title: Hybrid PET/MR imaging: an algorithm to reduce metal artifacts from dental implants in Dixon-based attenuation map generation using a multiacquisition variable-resonance image combination sequence.
abstract: It was the aim of this study to implement an algorithm modifying Dixon-based MR imaging datasets for attenuation correction in hybrid PET/MR imaging with a multiacquisition variable resonance image combination (MAVRIC) sequence to reduce metal artifacts.
  
  
  METHODS
  After ethics approval, in 8 oncologic patients with dental implants data were acquired in a trimodality setup with PET/CT and MR imaging. The protocol included a whole-body 3-dimensional dual gradient-echo sequence (Dixon) used for MR imaging-based PET attenuation correction and a high-resolution MAVRIC sequence, applied in the oral area compromised by dental implants. An algorithm was implemented correcting the Dixon-based μ maps using the MAVRIC in areas of Dixon signal voids. The artifact size of the corrected μ maps was compared with the uncorrected MR imaging μ maps.
  
  
  RESULTS
  The algorithm was robust in all patients. There was a significant reduction in mean artifact size of 70.5% between uncorrected and corrected μ maps from 697 ± 589 mm(2) to 202 ± 119 mm(2) (P = 0.016).
  
  
  CONCLUSIONS
  The proposed algorithm could improve MR imaging-based attenuation correction in critical areas, when standard attenuation correction is hampered by metal artifacts, using a MAVRIC.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland; and irene.burger@usz.ch.
authors.forename: Irene A
authors.initials: IA
authors.lastname: Burger
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Moritz C
authors.initials: MC
authors.lastname: Wurnig
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Anton S
authors.initials: AS
authors.lastname: Becker
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Kenkel
authors.affiliation: GE Healthcare, Waukesha, Wisconsin.
authors.forename: Gaspar
authors.initials: G
authors.lastname: Delso
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland; and.
authors.forename: Patrick
authors.initials: P
authors.lastname: Veit-Haibach
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Boss
mesh_terms: D000465:Algorithms; D016477:Artifacts; D015921:Dental Implants; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D008670:Metals; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D015921:Dental Implants; D008670:Metals
keywords: MRI based attenuation correction; signal void; μ maps