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Guzzardi DG, Barker AJ, van Ooij P, Malaisrie SC, Puthumana JJ, Belke DD, Mewhort HEM, Svystonyuk DA, Kang S, Verma S, Collins J, Carr J, Bonow RO, Markl M, Thomas JD, McCarthy PM, Fedak PWM. Valve-Related Hemodynamics Mediate Human Bicuspid Aortopathy: Insights From Wall Shear Stress Mapping. J Am Coll Cardiol 2015; 66:892-900. [PMID: 26293758 DOI: 10.1016/j.jacc.2015.06.1310] [Citation(s) in RCA: 313] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 06/08/2015] [Accepted: 06/12/2015] [Indexed: 01/27/2023]
Abstract
BACKGROUND Suspected genetic causes for extracellular matrix (ECM) dysregulation in the ascending aorta in patients with bicuspid aortic valves (BAV) have influenced strategies and thresholds for surgical resection of BAV aortopathy. Using 4-dimensional (4D) flow cardiac magnetic resonance imaging (CMR), we have documented increased regional wall shear stress (WSS) in the ascending aorta of BAV patients. OBJECTIVES This study assessed the relationship between WSS and regional aortic tissue remodeling in BAV patients to determine the influence of regional WSS on the expression of ECM dysregulation. METHODS BAV patients (n = 20) undergoing ascending aortic resection underwent pre-operative 4D flow CMR to regionally map WSS. Paired aortic wall samples (i.e., within-patient samples obtained from regions of elevated and normal WSS) were collected and compared for medial elastin degeneration by histology and ECM regulation by protein expression. RESULTS Regions of increased WSS showed greater medial elastin degradation compared to adjacent areas with normal WSS: decreased total elastin (p = 0.01) with thinner fibers (p = 0.00007) that were farther apart (p = 0.001). Multiplex protein analyses of ECM regulatory molecules revealed an increase in transforming growth factor β-1 (p = 0.04), matrix metalloproteinase (MMP)-1 (p = 0.03), MMP-2 (p = 0.06), MMP-3 (p = 0.02), and tissue inhibitor of metalloproteinase-1 (p = 0.04) in elevated WSS regions, indicating ECM dysregulation in regions of high WSS. CONCLUSIONS Regions of increased WSS correspond with ECM dysregulation and elastic fiber degeneration in the ascending aorta of BAV patients, implicating valve-related hemodynamics as a contributing factor in the development of aortopathy. Further study to validate the use of 4D flow CMR as a noninvasive biomarker of disease progression and its ability to individualize resection strategies is warranted.
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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: 32] [Impact Index Per Article: 3.6] [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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van Ooij P, Powell AL, Potters WV, Carr JC, Markl M, Barker AJ. Reproducibility and interobserver variability of systolic blood flow velocity and 3D wall shear stress derived from 4D flow MRI in the healthy aorta. J Magn Reson Imaging 2015; 43:236-48. [PMID: 26140480 DOI: 10.1002/jmri.24959] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 05/13/2015] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To investigate the reproducibility and interobserver variability of 3D aortic velocity vector fields and wall shear stress (WSS) averaged over five systolic timeframes derived from noncontrast 4D flow magnetic resonance imaging (MRI). MATERIALS AND METHODS Fourteen controls underwent test-retest 4D flow MRI examinations separated by 16 ± 3 days (resolution = 3.0-3.6 × 2.3-2.6 × 2.5-2.7 mm(3) ; TE/TR/FA = 2.5/4.9 msec/7°; Venc = 150 cm/s). Two observers segmented the aorta, and WSS was calculated for both series of scans and both segmentations. Test-retest and interobserver velocity and WSS vectors were compared on a voxel-by-voxel basis in the aorta and on a regional basis by subdividing the aortas in six segments. RESULTS Test-retest: voxel-by-voxel Bland-Altman analysis revealed small differences (-0.03/-0.02 m/s/Pa), limits of agreement (LOA) of 0.25 m/s/0.29 Pa, and coefficients of variation (CV) of 20% for velocity/WSS. Voxel-by-voxel orthogonal regression analysis showed moderate agreement (slope: 1.14/1.16, intraclass correlation coefficient [ICC]: 0.76/0.67 for velocity/WSS). The regional analysis revealed a CV of 9%/8% and ICC of 0.9/0.9 for velocity/WSS. Interobserver: voxel-by-voxel difference for WSS was 0, LOA: 0.17/0.19 Pa, CV: 12/13%, slope: 1.01/1.09, ICC: 0.87/0.85 for test/retest. The CV/ICC for WSS in the regional analysis was 4%/1.0 for test and 3%/1.0 for retest. CONCLUSION Systolic velocity and WSS derived from 4D flow MRI are reproducible between consecutive visits, with low interobserver variability in healthy volunteers.
