Optimization of gradient waveforms for velocity measurements and concurrent reduction of displacement artifacts in phase contrast imaging
(English)Manuscript (preprint) (Other academic)
The purpose of the present study was to develop gradient waveforms for phase contrast magnetic resonance imaging that provides concurrent reduction of displacement artifacts. A framework was developed which was based on a linear combination of three individual gradients, each gradient having a trapezoidal shape. The amplitude of each gradient trapezoid was determined by the desired values of the zeroth, first and second moments of the combined tripolar waveform. All calculations of moments of the tripolar gradient waveform were performed with the expansion point set equal to the echo time. The times of spatial and velocity encoding are simultaneous in all three encoding directions, implying elimination of the displacement artifact. The proposed phase contrast pulse sequence using tripolar gradients was compared to a conventional phase contrast pulse sequence based on bipolar gradients. The echo time increased with the use of tripolar gradients compared to the conventional pulse sequence. Compensation for the increase in scan time can be achieved with the use of parallel imaging techniques.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-85889OAI: oai:DiVA.org:liu-85889DiVA: diva2:573611