Arterial MR Imaging Phase-Contrast Flow Measurement: Improvements with Varying Velocity Sensitivity during Cardiac Cycle1

MR Center, Institute of Experimental Clinical Research, Aarhus University Hospital, Skejby Sygehus, Brendstrupgaardsvej, DK-8200 Aarhus N, Denmark.
Radiology (Impact Factor: 6.87). 08/2004; 232(1):289-94. DOI: 10.1148/radiol.2321030783
Source: PubMed


To reduce noise in velocity images of magnetic resonance (MR) phase-contrast measurements, the authors implemented and evaluated a pulse sequence that enables automatic optimization of the velocity-encoding parameter V(enc) for individual heart phases in pulsatile flow on the basis of a rapid prescan. This sequence was prospectively evaluated by comparing velocity-to-noise ratios with those from a standard MR flow scan obtained in the carotid artery in eight volunteers. This sequence was shown to improve velocity-to-noise ratios by a factor of 2.0-6.0 in all but the systolic heart phase and was determined to be an effective technique for reducing noise in phase-contrast velocity measurements.

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    • "For phase-contrast blood velocity mapping scans, some a priori knowledge about expected peak velocities is necessary in order to set velocity encoding correctly. Techniques have been described whereby acquisition of an extra segment allows automatic correction for aliased velocities to eliminate this restriction [25, 26]. With scan durations of the presented acquisitions of less than 30 min combined, they can all be acquired in a single scanning session. "
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