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Zong X, Lin W. Quantitative phase contrast MRI of penetrating arteries in centrum semiovale at 7T. Neuroimage 2019; 195:463-474. [PMID: 30935910 DOI: 10.1016/j.neuroimage.2019.03.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 02/27/2019] [Accepted: 03/25/2019] [Indexed: 12/24/2022] Open
Abstract
Pathological changes of penetrating arteries (PA) within the centrum semiovale is an important contributing factor of cerebral small vessel disease (SVD). However, quantitative characterization of the PAs remains challenging due to their sub-voxel sizes. Here, we proposed a Model-based Analysis of Complex Difference images (MACD) of phase contrast MRI capable of measuring the mean velocities (vmean), diameters (D), and volume flow rates (VFR) of PAs without contamination from neighboring static tissues at 7 T. Simulation, phantom and in vivo studies were performed to evaluate the reproducibility and errors of the proposed method. For comparison, a Model-based Analysis of Phase difference images (MAP) was also carried out in the simulation. The proposed MACD analysis approach was applied in vivo to study the age dependence of PA properties in healthy subjects between 21 and 55 years old. Simulation showed that our proposed MACD approach yielded smaller errors than MAP, with errors increasing at lower velocities and diameters for both methods. In the phantom study, errors of the MACD-derived vmean, D, and VFR were ≤20% of their true values when vmean≥1cm/s and similar at different spatial resolutions. On the other hand, errors of the uncorrected apparent velocities were 24-60% and depended strongly on voxel size. The MACD errors linearly increased with the angle (α) between the vessel and slice normal direction at α ≤ 2° but remained almost constant at larger α. Results of the in vivo studies showed that the coefficients of repeatability for vmean, D, and VFR for PAs with α = 0° were 0.67 cm/s, 0.060 mm, and 0.067 mm3/s, respectively. No significant age dependence was found for the number, vmean, D, and VFR of PAs. The mean vmean, D, and VFR over all PAs with α = 0° were 1.79 ± 0.62 cm/s, 0.17 ± 0.05 mm, and 0.36 ± 0.18 mm3/s, respectively. Quantitative measurements of PAs with the MACD method may serve as a useful tool for illuminating the vascular pathology in cerebral SVD.
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Affiliation(s)
- Xiaopeng Zong
- Department of Radiology and Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
| | - Weili Lin
- Department of Radiology and Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
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Dolui S, Wang Z, Wang DJJ, Mattay R, Finkel M, Elliott M, Desiderio L, Inglis B, Mueller B, Stafford RB, Launer LJ, Jacobs DR, Bryan RN, Detre JA. Comparison of non-invasive MRI measurements of cerebral blood flow in a large multisite cohort. J Cereb Blood Flow Metab 2016; 36:1244-56. [PMID: 27142868 PMCID: PMC4929707 DOI: 10.1177/0271678x16646124] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/22/2016] [Indexed: 11/16/2022]
Abstract
UNLABELLED Arterial spin labeling and phase contrast magnetic resonance imaging provide independent non-invasive methods for measuring cerebral blood flow. We compared global cerebral blood flow measurements obtained using pseudo-continuous arterial spin labeling and phase contrast in 436 middle-aged subjects acquired at two sites in the NHLBI CARDIA multisite study. Cerebral blood flow measured by phase contrast (CBFPC: 55.76 ± 12.05 ml/100 g/min) was systematically higher (p < 0.001) and more variable than cerebral blood flow measured by pseudo-continuous arterial spin labeling (CBFPCASL: 47.70 ± 9.75). The correlation between global cerebral blood flow values obtained from the two modalities was 0.59 (p < 0.001), explaining less than half of the observed variance in cerebral blood flow estimates. Well-established correlations of global cerebral blood flow with age and sex were similarly observed in both CBFPCASL and CBFPC CBFPC also demonstrated statistically significant site differences, whereas no such differences were observed in CBFPCASL No consistent velocity-dependent effects on pseudo-continuous arterial spin labeling were observed, suggesting that pseudo-continuous labeling efficiency does not vary substantially across typical adult carotid and vertebral velocities, as has previously been suggested. CONCLUSIONS Although CBFPCASL and CBFPC values show substantial similarity across the entire cohort, these data do not support calibration of CBFPCASL using CBFPC in individual subjects. The wide-ranging cerebral blood flow values obtained by both methods suggest that cerebral blood flow values are highly variable in the general population.
