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Wall shear stress estimated with phase contrast MRI in an in vitro and in vivo intracranial aneurysm
Pim van Ooij PhD Wouter V. Potters MSc Annetje Guédon MSc Joppe J. Schneiders MD Henk A. Marquering PhD Charles B. Majoie MD PhD Ed vanBavel PhD Aart J. Nederveen PhD 《Journal of magnetic resonance imaging : JMRI》2013,38(4):876-884
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目的 通过比较颅内无症状动脉瘤和症状动脉瘤的血流动力学参数,寻找与动脉瘤破裂有关的血流动力学因素.方法 5例患者DSA检查共发现8个颈内动脉动脉瘤,分别位于颈内动脉后交通段及颈眼动脉段.通过旋转DSA,重建动脉瘤三维模型,并使用有限体积法进行血流动力学数值模拟,比较不同组动脉瘤及载瘤动脉的血流动力学参数.两组数据对比时采用独立样本t检验,瘤颈与载瘤动脉比较使用配对t检验.结果 无症状组和症状组动脉瘤瘤颈部平均切应力分别为(5.54±2.89)Pa和(4.78±3.84)Pa,两组间差异无统计学意义(P=0.78);动脉瘤临近载瘤动脉平均切应力分别为(6.6±3.47)Pa和(7.30±3.80)Pa,两组间差异无统计学意义(P=0.80);动脉瘤低切应力区域的大小分别为0.33%和4.72%,两组间差异有统计学意义(P=0.01).结论 动脉瘤壁低切应力区域的大小可能是影响颅内囊状动脉瘤破裂的因素之一. 相似文献
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In vitro validation of flow measurement with phase contrast MRI at 3 tesla using stereoscopic particle image velocimetry and stereoscopic particle image velocimetry‐based computational fluid dynamics
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Iman Khodarahmi MD PhD Mostafa Shakeri PhD Melanie Kotys‐Traughber PhD Stefan Fischer PhD M. Keith Sharp PhD Amir A. Amini PhD 《Journal of magnetic resonance imaging : JMRI》2014,39(6):1477-1485
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Purpose:
To systematically investigate the scan–rescan reproducibility and observer variability of flow‐sensitive four‐dimensional (4D) MRI in the aorta for the assessment of blood flow and global and segmental wall shear stress.Materials and Methods:
ECG and respiration‐synchronized flow‐sensitive 4D MRI data (spatio‐temporal resolution = 1.7 × 2.0 × 2.2 mm3/40.8 ms) were acquired in 12 healthy volunteers. To analyze scan–rescan variability, flow‐sensitive 4D MRI was repeated in 10 volunteers during a second visit. Data analysis included calculation of time‐resolved and total flow, peak systolic velocity, and regional and global wall shear stress (WSS) in up to 24 analysis planes distributed along the aorta.Results:
Scan–rescan, inter‐observer, and intra‐observer agreement was excellent for the calculation of total flow and peak systolic velocity (mean differences <5% of the average flow parameter). Global WSS demonstrated moderate agreement and increased variability regarding wall shear stress (scan‐rescan, inter‐observer, and intra‐observer agreement; mean differences <10% of the average WSS parameters). The segmental distribution of wall shear stress in the thoracic aorta could reliably be reproduced (r > 0.87; P < 0.001) for different observers and examinations.Conclusion:
Flow‐sensitive 4D MRI‐based analysis of aortic blood flow can be performed with good reproducibility. Robustness of global and regional WSS quantification was limited, but spatio‐temporal WSS distributions could reliably be replicated. J. Magn. Reson. Imaging 2011;33:988–994. © 2011 Wiley‐Liss, Inc. 相似文献5.
