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The need for phase-encoding flow compensation in high-resolution intracranial magnetic resonance angiography
Dennis L Parker1, K Craig Goodrich, John A Roberts
1Department of Radiology, University of Utah, Salt Lake City 84108, USA. parker@doug.med.utah.edu
Purpose:
To demonstrate that the time delay between phase and frequency encoding and the presence of pulsatile blood flow in high-resolution time-of-flight (TOF) imaging of the intracranial arteries (especially near the circle of Willis) can distort the appearance of blood vessels and result in a cross-hatch-appearing artifact in surrounding tissue.
Materials And Methods:
Two techniques to reduce the artifact, tri-directional flow compensation (3DFC) and elliptical-centric (EC) phase-encoding order, are investigated in five volunteer studies.
Results:
3DFC eliminates the pulsation-related artifacts and the vessel distortion. A residual amplitude variation artifact is observed. EC phase encoding nearly eliminates the pulsatile motion-related artifact, but it does not eliminate vessel distortion.
Conclusion:
The combination of 3DFC and EC phase encoding appears to provide the greatest artifact reduction in the five volunteer studies performed.