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Multilevel wavelet‐transform encoding in MRI

1996; Wiley; Volume: 6; Issue: 3 Linguagem: Inglês

10.1002/jmri.1880060317

1522-2586

Robert D. Peters, Michael L. Wood,

Medical Imaging Techniques and Applications

Abstract This paper explores an alternative to standard Fourier MRI called wavelet‐transform encoding. Spatially selective radiofrequency (RF) pulses are used to excite slice profiles in the shape of the wavelet‐basis functions of a discrete wavelet transform. Our implementation on a standard commercial whole body MRI system resolves one spatial dimension through wavelet encoding and orthogonal directions through conventional frequency encoding and rectangular‐slice selection. The wavelet transform is described as a method for multiresolution analysis, and we show how a high resolution MR image can be constructed from lower resolution images, representing the approximation and detail structures of the object. A multiple level architecture of the wavelet reconstruction is described, thereby allowing wavelet‐encoded images to be reconstructed through several modes. Multilevel wavelet‐encoded images of a gel phantom are presented that show comparable image quality to Fourier‐encoded images of similar signal‐to‐noise ratio. However, a chemical‐shift artifact is identified with this particular implementation.