In order to reduce geometric distortion phenomena in MR images, every MRI system main magnet undergoes a shimming process. Since this process aims at optimizing magnetic field homogeneity within a so-called uniformity sphere, image quality outside this sphere is neglected.Since the fields vary smoothly in space, MR signal-to-noise ratio is still non-zero just outside the uniformity region, but correction of MR image distortion fails due to lack of magnetic field knowledge outside it.We propose a novel algorithm for measuring all the fields involved in the generation of images. Our proposal is based on exploitation of the distortion which can be observed in images of a known phantom. The proposed method will enable measurement of the fields in a region that can be bigger than the uniformity sphere depending on the phantom dimensions.
|Numero di pagine||7|
|Rivista||Magnetic Resonance Imaging|
|Stato di pubblicazione||Published - 2018|
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