Clarence P. Davis Pei-Fang Liu Markus Hauser Susanne C. Ghde Gustav K. Von Schulthess Jrg F. Debatin 《Magnetic resonance in medicine》1997,37(4):537-544
Objective evidence for coronary lesion significance can be obtained with ischemic stress testing. Since flow-limiting stenoses have already undergone compensatory vasodilatation to maintain flow, the response to vasoactive stimulation is dampened. The degree of response limitation is reflected by the coronary flow reserve (CFR). Absolute volume flow rates can be accurately and noninvasively measured with MRI techniques. The purpose was to assess the ability to measure coronary volume flow rate noninvasively, and characterize the effect of pharmacologic stress on coronary flow quantitatively by using ultrafast, breath-held segmented k-space phasecontrast-MR imaging (PC-MRI). Ten healthy volunteers were examined by using ultrafast breath-held PC-MRI. Coronary volume flow rates were measured in the anterior descending coronary artery (LAD) at rest and following intravenous administration of dipyridamole. CFR was determined based on these data. Mean LAD volume flow rates increased from 38 ± 11 ml/min before application of dipyridamole to 169 ± 42 ml/min. The mean CFR amounted to 5.0 ± 2.6 (median = 4.15). This study demonstrates the feasibility of breath-held PC-MRI to noninvasively quantify coronary volume flow rates over the cardiac cycle. Pharmacologically induced changes in volume flow rate and thus CFR can be quantitated. 相似文献
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Kevin M. Johnson Oliver Wieben Alexey A. Samsonov 《Magnetic resonance in medicine》2010,63(6):1564-1574
Phase‐contrast MRI can provide high‐resolution angiographic velocity images, especially in conjunction with non‐Cartesian k‐space sampling. However, acquisitions can be sensitive to errors from artifacts from main magnetic field inhomogeneities and chemical shift from fat. Particularly in body imaging, fat content can cause degraded image quality, create errors in the velocity measurements, and prevent the use of self‐calibrated amplitude of static field heterogeneity corrections. To reduce the influence of fat and facilitate self‐calibrated amplitude of static field heterogeneity corrections, a combination of chemical shift imaging with phase‐contrast velocimetry with nonlinear least‐squares estimation of velocity, fat, and water signals is proposed. A chemical shift and first‐moment symmetric dual‐echo sequence is proposed to minimize the scan time penalty, and initial investigations are performed in phantoms and volunteers that show reduced influence from fat in velocity images. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
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Comparison of flow patterns in ascending aortic aneurysms and volunteers using four-dimensional magnetic resonance velocity mapping 总被引:2,自引:0,他引:2
Hope TA Markl M Wigström L Alley MT Miller DC Herfkens RJ 《Journal of magnetic resonance imaging : JMRI》2007,26(6):1471-1479
PURPOSE: To determine the difference in flow patterns between healthy volunteers and ascending aortic aneurysm patients using time-resolved three-dimensional (3D) phase contrast magnetic resonance velocity (4D-flow) profiling. MATERIALS AND METHODS: 4D-flow was performed on 19 healthy volunteers and 13 patients with ascending aortic aneurysms. Vector fields placed on 2D planes were visually graded to analyze helical and retrograde flow patterns along the aortic arch. Quantitative analysis of the pulsatile flow was carried out on manually segmented planes. RESULTS: In volunteers, flow progressed as follows: an initial jet of blood skewed toward the anterior right wall of the ascending aorta is reflected posterolaterally toward the inner curvature creating opposing helices, a right-handed helix along the left wall and a left-handed helix along the right wall; retrograde flow occurred in all volunteers along the inner curvature between the location of the two helices. In the aneurysm patients, the helices were larger; retrograde flow occurred earlier and lasted longer. The average velocity decreased between the ascending aorta and the transverse aorta in volunteers (47.9 mm/second decrease, P = 0.023), while in aneurysm patients the velocity increased (145 mm/second increase, P < 0.001). CONCLUSION: Dilation of the ascending aorta skews normal flow in the ascending aorta, changing retrograde and helical flow patterns. 相似文献
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Four‐dimensional flow assessment of pulmonary artery flow and wall shear stress in adult pulmonary arterial hypertension: Results from two institutions
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Alex J. Barker Alejandro Roldán‐Alzate Pegah Entezari Sanjiv J. Shah Naomi C. Chesler Oliver Wieben Michael Markl Christopher J. François 《Magnetic resonance in medicine》2015,73(5):1904-1913