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van Ooij P, Semaan E, Schnell S, Giri S, Stankovic Z, Carr J, Barker AJ, Markl M. Improved respiratory navigator gating for thoracic 4D flow MRI. Magn Reson Imaging 2015; 33:992-9. [PMID: 25940391 DOI: 10.1016/j.mri.2015.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 04/25/2015] [Accepted: 04/27/2015] [Indexed: 12/25/2022]
Abstract
BACKGROUND Thoracic and abdominal 4D flow MRI is typically acquired in combination with navigator respiration control which can result in highly variable scan efficiency (Seff) and thus total scan time due to inter-individual variability in breathing patterns. The aim of this study was to test the feasibility of an improved respiratory control strategy based on diaphragm navigator gating with fixed Seff, respiratory driven phase encoding, and a navigator training phase. METHODS 4D flow MRI of the thoracic aorta was performed in 10 healthy subjects at 1.5T and 3T systems for the in-vivo assessment of aortic time-resolved 3D blood flow velocities. For each subject, four 4D flow scans (1: conventional navigator gating, 2-4: new implementation with fixed Seff =60%, 80% and 100%) were acquired. Data analysis included semi-quantitative evaluation of image quality of the 4D flow magnitude images (image quality grading on a four point scale), 3D segmentation of the thoracic aorta, and voxel-by-voxel comparisons of systolic 3D flow velocity vector fields between scans. RESULTS Conventional navigator gating resulted in variable Seff=74±13% (range=56%-100%) due to inter-individual variability of respiration patterns. For scans 2-4, the new navigator implementation was able to achieve predictable total scan times with stable Seff, only depending on heart rate. Semi- and fully quantitative analysis of image quality in 4D flow magnitude images was similar for the new navigator scheme compared to conventional navigator gating. For aortic systolic 3D velocities, good agreement was found between all new navigator settings (scan 2-4) with the conventional navigator gating (scan 1) with best performance for Seff=80% (mean difference=-0.01 m/s; limits of agreement=0.23 m/s, Pearson's ρ=0.89, p<0.001). No significant differences for image quality or 3D systolic velocities were found for 1.5T compared to 3T. CONCLUSIONS The findings of this study demonstrate the feasibility of the new navigator scheme to acquire 4D flow data with more predictable scan time while maintaining image quality and 3D velocity information, which may prove beneficial for clinical applications.
