TY - GEN
T1 - Nonrigid registration of dynamic breast F-18-FDG PET/CT images using deformable FEM model and CT image warping
AU - Magri, Alphonso
AU - Krol, Andrzej
AU - Unlu, Mehmet
AU - Lipson, Edward
AU - Mandel, James
AU - McGraw, Wendy
AU - Lee, Wei
AU - Coman, Ioana
AU - Feiglin, David
PY - 2007
Y1 - 2007
N2 - 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 μCi of Ge-68 were taped to each breast. In our PET/PET registration method we utilized CT data. For corresponding FSMs visible on the 1 st and n th 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 1 st PET frame) to match the consecutive dynamic PET time frames. Each mesh was then deformed to match the 1 st 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 1 stt and n th 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.
AB - 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 μCi of Ge-68 were taped to each breast. In our PET/PET registration method we utilized CT data. For corresponding FSMs visible on the 1 st and n th 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 1 st PET frame) to match the consecutive dynamic PET time frames. Each mesh was then deformed to match the 1 st 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 1 stt and n th 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.
KW - Deformable FEM soft tissue model
KW - Differential images
KW - Dynamic breast PET/CT
KW - Nonrigid 3D image registration
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U2 - 10.1117/12.710014
DO - 10.1117/12.710014
M3 - Conference contribution
AN - SCOPUS:36248944531
SN - 0819466301
SN - 9780819466303
T3 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE
BT - Medical Imaging 2007
T2 - Medical Imaging 2007: Image Processing
Y2 - 18 February 2007 through 20 February 2007
ER -