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Proceedings Paper

Nonrigid registration of dynamic breast F-18-FDG PET/CT images using deformable FEM model and CT image warping
Author(s): Alphonso Magri; Andrzej Krol; Mehmet Unlu; Edward Lipson; James Mandel; Wendy McGraw; Wei Lee; Ioana Coman; David Feiglin
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Paper Abstract

This study was undertaken to correct for motion artifacts in dynamic breast F-18-FDG PET/CT images, to improve differential-image quality, and to increase accuracy of time-activity curves. Dynamic PET studies, with subjects prone, and breast suspended freely employed a protocol with 50 frames, each 1-minute long. A 30 s long CT scan was acquired immediately before the first PET frame. F-18-FDG was administered during the first PET time frame. Fiducial skin markers (FSMs) each containing ~0.5 &mgr;Ci of Ge-68 were taped to each breast. In our PET/PET registration method we utilized CT data. For corresponding FSMs visible on the 1st and nth frames, the geometrical centroids of FSMs were found and their displacement vectors were estimated and used to deform the finite element method (FEM) mesh of the CT image (registered with 1st PET frame) to match the consecutive dynamic PET time frames. Each mesh was then deformed to match the 1st PET frame using known FSM displacement vectors as FEM loads, and the warped PET timeframe volume was created. All PET time frames were thus nonrigidly registered with the first frame. An analogy between orthogonal components of the displacement field and the temperature distribution in steady-state heat transfer in solids is used, via standard heat-conduction FEM software with "conductivity" of surface elements set arbitrarily significantly higher than that of volume elements. Consequently, the surface reaches steady state before the volume. This prevents creation of concentrated FEM loads at the locations of FSMs and reaching incorrect FEM solution. We observe improved similarity between the 1st and nth frames. The contrast and the spatial definition of metabolically hyperactive regions are superior in the registered 3D images compared to unregistered 3D images. Additional work is needed to eliminate small image artifacts due to FSMs.

Paper Details

Date Published: 26 March 2007
PDF: 11 pages
Proc. SPIE 6512, Medical Imaging 2007: Image Processing, 65120D (26 March 2007); doi: 10.1117/12.710014
Show Author Affiliations
Alphonso Magri, Syracuse Univ. (United States)
Andrzej Krol, SUNY Upstate Medical Univ. (United States)
Syracuse Univ. (United States)
Mehmet Unlu, Syracuse Univ. (United States)
Edward Lipson, Syracuse Univ. (United States)
SUNY Upstate Medical Univ. (United States)
James Mandel, Syracuse Univ. (United States)
Wendy McGraw, Central New York PET, LLC (United States)
Wei Lee, Syracuse Univ. (United States)
Ioana Coman, Ithaca College (United States)
SUNY Upstate Medical Univ. (United States)
Syracuse Univ. (United States)
David Feiglin, SUNY Upstate Medical Univ. (United States)

Published in SPIE Proceedings Vol. 6512:
Medical Imaging 2007: Image Processing
Josien P. W. Pluim; Joseph M. Reinhardt, Editor(s)

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