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Andreas Harloff Andrea Nußbaumer Simon Bauer Aurélien F. Stalder Alex Frydrychowicz Cornelius Weiller Jürgen Hennig Michael Markl 《Magnetic resonance in medicine》2010,63(6):1529-1536
Our purpose was to correlate atherogenic low wall shear stress (WSS) and high oscillatory shear index (OSI) with the localization of aortic plaques. Flow‐sensitive four‐dimensional MRI was used to acquire three‐dimensional blood flow in the aorta of 62 patients with proven aortic atherosclerosis and 31 healthy volunteers. Multiplanar data analysis of WSS magnitude and OSI in 12 wall segments was performed in analysis planes distributed along the aorta. Disturbed WSS and OSI were defined as areas exposed to low WSS magnitude and high OSI beyond individual 15% thresholds. Planewise analysis revealed a good correlation (r = 0.85) of individual low WSS magnitude but not of high OSI with plaque distribution. Although plaques occurred only rarely in the ascending aorta, the incidence of low WSS magnitude and high OSI was similar to findings in other aortic segments where plaques occurred more frequently. Case‐by‐case comparisons of plaque location and critical wall parameters revealed a shift of atherogenic WSS magnitude (78% of all cases) and OSI (91%) to wall segments adjacent to the atheroma. Our results indicate that the predictive value of WSS for plaque existence depends on the aortic segment and that locations of critical wall parameters move to neighboring segments of regions affected by atherosclerosis. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
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Alex Frydrychowicz MD Aurélien F. Stalder MSc Maximilian F. Russe Jelena Bock MSc Simon Bauer MSc Andreas Harloff MD Alexander Berger Mathias Langer MD MBA Jürgen Hennig PhD Michael Markl PhD 《Journal of magnetic resonance imaging : JMRI》2009,30(1):77-84
Purpose
To assess the distribution and regional differences of flow and vessel wall parameters such as wall shear stress (WSS) and oscillatory shear index (OSI) in the entire thoracic aorta.Materials and Methods
Thirty‐one healthy volunteers (mean age = 23.7 ± 3.3 years) were examined by flow‐sensitive four‐dimensional (4D)‐MRI at 3T. For eight retrospectively positioned 2D analysis planes distributed along the thoracic aorta, flow parameters and vectorial WSS and OSI were assessed in 12 segments along the vascular circumference.Results
Mean absolute time‐averaged WSS ranged between 0.25 ± 0.04 N/m2 and 0.33 ± 0.07 N/m2 and incorporated a substantial circumferential component (–0.05 ± 0.04 to 0.07 ± 0.02 N/m2). For each analysis plane, a segment with lowest absolute WSS and highest OSI was identified which differed significantly from mean values within the plane (P < 0.05). The distribution of atherogenic low WSS and high OSI closely resembled typical locations of atherosclerotic lesions at the inner aortic curvature and supraaortic branches.Conclusion
The normal distribution of vectorial WSS and OSI in the entire thoracic aorta derived from flow‐sensitive 4D‐MRI data provides a reference constituting an important perquisite for the examination of patients with aortic disease. Marked regional differences in absolute WSS and OSI may help explaining why atherosclerotic lesions predominantly develop and progress at specific locations in the aorta. J. Magn. Reson. Imaging 2009;30:77–84. © 2009 Wiley‐Liss, Inc. 相似文献16.
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Julia Busch Daniel Giese Lukas Wissmann Sebastian Kozerke 《Magnetic resonance in medicine》2013,69(1):200-210
Three‐dimensional phase‐contrast velocity vector field mapping shows great potential for clinical applications; however measurement inaccuracies may limit the utility and robustness of the technique. While parts of the error in the measured velocity fields can be minimized by background phase estimation in static tissue and magnetic field monitoring, considerable inaccuracies remain. The present work introduces divergence‐reduction processing of 3D phase‐contrast flow data based on a synergistic combination of normalized convolution and divergence‐free radial basis functions. It is demonstrated that this approach effectively addresses erroneous flow for image reconstructions from both fully sampled and undersampled data. Using computer simulations and in vivo data acquired in the aorta of healthy subjects and a stenotic valve patient it is shown that divergence arising from measurement imperfections can be reduced by up to 87% resulting in improved vector field representations. Based on the results obtained it is concluded that integration of the divergence‐free condition into postprocessing of vector fields presents an efficient approach to addressing flow field inaccuracies. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
