title: Potential influence of Gadolinium contrast on image segmentation in MR-based attenuation correction with Dixon sequences in whole-body 18F-FDG PET/MR.
abstract: OBJECTIVE
  To evaluate the influence of Gadolinium contrast agent on image segmentation in magnetic resonance (MR)-based attenuation correction (AC) with four-segment dual-echo time Dixon-sequences in whole-body [18F]-fluorodeoxyglucose positron emission tomography (PET)/MR imaging, and to analyze the consecutive effect on standardized uptake value (SUV).
  
  
  METHODS
  Hybrid imaging with an integrated PET/MR system was performed in 30 oncological patients. AC was based on MR imaging with a Dixon sequence with subsequent automated image segmentation. AC maps (µmaps) were acquired and reconstructed prior to (µmap-gd) and after (µmap+gd) Gd-contrast agent application. For quantification purposes, the SUV of organs and tumors based on both µmaps were compared.
  
  
  RESULTS
  Tissue classification based on µmap-gd was correct in 29/30 patients; based on µmap+gd, the brain was falsely classified as fat in 12/30 patients with significant underestimation of SUV. In all cancerous lesions, tissue segmentation was correct. All concordant µmaps-gd/+gd resulted in no significant difference in SUV.
  
  
  CONCLUSIONS
  In PET/MR, Gd-contrast agent potentially influences fat/water separation in Dixon-sequences of the head with above-average false tissue segmentation and an associated underestimation of SUV. Thus, MR-based AC should be acquired prior to Gd-contrast agent application. Additionally, integrating the MR-based AC maps into the reading-routine in PET/MR is recommended to avoid interpretation errors in cases where tissue segmentation fails.
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstr. 55, 45122, Essen, Germany. verena.ruhlmann@uk-essen.de.
authors.forename: Verena
authors.initials: V
authors.lastname: Ruhlmann
authors.affiliation: Department of Diagnostic and Interventional Radiology, Medical Faculty, University of Dusseldorf, 40225, Dusseldorf, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Heusch
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University of Duisburg-Essen, 45147, Essen, Germany.
authors.forename: Hilmar
authors.initials: H
authors.lastname: Kühl
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University of Duisburg-Essen, 45147, Essen, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Beiderwellen
authors.affiliation: Department of Diagnostic and Interventional Radiology, Medical Faculty, University of Dusseldorf, 40225, Dusseldorf, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Antoch
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University of Duisburg-Essen, 45147, Essen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Forsting
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstr. 55, 45122, Essen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bockisch
authors.affiliation: Department of Diagnostic and Interventional Radiology, Medical Faculty, University of Dusseldorf, 40225, Dusseldorf, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Buchbender
authors.affiliation: Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, 45141, Essen, Germany.|High Field and Hybrid MR Imaging, University Hospital Essen, 45147, Essen, Germany.
authors.forename: Harald H
authors.initials: HH
authors.lastname: Quick
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D005260:Female; D019788:Fluorodeoxyglucose F18; D005682:Gadolinium; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D009369:Neoplasms / Q000188:drug therapy*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005682:Gadolinium
keywords: Attenuation correction (AC); MR-based tissue segmentation; PET/MR; SUV