A multi-scale application of the N3 method for intensity correction of MR images

Craig Jones, Erick B. Wong

Research output: Contribution to journalArticle

Abstract

Spatial inhomogeneity due to the radio-frequency coil in MR imaging can confound segmentation results. In 1994, Sled introduced the N3 technique, using histogram deconvolution, for reducing inhomogeneity. We found some scans whose steep inhomogeneity gradient was not fully eliminated by N3. We created a multi-scale application of N3 that further reduces this gradient, and validated it on MNI BrainWeb and actual MRI data. The algorithm was applied to proton density simulated BrainWeb scans (with known inhomogeneity) and 100 standard MRI scans. Intra-slice and inter-slice inhomogeneity measures were created to compare the technique with standard N3. The slope of the estimated bias versus the known bias of BrainWeb data was 1.0 (r=0.9844) for N3 and 1.04 (r=0.9828) for multi-scale N3. The bias field estimated by multi-scale N3 was within 1% rootmean-square of that of standard N3. Over 100 MS patient scans, the average intra-slice measure (0 meaning bias-free) was 0.0694 (uncorrected), 0.0530 (N3) and 0.0402 (multi-scale). The average inter-slice measure (1 meaning bias-free) was 0.9121 (uncorrected), 0.9367 (N3) and 0.9508 (multi-scale). The multi-scale N3 algorithm showed a greater inhomogeneity reduction than N3 in the small percentage of scans bearing a strong gradient, and results similar to N3 in the remaining scans.

Original languageEnglish (US)
Pages (from-to)1123-1129
Number of pages7
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume4684 II
DOIs
StatePublished - 2002
Externally publishedYes

Fingerprint

Inhomogeneity
inhomogeneity
Slice
Bearings (structural)
Deconvolution
Gradient
Magnetic resonance imaging
gradients
Protons
sleds
Imaging techniques
Coil
histograms
Histogram
Percentage
Slope
radio frequencies
coils
Segmentation
Imaging

Keywords

  • Image Processing
  • Magnetic Resonance Imaging
  • RF Inhomogeneity Correction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Cite this

A multi-scale application of the N3 method for intensity correction of MR images. / Jones, Craig; Wong, Erick B.

In: Proceedings of SPIE - The International Society for Optical Engineering, Vol. 4684 II, 2002, p. 1123-1129.

Research output: Contribution to journalArticle

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