The role of parallel imaging technique in decreasing geometric distortion artifact in diffusion weighted imaging of the brain

Abstract

Introduction: The purpose of this study was to evaluate the role of parallel imaging technique in obtaining a more accurate geometric representation of the studied anatomy and how far this technique can reduce the pixel displacement and increase resolution in echo planner imaging- diffusion weighted (EPI-DW) images of the brain. Patients & methods: The study was done on 6 patients, they were subjected to routine brain MRI examination for different symptoms, examination was done on 1.5 T scanner, the degree of geometric distortion was measured in the phase encoding direction (from anterior to posterior (A/P) in the used sequence) in both DWI sequence acquired without and with parallel imaging technique respectively and was compared with T2-FSE sequence which has no geometric distortion as in EPI. Results: Parallel imaging technique reduced artifact (pixel displacement) in frontal and occipital lobes in addition to increasing resolution for EPI-DWI for the brain. This technique reduced pixel displacement in the frontal lobe by 47 ± 11.7% and 47.3 ± 11% reduction in the occipital lobe. Conclusion: Parallel imaging technique can be used with EPI-DWI to increase resolution and decrease geometric distortion artifact to acquire more accurate geometric representation of the acquired anatomy. Keywords: EPI, DWI, Geometric distortion artifact, Parallel imaging technique