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Straccia A, Barbour MC, Chassagne F, Bass D, Barros G, Leotta D, Sheehan F, Sharma D, Levitt MR, Aliseda A. Numerical Modeling of Flow in the Cerebral Vasculature: Understanding Changes in Collateral Flow Directions in the Circle of Willis for a Cohort of Vasospasm Patients Through Image-Based Computational Fluid Dynamics. Ann Biomed Eng 2024; 52:2417-2439. [PMID: 38758460 PMCID: PMC11329356 DOI: 10.1007/s10439-024-03533-w] [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: 03/13/2024] [Accepted: 04/30/2024] [Indexed: 05/18/2024]
Abstract
The Circle of Willis (CoW) is a ring-like network of blood vessels that perfuses the brain. Flow in the collateral pathways that connect major arterial inputs in the CoW change dynamically in response to vessel narrowing or occlusion. Vasospasm is an involuntary constriction of blood vessels following subarachnoid hemorrhage (SAH), which can lead to stroke. This study investigated interactions between localization of vasospasm in the CoW, vasospasm severity, anatomical variations, and changes in collateral flow directions. Patient-specific computational fluid dynamics (CFD) simulations were created for 25 vasospasm patients. Computed tomographic angiography scans were segmented capturing the anatomical variation and stenosis due to vasospasm. Transcranial Doppler ultrasound measurements of velocity were used to define boundary conditions. Digital subtraction angiography was analyzed to determine the directions and magnitudes of collateral flows as well as vasospasm severity in each vessel. Percent changes in resistance and viscous dissipation were analyzed to quantify vasospasm severity and localization of vasospasm in a specific region of the CoW. Angiographic severity correlated well with percent changes in resistance and viscous dissipation across all cerebral vessels. Changes in flow direction were observed in collateral pathways of some patients with localized vasospasm, while no significant changes in flow direction were observed in others. CFD simulations can be leveraged to quantify the localization and severity of vasospasm in SAH patients. These factors as well as anatomical variation may lead to changes in collateral flow directions. Future work could relate localization and vasospasm severity to clinical outcomes like the development of infarct.
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Affiliation(s)
- Angela Straccia
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
| | - Michael C Barbour
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | | | - David Bass
- Department of Neurological Surgery, University of Washington, Seattle, WA, USA
| | - Guilherme Barros
- Department of Neurological Surgery, University of Washington, Seattle, WA, USA
| | - Daniel Leotta
- Applied Physics Laboratory, University of Washington, Seattle, WA, USA
| | - Florence Sheehan
- Department of Medicine, University of Washington, Seattle, WA, USA
| | - Deepak Sharma
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA
| | - Michael R Levitt
- Department of Neurological Surgery, University of Washington, Seattle, WA, USA
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
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Caddy HT, Kelsey LJ, Parker LP, Green DJ, Doyle BJ. Modelling large scale artery haemodynamics from the heart to the eye in response to simulated microgravity. NPJ Microgravity 2024; 10:7. [PMID: 38218868 PMCID: PMC10787773 DOI: 10.1038/s41526-024-00348-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 01/03/2024] [Indexed: 01/15/2024] Open
Abstract
We investigated variations in haemodynamics in response to simulated microgravity across a semi-subject-specific three-dimensional (3D) continuous arterial network connecting the heart to the eye using computational fluid dynamics (CFD) simulations. Using this model we simulated pulsatile blood flow in an upright Earth gravity case and a simulated microgravity case. Under simulated microgravity, regional time-averaged wall shear stress (TAWSS) increased and oscillatory shear index (OSI) decreased in upper body arteries, whilst the opposite was observed in the lower body. Between cases, uniform changes in TAWSS and OSI were found in the retina across diameters. This work demonstrates that 3D CFD simulations can be performed across continuously connected networks of small and large arteries. Simulated results exhibited similarities to low dimensional spaceflight simulations and measured data-specifically that blood flow and shear stress decrease towards the lower limbs and increase towards the cerebrovasculature and eyes in response to simulated microgravity, relative to an upright position in Earth gravity.
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Affiliation(s)
- Harrison T Caddy
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, WA, Australia
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Perth, WA, Australia
| | - Lachlan J Kelsey
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, WA, Australia
- School of Engineering, The University of Western Australia, Perth, WA, Australia
| | - Louis P Parker
- FLOW, Department of Engineering Mechanics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Daniel J Green
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Perth, WA, Australia
| | - Barry J Doyle
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia and the UWA Centre for Medical Research, The University of Western Australia, Perth, WA, Australia.
- School of Engineering, The University of Western Australia, Perth, WA, Australia.
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Straccia A, Chassagne F, Bass DI, Barros G, Leotta DF, Sheehan F, Sharma D, Levitt MR, Aliseda A. A Novel Patient-Specific Computational Fluid Dynamics Study of the Activation of Primary Collateral Pathways in the Circle of Willis During Vasospasm. J Biomech Eng 2023; 145:041008. [PMID: 36173034 PMCID: PMC9791673 DOI: 10.1115/1.4055813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 09/17/2022] [Indexed: 12/30/2022]
Abstract
The Circle of Willis (CoW) is a redundant network of blood vessels that perfuses the brain. The ringlike anatomy mitigates the negative effects of stroke by activating collateral pathways that help maintain physiological perfusion. Previous studies have investigated the activation of these pathways during embolic stroke and internal carotid artery occlusion. However, the role of collateral pathways during cerebral vasospasm-an involuntary constriction of blood vessels after subarachnoid hemorrhage-is not well-documented. This study presents a novel technique to create patient-specific computational fluid dynamics (CFD) simulations of the Circle of Willis before and during vasospasm. Computed tomographic angiography (CTA) scans are segmented to model the vasculature, and transcranial Doppler ultrasound (TCD) measurements of blood flow velocity are applied as boundary conditions. Bayesian analysis leverages information about the uncertainty in the measurements of vessel diameters and velocities to find an optimized parameter set that satisfies mass conservation and that is applied in the final simulation. With this optimized parameter set, the diameters, velocities, and flow rates fall within typical literature values. Virtual angiograms modeled using passive scalar transport agree closely with clinical angiography. A sensitivity analysis quantifies the changes in collateral flow rates with respect to changes in the inlet and outlet flow rates. This analysis can be applied in the future to a cohort of patients to investigate the relationship between the locations and severities of vasospasm, the patient-to-patient anatomical variability in the Circle of Willis, and the activation of collateral pathways.
