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Resolution‐insensitive velocity and flow rate measurement in low‐background phase‐contrast MRA
Author(s) -
van der Weide Remko,
Viergever Max A.,
Bakker Chris J. G.
Publication year - 2004
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.20035
Subject(s) - signal (programming language) , hagen–poiseuille equation , flow (mathematics) , partial volume , imaging phantom , cross section (physics) , flow velocity , radius , contrast (vision) , physics , volumetric flow rate , nuclear magnetic resonance , image resolution , resolution (logic) , phase (matter) , flow measurement , acoustics , materials science , optics , mechanics , computer science , artificial intelligence , computer security , quantum mechanics , programming language
Magnetic resonance (MR) phase‐contrast (PC) flow measurements are degraded by partial volume errors when the spatial resolution is low, in particular when a large difference in signal magnitude exists between the fluid and the surrounding material. The latter is often the case in phantom studies and may be encountered when flow is measured in prosthetic vessel segments (such as shunts, grafts, and bypasses) and in contrast‐enhanced blood. This paper presents a new method that is designed to measure flow in vessels of circular cross‐section with Poiseuille flow and negligible background signal arising from static material around the lumen. The method calculates the average flow velocity directly from the original complex image data by integrating the signal in oppositely velocity‐sensitized PC images. The radius is calculated from the summed signal modulus. The method allows accurate and resolution‐insensitive measurements of the average flow velocity to be obtained in both cross‐sectional and in‐plane acquisitions. It is not critical to any of the assumed conditions. The validity and capabilities of the proposed technique are demonstrated by in vitro experiments. Magn Reson Med 51:785–793, 2004. © 2004 Wiley‐Liss, Inc.