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Affiliation(s)
- Sudipto Dolui
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA Center for Functional Neuroimaging, University of Pennsylvania, Philadelphia, PA, USA
| | - Ze Wang
- Center for Cognition and Brain Disorders and the Affiliated Hospital, Hangzhou Normal University, Hangzhou, China Departments of Psychiatry and Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Danny J J Wang
- Department of Neurology, University of California, Los Angeles, CA, USA
| | - Raghav Mattay
- Raymond and Ruth Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Mack Finkel
- School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA
| | - Mark Elliott
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Lisa Desiderio
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Ben Inglis
- Henry H. Wheeler Jr. Brain Imaging Center, University of California, Berkeley, CA, USA
| | - Bryon Mueller
- Department of Psychiatry, University of Minnesota, Minneapolis, MN, USA
| | - Randall B Stafford
- Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - Lenore J Launer
- Laboratory of Epidemiology and Population Science, National Institute on Aging, Bethesda, MD, USA
| | - David R Jacobs
- Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN, USA
| | - R Nick Bryan
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - John A Detre
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA Center for Functional Neuroimaging, University of Pennsylvania, Philadelphia, PA, USA
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van Ooij P, Allen BD, Contaldi C, Garcia J, Collins J, Carr J, Choudhury L, Bonow RO, Barker AJ, Markl M. 4D flow MRI and T1 -Mapping: Assessment of altered cardiac hemodynamics and extracellular volume fraction in hypertrophic cardiomyopathy. J Magn Reson Imaging 2015; 43:107-14. [PMID: 26227419 DOI: 10.1002/jmri.24962] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/15/2015] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Hypertrophic cardiomyopathy (HCM) is associated with altered hemodynamics in the left ventricular outflow tract (LVOT) and myocardial tissue abnormalities such as fibrosis. The aim of this study was to quantify changes in LVOT 3D hemodynamics and myocardial extracellular volume fraction (ECV, measure of fibrosis) and to investigate relationships between elevated flow metrics and left ventricular (LV) tissue abnormalities. MATERIALS AND METHODS Cardiac magnetic resonance imaging (MRI) including 4D flow (field strength = 1.5T, resolution = 2.1-4.0 × 2.1-4.0 × 2.5-3.2 mm(3) ; venc = 150-250 cm/s; TE/TR/FA = 2.2-2.5msec/4.6-4.9msec/15°) for the in vivo assessment of 3D blood flow velocities with full coverage of the LVOT was applied in 35 patients with HCM (54 ± 15 years) and 10 age-matched healthy controls (45 ± 14 years). In addition, pre- and postcontrast myocardial T1 -mapping (resolution = 2.3 × 1.8 mm, slice thickness = 8 mm, TE/TR-FA = 1.0-1.1msec/2.0-2.2msec/35°) of the LV (basal, mid-ventricular, apical short axis) was performed in a subgroup of 23 HCM patients. Analysis included the segmentation of the LVOT and quantification of peak systolic LVOT pressure gradients and rate of viscous energy loss EL ' as well as left ventricular ECV. RESULTS HCM patients demonstrated significantly elevated peak systolic LVOT pressure gradients (21 ± 16 mmHg vs. 9 ± 2 mmHg) and energy loss EL ' (3.8 ± 2.5 mW vs. 1.5 ± 0.7 mW, P < 0.005) compared to controls. There was a significant relationship between increased LV fibrosis (ECV) with both elevated pressure gradients (R(2) = 0.44, P < 0.001) and energy loss EL ' (R(2) = 0.46, P < 0.001). CONCLUSIONS The integration of 4D-flow and T1 -mapping-MRI allowed for the evaluation of tissue and flow abnormalities in HCM patients. Our findings suggest a mechanistic link between abnormal LVOT flow, increased LV loading, and adverse myocardial remodeling in HCM.