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Affiliation(s)
- Angela Straccia
- Department of Mechanical Engineering, University of Washington, 3900 E Stevens Way NE, Seattle, WA 98195
| | - Fanette Chassagne
- INSERM U1059 Sainboise, Mines Saint-Étienne, 158 cours Fauriel, Saint-Étienne 42000, France
| | - David I. Bass
- Department of Neurological Surgery, University of Washington, 325 Ninth Avenue, Box 359924, Seattle, WA 98104
| | - Guilherme Barros
- Department of Neurological Surgery, University of Washington, 325 Ninth Avenue, Box 359924, Seattle, WA 98104
| | - Daniel F. Leotta
- Applied Physics Laboratory, University of Washington, 1013 NE 40th 28 St, Box 355640, Seattle, WA 98105
| | - Florence Sheehan
- Department of Medicine, University of Washington, 1959 NE Pacific St, RR-616, Seattle, WA 98195
| | - Deepak Sharma
- Department of Neurological Surgery, University of Washington, 325 Ninth Avenue, Box 359924, Seattle, WA 98104
| | - Michael R. Levitt
- Department of Neurological Surgery, University of Washington, 325 Ninth Avenue, Box 359924, Seattle, WA 98104; Department of Mechanical Engineering, University of Washington, 3900 E Stevens Way NE, Seattle, WA 98195; Department of Radiology, University of Washington, 325 Ninth Avenue, Box 359924, Seattle, WA 98104
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, 3900 E Stevens Way NE, Seattle, WA 98195; Department of Neurological Surgery, University of Washington, 325 Ninth Avenue, Box 359924, Seattle, WA 98104
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Hibert ML, Chen YI, Ohringer N, Wilbur LR, Waheed NK, Heier JS, Calhoun MW, Rosenfeld PJ, Polimeni JR. Reply. AJNR Am J Neuroradiol 2022; 43:E62-E63. [PMID: 36423952 DOI: 10.3174/ajnr.a7717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- M L Hibert
- Athinoula A. Martinos Center for Biomedical ImagingMassachusetts General HospitalCharlestown, Massachusetts
| | - Y I Chen
- Athinoula A. Martinos Center for Biomedical ImagingMassachusetts General HospitalCharlestown, MassachusettsDepartment of RadiologyHarvard Medical SchoolBoston, Massachusetts
| | - N Ohringer
- Athinoula A. Martinos Center for Biomedical ImagingMassachusetts General HospitalCharlestown, Massachusetts
| | | | - N K Waheed
- New England Eye CenterTufts Medical CenterBoston, Massachusetts
| | - J S Heier
- Ophthalmic Consultants of BostonBoston, Massachusetts
| | | | - P J Rosenfeld
- Department of Ophthalmology, Bascom Palmer Eye InstituteUniversity of Miami Miller School of MedicineMiami, Florida
| | - J R Polimeni
- Athinoula A. Martinos Center for Biomedical ImagingMassachusetts General HospitalCharlestown, MassachusettsDepartment of RadiologyHarvard Medical SchoolBoston, MassachusettsHarvard-MIT Division of Health Sciences and TechnologyMassachusetts Institute of TechnologyCambridge, Massachusetts
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Chen X, Hong Y, Di H, Wu Q, Zhang D, Zhang C. Change of Retinal Vessel Density After Lowering Intraocular Pressure in Ocular Hypertension. Front Med (Lausanne) 2021; 8:730327. [PMID: 34957136 PMCID: PMC8695549 DOI: 10.3389/fmed.2021.730327] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 11/19/2021] [Indexed: 11/26/2022] Open
Abstract
Purpose: To investigate the relationship between retinal microvasculature changes and intraocular pressure (IOP) for ocular hypertension (OHT) patients and further assess the factors associated with retinal microcirculation changes. Methods: This was a single-center prospective study designed for OHT patients, which consisted of two visits. After collecting baseline data of those who met the eligibility criteria, these patients were treated with latanoprost 0.005% ophthalmic solution for 4 weeks. Peripapillary vessel density (VD) of radial peripapillary capillaries (RPC) layer, macular VD in both superficial and deep layers, and foveal avascular zone (FAZ) area were measured by optical coherence tomography angiography (OCTA) before and after the treatment. We compared the changes in IOP and VD among the two visits by paired-sample t-test. Bonferroni correction was applied. Factors associated with VD changes were analyzed by linear regression analysis. Results: Thirty-four eyes of thirty-four patients were included. The mean IOP decreased by 6.5 ± 2.2 mmHg (p < 0.001). The peripapillary RPC VD increased significantly from 51.8 ± 2.5 to 53.0 ± 3.1% (Adjusted-p = 0.012). We found no significant difference in detailed sectors of the peripapillary region after correction. In the macular area, both the superficial and deep layers in foveal (superficial: 0.2 ± 1.9%, p = 0.523; deep: 0.0 ± 2.3%, p = 0.969) and parafoveal (superficial: 0.3 ± 3.0%, p = 0.565; deep: 0.5 ± 3.1%, p = 0.423) VD remained unchanged. The decrease of the mean FAZ area was insignificant (p = 0.295). The percentage of IOP reduction (β = 0.330, p = 0.031) and the baseline RNFL thickness (β = 0.450, p = 0.004) significantly correlated with the percentage of peripapillary RPC VD improvement in the multivariate linear regression analysis. Conclusion: The peripapillary VD in OHT patients increased after the reduction of IOP. The mild change of IOP did not alter the microcirculation in the macula. In addition, the percentage of IOP change and the baseline RNFL thickness were independent factors for the peripapillary RPC VD improvement.
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Affiliation(s)
- Xuhao Chen
- Department of Ophthalmology, Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Peking University Third Hospital, Beijing, China
| | - Ying Hong
- Department of Ophthalmology, Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Peking University Third Hospital, Beijing, China
| | - Haohao Di
- Department of Ophthalmology, Zhengzhou Second Hospital, Zhengzhou, China
| | - Qianru Wu
- Department of Ophthalmology, Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Peking University Third Hospital, Beijing, China
| | - Di Zhang
- Department of Ophthalmology, Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Peking University Third Hospital, Beijing, China
| | - Chun Zhang
- Department of Ophthalmology, Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Peking University Third Hospital, Beijing, China
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Hibert M, Chen Y, Ohringer N, Feuer W, Waheed N, Heier J, Calhoun M, Rosenfeld P, Polimeni J. Altered Blood Flow in the Ophthalmic and Internal Carotid Arteries in Patients with Age-Related Macular Degeneration Measured Using Noncontrast MR Angiography at 7T. AJNR Am J Neuroradiol 2021; 42:1653-1660. [PMID: 34210664 PMCID: PMC8423057 DOI: 10.3174/ajnr.a7187] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 04/04/2021] [Indexed: 02/01/2023]
Abstract
BACKGROUND AND PURPOSE Age-related macular degeneration is associated with reduced perfusion of the eye; however, the role of altered blood flow in the upstream ophthalmic or internal carotid arteries is unclear. We used ultra-high-field MR imaging to investigate whether the diameter of and blood flow in the ophthalmic artery and/or the ICA are altered in age-related macular degeneration and whether any blood flow changes are associated with disease progression. MATERIALS AND METHODS Twenty-four patients with age-related macular degeneration and 13 similarly-aged healthy controls participated. TOF and high-resolution dynamic 2D phase-contrast MRA (0.26 × 0.26 × 2mm3, 100-ms effective sampling rate) was acquired at 7T. Vessel diameters were calculated from cross-sectional areas in phase-contrast acquisitions. Blood flow time-series were measured across the cardiac cycle. RESULTS The ophthalmic artery vessel diameter was found to be significantly smaller in patients with age-related macular degeneration than in controls. Volumetric flow through the ophthalmic artery was significantly lower in patients with late age-related macular degeneration, with a significant trend of decreasing volumetric ophthalmic artery flow rates with increasing disease severity. The resistance index was significantly greater in patients with age-related macular degeneration than in controls in the ophthalmic artery. Flow velocity through the ophthalmic artery and ICA was significantly higher in patients with age-related macular degeneration. Ophthalmic artery blood flow as a percentage of ipsilateral ICA blood flow was nearly double in controls than in patients with age-related macular degeneration. CONCLUSIONS These findings support the hypothesis that vascular changes upstream to the eye are associated with the severity of age-related macular degeneration. Additional investigation into the potential causality of this relationship and whether treatments that improve ocular circulation slow disease progression is warranted.
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Affiliation(s)
- M.L. Hibert
- From the Athinoula A. Martinos Center for Biomedical Imaging (M.L.H., Y.I.C., N. O., J.R.P.), Massachusetts General Hospital, Charlestown, Massachusetts
| | - Y.I. Chen
- From the Athinoula A. Martinos Center for Biomedical Imaging (M.L.H., Y.I.C., N. O., J.R.P.), Massachusetts General Hospital, Charlestown, Massachusetts,Department of Radiology (Y.I.C., J.R.P.), Harvard Medical School, Boston, Massachusetts
| | - N. Ohringer
- From the Athinoula A. Martinos Center for Biomedical Imaging (M.L.H., Y.I.C., N. O., J.R.P.), Massachusetts General Hospital, Charlestown, Massachusetts
| | - W.J. Feuer
- Department of Ophthalmology (W.J.F., P.J.R.), Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - N.K. Waheed
- New England Eye Center (N.K.W.), Tufts Medical Center, Boston, Massachusetts
| | - J.S. Heier
- Ophthalmic Consultants of Boston (J.S.H.), Boston, Massachusetts
| | | | - P.J. Rosenfeld
- Department of Ophthalmology (W.J.F., P.J.R.), Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - J.R. Polimeni
- From the Athinoula A. Martinos Center for Biomedical Imaging (M.L.H., Y.I.C., N. O., J.R.P.), Massachusetts General Hospital, Charlestown, Massachusetts,Department of Radiology (Y.I.C., J.R.P.), Harvard Medical School, Boston, Massachusetts,Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology (J.R.P.), Massachusetts Institute of Technology, Cambridge, Massachusetts
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Ophthalmic Artery and Superior Ophthalmic Vein Blood Flow Dynamics in Glaucoma Investigated by Phase Contrast Magnetic Resonance Imaging. J Glaucoma 2021; 30:65-70. [PMID: 32969916 DOI: 10.1097/ijg.0000000000001684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 09/03/2020] [Indexed: 11/26/2022]
Abstract
PRECIS Ophthalmic artery (OA) and superior ophthalmic vein (SOV) blood flow were quantified by phase contrast magnetic resonance imaging (PC MRI) and seemed lower in glaucoma. Venous flow dynamics was different in glaucoma patients with a significantly decreased pulsatility. INTRODUCTION Studies using color Doppler imaging and optical coherence tomography flowmetry strongly suggested that vascular changes are involved in the pathophysiology of glaucoma, but the venous outflow has been little studied beyond the episcleral veins. This study measured the OA and the SOV flow by PC MRI in glaucoma patients compared with controls. METHODS Eleven primary open-angle glaucoma patients, with a mean±SD visual field deficit of -2.3±2.7 dB and retinal nerve fiber layer thickness of 92±13 µ, and 10 controls of similar age, were examined by PC MRI. The mean, maximal and minimal flow over cardiac cycle were measured. The variation of flow (ΔQ) was calculated. RESULTS The OA mean±SD mean flow was 13.21±6.79 in patients and 15.09±7.62 mL/min in controls (P=0.35) and the OA maximal flow was 25.70±12.08 mL/min in patients, and 28.45±10.64 mL/min in controls (P=0.22). In the SOV the mean±SD mean flow was 6.46±5.50 mL/min in patients and 7.21±6.04 mL/min in controls (P=0.81) and the maximal flow was 9.06±6.67 in patients versus 11.96±9.29 mL/min in controls (P=0.47). The ΔQ in the SOV was significantly lower in patients (5.45±2.54 mL/min) than in controls (9.09±5.74 mL/min) (P=0.04). DISCUSSION Although no significant difference was found, the mean and maximal flow in the OA and SOV seemed lower in glaucoma patients than in controls. The SOV flow waveform might be affected in glaucoma, corroborating the hypothesis of an impairment of venous outflow in those patients.
