title: Magnetic resonance-based motion correction for positron emission tomography imaging.
abstract: Positron emission tomography (PET) image quality is limited by patient motion. Emission data are blurred owing to cardiac and/or respiratory motion. Although spatial resolution is 4 mm for standard clinical whole-body PET scanners, the effective resolution can be as low as 1 cm owing to motion. Additionally, the deformation of attenuation medium causes image artifacts. Previously, gating has been used to "freeze" the motion, but led to significantly increased noise level. Simultaneous PET/magnetic resonance (MR) modality offers a new way to perform PET motion correction. MR can be used to measure 3-dimensional motion fields, which can then be incorporated into the iterative PET reconstruction to obtain motion-corrected PET images. In this report, we present MR imaging techniques to acquire dynamic images, a nonrigid image registration algorithm to extract motion fields from acquired MR images, and a PET reconstruction algorithm with motion correction. We also present results from both phantom and in vivo animal PET/MR studies. We demonstrate that MR-based PET motion correction using simultaneous PET/MR improves image quality and lesion detectability compared with gating and no motion correction.
authors.affiliation: Center for Advanced Radiological Sciences, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Jinsong
authors.initials: J
authors.lastname: Ouyang
authors.forename: Quanzheng
authors.initials: Q
authors.lastname: Li
authors.forename: Georges
authors.initials: G
authors.lastname: El Fakhri
mesh_terms: D000818:Animals; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009068:Movement; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*