Accuracy of phase‐contrast flow measurements in the presence of partial‐volume effects

Tang, Chao; Blatter, Duane D.; Parker, Dennis L.

doi:10.1002/jmri.1880030213

Cited by 286 publications

(256 citation statements)

References 13 publications

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“…To obtain accurate results, Tang et al (31) recommend ensuring that the flow region is covered by at least 16 isotropic voxels to minimize partial volume effects within the flow region. This recommendation was fulfilled for the PC-MRA measurements at the inlet, outlet 3, and the aneurysm, though not for outlet 1 (nine voxels) and outlet 2 (12 voxels).…”

Section: Discussionmentioning

confidence: 99%

“…Vessel-slice obliquity is a recognized source of partial volume effects as described (31), with the severity dependent on vessel size and the voxel dimensions of the image. This is a probable explanation for the poor performance in outlet 1, which was measured with a significant angle between the imaging plane and the artery's main flow direction.…”

Section: Discussionmentioning

confidence: 99%

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Laser Doppler velocimetry (LDV) and 3D phase‐contrast magnetic resonance angiography (PC‐MRA) velocity measurements: Validation in an anatomically accurate cerebral artery aneurysm model with steady flow

Hollnagel

Summers

Kollias

et al. 2007

Magnetic Resonance Imaging

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Purpose:To verify the accuracy of velocity mapping with three-dimensional (3D) phase-contrast magnetic resonance angiography (PC-MRA) for steady flow in a realistic model of a cerebral artery aneurysm at a 3T scanner. Materials and Methods:Steady flow through an original geometry model of a cerebral aneurysm was mapped at characteristic positions by state-of-the-art laser Doppler velocimetry (LDV) as well as 3D PC-MRA at 3T. The spatial distributions and local values of two velocity components obtained with these two measurement methods were compared. Results:The 3D PC-MRA velocity field distribution and mean velocity values exhibited only minor differences to compare to the LDV measurements in straight artery regions for both main and secondary velocities. The differences increased in regions with disturbed flow and in cases where the measurement plane was not perpendicular to the main flow direction.Conclusion: 3D PC-MRA can provide reliable measurements of velocity components of steady flow in small arteries. The accuracy of such measurements depends on the artery size and the measurement plane positioning.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Laser Doppler velocimetry (LDV) and 3D phase‐contrast magnetic resonance angiography (PC‐MRA) velocity measurements: Validation in an anatomically accurate cerebral artery aneurysm model with steady flow

Hollnagel

Summers

Kollias

et al. 2007

Magnetic Resonance Imaging

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“…Low spatial resolution may account for the inaccurate flow measurements obtained using the spinwarp acquisition. It has been demonstrated that flow measurements will be inaccurate if an insufficient number of pixels spans the vessel of interest (11).…”

Section: Discussionmentioning

confidence: 99%

“…The accurate measurement of flow requires high spatial resolution for a true depiction of the cross-sectional area of the vessel of interest (11). In addition, a high temporal resolution is required for an accurate representation of the varying shape of a flow waveform throughout the cardiac cycle.…”

mentioning

confidence: 99%

Cine flow measurements using phase contrast with undersampled projections: In vitro validation and preliminary results in vivo

Wentland

Korosec

Vigen

et al. 2006

Magnetic Resonance Imaging

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Purpose:To assess the accuracy of flow measurements in vitro and in vivo during scan times shorter than a breathhold using a 2D cine phase contrast (PC) undersampled radial acquisition method, which may be useful for measuring flow, especially in vessels subject to motion during respiration. Materials and Methods:For in vitro assessment, a flow phantom was imaged at various flow rates and undersampling factors. For in vivo assessment, five normal subjects were imaged and the flow rate in the aorta was compared with the sum of the flow rates in the iliac arteries. Results:For results in vitro, the accuracy of flow measurements was maintained with scan times as low as 13-17 seconds. For results in vivo, scans acquired in less than 25 seconds provided flow measurements in the aorta that corresponded well to the sum of flow measurements in the iliac arteries. Conclusion:The undersampled radial acquisition cine PC technique provided accurate flow measurements in a flow phantom and in healthy human volunteers in scan times shorter than a typical breath-hold.

