Improved phase-contrast flow quantification by three-dimensional vessel localization

In this paper, a method of three-dimensional (3D) vessel localization is pr esented to allow the identification of a vessel of interest, the selection of a Vessel segment, and the determination of a slice orientation to improv e the accuracy of phase-contrast magnetic resonance (PCMR) angiography. A m arching-cube surface-rendering algorithm was used to reconstruct the 3D vas culature. Surface-rendering was obtained using an iso-surface value determi ned from a maximum intensity projection (MIP) image. This 3D vasculature wa s used to find a vessel of interest, select a vessel segment, and to determ ine the slice orientation perpendicular to the vessel axis. Volumetric flow rate (VFR) was obtained in a phantom model and in vivo using 3D localizati on with double oblique cine PCMR scanning. PCMR flow measurements in the ph antom showed 5.2% maximum error and a standard deviation of 9 mL/min during steady flow, 7.9% maximum error and a standard deviation of 13 mL/min duri ng pulsatile flow compared with measurements using an ultrasonic transit-ti me flowmeter. PCMR VFR measurement error increased with misalignment at 10, 20, and 30 degrees oblique to the perpendicular slice in vitro and in vivo . The 3D localization technique allowed precise localization of the vessel of interest and optimal placement of the slice orientation for minimum erro r in flow measurements. (C) 2000 Elsevier Science Inc. All rights reserved.