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Adam S. Tenforde Christopher P. Cheng Ga‐Young Suh Robert J. Herfkens Ronald L. Dalman Charles A. Taylor 《Journal of magnetic resonance imaging : JMRI》2010,31(2):425-429
Purpose:
To evaluate rest and exercise hemodynamics in patients with abdominal aortic aneurysms (AAA) and peripheral occlusive disease (claudicants) using phase‐contrast MRI.Materials and Methods:
Blood velocities were acquired by means of cardiac‐gated cine phase‐contrast in a 0.5 Tesla (T) open MRI. Volumetric flow was calculated at the supraceliac (SC), infrarenal (IR), and mid‐aneurysm (MA) levels during rest and upright cycling exercise using an MR‐compatible exercise cycle.Results:
Mean blood flow increased during exercise (AAA: 130%, Claudicants: 136% of resting heart rate) at the SC and IR levels for AAA participants (2.6 ± 0.6 versus 5.8 ± 1.6 L/min, P < 0.001 and 0.8 ± 0.4 versus 5.1 ± 1.7 L/min, P < 0.001) and claudicants (2.3 ± 0.5 versus 4.5 ± 0.9 L/min, P < 0.005 and 0.8 ± 0.2 versus 3.3 ± 0.9 L/min, P < 0.005). AAA participants had a significant decrease in renal and digestive blood flow from rest to exercise (1.8 ± 0.7 to 0.7 ± 0.6 L/min, P < 0.01). The decrease in renal and digestive blood flow during exercise correlated with daily activity level for claudicants (R = 0.81).Conclusion:
Abdominal aortic hemodynamic changes due to lower extremity exercise can be quantified in patients with AAA and claudication using PC‐MRI. The redistribution of blood flow during exercise was significant and different between the two disease states. J. Magn. Reson. Imaging 2010; 31: 425–429. © 2010 Wiley‐Liss, Inc.19.
Daniel Giese Maximilian Haeberlin Christoph Barmet Klaas P. Pruessmann Tobias Schaeffter Sebastian Kozerke 《Magnetic resonance in medicine》2012,67(5):1294-1302
The value of phase‐contrast magnetic resonance imaging for quantifying tissue motion and blood flow has been long recognized. However, the sensitivity of the method to system imperfections can lead to inaccuracies limiting its clinical acceptance. A key source of error relates to eddy current‐induced phase fluctuations, which can offset the measured object velocity significantly. A higher‐order dynamic field camera was used to study the spatiotemporal evolution of background phases in cine phase‐contrast measurements. It is demonstrated that eddy current‐induced offsets in phase‐difference data are present up to the second spatial order. Oscillatory temporal behaviors of offsets in the kHz range suggest mechanical resonances of the MR system to be non‐negligible in phase‐contrast imaging. By careful selection of the echo time, their impact can be significantly reduced. When applying field monitoring data for correcting eddy current and mechanically induced velocity offsets, errors decrease to less than 0.5% of the maximum velocity for various sequence settings proving the robustness of the correction approach. In vivo feasibility is demonstrated for aortic and pulmonary flow measurements in five healthy subjects. Using field monitoring data, mean error in stroke volume was reduced from 10% to below 3%. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc. 相似文献
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A.F. Stalder M.F. Russe A. Frydrychowicz J. Bock J. Hennig M. Markl 《Magnetic resonance in medicine》2008,60(5):1218-1231
Quantification of CINE phase contrast (PC)‐MRI data is a challenging task because of the limited spatiotemporal resolution and signal‐to‐noise ratio (SNR). The method presented in this work combines B‐spline interpolation and Green's theorem to provide optimized quantification of blood flow and vessel wall parameters. The B‐spline model provided optimal derivatives of the measured three‐directional blood velocities onto the vessel contour, as required for vectorial wall shear stress (WSS) computation. Eight planes distributed along the entire thoracic aorta were evaluated in a 19‐volunteer study using both high‐spatiotemporal‐resolution planar two‐dimensional (2D)‐CINE‐PC (~1.4 × 1.4 mm2/24.4 ms) and lower‐resolution 3D‐CINE‐PC (~2.8 × 1.6 × 3 mm3/48.6 ms) with three‐directional velocity encoding. Synthetic data, error propagation, and interindividual, intermodality, and interobserver variability were used to evaluate the reliability and reproducibility of the method. While the impact of MR measurement noise was only minor, the limited resolution of PC‐MRI introduced systematic WSS underestimations. In vivo data demonstrated close agreement for flow and WSS between 2D‐ and 3D‐CINE‐PC as well as observers, and confirmed the reliability of the method. WSS analysis along the aorta revealed the presence of a circumferential WSS component accounting for 10–20%. Initial results in a patient with atherosclerosis suggest the potential of the method for understanding the formation and progression of cardiovascular diseases. Magn Reson Med 60:1218–1231, 2008. © 2008 Wiley‐Liss, Inc. 相似文献