA in vivo was about nine times faster than that post mortem. The in vivo and post mortem clearance rates of Gd-albumin were not significantly different. The in vivo half-life of Gd-DTPA was about 22 min while that of Gd-albumin was about 5.3 h. CONCLUSIONS DCE-MRI was used to quantitatively compare the subconjunctival clearance rates of Gd-DTPA and Gd-albumin. Dynamic clearance mechanisms present in vivo significantly reduced the subconjunctival concentration of Gd-DTPA but not Gd-albumin. Lymphatic clearance does not seem to be as significant as clearance by blood, as evidenced by data from Gd-albumin injections. Larger injection volumes may allow for longer retention times and prolonged release of drug.
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Affiliation(s)
- Stephanie H Kim
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland, USA.
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Itakura H, Akiyama H, Hagimura N, Doi H, Tanaka T, Kishi S, Kurabayashi M. Triamcinolone acetonide suppresses interleukin-1 beta-mediated increase in vascular endothelial growth factor expression in cultured rat Müller cells. Graefes Arch Clin Exp Ophthalmol 2005; 244:226-31. [PMID: 16049703 DOI: 10.1007/s00417-005-0052-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 06/02/2005] [Accepted: 06/04/2005] [Indexed: 02/03/2023] Open
Abstract
PURPOSE Intravitreal injection of triamcinolone acetonide (TA) is used for the treatment of diabetic macular edema and other vitreoretinal diseases. Vascular endothelial growth factor (VEGF) plays a key role in regulating vascular permeability associated with macular edema. We investigated the effect of TA on the expression of VEGF mRNA and protein induced by interleukin-1 beta (IL-1b) and hypoxia in cultured rat Müller cells. METHODS Müller cells were isolated from removed eyeballs of 40 rats. Total RNA was prepared from Müller cells stimulated by IL-1b or hypoxia, in the absence or presence of TA, and then was subjected to Northern blot analyses. The amount of VEGF protein in the culture medium was measured by enzyme-linked immunosorbent assay (ELISA). The stability of RNA was determined by actinomycin D decay assay. Reporter construct, consisting of the VEGF promoter-luciferase gene, was transiently transfected into Müller cells for luciferase assays. RESULTS Stimulation of Müller cells by either IL-1b or hypoxia induced VEGF mRNA expression. Pretreatment of cells with TA efficiently suppressed VEGF induction by IL-1b but not by hypoxia. ELISA showed that TA significantly reduced the production of VEGF protein from IL-1b-stimulated cells. RNA decay assays and promoter analysis of the VEGF gene indicated that TA inhibited the IL-1b-mediated increase in VEGF gene expression at the transcriptional level. CONCLUSIONS TA suppressed VEGF expression induced by IL-1b in Müller cells at the transcriptional level. Our data sustained the clinical effect of TA for diabetic macular edema and suggested an important role of TA for the suppression of the VEGF gene expression in ocular tissues.
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Affiliation(s)
- Hirotaka Itakura
- Department of Ophthalmology, Gunma University Graduate School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma, 371-8511, Japan.
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