Presentation on theme: "Chapter 14: Artifacts Mark D. Herbst, MD, PhD. Artifact Something on the image that does not represent something in the patient –Many causes Equipment."— Presentation transcript:
How to avoid Aliasing Use larger FOV http://www.e-mri.org/quality- artifacts/aliasing.htmlhttp://www.e-mri.org/quality- artifacts/aliasing.html Apply “no phase wrap” – this acquires data for a larger FOV and discards the data outside your original FOV, but it takes 2x longer to do since it is done in the phase encoding direction, unless NEX is cut in half.
How to reduce motion artifacts Consider swapping phase and frequency directions to move artifact away from area of interest (SPF) Apply sat pulses to reduce signal from pulsating vessels Apply flow compensation Apply EKG triggering or gating –requires constant heart rate Consider “Stark technique”—high NEX T1WI
Metal Artifacts Can warp image with black area with white border Can appear as just black dots if microscopic bits of metal (post-op shoulder)