Multilevel wavelet-transform encoding in MRI

J Magn Reson Imaging. May-Jun 1996;6(3):529-40. doi: 10.1002/jmri.1880060317.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Artifacts
  • Fourier Analysis
  • Humans
  • Image Enhancement / instrumentation*
  • Image Processing, Computer-Assisted / instrumentation*
  • Magnetic Resonance Imaging / instrumentation*
  • Phantoms, Imaging
  • Software