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Kristiansen M, Lindén C, Qvarlander S, Wåhlin A, Ambarki K, Hallberg P, Eklund A, Jóhannesson G. Feasibility of MRI to assess differences in ophthalmic artery blood flow rate in normal tension glaucoma and healthy controls. Acta Ophthalmol 2021; 99:e679-e685. [PMID: 33210819 PMCID: PMC8451810 DOI: 10.1111/aos.14673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/05/2020] [Accepted: 10/14/2020] [Indexed: 11/30/2022]
Abstract
Purpose To examine feasibility of phase‐contrast magnetic resonance imaging (PCMRI) and to assess blood flow rate in the ophthalmic artery (OA) in patients with normal tension glaucoma (NTG) compared with healthy controls. Methods Sixteen patients with treated NTG and 16 age‐ and sex‐matched healthy controls underwent PCMRI using a 3‐Tesla scanner and ophthalmological examinations. OA blood flow rate was measured using a 2D PCMRI sequence with a spatial resolution of 0.35 mm2. Results The blood flow rate in the NTG group was 9.6 ± 3.9 ml/min [mean ± SD] compared with 11.9 ± 4.8 ml/min in the control group. Resistance Index (RI) and Pulsatility Index (PI) were 0.73 ± 0.08 and 1.36 ± 0.29, respectively, in the NTG group and 0.68 ± 0.13 and 1.22 ± 0.40, respectively, in the healthy group. The mean visual field index (VFI) was 46% ± 25 for the worse NTG eyes. The measured differences observed between the NTG group and the control group in blood flow rate (p = 0.12), RI (p = 0.18) and PI (p = 0.27) were non‐significant. Conclusions This case–control study, using PCMRI, showed a slight, but non‐significant, reduction in OA blood flow rate in the NTG patients compared with the healthy controls. These results indicate that blood flow may be of importance in the pathogenesis of NTG. Considering that only a limited portion of the total OA blood flow supplies the ocular system and the large inter‐individual differences, a larger study or more advanced PCMRI technique might give the answer.
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Affiliation(s)
- Martin Kristiansen
- Department of Clinical Sciences Ophthalmology Umeå University Umeå Sweden
| | - Christina Lindén
- Department of Clinical Sciences Ophthalmology Umeå University Umeå Sweden
| | - Sara Qvarlander
- Department of Radiation Sciences Biomedical Engineering Umeå University Umeå Sweden
- Centre for Biomedical Engineering and Physics Umeå University Umeå Sweden
| | - Anders Wåhlin
- Department of Radiation Sciences Biomedical Engineering Umeå University Umeå Sweden
- Centre for Biomedical Engineering and Physics Umeå University Umeå Sweden
- Umeå Center for Functional Brain Imaging Umeå University Umeå Sweden
| | - Khalid Ambarki
- Department of Radiation Sciences Biomedical Engineering Umeå University Umeå Sweden
- Centre for Biomedical Engineering and Physics Umeå University Umeå Sweden
| | - Per Hallberg
- Centre for Biomedical Engineering and Physics Umeå University Umeå Sweden
- Dept. of Applied Physics and Electronics Umeå University Umeå Sweden
| | - Anders Eklund
- Department of Radiation Sciences Biomedical Engineering Umeå University Umeå Sweden
- Centre for Biomedical Engineering and Physics Umeå University Umeå Sweden
| | - Gauti Jóhannesson
- Department of Clinical Sciences Ophthalmology Umeå University Umeå Sweden
- Wallenberg Center for Molecular Medicine Umeå University Umeå Sweden
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Rutland JW, Delman BN, Feldman RE, Tsankova N, Lin HM, Padormo F, Shrivastava RK, Balchandani P. Utility of 7 Tesla MRI for Preoperative Planning of Endoscopic Endonasal Surgery for Pituitary Adenomas. J Neurol Surg B Skull Base 2021; 82:303-312. [PMID: 34026406 PMCID: PMC8133814 DOI: 10.1055/s-0039-3400222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 09/28/2019] [Indexed: 10/25/2022] Open
Abstract
Objective There is increasing interest in investigating the utility of 7 Tesla (7 T) magnetic resonance imaging (MRI) for imaging of skull base tumors. The present study quantifies visualization of tumor features and adjacent skull base anatomy in a homogenous cohort of pituitary adenoma patients. Methods Eighteen pituitary adenoma patients were scanned at 7 T in this prospective study. All patients had reference standard-of-care clinical imaging at either 3 T (7/18, 39%) or 1.5 T (11/18, 61%). Visualization of tumor features and conspicuity of arteries and cranial nerves (CNs) was rated by an expert neuroradiologist on 7 T and clinical field strength MRI. Overall image quality and severity of image artifacts were also characterized and compared. Results Ability to visualize tumor features did not differ between 7 T and lower field MRI. Cranial nerves III, IV, and VI were better detected at 7 T compared with clinical field strength scans. Cranial nerves III, IV, and VI were also better detected at 7 T compared with only 1.5 T, and CN III was better visualized at 7 T compared with 3 T MRI. The ophthalmic arteries and posterior communicating arteries (PCOM) were better detected at 7 T compared with clinical field strength imaging. The 7 T also provided better visualization of the ophthalmic arteries compared with 1.5 T scans. Conclusion This study demonstrates that 7 T MRI is feasible at the skull base and identifies various CNs and branches of the internal carotid artery that were better visualized at 7 T. The 7 T MRI may offer important preoperative information that can help to guide resection of pituitary adenoma and reduce operative morbidity.
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Affiliation(s)
- John W. Rutland
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States
- Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Bradley N. Delman
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Rebecca E. Feldman
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Nadejda Tsankova
- Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Hung-Mo Lin
- Department of Population Health Science and Policy, Mount Sinai Hospital, New York, New York, United States
| | - Francesco Padormo
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States
- Department of Medical Physics, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Raj K. Shrivastava
- Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Priti Balchandani
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States
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van Hespen KM, Kuijf HJ, Hendrikse J, Luijten PR, Zwanenburg JJM. Blood Flow Velocity Pulsatility and Arterial Diameter Pulsatility Measurements of the Intracranial Arteries Using 4D PC-MRI. Neuroinformatics 2021; 20:317-326. [PMID: 34019208 PMCID: PMC9546978 DOI: 10.1007/s12021-021-09526-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2021] [Indexed: 10/28/2022]
Abstract
4D phase contrast magnetic resonance imaging (PC-MRI) allows for the visualization and quantification of the cerebral blood flow. A drawback of software that is used to quantify the cerebral blood flow is that it oftentimes assumes a static arterial luminal area over the cardiac cycle. Quantifying the lumen area pulsatility index (aPI), i.e. the change in lumen area due to an increase in distending pressure over the cardiac cycle, can provide insight in the stiffness of the arteries. Arterial stiffness has received increased attention as a predictor in the development of cerebrovascular disease. In this study, we introduce software that allows for measurement of the aPI as well as the blood flow velocity pulsatility index (vPI) from 4D PC-MRI. The internal carotid arteries of seven volunteers were imaged using 7 T MRI. The aPI and vPI measurements from 4D PC-MRI were validated against measurements from 2D PC-MRI at two levels of the internal carotid arteries (C3 and C7). The aPI and vPI computed from 4D PC-MRI were comparable to those measured from 2D PC-MRI (aPI: mean difference: 0.03 (limits of agreement: -0.14 - 0.23); vPI: 0.03 (-0.17-0.23)). The measured blood flow rate for the C3 and C7 segments was similar, indicating that our proposed software correctly captures the variation in arterial lumen area and blood flow velocity that exists along the distal end of the carotid artery. Our software may potentially aid in identifying changes in arterial stiffness of the intracranial arteries caused by pathological changes to the vessel wall.