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Feliciani G, Potters WV, van Ooij P, Schneiders JJ, Nederveen AJ, van Bavel E, Majoie CB, Marquering HA. Multiscale 3-D + t Intracranial Aneurysmal Flow Vortex Detection. IEEE Trans Biomed Eng 2015; 62:1355-62. [DOI: 10.1109/tbme.2014.2387874] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Allen BD, Markl M, Barker AJ, van Ooij P, Carr JC, Malaisrie SC, Bonow RO, Kansal P. Beta-blocker therapy does not reduce ascending aorta wall shear stress in patients with bicuspid aortic valve. J Cardiovasc Magn Reson 2015. [PMCID: PMC4328268 DOI: 10.1186/1532-429x-17-s1-p399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Allen BD, van Ooij P, Barker AJ, Carr M, Gabbour M, Schnell S, Jarvis KB, Carr JC, Markl M, Rigsby C, Robinson JD. Thoracic aorta 3D hemodynamics in pediatric and young adult patients with bicuspid aortic valve. J Magn Reson Imaging 2015; 42:954-63. [PMID: 25644073 DOI: 10.1002/jmri.24847] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 12/17/2014] [Accepted: 12/18/2014] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND To evaluate the 3D hemodynamics in the thoracic aorta of pediatric and young adult bicuspid aortic valve (BAV) patients. METHODS 4D flow MRI was performed in 30 pediatric and young adult BAV patients (age: 13.9 ± 4.4 (range: [3.4, 20.7]) years old, M:F = 17:13) as part of this Institutional Review Board-approved study. Nomogram-based aortic root Z-scores were calculated to assess aortic dilatation and degree of aortic stenosis (AS) severity was assessed on MRI. Data analysis included calculation of time-averaged systolic 3D wall shear stress (WSSsys ) along the entire aorta wall, and regional quantification of maximum and mean WSSsys and peak systolic velocity (velsys ) in the ascending aorta (AAo), arch, and descending aorta (DAo). The 4D flow MRI AAo velsys was also compared with echocardiography peak velocity measurements. RESULTS There was a positive correlation with both mean and max AAo WSSsys and peak AAo velsys (mean: r = 0.84, P < 0.001, max: r = 0.94, P < 0.001) and AS (mean: rS = 0.43, P = 0.02, max: rS = 0.70, P < 0.001). AAo peak velocity was significantly higher when measured with echo compared with 4D flow MRI (2.1 ± 0.98 m/s versus 1.27 ± 0.49 m/s, P < 0.001). CONCLUSION In pediatric and young adult patients with BAV, AS and peak ascending aorta velocity are associated with increased AAo WSS, while aortic dilation, age, and body surface area do not significantly impact AAo hemodynamics. Prospective studies are required to establish the role of WSS as a risk-stratification tool in these patients.
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Allen BD, Choudhury L, Barker AJ, van Ooij P, Collins JD, Bonow RO, Carr JC, Markl M. Three-dimensional haemodynamics in patients with obstructive and non-obstructive hypertrophic cardiomyopathy assessed by cardiac magnetic resonance. Eur Heart J Cardiovasc Imaging 2015; 16:29-36. [PMID: 25108915 PMCID: PMC4366608 DOI: 10.1093/ehjci/jeu146] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 06/30/2014] [Indexed: 11/13/2022] Open
Abstract
AIMS The left ventricular outflow tract (LVOT) peak pressure gradient is an important haemodynamic descriptor in patients with hypertrophic cardiomyopathy (HCM); however, secondary alterations in aortic blood flow have not been well described in these patients. Aortic flow derangement is not easily assessed by traditional imaging methods, but may provide unique characterization of this disease. In this study, we demonstrated how four-dimensional (4D) flow MRI can assess LVOT peak pressure gradients in HCM patients and also evaluated the ascending aorta (AAo) haemodynamic derangement associated with HCM. METHODS AND RESULTS Obstructive (n = 12) and non-obstructive (n = 18) HCM patients were included in the study along with 10 normal volunteers. 4D flow MRI was used to visualize three-dimensional (3D) blood flow patterns within the LVOT and AAo, which were graded for the presence of helical flow as a marker of flow derangement (absent = 0, mild/moderate = 1, and severe = 2). MRI-estimated pressure gradient (ΔPMRI) was calculated from the peak systolic 3D blood velocity profile within the LVOT. There was higher grade helical flow in obstructive HCM patients compared with non-obstructive patients (P = 0.04) and volunteers (P < 0.001). Non-obstructive patients also had higher helix grade than volunteers (P = 0.002). There was a significant correlation between helical grade and increasing ΔPMRI (rS = 0.69, P < 0.001). Systolic anterior motion (SAM) of the mitral valve was associated with both increasing helix grade (P < 0.001) and ΔPMRI (P = 0.006). CONCLUSIONS Ascending aorta flow derangement occurs in both obstructive and non-obstructive HCM patients and can be identified using 4D flow MRI. The degree of flow derangement correlates with LVOT gradient, SAM, and outflow tract geometry.
