Correction of intensity nonuniformity in MR images of any orientation

doi:10.1016/0730-725X(93)90023-7

Magnetic Resonance Imaging

Volume 11, Issue 2, 1993, Pages 183-196

https://doi.org/10.1016/0730-725X(93)90023-7 Get rights and content

Abstract

The specialised radiofrequency (RF) coils used in MRI such as head or surface coils can give rise to marked image intensity nonuniformities. There are two situations in which it is essential to correct this: (1) When a global intensity threshold is used to segment particular tissues; and (2) in proton density images, from which the proton concentration can be measured provided that the system gain is uniform or known over the whole image. We describe experiments to determine the magnitude and sources of nonuniformity in a 0.5-T system, and assess methods devised to correct for them in scans of any orientation, including oblique scans at arbitrary angles to the magnet axis and arbitrary offsets from the magnet iso-centre. A correction based on the response of a system to a uniform phantom was implemented. Tests of the correction with orthogonal views demonstrate that the uniformity of images of any orientation can be improved significantly with a correction matrix from just one orientation and still further with two matrices, one axial and the other either coronal or sagittal. We expect further improvements to be possible if gradient coil eddy current effects can be reduced.

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Citation Excerpt :
Finally, we conclude the paper in Section V. The most classical methods estimate the bias field based on phantom studies (Condon et al., 1987; Wicks et al., 1993; Collewet et al., 2002). That is, they use imaging phantoms to measure the bias field induced by the hardware of a scanner, and then apply the estimated bias field to other images reconstructed from the same scanner for intensity correction.
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Original contributionCorrection of intensity nonuniformity in MR images of any orientation

Abstract

Computer Vision, Graphics and Image Processing

Computer Vision, Graphics and Image Processing

Magn. Reson. Imaging

Non-uniform sensitivity of receiver coils in MR imaging

Abstracts of the SMRM

Intensity correction in surface-coil imaging

Am. J. Roentgenol.

Original contribution
Correction of intensity nonuniformity in MR images of any orientation