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Affiliation(s)
| | - Hugo J Kuijf
- Image Sciences Institute, UMC Utrecht, Utrecht, The Netherlands
| | | | - Peter R Luijten
- Department of Radiology, UMC Utrecht, Utrecht, The Netherlands
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Zarrinkoob L, Wåhlin A, Ambarki K, Eklund A, Malm J. Quantification and mapping of cerebral hemodynamics before and after carotid endarterectomy, using four-dimensional flow magnetic resonance imaging. J Vasc Surg 2021; 74:910-920.e1. [PMID: 33812036 DOI: 10.1016/j.jvs.2021.01.074] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 01/26/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND Carotid stenosis can profoundly affect cerebral hemodynamics, which cannot simply be inferred from the degree of stenosis. We quantified and mapped the distribution of the blood flow rate (BFR) in the cerebral arteries before and after carotid endarterectomy using four-dimensional (4D) phase-contrast (PC) magnetic resonance imaging (MRI). METHODS Nineteen patients (age, 71 ± 6 years; 2 women) with symptomatic carotid stenosis (≥50%) undergoing carotid endarterectomy (CEA) were investigated using 4D PC-MRI before and after surgery. The BFR was measured in 17 cerebral arteries and the ophthalmic arteries. Collateral recruitment through the anterior and posterior communicating arteries, ophthalmic arteries, and leptomeningeal arteries was quantified. BFR laterality was significantly different between the paired contralateral and ipsilateral arteries. Subgroups were defined according to the presence of collateral recruitment. RESULTS The total cerebral blood flow had increased by 15% (P < .01) after CEA. Before CEA, laterality was seen in the internal carotid artery, anterior cerebral artery, and middle cerebral artery (MCA). On the ipsilateral side, an increased BFR was found after CEA in the internal carotid artery (246 ± 62 mL/min vs 135 ± 80 mL/min; P < .001), anterior cerebral artery (87 ± mL/min vs 38 ± 58 mL/min; P < .01), and MCA (149 ± 43 mL/min vs 119 ± 34 mL/min; P < .01), resulting in a postoperative BFR distribution without signs of laterality. In the nine patients with preoperatively recruited collaterals, BFR laterality was found in the MCA before, but not after, CEA (P < .01). This laterality was not found in the 10 patients without collateral recruitment (P = .2). The degree of stenosis did not differ between the groups with and without collateral recruitment (P = .85). CONCLUSIONS Using 4D PC-MRI, we have presented a comprehensive and noninvasive method to evaluate the cerebral hemodynamics due to carotid stenosis before and after CEA. MCA laterality, seen in the patients with collateral recruitment before CEA, pointed toward a hemodynamic disturbance in MCA territory for those patients. This methodologic advancement provides an insight into the pathophysiology of cerebral hemodynamics in patients with carotid stenosis.
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Affiliation(s)
- Laleh Zarrinkoob
- Division of Neuroscience, Department of Clinical Sciences, Umeå University, Umeå, Sweden; Department of Surgical and Perioperative Sciences, Umeå University, Umeå, Sweden.
| | - Anders Wåhlin
- Department of Radiation Sciences, Umeå University, Umeå, Sweden; Centre for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden; Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden
| | - Khalid Ambarki
- Department of Radiation Sciences, Umeå University, Umeå, Sweden; Centre for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden; Centre for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden
| | - Jan Malm
- Division of Neuroscience, Department of Clinical Sciences, Umeå University, Umeå, Sweden
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12
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Jóhannesson G, Qvarlander S, Wåhlin A, Ambarki K, Hallberg P, Eklund A, Lindén C. Intraocular Pressure Decrease Does Not Affect Blood Flow Rate of Ophthalmic Artery in Ocular Hypertension. Invest Ophthalmol Vis Sci 2020; 61:17. [PMID: 33074299 PMCID: PMC7585392 DOI: 10.1167/iovs.61.12.17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Purpose To investigate if decrease of IOP affects the volumetric blood flow rate in the ophthalmic artery (OA) in patients with previously untreated ocular hypertension. Methods Subjects with untreated ocular hypertension (n = 30; mean age 67 ± 8 years; 14 females) underwent ophthalmologic examination and a 3-Tesla magnetic resonance imaging investigation. The magnetic resonance imaging included three-dimensional high-resolution phase-contrast magnetic resonance imaging to measure the OA blood flow rate. The subjects received latanoprost once daily in the eye with higher pressure, the untreated eye served as control. The same measurements were repeated approximately 1 week later. Results The mean OA blood flow rate before and after treatment was 12.4 ± 4.4 and 12.4 ± 4.6 mL/min in the treated eye (mean ± SD; P = 0.92) and 13.5 ± 5.2 and 13.4 ± 4.1 mL/min in the control eye (P = 0.92). There was no significant difference between the treated and control eye regarding blood flow rate before (P = 0.13) or after treatment (P = 0.18), or change in blood flow rate after treatment (0.1 ± 3.1 vs. -0.1 ± 4.0 mL/min, P = 0.84). Latanoprost decreased the IOP by 7.2 ± 3.1 mm Hg in the treated eye (P < 0.01). Conclusions The results indicate that a significant lowering of IOP does not affect the blood flow rate of the OA in ocular hypertension subjects. The ability to maintain blood supply to the eye independent of the IOP could be a protective mechanism in preserving vision in subjects with ocular hypertension.
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Affiliation(s)
- Gauti Jóhannesson
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden.,Wallenberg Center for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Sara Qvarlander
- Department of Radiation Sciences, Biomedical Engineering, Umeå University, Umeå, Sweden.,Centre for Biomedical Engineering and Physics, Umeå University, Umeå Sweden
| | - Anders Wåhlin
- Department of Radiation Sciences, Biomedical Engineering, Umeå University, Umeå, Sweden.,Centre for Biomedical Engineering and Physics, Umeå University, Umeå Sweden.,Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden
| | - Khalid Ambarki
- Department of Radiation Sciences, Biomedical Engineering, Umeå University, Umeå, Sweden
| | - Per Hallberg
- Centre for Biomedical Engineering and Physics, Umeå University, Umeå Sweden.,Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden
| | - Anders Eklund
- Department of Radiation Sciences, Biomedical Engineering, Umeå University, Umeå, Sweden.,Centre for Biomedical Engineering and Physics, Umeå University, Umeå Sweden
| | - Christina Lindén
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden
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13
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Zarrinkoob L, Wåhlin A, Ambarki K, Birgander R, Eklund A, Malm J. Blood Flow Lateralization and Collateral Compensatory Mechanisms in Patients With Carotid Artery Stenosis. Stroke 2020; 50:1081-1088. [PMID: 30943887 PMCID: PMC6485302 DOI: 10.1161/strokeaha.119.024757] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Background and Purpose- Four-dimensional phase-contrast magnetic resonance imaging enables quantification of blood flow rate (BFR; mL/min) in multiple cerebral arteries simultaneously, making it a promising technique for hemodynamic investigation in patients with stroke. The aim of this study was to quantify the hemodynamic disturbance and the compensatory pattern of collateral flow in patients with symptomatic carotid stenosis. Methods- Thirty-eight patients (mean, 72 years; 27 men) with symptomatic carotid stenosis (≥50%) or occlusion were investigated using 4-dimensional phase-contrast magnetic resonance imaging. For each patient, BFR was measured in 19 arteries/locations. The ipsilateral side to the symptomatic carotid stenosis was compared with the contralateral side. Results- Internal carotid artery BFR was lower on the ipsilateral side (134±87 versus 261±95 mL/min; P<0.001). BFR in anterior cerebral artery (A1 segment) was lower on ipsilateral side (35±58 versus 119±72 mL/min; P<0.001). Anterior cerebral artery territory bilaterally was primarily supplied by contralateral internal carotid artery. The ipsilateral internal carotid artery mainly supplied the ipsilateral middle cerebral artery (MCA) territory. MCA was also supplied by a reversed BFR found in the ophthalmic and the posterior communicating artery routes on the ipsilateral side (-5±28 versus 10±28 mL/min, P=0.001, and -2±12 versus 6±6 mL/min, P=0.03, respectively). Despite these compensations, BFR in MCA was lower on the ipsilateral side, and this laterality was more pronounced in patients with severe carotid stenosis (≥70%). Although comparing ipsilateral MCA BFR between stenosis groups (<70% and ≥70%), there was no difference ( P=0.95). Conclusions- With a novel approach using 4-dimensional phase-contrast magnetic resonance imaging, we could simultaneously quantify and rank the importance of collateral routes in patients with carotid stenosis. An important observation was that contralateral internal carotid artery mainly secured the bilateral anterior cerebral artery territory. Because of the collateral recruitment, compromised BFR in MCA is not necessarily related to the degree of carotid stenosis. These findings highlight the importance of simultaneous investigation of the hemodynamics of the entire cerebral arterial tree.