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Garcia J, Barker AJ, van Ooij P, Schnell S, Puthumana J, Bonow RO, Collins JD, Carr JC, Markl M. Assessment of altered three-dimensional blood characteristics in aortic disease by velocity distribution analysis. Magn Reson Med 2014; 74:817-25. [PMID: 25252029 DOI: 10.1002/mrm.25466] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/27/2014] [Accepted: 08/28/2014] [Indexed: 01/15/2023]
Abstract
PURPOSE To test the feasibility of velocity distribution analysis for identifying altered three-dimensional (3D) flow characteristics in patients with aortic disease based on 4D flow MRI volumetric analysis. METHODS Forty patients with aortic (Ao) dilation (mid ascending aortic diameter MAA = 40 ± 7 mm, age = 56 ± 17 years, 11 females) underwent cardiovascular MRI. Four groups were retrospectively defined: mild Ao dilation (n = 10; MAA < 35 mm); moderate Ao dilation (n = 10; 35 < MAA < 45 mm); severe Ao dilation (n = 10; MAA > 45 mm); Ao dilation+aortic stenosis AS (n = 10; MAA > 35 mm and peak velocity > 2.5 m/s). The 3D PC-MR angiograms were computed and used to obtain a 3D segmentation of the aorta which was divided into four segments: root, ascending aorta, arch, descending aorta. Radial chart displays were used to visualize multiple parameters representing segmental changes in the 3D velocity distribution associated with aortic disease. RESULTS Changes in the velocity field and geometry between cohorts resulted in distinct hemodynamic patterns for each aortic segment. Disease progression from mild to Ao dilation + AS resulted in significant differences (P < 0.05) in flow parameters across cohorts and increased radial chart size for root and ascending aorta segments by 146% and 99%, respectively. CONCLUSION Volumetric 4D velocity distribution analysis has the potential to identify characteristic changes in regional blood flow patterns in patients with aortic disease.
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Barker AJ, van Ooij P, Bandi K, Garcia J, Albaghdadi M, McCarthy P, Bonow RO, Carr J, Collins J, Malaisrie SC, Markl M. Viscous energy loss in the presence of abnormal aortic flow. Magn Reson Med 2014; 72:620-8. [PMID: 24122967 PMCID: PMC4051863 DOI: 10.1002/mrm.24962] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/29/2013] [Accepted: 08/31/2013] [Indexed: 01/12/2023]
Abstract
PURPOSE To present a theoretical basis for noninvasively characterizing in vivo fluid-mechanical energy losses and to apply it in a pilot study of patients known to express abnormal aortic flow patterns. METHODS Four-dimensional flow MRI was used to characterize laminar viscous energy losses in the aorta of normal controls (n = 12, age = 37 ± 10 yr), patients with aortic dilation (n = 16, age = 52 ± 8 yr), and patients with aortic valve stenosis matched for age and aortic size (n = 14, age = 46 ± 15 yr), using a relationship between the three-dimensional velocity field and viscous energy dissipation. RESULTS Viscous energy loss was elevated significantly in the thoracic aorta in patients with dilated aorta (3.6 ± 1.3 mW, P = 0.024) and patients with aortic stenosis (14.3 ± 8.2 mW, P < 0.001) compared with healthy volunteers (2.3 ± 0.9 mW). The same pattern of significant differences was seen in the ascending aorta, where viscous energy losses in patients with dilated aortas (2.2 ± 1.1 mW, P = 0.021) and patients with aortic stenosis (10.9 ± 6.8 mW, P < 0.001) were elevated compared with healthy volunteers (1.2 ± 0.6 mW). CONCLUSION This technique provides a capability to quantify the contribution of abnormal laminar blood flow to increased ventricular afterload. In this pilot study, viscous energy loss in patient cohorts was significantly elevated and indicates that cardiac afterload is increased due to abnormal flow.
