MR imaging of flow through tortuous vessels: A numerical simulation

Tyen, R. van; Saloner, David; Jou, Liang Der; Berger, Stanley A.

doi:10.1002/mrm.1910310212

Cited by 41 publications

(35 citation statements)

References 18 publications

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“…Such techniques have been used previously to study signal artifacts in bright blood MR angiography (16,17) and displacement artifacts in phase-contrast velocimetry (14). We approximated the signal recovery in presaturated black blood MRI as a monoexponential TI regrowth: after saturation, spins were assumed to recover their signal via:…”

Section: Model Studiesmentioning

confidence: 99%

On the nature and reduction of plaque‐mimicking flow artifacts in black blood MRI of the carotid bifurcation

Steinman

Rutt

1998

Magnetic Resonance in Med

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Cardiac-gated black blood MRI of the carotid artery bifurcation in normal human subjects shows signal within the lumen suggesting wall thickening or atherosclerotic plaque. This signal was believed to be artifactual, arising from complex flow patterns present at the carotid bifurcation. Computer simulation of the hemodynamics and black blood multislice image acquisition in a model of the carotid bifurcation showed that these artifacts arise from spins recovering their signal within the slow, recirculating flow of the carotid bulb. The computed hemodynamics also suggested that these artifacts could be minimized or eliminated entirely by gating the acquisition of slices in the most artifact-prone region of the carotid bulb within a 250-ms window after peak systole. Application of these predictions to studies of normal volunteers showed that, in most cases, these flow artifacts in black blood MRI can be eliminated simply by altering the phase of the cardiac cycle to which the image acquisition is gated. The observation that the size and placement of the saturation slabs had little effect on these artifacts suggested that, in those cases in which recirculation persists throughout the cardiac cycle, either inversion-recovery or presaturation within the bulb itself would be required to suppress them.

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Section: Model Studiesmentioning

confidence: 99%

On the nature and reduction of plaque‐mimicking flow artifacts in black blood MRI of the carotid bifurcation

Steinman

Rutt

1998

Magnetic Resonance in Med

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“…Combined with a suitable model of the MR imaging process, complex displacement artifacts can be readily simulated and thus better understood. Such techniques have been used to study signal enhancement/loss artifacts in time-of-flight angiography, either by examining phase dispersion (17) or by direct numerical simulation of the Bloch equations (18,191.…”

mentioning

confidence: 99%

Combined analysis of spatial and velocity displacement artifacts in phase contrast measurements of complex flows

Steinman

Ethier

Rutt

1997

Magnetic Resonance Imaging

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MR phase contrast (PC) velocity imaging is a promising tool for quantifying blood flow velocity in vivo. PC velocity imaging is, however, susceptible to artifacts that result from the displacement of spins during the finite duration pulse sequences. Such displacement artifacts can lead to errors in velocity measurements, especially in the presence of oblique and accelerating flows, which are common throughout the cardiovascular system. By tracking particles (representing spins) through a computed velocity field, and assuming that spatial and velocity encodings occur at discrete times during the pulse sequence, we simulate the separate and combined effects of oblique and acceleration artifacts on PC velocity images. We demonstrate, both by simulation and MR measurement, the errors associated with such artifacts in PC velocity measurements in a representative flow geometry. Using example particle trajectories, we provide a fluid dynamic basis for characteristic phase-velocity image distortions that can arise when imaging complex, physiologically relevant flows.

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“…This can be shown easily by evaluating the moments for a single square lobe as expressed in Eqs. [4] through [7]. Looking then at Eq.…”

Section: Discussionmentioning

confidence: 99%

Effects of acceleration, jerk, and field inhomogeneities on vessel positions in magnetic resonance angiography

Stefansic

Paschal

1998

Magnetic Resonance in Med

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Blood flow and magnetic field inhomogeneities lead to distortions in MR angiography (MRA) images that present added risk for stereotactic neurosurgical applications. These effects are demonstrated in an MRA image of a model of cerebrovasculature. Analysis of the effects of velocity, acceleration, jerk, and field inhomogeneities on vessel position is presented; results are used to predict vessel shifts for several cerebral blood vessels. The actual encoded position for flowing spins is shown to be a moment-weighted average position. Maximum shift of 3.11 mm was reduced to 0.05 mm when velocity compensation was added. Velocity compensation applied specifically in the phase-encoding direction reduces flow-dependent shifts to the point that they can be safely ignored even if acceleration and jerk are present. Those prescribing and using MRA images for stereotactic applications must be aware of whether compensation is actually applied along the phase-encoding axis when a flow-compensated sequence is used.

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MR imaging of flow through tortuous vessels: A numerical simulation

Cited by 41 publications

References 18 publications

On the nature and reduction of plaque‐mimicking flow artifacts in black blood MRI of the carotid bifurcation

On the nature and reduction of plaque‐mimicking flow artifacts in black blood MRI of the carotid bifurcation

Combined analysis of spatial and velocity displacement artifacts in phase contrast measurements of complex flows

Effects of acceleration, jerk, and field inhomogeneities on vessel positions in magnetic resonance angiography

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