Magnetic Resonance (NMR) Echo Planar Imaging Ghost Artifact Correction Algorithms

As one of the important means of modern medical diagnosis and detection of material composition,nuclear magnetic resonance imaging(nuclear magnetic resonance imaging,NMRI)technology development is very perfect,with energy for X ray imaging,Ultrasonic imaging modalities and nuclear medicine imaging,magnetic resonance imaging is a completely different imaging principle of image display and analyzes structural images.With the development of modern medical technology and the rapid development of computer technology,MRI is also constantly being updated.Now EPI(Echo Planar Imaging)is one of the fastest and effective methods for MRI.It usually takes only a few seconds to get a highquality image.However,because the special way of EPI acquisition process,and due to the non-uniformity of static magnetic field,the gradient of the eddy current magnetic field highspeed switching and chemical shift,resulting in the echo of EPI acquisition process have different phase between odd and even,appear to the ghost artifact in phase encoding direction.N/2 Ghost artifact is one of common artifacts in EPI imaging.The error informations carried by artifacts make clinicians appear misdiagnosis easily.Therefore,Ghost artifacts elimination method research is one of the hot spot of research.The paper studies the causes of the EPI N/2 ghost artifact,and N / 2 Ghost artifact was corrected based on image domain and K spatial domain.In image domain,mainly adopt the method of the post-processing,first to study and verify the odd and even lines of the current mature data reconstruction method respectively,and the second moment algorithm on the basis of the above algorithm study and revision.Based on the K spatial domain,using the most common reference scans to measure echo inconsistent between the odd and even echo phase error,to optimize the process of collecting data,improves the robustness of phase error calculation.A variety of algorithms by actual data collected on the experimental validation of the proposed method.The EPI can inhibit the Ghost artifacts effectively,improve the image quality of EPI imaging.