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van Ooij P, Potters WV, Collins J, Carr M, Carr J, Malaisrie SC, Fedak PWM, McCarthy PM, Markl M, Barker AJ. Characterization of abnormal wall shear stress using 4D flow MRI in human bicuspid aortopathy. Ann Biomed Eng 2014; 43:1385-97. [PMID: 25118671 DOI: 10.1007/s10439-014-1092-7] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 08/06/2014] [Indexed: 12/14/2022]
Abstract
There exists considerable controversy surrounding the timing and extent of aortic resection for patients with BAV disease. Since abnormal wall shear stress (WSS) is potentially associated with tissue remodeling in BAV-related aortopathy, we propose a methodology that creates patient-specific 'heat maps' of abnormal WSS, based on 4D flow MRI. The heat maps were created by detecting outlier measurements from a volumetric 3D map of ensemble-averaged WSS in healthy controls. 4D flow MRI was performed in 13 BAV patients, referred for aortic resection and 10 age-matched controls. Systolic WSS was calculated from this data, and an ensemble-average and standard deviation (SD) WSS map of the controls was created. Regions of the individual WSS maps of the BAV patients that showed a higher WSS than the mean + 1.96SD of the ensemble-average control WSS map were highlighted. Elevated WSS was found on the greater ascending aorta (35% ± 15 of the surface area), which correlated significantly with peak systolic velocity (R (2) = 0.5, p = 0.01) and showed good agreement with the resected aortic regions. This novel approach to characterize regional aortic WSS may allow clinicians to gain unique insights regarding the heterogeneous expression of aortopathy and may be leveraged to guide patient-specific resection strategies for aorta repair.
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van Ooij P, Potters WV, Nederveen AJ, Allen BD, Collins J, Carr J, Malaisrie SC, Markl M, Barker AJ. A methodology to detect abnormal relative wall shear stress on the full surface of the thoracic aorta using four-dimensional flow MRI. Magn Reson Med 2014; 73:1216-27. [PMID: 24753241 DOI: 10.1002/mrm.25224] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 01/02/2023]
Abstract
PURPOSE To compute cohort-averaged wall shear stress (WSS) maps in the thoracic aorta of patients with aortic dilatation or valvular stenosis and to detect abnormal regional WSS. METHODS Systolic WSS vectors, estimated from four-dimensional flow MRI data, were calculated along the thoracic aorta lumen in 10 controls, 10 patients with dilated aortas, and 10 patients with aortic valve stenosis. Three-dimensional segmentations of each aorta were coregistered by group and used to create a cohort-specific aortic geometry. The WSS vectors of each subject were interpolated onto the corresponding cohort-specific geometry to create cohort-averaged WSS maps. A Wilcoxon rank sum test was used to generate aortic P-value maps (P<0.05) representing regional relative WSS differences between groups. RESULTS Cohort-averaged systolic WSS maps and P-value maps were successfully created for all cohorts and comparisons. The dilation cohort showed significantly lower WSS on 7% of the ascending aorta surface, whereas the stenosis cohort showed significantly higher WSS on 34% of the ascending aorta surface. CONCLUSIONS The findings of this study demonstrated the feasibility of generating cohort-averaged WSS maps for the visualization and identification of regionally altered WSS in the presence of disease, compared with healthy controls.
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Potters WV, van Ooij P, Marquering H, vanBavel E, Nederveen AJ. Volumetric arterial wall shear stress calculation based on cine phase contrast MRI. J Magn Reson Imaging 2014; 41:505-16. [PMID: 24436246 DOI: 10.1002/jmri.24560] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 12/03/2013] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To assess the accuracy and precision of a volumetric wall shear stress (WSS) calculation method applied to cine phase contrast magnetic resonance imaging (PC-MRI) data. MATERIALS AND METHODS Volumetric WSS vectors were calculated in software phantoms. WSS algorithm parameters were optimized and the influence of spatial resolution and segmentation was evaluated. Subsequently, 2D cine PC-MRI data in the carotid and the aorta at varying spatial resolutions were obtained (n = 2) and compared with the simulations. Finally, volumetric WSS was calculated in 3D cine PC-MRI data of the carotid bifurcation and the aorta (n = 6). RESULTS We found that at least 8 voxels across the diameter are required to obtain a WSS accuracy of 5% and a precision of 20% in software phantoms. Systematic WSS quantification errors up to 40% were found in the case of segmentation errors. The in vivo measurements using 2D cine PC-MRI exhibited WSS increase at increasing spatial resolutions, similar to the results in software phantoms. Volumetric WSS vectors were successfully calculated in three healthy carotid bifurcations and aortas. CONCLUSION The effects of resolution and segmentation on the accuracy and precision of the WSS algorithm were quantified. We were able to calculate volumetric WSS in the carotid bifurcation and the aorta.
