Dealing with the subvoxel vessel position relative to the reconstruction voxel grid in 2D MR quantitative flow measurements

Kaandorp, DW Dave; Kopinga, K.; Kouwenhoven, Marc; Wijn, Pff Pieter

doi:10.1016/s0730-725x(99)00108-3

Cited by 6 publications

(4 citation statements)

References 11 publications

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“…Earlier studies have suggested that the threshold value in this algorithm should be chosen halfway between vessel and background signal intensity (Pelc et al 1991, Tang et al 1993, Hofman et al 1995. A recent study has shown that this choice of threshold value is indeed systematically correct (Kaandorp et al 1997). The above procedure resulted in the vessel area as a function of time with a temporal resolution of 26 ms.…”

Section: Methodsmentioning

confidence: 99%

Separation of haemodynamic flow waves measured by MR into forward and backward propagating components

Kaandorp¹,

Kopinga

Wijn

1999

Physiol. Meas.

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Physiological information on the action of the heart and on the reflection sites in the arterial system can be derived respectively from the forward and the backward propagating pressure or flow wave components. Earlier work on the separation of these components was exclusively based on invasive measurements of pressure or flow. In this study magnetic resonance (MR), which is a non-invasive imaging technique, was used to measure the blood flow waveform simultaneously at multiple positions along a vessel. Linear one dimensional transmission-line theory was used to separate the flow waves into forward and backward propagating components. First results, obtained from the thoracic aorta of five healthy male volunteers, consistently showed a negative reflection with a delay of about 100 ms between the foot of the forward and the foot of the backward propagating flow wave. Our model, consisting of a single vessel segment with constant diameter and wall properties, was validated by the excellent agreement between the vessel area as calculated from the flow data using the law of mass conservation and as directly measured with a different independent MR technique.

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Section: Methodsmentioning

confidence: 99%

Separation of haemodynamic flow waves measured by MR into forward and backward propagating components

Kaandorp¹,

Kopinga

Wijn

1999

Physiol. Meas.

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“…This widely accepted target is readily achieved in imaging the great vessels, but is a constraint for more peripheral vessels. Consequently, several authors have focused their efforts on easing this restriction (11, 26, 29–32). Similarly, vascular narrowing is clinically interesting, but often leads to flow disturbances that may corrupt the velocity estimates obtained by phase mapping (33–35).…”

Section: Methodsmentioning

confidence: 99%

Multisite trial of MR flow measurement: Phantom and protocol design

Summers

Holdsworth

Nikolov

et al. 2005

Magnetic Resonance Imaging

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Purpose: To describe a portable, easily assembled phantom with well-defined bore geometry together with a series of tests that will form the basis of a standardized quality assurance protocol in a multicenter trial of flow measurement by the MR phase mapping technique. Materials and Methods:The phantom consists of silicone polymer layers containing parallel straight and stenosed flow channels in one layer and a U-bend in a second layer, separated by hermetically sealed agarose slabs. The phantom is constructed by casting low melting-point metal in an aluminum mold precisely milled to the desired geometry, and then using the low melting-point metal core as a negative around which the silicone is allowed to set. By melting out the metal, the flow channels are established. The milled aluminum mold is reusable, ensuring faithful reproduction of the flow geometry for all phantoms thus produced. The agarose layers provide additional loading and static background signal for background correction. With the use of the described phantom, one can evaluate flow measurement accuracy and repeatability, as well as the influence of several imaging geometry factors: slice offset, in-plane position, and slice-flow obliquity. Results:The new phantom is compact and portable, and is well suited for reassembly. We were able to demonstrate its facility in a battery of tests of interest in evaluating MR flow measurements. Conclusion:The phantom is a robust standardized test object for use in a multicenter trial. Such a trial, to investigate the performance of MR flow measurement using the phantom and the tests we describe, has been initiated.

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“…1). To improve accuracy, the images should be zero-interpolated at a factor of 2 or 4 before reconstruction (13,14).…”

Section: In-plane Imagingmentioning

confidence: 99%

Resolution‐insensitive velocity and flow rate measurement in low‐background phase‐contrast MRA

Weide

Viergever

Bakker

2004

Magnetic Resonance in Med

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Dealing with the subvoxel vessel position relative to the reconstruction voxel grid in 2D MR quantitative flow measurements

Cited by 6 publications

References 11 publications

Separation of haemodynamic flow waves measured by MR into forward and backward propagating components

Separation of haemodynamic flow waves measured by MR into forward and backward propagating components

Multisite trial of MR flow measurement: Phantom and protocol design

Resolution‐insensitive velocity and flow rate measurement in low‐background phase‐contrast MRA

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