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Affiliation(s)
- Laleh Zarrinkoob
- From the Department of Pharmacology and Clinical Neuroscience, Umeå, Sweden (L.Z., J.M.).,Department of Surgical and Perioperative Sciences, Umeå, Sweden (L.Z.)
| | - Anders Wåhlin
- Department of Radiation Science, Umeå, Sweden (A.W., K.A., R.B., A.E.).,Centre for Biomedical Engineering and Physics, Umeå, Sweden (A.W., K.A., A.E.).,Umeå Center for Functional Brain Imaging, Sweden (A.W., A.E.)
| | - Khalid Ambarki
- Department of Radiation Science, Umeå, Sweden (A.W., K.A., R.B., A.E.).,Centre for Biomedical Engineering and Physics, Umeå, Sweden (A.W., K.A., A.E.)
| | - Richard Birgander
- Department of Radiation Science, Umeå, Sweden (A.W., K.A., R.B., A.E.)
| | - Anders Eklund
- Department of Radiation Science, Umeå, Sweden (A.W., K.A., R.B., A.E.).,Centre for Biomedical Engineering and Physics, Umeå, Sweden (A.W., K.A., A.E.).,Umeå Center for Functional Brain Imaging, Sweden (A.W., A.E.)
| | - Jan Malm
- From the Department of Pharmacology and Clinical Neuroscience, Umeå, Sweden (L.Z., J.M.)
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14
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Birnefeld J, Wåhlin A, Eklund A, Malm J. Cerebral arterial pulsatility is associated with features of small vessel disease in patients with acute stroke and TIA: a 4D flow MRI study. J Neurol 2019; 267:721-730. [PMID: 31728712 PMCID: PMC7035303 DOI: 10.1007/s00415-019-09620-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 10/30/2019] [Accepted: 11/02/2019] [Indexed: 11/16/2022]
Abstract
Cerebral small vessel disease (SVD) is a major cause of stroke and cognitive impairment. However, the underlying mechanisms behind SVD are still poorly understood. High cerebral arterial pulsatility has been suggested as a possible cause of SVD. In population studies, arterial pulsatility has been linked to white matter hyperintensities (WMH), cerebral atrophy, and cognitive impairment, all features of SVD. In stroke, pulsatility data are scarce and contradictory. The aim of this study was to investigate the relationship between arterial pulsatility and SVD in stroke patients. With a cross-sectional design, 89 patients with acute ischemic stroke or TIA were examined with MRI. A neuropsychological assessment was performed 1 year later. Using 4D flow MRI, pulsatile indices (PI) were calculated for the internal carotid artery (ICA) and middle cerebral artery (M1, M3). Flow volume pulsatility (FVP), a measure corresponding to the cyclic expansion of the arterial tree, was calculated for the same locations. These parameters were assessed for associations with WMH volume, brain volume and cognitive function. ICA-FVP was associated with WMH volume (β = 1.67, 95% CI: [0.1, 3.24], p = 0.037). M1-PI and M1-FVP were associated with decreasing cognitive function (β = − 4.4, 95% CI: [− 7.7, − 1.1], p = 0.009 and β = − 13.15, 95% CI: [− 24.26, − 2.04], p = 0.02 respectively). In summary, this supports an association between arterial pulsatility and SVD in stroke patients, and provides a potential target for further research and preventative treatment. FVP may become a useful biomarker for assessing pulsatile stress with PCMRI and 4D flow MRI.
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Affiliation(s)
- Johan Birnefeld
- Department of Pharmacology and Clinical Neuroscience, Umeå University, 90187, Umeå, Sweden.
| | - Anders Wåhlin
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Umeå Centre for Functional Brain Imaging, Umeå University, Umeå, Sweden
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Centre for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden
| | - Jan Malm
- Department of Pharmacology and Clinical Neuroscience, Umeå University, 90187, Umeå, Sweden
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15
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Holmgren M, Wåhlin A, Dunås T, Malm J, Eklund A. Assessment of Cerebral Blood Flow Pulsatility and Cerebral Arterial Compliance With 4D Flow MRI. J Magn Reson Imaging 2019; 51:1516-1525. [PMID: 31713964 PMCID: PMC7216927 DOI: 10.1002/jmri.26978] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/08/2019] [Accepted: 10/08/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Four-dimensional flow magnetic resonance imaging (4D flow MRI) enables efficient investigation of cerebral blood flow pulsatility in the cerebral arteries. This is important for exploring hemodynamic mechanisms behind vascular diseases associated with arterial pulsations. PURPOSE To investigate the feasibility of pulsatility assessments with 4D flow MRI, its agreement with reference two-dimensional phase-contrast MRI (2D PC-MRI) measurements, and to demonstrate how 4D flow MRI can be used to assess cerebral arterial compliance and cerebrovascular resistance in major cerebral arteries. STUDY TYPE Prospective. SUBJECTS Thirty-five subjects (20 women, 79 ± 5 years, range 70-91 years). FIELD STRENGTH/SEQUENCE 4D flow MRI (PC-VIPR) and 2D PC-MRI acquired with a 3T scanner. ASSESSMENT Time-resolved flow was assessed in nine cerebral arteries. From the pulsatile flow waveform in each artery, amplitude (ΔQ), volume load (ΔV), and pulsatility index (PI) were calculated. To reduce high-frequency noise in the 4D flow MRI data, the flow waveforms were low-pass filtered. From the total cerebral blood flow, total PI (PItot ), total volume load (ΔVtot ), cerebral arterial compliance (C), and cerebrovascular resistance (R) were calculated. STATISTICAL TESTS Two-tailed paired t-test, intraclass correlation (ICC). RESULTS There was no difference in ΔQ between 4D flow MRI and the reference (0.00 ± 0.022 ml/s, mean ± SEM, P = 0.97, ICC = 0.95, n = 310) with a cutoff frequency of 1.9 Hz and 15 cut plane long arterial segments. For ΔV, the difference was -0.006 ± 0.003 ml (mean ± SEM, P = 0.07, ICC = 0.93, n = 310) without filtering. Total R was 11.4 ± 2.41 mmHg/(ml/s) (mean ± SD) and C was 0.021 ± 0.009 ml/mmHg (mean ± SD). ΔVtot was 1.21 ± 0.29 ml (mean ± SD) with an ICC of 0.82 compared with the reference. PItot was 1.08 ± 0.21 (mean ± SD). DATA CONCLUSION We successfully assessed 4D flow MRI cerebral arterial pulsatility, cerebral arterial compliance, and cerebrovascular resistance. Averaging of multiple cut planes and low-pass filtering was necessary to assess accurate peak-to-peak features in the flow rate waveforms. LEVEL OF EVIDENCE 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:1516-1525.
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Affiliation(s)
| | - Anders Wåhlin
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden
| | - Tora Dunås
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden.,Center for Demographic and Aging Research, Umeå University, Umeå, Sweden
| | - Jan Malm
- Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden
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16
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Makki MI, O'Gorman RL, Buhler P, Baledent O, Kellenberger CJ, Sabandal C, Weiss M, Scheer I, Schmitz A. Total cerebrovascular blood flow and whole brain perfusion in children sedated using propofol with or without ketamine at induction: An investigation with 2D-Cine PC and ASL. J Magn Reson Imaging 2019; 50:1433-1440. [PMID: 30892782 DOI: 10.1002/jmri.26725] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/06/2019] [Accepted: 03/07/2019] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Multiple sedation regimes may be used to facilitate pediatric MRI scans. These regimes might affect cerebral blood flow and hemodynamics to varying degrees, particularly in children who may be vulnerable to anesthetic side effects. PURPOSE To compare the effects of propofol monosedation solely (Pm group) vs. a combination of propofol and ketamine (KP group) on brain hemodynamics and perfusion. STUDY TYPE Prospective double-blind randomized trial. FIELD STRENGTH/SEQUENCES 1.5T and 3T. 2D-Cine phase contrast (2D-Cine PC) and pseudocontinuous arterial spin labeling (ASL). POPULATION Children aged from 3 months to 10 years referred for MRI with deep sedation were randomized into either the KP or the Pm group. Perfusion images were acquired with ASL followed by single-slice 2D-Cine PC acquired between the cervical vertebra C2 and C3. ASSESSMENT Average whole-brain perfusion (WBP ml.min-1 .100 ml-1 ) was extracted from the ASL perfusion maps and total cerebrovascular blood flow (CVF) was quantified by bilaterally summing the flow in the vertebral and the internal carotid arteries. The CVF values were converted to units of ml.min-1 .100 g-1 to calculate the tissue CVF100g (ml.min-1 .100 g-1 ). Images were assessed by a neuroradiologist and data from n = 81 (ASL) and n = 55 (PC) cases with no apparent pathology were entered into the analysis. STATISTICAL TESTS Multivariate analysis of covariance was performed to compare drug sedation effects on WBP, CVF, and CVF100g . RESULTS No significant difference in arterial flow was observed (P = 0.57), but the KP group showed significantly higher WBP than the Pm group, covarying for scanner and age (P = 0.003). A correlation analysis showed a significant positive correlation between mean WBP (ml.min-1 .100 g-1 ) and mean CVF100g . DATA CONCLUSION The KP group showed higher perfusion but no significant difference in vascular flow compared with the Pm group. WBP and CVF100g correlated significantly, but ASL appeared to have more susceptibility to perfusion differences arising from the different sedation regimes. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2019;50:1433-1440.