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Allen BD, van Ooij P, Barker AJ, Collins JD, Carr JC, Markl M, Kansal P. Impact of beta-blocker therapy on thoracic aorta 3D wall shear stress in patients with bicuspid aortic valve. J Cardiovasc Magn Reson 2014. [PMCID: PMC4043193 DOI: 10.1186/1532-429x-16-s1-o47] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Allen BD, Choudhury L, Barker AJ, Ooij PV, Collins JD, Bonow RO, Carr JC, Markl M. Ascending aorta flow derangement is a marker of outflow obstruction in hypertrophic cardiomyopathy. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044949 DOI: 10.1186/1532-429x-16-s1-p293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Garcia J, Markl M, van Ooij P, Schnell S, Collins JD, Malaisrie SC, Carr JC, Barker AJ. Assessment of transvalvular flow jet angle in aortic dilation patients using 4D flow jet shear layer detection method. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044161 DOI: 10.1186/1532-429x-16-s1-p47] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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van Ooij P, Potters WV, Guédon A, Schneiders JJ, Marquering HA, Majoie CB, vanBavel E, Nederveen AJ. Wall shear stress estimated with phase contrast MRI in an in vitro and in vivo intracranial aneurysm. J Magn Reson Imaging 2013; 38:876-84. [PMID: 23417769 DOI: 10.1002/jmri.24051] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 12/19/2012] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To evaluate wall shear stress (WSS) estimations in an in vitro and in vivo intracranial aneurysm, WSS was estimated from phase contrast magnetic resonance imaging (PC-MRI) and compared with computational fluid dynamics (CFD). MATERIALS AND METHODS First, WSS was estimated using a high-resolution in vitro PC-MRI measurement under steady and pulsatile flow conditions and compared with CFD simulations. Second, WSS was estimated in steady PC-MRI data acquired at different spatial resolutions. Third, WSS estimations in pulsatile in vivo data were compared with CFD. The direction and magnitude of WSS vectors were computed and compared. RESULTS Quantitative agreement between PC-MRI and CFD-based WSS estimations was moderate for the phantom (Spearman ρ = 0.69). The WSS magnitude derived from PC-MRI data was lower than CFD for both the in vitro and in vivo case. However, there was qualitative agreement between PC-MRI and CFD, i.e. WSS vector direction was similar for both modalities. Circular WSS patterns were found both in vitro and in vivo for PC-MRI and CFD. Increasing PC-MRI resolution increased mean WSS magnitude and uncovered complex WSS patterns. CONCLUSION WSS patterns can be estimated based on PC-MRI data in in vitro and in vivo aneurysm geometries. Similar WSS directions as CFD can be discerned.
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van Ooij P, Zwanenburg JJ, Visser F, Majoie CB, vanBavel E, Hendrikse J, Nederveen A. Quantification and visualization of flow in small vessels of the Circle of Willis: time-resolved three-dimensional phase contrast MRI at 7T compared with 3T. J Cardiovasc Magn Reson 2012. [PMCID: PMC3305702 DOI: 10.1186/1532-429x-14-s1-w42] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
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van Ooij P, Guédon A, Marquering HA, Schneiders JJ, Majoie CB, van Bavel E, Nederveen AJ. k-t BLAST and SENSE accelerated time-resolved three-dimensional phase contrast MRI in an intracranial aneurysm. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2012; 26:261-70. [PMID: 22955942 DOI: 10.1007/s10334-012-0336-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 07/20/2012] [Accepted: 08/06/2012] [Indexed: 10/27/2022]
Abstract
OBJECTIVE The objective of this study was to investigate the performance of k-t BLAST (Broad-use Linear Acquisition Speed-up Technique) accelerated time-resolved 3D PC-MRI compared to SENSE (SENSitivity Encoding) acceleration in an in vitro and in vivo intracranial aneurysm. MATERIALS AND METHODS Non-accelerated, SENSE and k-t BLAST accelerated time-resolved 3D PC-MRI measurements were performed in vivo and in vitro. We analysed the consequences of various temporal resolutions in vitro. RESULTS Both in vitro and in vivo measurements showed that the main effect of k-t BLAST was underestimation of velocity during systole. In the phantom, temporal blurring decreased with increasing temporal resolution. Quantification of the differences between the non-accelerated and accelerated measurements confirmed that in systole SENSE performed better than k-t BLAST in terms of mean velocity magnitude. In both in vitro and in vivo measurements, k-t BLAST had higher SNR compared to SENSE. Qualitative comparison between measurements showed good similarity. CONCLUSION Comparison with SENSE revealed temporal blurring effects in k-t BLAST accelerated measurements.
