Minimax emission computed tomography using high-resolutionanatomical side information and B-spline models
Hero, A.O.; Piramuthu, R.; Fessler, J.A.; Titus, S.R.
Information Theory, IEEE Transactions on
Volume 45, Issue 3, Apr 1999 Page(s):920 - 938
Digital Object Identifier 10.1109/18.761333
Summary:In this paper a minimax methodology is presented for combining
information from two imaging modalities having different intrinsic
spatial resolutions. The focus application is emission computed
tomography (ECT), a low-resolution modality for reconstruction of
radionuclide tracer density, when supplemented by high-resolution
anatomical boundary information extracted from a magnetic resonance
image (MRI) of the same imaging volume. The MRI boundary within the
two-dimensional (2-D) slice of interest is parameterized by a closed
planar curve. The Cramer-Rao (CR) lower bound is used to analyze
estimation errors for different boundary shapes. Under a spatially
inhomogeneous Gibbs field model for the tracer density a representation
for the minimax MRI-enhanced tracer density estimator is obtained. It is
shown that the estimator is asymptotically equivalent to a penalized
maximum likelihood (PML) estimator with resolution-selective Gibbs
penalty. Quantitative comparisons are presented using the iterative
space alternating generalized expectation maximization (SAGE-FM)
algorithm to implement the PML estimator with and without minimax weight
averaging
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