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Affiliation(s)
- Malek I Makki
- MRI Research Center, University Children's Hospital, Zurich, Switzerland.,Children's Research Center, University Children's Hospital, Zurich, Switzerland.,MRI Research GIE-FF, CHU Amiens Picardie, Amiens, France
| | - Ruth L O'Gorman
- MRI Research Center, University Children's Hospital, Zurich, Switzerland.,Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Philip Buhler
- Anesthesia, University Children Hospital, Zurich, Switzerland
| | | | - Christian J Kellenberger
- Children's Research Center, University Children's Hospital, Zurich, Switzerland.,Department of Diagnostic Radiology, University Children's Hospital, Zurich, Switzerland
| | - Carola Sabandal
- Children's Research Center, University Children's Hospital, Zurich, Switzerland.,Anesthesia, University Children Hospital, Zurich, Switzerland
| | - Markus Weiss
- Children's Research Center, University Children's Hospital, Zurich, Switzerland.,Anesthesia, University Children Hospital, Zurich, Switzerland
| | - Ianina Scheer
- Children's Research Center, University Children's Hospital, Zurich, Switzerland.,Department of Diagnostic Radiology, University Children's Hospital, Zurich, Switzerland
| | - Achim Schmitz
- Children's Research Center, University Children's Hospital, Zurich, Switzerland.,Anesthesia, University Children Hospital, Zurich, Switzerland
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17
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Quantification of blood flow in the superior ophthalmic vein using phase contrast magnetic resonance imaging. Exp Eye Res 2018; 176:40-45. [DOI: 10.1016/j.exer.2018.06.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 06/18/2018] [Accepted: 06/26/2018] [Indexed: 11/22/2022]
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18
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Manicam C, Ginter N, Li H, Xia N, Goloborodko E, Zadeh JK, Musayeva A, Pfeiffer N, Gericke A. Compensatory Vasodilator Mechanisms in the Ophthalmic Artery of Endothelial Nitric Oxide Synthase Gene Knockout Mice. Sci Rep 2017; 7:7111. [PMID: 28769073 PMCID: PMC5541003 DOI: 10.1038/s41598-017-07768-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 06/29/2017] [Indexed: 01/02/2023] Open
Abstract
Nitric oxide (NO) generated by endothelial nitric oxide synthase (eNOS) plays an important role in the maintenance of ocular vascular homeostasis. Therefore, perturbations in vascular NO synthesis have been implicated in the pathogenesis of several ocular diseases. We recently reported that eNOS contributes significantly to vasodilation of the mouse ophthalmic artery. Interestingly, dilatory responses were also retained in eNOS gene-deficient mice (eNOS-/-), indicating inherent endothelial adaptive mechanism(s) that act as back-up systems in chronic absence of eNOS to preserve vasorelaxation. Thus, this study endeavoured to identify the compensatory mechanism(s) in the ophthalmic artery of eNOS-/- mice employing isolated arterial segments and pharmacological inhibitors in vitro. Endothelium removal virtually abolished acetylcholine (ACh)-induced vasodilation, suggesting an obligatory involvement of the endothelium in cholinergic control of vascular tone. However, non-NOS and non-cyclooxygenase components compensate for eNOS deficiency via endothelium-derived hyperpolarizing factors (EDHFs). Notably, arachidonic acid-derived metabolites of the 12-lipoxygenase pathway were key mediators in activating the inwardly rectifying potassium channels to compensate for chronic lack of eNOS. Conclusively, endothelium-dependent cholinergic responses of the ophthalmic artery in the eNOS-/- mice are largely preserved and, this vascular bed has the ability to compensate for the loss of normal vasodilator responses solely via EDHFs.
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Affiliation(s)
- Caroline Manicam
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany.
| | - Natalja Ginter
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Huige Li
- Institute of Pharmacology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Ning Xia
- Institute of Pharmacology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Evgeny Goloborodko
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Jenia Kouchek Zadeh
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Aytan Musayeva
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Norbert Pfeiffer
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Adrian Gericke
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
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19
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Misiulis E, Džiugys A, Navakas R, Striūgas N. A fluid-structure interaction model of the internal carotid and ophthalmic arteries for the noninvasive intracranial pressure measurement method. Comput Biol Med 2017; 84:79-88. [DOI: 10.1016/j.compbiomed.2017.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 03/15/2017] [Accepted: 03/17/2017] [Indexed: 01/09/2023]
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20
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Bäcklund T, Frankel J, Israelsson H, Malm J, Sundström N. Trunk sway in idiopathic normal pressure hydrocephalus-Quantitative assessment in clinical practice. Gait Posture 2017; 54:62-70. [PMID: 28259041 DOI: 10.1016/j.gaitpost.2017.02.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 01/31/2017] [Accepted: 02/19/2017] [Indexed: 02/02/2023]
Abstract
BACKGROUND In diagnosis and treatment of patients with idiopathic normal pressure hydrocephalus (iNPH), there is need for clinically applicable, quantitative assessment of balance and gait. Using a body-worn gyroscopic system, the aim of this study was to assess postural stability of iNPH patients in standing, walking and during sensory deprivation before and after cerebrospinal fluid (CSF) drainage and surgery. A comparison was performed between healthy elderly (HE) and patients with various types of hydrocephalus (ventriculomegaly (VM)). METHODS Trunk sway was measured in 31 iNPH patients, 22 VM patients and 58 HE. Measurements were performed at baseline in all subjects, after CSF drainage in both patient groups and after shunt surgery in the iNPH group. RESULTS Preoperatively, the iNPH patients had significantly higher trunk sway compared to HE, specifically for the standing tasks (p<0.001). Compared to VM, iNPH patients had significantly lower sway velocity during gait in three of four cases on firm support (p<0.05). Sway velocity improved after CSF drainage and in forward-backward direction after surgery (p<0.01). Compared to HE both patient groups demonstrated less reliance on visual input to maintain stable posture. CONCLUSIONS INPH patients had reduced postural stability compared to HE, particularly during standing, and for differentiation between iNPH and VM patients sway velocity during gait is a promising parameter. A reversible reduction of visual incorporation during standing was also seen. Thus, the gyroscopic system quantitatively assessed postural deficits in iNPH, making it a potentially useful tool for aiding in future diagnoses, choices of treatment and clinical follow-up.
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Affiliation(s)
- Tomas Bäcklund
- Department of Radiation Sciences, Biomedical Engineering, Umeå University, Umeå, Sweden.
| | - Jennifer Frankel
- Department of Radiation Sciences, Radiation Physics, Umeå University, Umeå, Sweden.
| | - Hanna Israelsson
- Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden; Vrinnevi Hospital, Norrköping, Sweden.
| | - Jan Malm
- Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden.
| | - Nina Sundström
- Department of Radiation Sciences, Biomedical Engineering, Umeå University, Umeå, Sweden.
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21
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Sekine T, Takagi R, Amano Y, Murai Y, Orita E, Fukushima Y, Matsumura Y, Kumita SI. 4D Flow MR Imaging of Ophthalmic Artery Flow in Patients with Internal Carotid Artery Stenosis. Magn Reson Med Sci 2017; 17:13-20. [PMID: 28367905 PMCID: PMC5760228 DOI: 10.2463/mrms.mp.2016-0074] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Background and Purpose: To assess the clinical feasibility of time-resolved 3D phase contrast (4D Flow) MRI assessment of the ophthalmic artery (OphA) flow in patients with internal carotid artery stenosis (ICS). Materials and Methods: Twenty-one consecutive patients with unilateral ICS were recruited. 4D Flow MRI and acetazolamide-stress brain perfusion single photon emission computed tomography (SPECT) were performed. The flow direction on the affected-side OphA was categorized into native flow (anterograde or unclear) and non-native flow (retrograde flow) based on 4D Flow MRI. In the affected-side middle cerebral artery (MCA) territory, the ratio of rest cerebral blood flow to normal control (RCBFMCA) and cerebral vascular reserve (CVRMCA) were calculated from SPECT dataset. High-risk patients were defined based on the previous large cohort study (RCBFMCA < 80% and CVRMCA < 10%). Results: Eleven patients had native OphA flow (4 anterograde, 7 unclear) and the remaining 10 had non-native OphA flow. RCBFMCA and CVRMCA each were significantly lower in non-native flow group (84.9 ± 18.9% vs. 69.8 ± 7.3%, P < 0.05; 36.4 ± 20.6% vs. 17.0 ± 15.0%, P < 0.05). Four patients in the non-native flow group and none in the native flow group were confirmed as high-risk (Sensitivity/Specificity, 1.00/0.65). Conclusion: The 6 min standard 4D Flow MRI assessment of OphA in patients with ICS can predict intracranial hemodynamic impairment.