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Affiliation(s)
- Pim van Ooij
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Bradley D Allen
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Carla Contaldi
- Department of Medicine-Cardiology, Northwestern University, Chicago, Illinois, USA
| | - Julio Garcia
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Jeremy Collins
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - James Carr
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Lubna Choudhury
- Department of Medicine-Cardiology, Northwestern University, Chicago, Illinois, USA
| | - Robert O Bonow
- Department of Medicine-Cardiology, Northwestern University, Chicago, Illinois, USA
| | - Alex J Barker
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Michael Markl
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, Illinois, USA
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4
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Niesporek SC, Hoffmann SH, Berger MC, Benkhedah N, Kujawa A, Bachert P, Nagel AM. Partial volume correction for in vivo 23 Na-MRI data of the human brain. Neuroimage 2015; 112:353-363. [DOI: 10.1016/j.neuroimage.2015.03.025] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 02/02/2015] [Accepted: 03/11/2015] [Indexed: 12/16/2022] Open
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Krishnamurthy R, Cheong B, Muthupillai R. Tools for cardiovascular magnetic resonance imaging. Cardiovasc Diagn Ther 2014; 4:104-25. [PMID: 24834409 DOI: 10.3978/j.issn.2223-3652.2014.03.06] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 02/08/2014] [Indexed: 12/31/2022]
Abstract
In less than fifteen years, as a non-invasive imaging option, cardiovascular MR has grown from a being a mere curiosity to becoming a widely used clinical tool for evaluating cardiovascular disease. Cardiovascular magnetic resonance imaging (CMRI) is now routinely used to study myocardial structure, cardiac function, macro vascular blood flow, myocardial perfusion, and myocardial viability. For someone entering the field of cardiac MR, this rapid pace of development in the field of CMRI might make it difficult to identify a cohesive starting point. In this brief review, we have attempted to summarize the key cardiovascular imaging techniques that have found widespread clinical acceptance. In particular, we describe the essential cardiac and respiratory gating techniques that form the backbone of all cardiovascular imaging methods. It is followed by four sections that discuss: (I) the gradient echo techniques that are used to assess ventricular function; (II) black-blood turbo spin echo (SE) methods used for morphologic assessment of the heart; (III) phase-contrast based techniques for the assessment of blood flow; and (IV) CMR methods for the assessment of myocardial ischemia and viability. In each section, we briefly summarize technical considerations relevant to the clinical use of these techniques, followed by practical information for its clinical implementation. In each of those four areas, CMRI is considered either as the benchmark imaging modality against which the diagnostic performance of other imaging modalities are compared against, or provides a complementary capability to existing imaging techniques. We have deliberately avoided including cutting-edge CMR imaging techniques practiced at few academic centers, and restricted our discussion to methods that are widely used and are likely to be available in a clinical setting. Our hope is that this review would propel an interested reader toward more comprehensive reviews in the literature.
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Affiliation(s)
- Ramkumar Krishnamurthy
- Department of Diagnostic and Interventional Radiology, CHI St. Luke's Health, Texas Medical Center, Houston, Texas 77030, USA
| | - Benjamin Cheong
- Department of Diagnostic and Interventional Radiology, CHI St. Luke's Health, Texas Medical Center, Houston, Texas 77030, USA
| | - Raja Muthupillai
- Department of Diagnostic and Interventional Radiology, CHI St. Luke's Health, Texas Medical Center, Houston, Texas 77030, USA
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Sommer G, Bremerich J, Lund G. Magnetic resonance imaging in valvular heart disease: Clinical application and current role for patient management. J Magn Reson Imaging 2012; 35:1241-52. [DOI: 10.1002/jmri.23544] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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7
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Westenberg JJ, de Roos A, Grotenhuis HB, Steendijk P, Hendriksen D, van den Boogaard PJ, van der Geest RJ, Bax JJ, Jukema JW, Reiber JH. Improved aortic pulse wave velocity assessment from multislice two-directional in-plane velocity-encoded magnetic resonance imaging. J Magn Reson Imaging 2010; 32:1086-94. [DOI: 10.1002/jmri.22359] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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8
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Taviani V, Patterson AJ, Worters P, Sutcliffe MP, Graves MJ, Gillard JH. Accuracy of phase contrast, black-blood, and bright-blood pulse sequences for measuring compliance and distensibility coefficients in a human-tissue mimicking phantom. J Magn Reson Imaging 2009; 31:160-7. [DOI: 10.1002/jmri.22005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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9
