title: MRI for attenuation correction in PET: methods and challenges.
abstract: In current combined PET/MR systems, PET attenuation correction is based on MRI, since the small bore inside MRI systems and the strong magnetic field do not permit a rotating PET transmission source or a CT device to be integrated. Unlike CT measurements in PET/CT scanners, the MR signal is not directly correlated to tissue density and thus cannot be converted by a simple transformation of intensity values. Various approaches have been developed based on templates, atlas information, direct segmentation of T1-weighted MR images, or segmentation of images from special MR sequences. The advantages and disadvantages of these approaches as well as additional challenges will be discussed in this review.
authors.affiliation: Central Institute for Electronics, Forschungszentrum Jülich, 52425 Jülich, Germany. g.wagenknecht@fz-juelich.de
authors.forename: Gudrun
authors.initials: G
authors.lastname: Wagenknecht
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Kaiser
authors.forename: Felix M
authors.initials: FM
authors.lastname: Mottaghy
authors.forename: Hans
authors.initials: H
authors.lastname: Herzog
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D019275:Radiopharmaceuticals; D051598:Whole Body Imaging
chemical_list: D019275:Radiopharmaceuticals