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“…The accuracy of such methods is limited by data quality and the spatial resolution of the velocity estimates. Particularly, phase contrast (PC) MRI suffers from partial-volume effects (17) and inadequate signal-to-noise ratio (SNR) at high spatial resolutions (Fig. 1).…”

mentioning

confidence: 99%

Feasibility of in vivo measurement of carotid wall shear rate using spiral fourier velocity encoded MRI

Carvalho

Nielsen

Nayak

2010

Magnetic Resonance in Med

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Arterial wall shear stress is widely believed to influence the formation and growth of atherosclerotic plaque; however, there is currently no gold standard for its in vivo measurement. The use of phase contrast MRI has proved to be challenging due to partial-volume effects and inadequate signal-to-noise ratio at the high spatial resolutions that are required. This work evaluates the use of spiral Fourier velocity encoded MRI as a rapid method for assessing wall shear rate in the carotid arteries. Wall shear rate is calculated from velocity histograms in voxels spanning the blood/vessel wall interface, using a method Atherosclerosis affects over 18 million Americans. The associated formation, growth, and rupture of intraarterial plaque represent the fundamental process leading to myocardial infarction and thrombotic stroke. Arterial wall shear stress (WSS)-the drag force acting on the endothelium as a result of blood flow-is widely believed to influence the formation and growth of atherosclerotic plaque and may have prognostic value. WSS can be estimated as the product of wall shear rate (WSR) and blood viscosity (µ), where WSR is the radial gradient of blood flow velocity (dv /dr) at the vessel wall. Low WSS (1,2) and highly oscillatory WSS (3) have been linked to the formation and growth of atherosclerotic plaques, and this link has been validated in vitro (4). High WSS has also been hypothesized as a factor responsible for the topography of atherosclerotic lesions (5). Serial and noninvasive WSS measurement would be of value to the in vivo testing of these hypotheses and to better our understanding of the causal relationships between hemodynamics and the process of atherosclerotic plaque formation, growth, and rupture.Direct methods for measuring WSS are highly invasive and/or can only be used in conjunction with in vitro models (6-8). Indirect methods for measuring WSS are based on extrapolation of the measured axial velocity profile near the vessel wall (9), which can be measured by either ultrasound (10,11) or MRI (11-16). The accuracy of such methods is limited by data quality and the spatial resolution of the velocity estimates. Particularly, phase contrast (PC) MRI suffers from partial-volume effects (17) and inadequate signal-to-noise ratio (SNR) at high spatial resolutions (Fig. 1). PC is not currently capable of providing accurate absolute measurements of WSS (18) and has been shown to underestimate blood flow velocities in the carotid bifurcation by 31-39% (19). An alternative approach for estimating WSS is to reconstruct a complex flow field via computational fluid dynamics (CFD) simulation, using vascular geometries and input/output functions derived from noninvasive imaging data (20)(21)(22). This approach is computationally intense and may be sensitive to many assumptions and simplifications that are frequently made about the properties of blood and endothelium. CFD is also limited in modeling wall compliance and is sensitive to boundary conditions (11).In 1995, Frayne and Rutt (23) proposed a no...

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Accuracy of phase‐contrast flow measurements in the presence of partial‐volume effects

Cited by 286 publications

References 13 publications

Laser Doppler velocimetry (LDV) and 3D phase‐contrast magnetic resonance angiography (PC‐MRA) velocity measurements: Validation in an anatomically accurate cerebral artery aneurysm model with steady flow

Laser Doppler velocimetry (LDV) and 3D phase‐contrast magnetic resonance angiography (PC‐MRA) velocity measurements: Validation in an anatomically accurate cerebral artery aneurysm model with steady flow

Cine flow measurements using phase contrast with undersampled projections: In vitro validation and preliminary results in vivo

Feasibility of in vivo measurement of carotid wall shear rate using spiral fourier velocity encoded MRI

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