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Magnetic Resonance Imaging of Valvular Disease. CARDIOVASCULAR MEDICINE 2007. [DOI: 10.1007/978-1-84628-715-2_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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10
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Summers PE, Holdsworth DW, Nikolov HN, Rutt BK, Drangova M. Multisite trial of MR flow measurement: Phantom and protocol design. J Magn Reson Imaging 2005; 21:620-31. [PMID: 15834913 DOI: 10.1002/jmri.20311] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To describe a portable, easily assembled phantom with well-defined bore geometry together with a series of tests that will form the basis of a standardized quality assurance protocol in a multicenter trial of flow measurement by the MR phase mapping technique. MATERIALS AND METHODS The phantom consists of silicone polymer layers containing parallel straight and stenosed flow channels in one layer and a U-bend in a second layer, separated by hermetically sealed agarose slabs. The phantom is constructed by casting low melting-point metal in an aluminum mold precisely milled to the desired geometry, and then using the low melting-point metal core as a negative around which the silicone is allowed to set. By melting out the metal, the flow channels are established. The milled aluminum mold is reusable, ensuring faithful reproduction of the flow geometry for all phantoms thus produced. The agarose layers provide additional loading and static background signal for background correction. With the use of the described phantom, one can evaluate flow measurement accuracy and repeatability, as well as the influence of several imaging geometry factors: slice offset, in-plane position, and slice-flow obliquity. RESULTS The new phantom is compact and portable, and is well suited for reassembly. We were able to demonstrate its facility in a battery of tests of interest in evaluating MR flow measurements. CONCLUSION The phantom is a robust standardized test object for use in a multicenter trial. Such a trial, to investigate the performance of MR flow measurement using the phantom and the tests we describe, has been initiated.
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Affiliation(s)
- Paul E Summers
- Clinical Neurosciences, King's College London, London, England.
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11
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van der Weide R, Viergever MA, Bakker CJG. Resolution-insensitive velocity and flow rate measurement in low-background phase-contrast MRA. Magn Reson Med 2004; 51:785-93. [PMID: 15065252 DOI: 10.1002/mrm.20035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Magnetic resonance (MR) phase-contrast (PC) flow measurements are degraded by partial volume errors when the spatial resolution is low, in particular when a large difference in signal magnitude exists between the fluid and the surrounding material. The latter is often the case in phantom studies and may be encountered when flow is measured in prosthetic vessel segments (such as shunts, grafts, and bypasses) and in contrast-enhanced blood. This paper presents a new method that is designed to measure flow in vessels of circular cross-section with Poiseuille flow and negligible background signal arising from static material around the lumen. The method calculates the average flow velocity directly from the original complex image data by integrating the signal in oppositely velocity-sensitized PC images. The radius is calculated from the summed signal modulus. The method allows accurate and resolution-insensitive measurements of the average flow velocity to be obtained in both cross-sectional and in-plane acquisitions. It is not critical to any of the assumed conditions. The validity and capabilities of the proposed technique are demonstrated by in vitro experiments.
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Affiliation(s)
- Remko van der Weide
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
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12
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Köhler S, Hiller KH, Jakob PM, Bauer WR, Haase A. Time-resolved flow measurement in the isolated rat heart: characterization of left coronary artery stenosis. Magn Reson Med 2003; 50:449-52. [PMID: 12939750 DOI: 10.1002/mrm.10563] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The investigation of flow behavior in coronary arteries is of great importance for an understanding of heart failure and heart regulation mechanisms. The purpose of the present study was to demonstrate that flow velocity can be quantified in the coronary arteries of the isolated rat heart with high-resolution phase contrast MRI. A phase contrast cine-FLASH imaging sequence was used for flow quantification with an in-plane resolution of 70 microm and a slice thickness of 500 microm. With time-resolved measurements, coronary flow over the heart cycle was analyzed. Furthermore, the flow behavior in coronary stenosis was investigated and the degree of stenosis was quantified with MR phase contrast imaging. To achieve the required spatial resolution and a satisfactory signal-to-noise ratio, the experiments were performed at 11.75 T.