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Affiliation(s)
- Tetsuro Sekine
- Department of Medical Radiology, University Hospital Zurich.,Department of Radiology, Nippon Medical School
| | - Ryo Takagi
- Department of Radiology, Nippon Medical School
| | - Yasuo Amano
- Department of Radiology, Nippon Medical School
| | - Yasuo Murai
- Department of Neurological Surgery, Nippon Medical School
| | - Erika Orita
- Department of Radiology, Nippon Medical School
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22
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Zarrinkoob L, Ambarki K, Wåhlin A, Birgander R, Carlberg B, Eklund A, Malm J. Aging alters the dampening of pulsatile blood flow in cerebral arteries. J Cereb Blood Flow Metab 2016; 36:1519-27. [PMID: 26823470 PMCID: PMC5012521 DOI: 10.1177/0271678x16629486] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 12/28/2015] [Indexed: 01/13/2023]
Abstract
Excessive pulsatile flow caused by aortic stiffness is thought to be a contributing factor for several cerebrovascular diseases. The main purpose of this study was to describe the dampening of the pulsatile flow from the proximal to the distal cerebral arteries, the effect of aging and sex, and its correlation to aortic stiffness. Forty-five healthy elderly (mean age 71 years) and 49 healthy young (mean age 25 years) were included. Phase-contrast magnetic resonance imaging was used for measuring blood flow pulsatility index and dampening factor (proximal artery pulsatility index/distal artery pulsatility index) in 21 cerebral and extra-cerebral arteries. Aortic stiffness was measured as aortic pulse wave velocity. Cerebral arterial pulsatility index increased due to aging and this was more pronounced in distal segments of cerebral arteries. There was no difference in pulsatility index between women and men. Dampening of pulsatility index was observed in all cerebral arteries in both age groups but was significantly higher in young subjects than in elderly. Pulse wave velocity was not correlated with cerebral arterial pulsatility index. The increased pulsatile flow in elderly together with reduced dampening supports the pulse wave encephalopathy theory, since it implies that a higher pulsatile flow is reaching distal arterial segments in older subjects.
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Affiliation(s)
- Laleh Zarrinkoob
- Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - Khalid Ambarki
- Department of Radiation Sciences, Umeå University, Umeå, Sweden Centre for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden
| | - Anders Wåhlin
- Department of Radiation Sciences, Umeå University, Umeå, Sweden Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden
| | | | - Bo Carlberg
- Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden Centre for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden
| | - Jan Malm
- Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden
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23
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Postural stability in patients with chronic subdural hematoma. Acta Neurochir (Wien) 2016; 158:1479-85. [PMID: 27290662 DOI: 10.1007/s00701-016-2862-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/26/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Gait disturbances and falls are common in patients with chronic subdural hematoma (cSDH). Postural stability is mainly visually assessed and has not been described using an objective and quantitative measurement tool. The objective of this prospective study was to evaluate postural stability in cSDH patients by measuring trunk sway during stance and gait compared to healthy elderly (HE). It was also to evaluate the relationships among postural stability and age, hematoma size, brain midline shift and hematoma location. METHODS Using a gyroscopic method, trunk sway was measured in 22 cSDH patients preoperatively, 5 postoperatively and 58 HE during seven standing and walking tasks. Trunk sway amplitude and velocity in the anterior-posterior and medial-lateral directions were assessed. RESULTS Postural stability was reduced in the cSDH group compared to HE for all standing tasks. During gait, the sway angle was increased while velocity was decreased in the cSDH group. Only 18 % of the patients could perform all tasks without losing their balance. Postoperatively, postural stability was normalized in the medial-lateral direction during standing. There were no correlations among age, hematoma size, brain midline shift or location of the hematoma and trunk sway. CONCLUSIONS The majority of cSDH patients had reduced postural stability that was partly reversed soon after surgery. It was not correlated to hematoma characteristics, indicating that an increased risk to fall is present regardless of hematoma size and midline shift. This must be accounted for when handling these patients and measures taken to prevent further fall accidents during hospital stays.
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24
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Promelle V, Daouk J, Bouzerar R, Jany B, Milazzo S, Balédent O. Ocular blood flow and cerebrospinal fluid pressure in glaucoma. Acta Radiol Open 2016; 5:2058460115624275. [PMID: 26962460 PMCID: PMC4765818 DOI: 10.1177/2058460115624275] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 12/01/2015] [Indexed: 11/08/2022] Open
Abstract
Disease mechanism underlying glaucoma remains unclear. Extensive research on this pathology has highlighted changes in vascular parameters and in circulation of the cerebrospinal fluid (CSF). Here, we review the most recent research on alterations in ocular blood flow and/or CSF flow in glaucoma. Ultrasound Doppler imaging studies have shown an increased resistive index in ophthalmic artery’s in glaucoma. Furthermore, changes in optic nerve CSF circulation, which can be assessed with magnetic resonance imaging, may lead to a greater translaminar pressure difference, mechanical stress, and poor clearance of toxic substances. This constitutes a new approach for understanding blood–CSF interactions involved in glaucoma.
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Affiliation(s)
- Véronique Promelle
- Ophthalmology Department, Amiens University Medical Center, Amiens, France
| | - Joël Daouk
- Bioflow Image Unit, Jules Verne University of Picardie, Amiens, France
| | - Roger Bouzerar
- Bioflow Image Unit, Jules Verne University of Picardie, Amiens, France; Medical Image Processing Unit, Amiens University Medical Center, Amiens, France
| | - Benjamin Jany
- Ophthalmology Department, Amiens University Medical Center, Amiens, France
| | - Solange Milazzo
- Ophthalmology Department, Amiens University Medical Center, Amiens, France
| | - Olivier Balédent
- Bioflow Image Unit, Jules Verne University of Picardie, Amiens, France; Medical Image Processing Unit, Amiens University Medical Center, Amiens, France
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25
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Ambarki K, Wåhlin A, Zarrinkoob L, Wirestam R, Petr J, Malm J, Eklund A. Accuracy of Parenchymal Cerebral Blood Flow Measurements Using Pseudocontinuous Arterial Spin-Labeling in Healthy Volunteers. AJNR Am J Neuroradiol 2015; 36:1816-21. [PMID: 26251434 DOI: 10.3174/ajnr.a4367] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 02/16/2015] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The arterial spin-labeling method for CBF assessment is widely available, but its accuracy is not fully established. We investigated the accuracy of a whole-brain arterial spin-labeling technique for assessing the mean parenchymal CBF and the effect of aging in healthy volunteers. Phase-contrast MR imaging was used as the reference method. MATERIALS AND METHODS Ninety-two healthy volunteers were included: 49 young (age range, 20-30 years) and 43 elderly (age range, 65-80 years). Arterial spin-labeling parenchymal CBF values were averaged over the whole brain to quantify the mean pCBF(ASL) value. Total CBF was assessed with phase-contrast MR imaging as the sum of flows in the internal carotid and vertebral arteries, and subsequent division by brain volume returned the pCBF(PCMRI) value. Accuracy was considered as good as that of the reference method if the systematic difference was less than 5 mL/min/100 g of brain tissue and if the 95% confidence intervals were equal to or better than ±10 mL/min/100 g. RESULTS pCBF(ASL) correlated to pCBF(PCMRI) (r = 0.73; P < .001). Significant differences were observed between the pCBF(ASL) and pCBF(PCMRI) values in the young (P = .001) and the elderly (P < .001) volunteers. The systematic differences (mean ± 2 standard deviations) were -4 ± 14 mL/min/100 g in the young subjects and 6 ± 12 mL/min/100 g in the elderly subjects. Young subjects showed higher values than the elderly subjects for pCBF(PCMRI) (young, 57 ± 8 mL/min/100 g; elderly, 54 ± 7 mL/min/100 g; P = .05) and pCBF(ASL) (young, 61 ± 10 mL/min/100 g; elderly, 48 ± 10 mL/min/100 g; P < .001). CONCLUSIONS The limits of agreement were too wide for the arterial spin-labeling method to be considered satisfactorily accurate, whereas the systematic overestimation in the young subjects and underestimation in the elderly subjects were close to acceptable. The age-related decrease in parenchymal CBF was augmented in arterial spin-labeling compared with phase-contrast MR imaging.
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Affiliation(s)
- K Ambarki
- From the Department of Radiation Sciences (K.A., A.W., A.E.) Centre for Biomedical Engineering and Physics (K.A., A.E.)
| | - A Wåhlin
- From the Department of Radiation Sciences (K.A., A.W., A.E.) Center for Functional Brain Imaging (A.W., A.E.)
| | - L Zarrinkoob
- Department of Clinical Neuroscience (L.Z., J.M.), Umeå University, Umeå, Sweden
| | - R Wirestam
- Department of Medical Radiation Physics (R.W.), Lund University, Lund, Sweden
| | - J Petr
- PET Center (J.P.), Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - J Malm
- Department of Clinical Neuroscience (L.Z., J.M.), Umeå University, Umeå, Sweden
| | - A Eklund
- From the Department of Radiation Sciences (K.A., A.W., A.E.) Centre for Biomedical Engineering and Physics (K.A., A.E.) Center for Functional Brain Imaging (A.W., A.E.)
