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Quantification and Reduction of Ghosting Artifacts in Interleaved Echo-Planar Imaging
 

Summary: Quantification and Reduction of Ghosting Artifacts in
Interleaved Echo-Planar Imaging
Scott B. Reeder, Ergin Atalar, Bradley D. Bolster, Jr., Elliot R. McVeigh
A mathematicalanalysis of ghosting artifacts often seen in inter-
leavedecho-planarimages(EPI)ispresented.These artifactsresult
fromphaseandamplitudediscontinuitiesbetweenlinesofk-space
in lhe phase-encodingdirection,and timing misregistrationsfrom
systemfilter delays. Phaseoffsets and time delays are often mea-
sured using "reference"scans, to reduce ghosting through post-
prcicessing. From the expressions describing ghosting artifacts,
criteriawere established for reducingghostingto acceptable lev-
els..Subsequently,the signal-to-noise ratio (SNR) requirementsfor
estimationof time delaysand phaseoffsets,determinedfrom ref-
erence scans, was evaluatedto establishthe effect of estimation
emor on artifact reductionfor interleaved EPI. Artifacts resulting
from these effects can be reducedto very low levelswhen appro-
priate referencescan estimationis used.This hasimportantimpli-
cationsfor functionalMRI (MRI) and applicationsinvolvingsmall
changes in signal intensity.
Key words: MRI; artifacts; reconstruction;EPI; functional im-

  

Source: Atalar, Ergin - Department of Electrical and Electronics Engineering, Bilkent University

 

Collections: Engineering; Biology and Medicine