APPROPRIATE TECHNIQUE FOR REDUCE DISTORTION IN DIFFUSION WEIGHTED IMAGING MRI 1.5 TESLA

Abstract

Diffusion Weighted Imaging (DWI) is an essential technique for diagnosis ischemic stroke, brain tumor in short scan time. At susceptibility area such as base of skull most distortion affects the image quality cause by in-homogeneity of magnetic field. The purpose of this study is to determine the scan parameters to reduce distortion artifact in MRI 1.5 Tesla Diffusion Weighted Imaging using EPI in MRI phantom. Methods: CuSO4 solution was filled half of Magphan phantom to represent base of skull, scan at tube support disk location using routine scan acquisition parameters.15 objects consist of 3 locations, 5 objects each were scanned. Measure and record co-ordinates(x,y) of each objects at 4 Echo Planar Imaging(EPI) with and without parallel image techniques (GRAPPA and mSENSE) and acceleration factor ( R-factor) at 2 and 3 in b0 and b1000. Then compare the co-ordinates with Turbo Spin Echo T2 Technique (gold standard) and calculate the percent deviation. In sequence EPI with GRAPPA and mSENSE R- factor 2, the percent deviation of each objects were lower than EPI without parallel around 50% in both b0 and b1000. Sequence EPI with GRAPPA and mSENSE R-factor 3 show more reduction. In b1000 of mSENSE more noise than GRAPPA was observed Discussion and Conclusion: The techniques EPI with GRAPPA and mSENSE R-factor 2 show reduce distortion artifact at susceptibility area such as base of skull. In EPI with GRAPPA and mSENSE R-factor 3 distortion was reduced more than R-factor 2, but more noise was observed in b1000.