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26
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Jóhannesson G, Hallberg P, Ambarki K, Eklund A, Lindén C. Age-dependency of ocular parameters: a cross sectional study of young and elderly healthy subjects. Graefes Arch Clin Exp Ophthalmol 2015; 253:1979-83. [DOI: 10.1007/s00417-015-3129-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/28/2015] [Accepted: 07/28/2015] [Indexed: 10/23/2022] Open
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27
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Schrauben E, Wåhlin A, Ambarki K, Spaak E, Malm J, Wieben O, Eklund A. Fast 4D flow MRI intracranial segmentation and quantification in tortuous arteries. J Magn Reson Imaging 2015; 42:1458-64. [PMID: 25847621 DOI: 10.1002/jmri.24900] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 03/13/2015] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To describe, validate, and implement a centerline processing scheme (CPS) for semiautomated segmentation and quantification in carotid siphons of healthy subjects. 4D flow MRI enables blood flow measurement in all major cerebral arteries with one scan. Clinical translational hurdles are time demanding postprocessing and user-dependence induced variability during analysis. MATERIALS AND METHODS A CPS for 4D flow data was developed to automatically separate cerebral artery trees. Flow parameters were quantified at planes along the centerline oriented perpendicular to the vessel path. At 3T, validation against 2D phase-contrast (PC) magnetic resonance imaging (MRI) and 4D flow manual processing was performed on an intracranial flow phantom for constant flow, while pulsatile flow validation was performed in the internal carotid artery (ICA) of 10 healthy volunteers. The CPS and 4D manual processing times were measured and compared. Flow and area measurements were also demonstrated along the length of the ICA siphon. RESULTS Phantom measurements for area and flow were highly correlated between the CPS and 2D measurements (area: R = 0.95, flow: R = 0.94), while in vivo waveforms were highly correlated (R = 0.93). Processing time was reduced by a factor of 4.6 compared with manual processing. Whole ICA measurements revealed a significantly decreased area in the most distal segment of the carotid siphon (P = 0.0017), with flow unchanged (P = 0.84). CONCLUSION This study exhibits fast semiautomated analysis of intracranial 4D flow MRI. Internal consistency was shown through flow conservation along the tortuous ICA siphon, which is typically difficult to assess.
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Affiliation(s)
- Eric Schrauben
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, USA.,Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Anders Wåhlin
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Umeå, Sweden.,Department of Radiology, University of Wisconsin - Madison, Madison, Wisconsin, USA
| | - Khalid Ambarki
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Center for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden
| | - Erik Spaak
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Jan Malm
- Department of Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, USA.,Department of Radiology, University of Wisconsin - Madison, Madison, Wisconsin, USA
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.,Center for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden
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28
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Blood flow distribution in cerebral arteries. J Cereb Blood Flow Metab 2015; 35:648-54. [PMID: 25564234 PMCID: PMC4420884 DOI: 10.1038/jcbfm.2014.241] [Citation(s) in RCA: 203] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/11/2014] [Accepted: 12/03/2014] [Indexed: 01/25/2023]
Abstract
High-resolution phase-contrast magnetic resonance imaging can now assess flow in proximal and distal cerebral arteries. The aim of this study was to describe how total cerebral blood flow (tCBF) is distributed into the vascular tree with regard to age, sex and anatomic variations. Forty-nine healthy young (mean 25 years) and 45 elderly (mean 71 years) individuals were included. Blood flow rate (BFR) in 21 intra- and extracerebral arteries was measured. Total cerebral blood flow was defined as BFR in the internal carotid plus vertebral arteries and mean cerebral perfusion as tCBF/brain volume. Carotid/vertebral distribution was 72%/28% and was not related to age, sex, or brain volume. Total cerebral blood flow (717 ± 123 mL/min) was distributed to each side as follows: middle cerebral artery (MCA), 21%; distal MCA, 6%; anterior cerebral artery (ACA), 12%, distal ACA, 4%; ophthalmic artery, 2%; posterior cerebral artery (PCA), 8%; and 20% to basilar artery. Deviating distributions were observed in subjects with 'fetal' PCA. Blood flow rate in cerebral arteries decreased with increasing age (P<0.05) but not in extracerebral arteries. Mean cerebral perfusion was higher in women (women: 61 ± 8; men: 55 ± 6 mL/min/100 mL, P<0.001). The study describes a new method to outline the flow profile of the cerebral vascular tree, including reference values, and should be used for grading the collateral flow system.
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29
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Keegan J, Patel HC, Simpson RM, Mohiaddin RH, Firmin DN. Inter-study reproducibility of interleaved spiral phase velocity mapping of renal artery haemodynamics. J Cardiovasc Magn Reson 2015; 17:8. [PMID: 25648103 PMCID: PMC4316806 DOI: 10.1186/s12968-014-0105-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 12/16/2014] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Qualitative and quantitative assessment of renal blood flow is valuable in the evaluation of patients with renal and renovascular diseases as well as in patients with heart failure. The temporal pattern of renal flow velocity through the cardiac cycle provides important information about renal haemodynamics. High temporal resolution interleaved spiral phase velocity mapping could potentially be used to study temporal patterns of flow and measure resistive and pulsatility indices which are measures of downstream resistance. METHODS A retrospectively gated breath-hold spiral phase velocity mapping sequence (TR 19 ms) was developed at 3 Tesla. Phase velocity maps were acquired in the proximal right and left arteries of 10 healthy subjects in each of two separate scanning sessions. Each acquisition was analysed by two independent observers who calculated the resistive index (RI), the pulsatility index (PI), the mean flow velocity and the renal artery blood flow (RABF). Inter-study and inter-observer reproducibility of each variable was determined as the mean +/- standard deviation of the differences between paired values. The effect of background phase errors on each parameter was investigated. RESULTS RI, PI, mean velocity and RABF per kidney were 0.71+/- 0.06, 1.47 +/- 0.29, 253.5 +/- 65.2 mm/s and 413 +/- 122 ml/min respectively. The inter-study reproducibilities were: RI -0.00 +/- 0.04 , PI -0.03 +/- 0.17, mean velocity -6.7 +/- 31.1 mm/s and RABF per kidney 17.9 +/- 44.8 ml/min. The effect of background phase errors was negligible (<2% for each parameter). CONCLUSIONS High temporal resolution breath-hold spiral phase velocity mapping allows reproducible assessment of renal pulsatility indices and RABF.
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Affiliation(s)
- Jennifer Keegan
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
| | - Hitesh C Patel
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
| | - Robin M Simpson
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />Radiological Physics, University of Freiburg, Freiburg, Germany
| | - Raad H Mohiaddin
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />National Heart and Lung Institute, Imperial College London, London, UK
| | - David N Firmin
- />Cardiovascular Magnetic Resonance, Royal Brompton Hospital, Sydney Street, London, SW3 6NP UK
- />National Heart and Lung Institute, Imperial College London, London, UK
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30
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Nelson ES, Mulugeta L, Myers JG. Microgravity-induced fluid shift and ophthalmic changes. Life (Basel) 2014; 4:621-65. [PMID: 25387162 PMCID: PMC4284461 DOI: 10.3390/life4040621] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 09/17/2014] [Accepted: 10/17/2014] [Indexed: 11/16/2022] Open
Abstract
Although changes to visual acuity in spaceflight have been observed in some astronauts since the early days of the space program, the impact to the crew was considered minor. Since that time, missions to the International Space Station have extended the typical duration of time spent in microgravity from a few days or weeks to many months. This has been accompanied by the emergence of a variety of ophthalmic pathologies in a significant proportion of long-duration crewmembers, including globe flattening, choroidal folding, optic disc edema, and optic nerve kinking, among others. The clinical findings of affected astronauts are reminiscent of terrestrial pathologies such as idiopathic intracranial hypertension that are characterized by high intracranial pressure. As a result, NASA has placed an emphasis on determining the relevant factors and their interactions that are responsible for detrimental ophthalmic response to space. This article will describe the Visual Impairment and Intracranial Pressure syndrome, link it to key factors in physiological adaptation to the microgravity environment, particularly a cephalad shifting of bodily fluids, and discuss the implications for ocular biomechanics and physiological function in long-duration spaceflight.
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Affiliation(s)
- Emily S Nelson
- NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, OH 44135, USA.
| | - Lealem Mulugeta
- Universities Space Research Association, Division of Space Life Sciences, 3600 Bay Area Boulevard, Houston, TX 77058, USA.
| | - Jerry G Myers
- NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, OH 44135, USA.
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