The need for phase-encoding flow compensation in high-resolution intracranial magnetic resonance angiography.
OBJECTIVE
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.


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.


CONCLUSIONS
The combination of 3DFC and EC phase encoding appears to provide the greatest artifact reduction in the five volunteer studies performed.
Parker
Dennis L
DL
Department of Radiology, University of Utah, Salt Lake City 84108, USA. parker@doug.med.utah.edu
Goodrich
K Craig
KC
Roberts
John A
JA
Chapman
Brian E
BE
Jeong
Eun-Kee
EK
Kim
Seong-Eun
SE
Tsuruda
Jay S
JS
Katzman
Gregory L
GL
D000328:Adult; D002560:Cerebrovascular Circulation; D018056:Hemorheology; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008875:Middle Aged; D013997:Time Factors