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Affiliation(s)
- Sascha Köhler
- Physikalisches Institut, EP5, Universität Würzburg, Germany.
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13
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Lagerstrand KM, Lehmann H, Starck G, Vikhoff-Baaz B, Ekholm S, Forssell-Aronsson E. Method to correct for the effects of limited spatial resolution in phase-contrast flow MRI measurements. Magn Reson Med 2002; 48:883-9. [PMID: 12418004 DOI: 10.1002/mrm.10288] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Phase-contrast (PC) magnetic resonance imaging (MRI) flow measurements suffer from the effect of the point spread function (PSF) due to the limited sampling of k-space. The PSF, which in this case is a sinc function, deforms the flow profile and forms a ringing pattern around the vessel. In this work, an empirical method is presented that corrects for errors due to the deformation of the flow profile. The ringing pattern is used to obtain a well-defined vessel segmentation, which after correction provides more accurate vessel radius and volume flow rate (VFR). The correction method was developed from phantom measurements at constant flow and applied on phantom measurements at moderately pulsatile flow. After correction, the error of the estimated tube radius and the VFR was less than 10% and 5%, respectively. Corresponding errors without correction overestimated the radius by 60% and the VFR by 35%. Preliminary results indicate that the method is also valid in vivo. The variation in the estimated radius and VFR for different spatial resolution decreased when the method was applied. The presented method gives a more accurate estimation of the radius and VFR in vessels of the size of a few pixels without prior knowledge about the true vessel radius.
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Affiliation(s)
- K M Lagerstrand
- Department of Radiation Physics, Sahlgrenska University Hospital, Göteborg University, Göteborg, Sweden.
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14
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Klarhöfer M, Csapo B, Balassy C, Szeles JC, Moser E. High-resolution blood flow velocity measurements in the human finger. Magn Reson Med 2001; 45:716-9. [PMID: 11284002 DOI: 10.1002/mrm.1096] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
MR phase contrast blood flow velocity measurements in the human index finger were performed with triggered, nontriggered, and cine acquisition schemes. A strong (G(max) = 200 mT/m), small bore (inner diameter 12 cm) gradient system inserted in a whole body 3 Tesla MR scanner allowed high-resolution imaging at short echo times, which decreases partial volume effects and flow artifacts. Arterial blood flow velocities ranging from 4.9-19 cm/sec were measured, while venous blood flow was significantly slower at 1.5-7.1 cm/sec. Taking into account the corresponding vessel diameters ranging from 800 microm to 1.8 mm, blood flow rates of 3.0-26 ml/min in arteries and 1.2-4.8 ml/min in veins are obtained. The results were compared to ultrasound measurements, resulting in comparable blood flow velocities in the same subjects. Magn Reson Med 45:716-719, 2001.
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Affiliation(s)
- M Klarhöfer
- Arbeitsgruppe NMR, Institut für Medizinische Physik, Universität Wien, Vienna, Austria
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15
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Zhao M, Charbel FT, Alperin N, Loth F, Clark ME. Improved phase-contrast flow quantification by three-dimensional vessel localization. Magn Reson Imaging 2000; 18:697-706. [PMID: 10930779 DOI: 10.1016/s0730-725x(00)00157-0] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this paper, a method of three-dimensional (3D) vessel localization is presented to allow the identification of a vessel of interest, the selection of a vessel segment, and the determination of a slice orientation to improve the accuracy of phase-contrast magnetic resonance (PCMR) angiography. A marching-cube surface-rendering algorithm was used to reconstruct the 3D vasculature. Surface-rendering was obtained using an iso-surface value determined from a maximum intensity projection (MIP) image. This 3D vasculature was used to find a vessel of interest, select a vessel segment, and to determine the slice orientation perpendicular to the vessel axis. Volumetric flow rate (VFR) was obtained in a phantom model and in vivo using 3D localization with double oblique cine PCMR scanning. PCMR flow measurements in the phantom showed 5. 2% maximum error and a standard deviation of 9 mL/min during steady flow, 7.9% maximum error and a standard deviation of 13 mL/min during pulsatile flow compared with measurements using an ultrasonic transit-time flowmeter. PCMR VFR measurement error increased with misalignment at 10, 20, and 30 degrees oblique to the perpendicular slice in vitro and in vivo. The 3D localization technique allowed precise localization of the vessel of interest and optimal placement of the slice orientation for minimum error in flow measurements.
