title: Estimation of images and nonrigid deformations in gated emission CT.
abstract: In this paper, we propose and test a new iterative algorithm to simultaneously estimate the nonrigid motion vector fields and the emission images for a complete cardiac cycle in gated cardiac emission tomography. We model the myocardium as an elastic material whose motion does not generate large amounts of strain. As a result, our method is based on minimizing an objective function consisting of the negative logarithm of a maximum likelihood image reconstruction term, the standard biomechanical model of strain energy, and an image matching term that ensures a measure of agreement of intensities between frames. Simulations are obtained using data for the four-dimensional (4-D) NCAT phantom. The data models realistic noise levels in a typical gated myocardial perfusion SPECT study. We show that our simultaneous algorithm produces images with improved spatial resolution characteristics and noise properties compared with those obtained from postsmoothed 4-D maximum likelihood methods. The simulations also demonstrate improved motion estimates over motion estimation using independently reconstructed images.
authors.affiliation: Department of Mathematics, University of Florida, Gainesville, FL 32611, USA. bam@math.ufl.edu
authors.forename: B A
authors.initials: BA
authors.lastname: Mair
authors.forename: David R
authors.initials: DR
authors.lastname: Gilland
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
mesh_terms: D000465:Algorithms; D015637:Gated Blood-Pool Imaging / Q000295:instrumentation / Q000379:methods*; D006321:Heart / Q000000981:diagnostic imaging*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods; D009038:Motion; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed / Q000295:instrumentation / Q000379:methods*