MR measurement of pulsatile pressure gradients

Urchuk, Steven N.; Plewes, Donald B.

doi:10.1002/jmri.1880040615

Cited by 42 publications

(36 citation statements)

References 25 publications

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“…17,18,29 The Navier-Stokes equation is an experimentally established method used to calculate the pressure gradient. Its accuracy was reported at better than 8% in model vessel segments, 30 and a high correlation coefficient was determined by invasive measurement methods using manometers in a pulsatile flow phantom. 28 Thus, we speculated that heterogeneous membrane tension would cause variability of the velocity and pressure gradient along the diameter of the tube in each ROI in the phantom experiment and that bifurcation in the Y-shaped connectors would cause turbulent flow.…”

Section: Discussionmentioning

confidence: 98%

Visualization of Pulsatile CSF Motion Around Membrane-like Structures with both 4D Velocity Mapping and Time-SLIP Technique

et al. 2015

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Purpose: We compared the depiction of pulsatile CSF motion obtained by 4-dimensional phase-contrast velocity mapping (4D-VM) with that by time-spatial labeling inversion pulse (time-SLIP) technique in the presence of membrane structures.Materials and Methods: We compared the 2 techniques using a flow phantom comprising tubes with and without a thin rubber membrane and applied the techniques to 6 healthy volunteers and 2 patients to analyze CSF dynamics surrounding thin membrane structures, such as the Liliequist membrane (LM), or the wall of an arachnoid cyst.Results: Phantom images exhibited propagation of the flow and pressure gradient beyond the membrane in the tube. In contrast, fluid labeled by the time-SLIP technique showed little displacement from the blockage of spin travelling by the membrane. A similar phenomenon was observed around the LM in healthy volunteers and the arachnoid cyst wall in a patient.Conclusion: Four-dimensional phase-contrast velocity mapping permitted visualization of the propagation of CSF pulsation through the intracranial membranous structures. This suggests that 4D-VM and the time-SLIP technique provide different information on flow and that both techniques are useful for classifying the pathophysiological status of CSF and elucidating the propagation pathway of CSF pulsation in the cranium.

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Section: Discussionmentioning

confidence: 98%

Visualization of Pulsatile CSF Motion Around Membrane-like Structures with both 4D Velocity Mapping and Time-SLIP Technique

et al. 2015

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“…At present, it is impossible to measure these characteristics non-invasively. Two possibilities exist for obtaining these descriptors of the hemodynamic forces in a specific arterial segment of an individual patient based on non-invasive measurements: either deriving them directly from the measured velocity field (16)(17)(18), or to use the velocity field measurements as patient-specific inlet and outlet conditions in a numerical simulation (CFD) of the flow field and derive the flow characteristics from this field (19)(20)(21)(22)(23)(24). In either approach, the quality of the derived parameters relies on the accuracy of the PC-MRA as a source of the velocity field data.…”

Section: Research Article 795mentioning

confidence: 99%

Comparative velocity investigations in cerebral arteries and aneurysms: 3D phase‐contrast MR angiography, laser Doppler velocimetry and computational fluid dynamics

et al. 2009

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In western populations, cerebral aneurysms develop in approximately 4% of humans and they involve the risk of rupture. Blood flow patterns are of interest for understanding the pathogenesis of the lesions and may eventually contribute to deciding on the most efficient treatment procedure for a specific patient. Velocity mapping with phase-contrast magnetic resonance angiography (PC-MRA) is a non-invasive method for performing in vivo measurements on blood velocity. Several hemodynamic properties can either be derived directly from these measurements or a flow field with all its parameters can be simulated on the basis of the measurements. For both approaches, the accuracy of the PC-MRA data and subsequent modeling must be validated. Therefore, a realistic transient flow field in a well-defined patient-specific silicone phantom was investigated. Velocity investigations with PC-MRA in a 3 Tesla MR scanner, laser Doppler velocimetry (LDV) and computational fluid dynamics (CFD) were performed in the same model under equal flow conditions and compared to each other. The results showed that PC-MRA was qualitatively similar to LDV and CFD, but showed notable quantitative differences, while LDV and CFD agreed well. The accuracy of velocity quantification by PC-MRA was best in straight artery regions with the measurement plane being perpendicular to the primary flow direction. The accuracy decreased in regions with disturbed flow and in cases where the measurement plane was not perpendicular to the primary flow. Due to these findings, it is appropriate to use PC-MRA as the inlet and outlet conditions for numerical simulations to calculate velocities and shear stresses in disturbed regions like aneurysms, rather than derive these values directly from the full PC-MRA measured velocity field.

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“…Pressure gradients were determined from iterative methods, which have been validated in both phantom and animal models to provide relatively accurate answers. 11,[24][25][26][27] This technique is based on the Navier-Stokes equation, which simplifies more complex relationships by assuming the fluid to be both incompressible and Newtonian. Arterial blood flow generally satisfies these assumptions with a dynamic viscosity of approximately 4 cP (centipoise).…”

Section: Pc-viprmentioning

confidence: 99%

“…Subsequent to that, we iteratively refined this pressure map by using a path-averaging algorithm. 11,[24][25][26][27] Dynamic pressure maps were then averaged for comparison with in vivo measurements, and pressure differences were compared on a pressure map registered to DSA images.…”

Section: Pc-viprmentioning

confidence: 99%

Noninvasive Measurement of Intra-Aneurysmal Pressure and Flow Pattern Using Phase Contrast with Vastly Undersampled Isotropic Projection Imaging

Moftakhar¹,

Aagaard-Kienitz²,

Johnson³

et al. 2007

American Journal of Neuroradiology

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BACKGROUND AND PURPOSE:Currently, more reliable parameters to predict the risk of aneurysmal rupture are needed. Intra-aneurysmal pressure gradients and flow maps could provide additional information regarding the risk of rupture. Our hypothesis was that phase contrast with vastly undersampled isotropic projection reconstruction (PC-VIPR), a novel 3D MR imaging sequence, could accurately assess intra-aneurysmal pressure gradients in a canine aneurysmal model when compared with invasive measurements.

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MR measurement of pulsatile pressure gradients

Cited by 42 publications

References 25 publications

Visualization of Pulsatile CSF Motion Around Membrane-like Structures with both 4D Velocity Mapping and Time-SLIP Technique

Visualization of Pulsatile CSF Motion Around Membrane-like Structures with both 4D Velocity Mapping and Time-SLIP Technique

Comparative velocity investigations in cerebral arteries and aneurysms: 3D phase‐contrast MR angiography, laser Doppler velocimetry and computational fluid dynamics

Noninvasive Measurement of Intra-Aneurysmal Pressure and Flow Pattern Using Phase Contrast with Vastly Undersampled Isotropic Projection Imaging

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