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摘要
Magnetic resonance imaging (MRI) is compromised by field drift during image encoding. The purpose of this study was to address this issue by correcting the phase error. To investigate the field drift characterization, the magnetic field changes over the duration of entire scans were recorded and analyzed. Base on the analyzed result, we assume that the magnetic field changes linearly with time. Since the resonance frequency changes very slowly over time, two measurements of the resonance frequency, immediately before and after a scan, are sufficient to get the instantaneous frequency offset. The phase error for k-space can be corrected by creating a mathematical model for different sequence type. k-space data of four types of sequences were acquired at a 0.35 T permanent magnet MRI scanner. Depending on different sequence, one (or several) phase encoding step is collected into a group. Each group uses a unique frequency to correct the linear phase error. Experimental results confirm that the proposed method efficiently corrects image artifacts caused by magnetic field drifts.
- 出版日期2018-9
- 单位东北大学