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van Ooij P, Schneiders J, Marquering H, Majoie CB, vanBavel E, Nederveen A. 4D phase contrast MRI in intracranial aneurysms: a comparison with patient-specific computational fluid dynamics with temporal and spatial velocity boundary conditions as measured with 3D phase contrast MRI. J Cardiovasc Magn Reson 2012. [PMCID: PMC3305732 DOI: 10.1186/1532-429x-14-s1-w3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Potters WV, van Ooij P, vanBavel E, Nederveen A. Vectorial wall shear stress calculations in vessel structures using 4D PC-MRI. J Cardiovasc Magn Reson 2012. [PMCID: PMC3305771 DOI: 10.1186/1532-429x-14-s1-w5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Gevers S, Nederveen AJ, Fijnvandraat K, van den Berg SM, van Ooij P, Heijtel DF, Heijboer H, Nederkoorn PJ, Engelen M, van Osch MJ, Majoie CB. Arterial spin labeling measurement of cerebral perfusion in children with sickle cell disease. J Magn Reson Imaging 2011; 35:779-87. [PMID: 22095695 DOI: 10.1002/jmri.23505] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 10/21/2011] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To evaluate the applicability of arterial spin labeling (ASL) cerebral blood flow (CBF) measurements in children with sickle cell disease (SCD). MATERIALS AND METHODS We included 12 patients and five controls. Conventional magnetic resonance imaging (MRI) (T2, fluid attenuated inversion recovery [FLAIR], and MR angiography) was performed to diagnose silent infarcts, vasculopathy, or leukoencephalopathy. Pseudo-continuous ASL was performed to measure CBF using two postlabeling delays to identify transit-time effects. Perfusion estimates were corrected for hematocrit and blood velocity in the labeling plane and compared to phase-contrast MR. CBF asymmetries between the flow maps of the left and right internal carotid arteries were tested for significance using paired t-tests. Significant asymmetries were expressed in terms of an asymmetry ratio (AR = absolute difference/mean). An AR >10% was considered clinically relevant. RESULTS Mean CBF was higher in patients than in controls. Agreement between CBF and flow improved after applying hematocrit and velocity corrections. At a 2100 msec postlabeling delay one patient had a clinically relevant asymmetry. No association was observed between CBF asymmetries and silent infarcts. CONCLUSION Care must be taken in the interpretation of ASL-CBF measurements in SCD patients. A long postlabeling delay with blood velocity correction anticipates overestimation of CBF asymmetries.
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Marquering HA, van Ooij P, Streekstra GJ, Schneiders JJ, Majoie CB, vanBavel E, Nederveen AJ. Multiscale flow patterns within an intracranial aneurysm phantom. IEEE Trans Biomed Eng 2011; 58:3447-50. [PMID: 21803678 DOI: 10.1109/tbme.2011.2163070] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Straightforward quantification of variations of flow patterns within aneurysms fails to accurately describe flow patterns of interest. We applied a multiscale decomposition of the flow in well-defined patterns to detect and quantify flow patterns in an aneurysm phantom that was studied with three different modalities: MRI, computational fluid dynamics, and particle image velocimetry. The method intuitively visualizes main patterns such as locally uniform flow, in- and outflow, and vortices. It is shown that this method is a valuable tool to quantitatively compare scale-dependent complex flow patterns in aneurysms.
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