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Affiliation(s)
- M Zhao
- Neurosurgery Department, University of Illinois at Chicago, Chicago, IL 60612, USA.
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16
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Abstract
The optimum management of patients with valvular heart diseases requires accurate and reproducible assessment of the valvular lesion and its hemodynamic consequences. Magnetic resonance imaging (MRI) techniques, such as volume measurements, signal-void phenomena, and velocity mapping, can be used in an integrated approach to gain qualitative and quantitative information on valvular heart disease as well as ventricular dimensions and functions. Thus, MRI may be advantageous to the established diagnostic tools in assessing the severity of valvular heart disease as well as monitoring the lesion and predicting the optimal timing for valvular surgery. This paper reviews the validation of these MRI techniques in assessing valvular heart disease and discusses some typical pitfalls of the techniques, including suggestions for solutions.J. Magn. Reson. Imaging 1999;10:627-638.
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Affiliation(s)
- L Søndergaard
- Department of Magnetic Resonance, Hvidovre Hospital, 2650 Hvidovre, Denmark.
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Bakker CJ, Hoogeveen RM, Viergever MA. Construction of a protocol for measuring blood flow by two-dimensional phase-contrast MRA. J Magn Reson Imaging 1999; 9:119-27. [PMID: 10030659 DOI: 10.1002/(sici)1522-2586(199901)9:1<119::aid-jmri16>3.0.co;2-f] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Our aim is to describe and demonstrate the steps we have found to be useful in the construction and evaluation of protocols for triggered and nontriggered measurement of blood flow by two-dimensional phase-contrast magnetic resonance angiography (MRA). To achieve this goal, we start with a survey of factors governing the accuracy (validity) and precision (repeatability) of MR flow measurements. This knowledge, combined with prior information regarding the diameter of the target vessel and the prevailing flow conditions, is then employed to define a protocol for measuring flow with negligible systematic error. In the absence of a gold standard for in vivo flow measurements, the protocol is subsequently validated for a range of flow conditions by representative phantom experiments. Precision is then calculated from the signal-to-noise ratio (SNR) of blood in the accompanying magnitude images or, less conveniently, estimated from the standard deviation of repeated measurements. The desired precision is finally achieved by adjusting the appropriate SNR parameters. All steps involved in protocol development are demonstrated for both flow-independent and flow-dependent acquisitions.
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Affiliation(s)
- C J Bakker
- Department of Radiology, Image Sciences Institute, University Hospital Utrecht, The Netherlands.
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Abstract
A customized computer program (MRIView) is described for visualizing and quantifying complex blood flow patterns in major vessels, using nongated and cardiac-gated three-dimensional (3D) velocity data obtained with MR velocity-encoded phase pulse sequences. Streamlines, arrows, and particle paths (collectively referred to as "paths") can be computed interactively, using both forward and backward time integration of the velocity field. The program provides interactive cross-sectional and 3D perspective visualization of the paths, with quantification and statistical analysis of average speed, through-plane velocity, cross-sectional area, and flow. Normal flow patterns in the carotid artery, basilar artery tip, ascending aorta, coronary arteries, descending aorta, and renal arteries, as well as abnormal flow patterns in basilar tip aneurysms, have been investigated. The program revealed flow patterns in these regions with features that are well known from Doppler ultrasound and other features that have not been reported previously. The association between specific abnormal flow patterns and development of atherosclerosis suggests that particle paths can be used to assess risk of plaque formation and progression, as well as to evaluate flow dynamics and vascular patency before and after vascular interventions.
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Affiliation(s)
- M H Buonocore
- Department of Radiology, UC Davis Medical Center, Sacramento 95817, USA
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