title: Progressing Toward a Cohesive Pediatric 18F-FDG PET/MR Protocol: Is Administration of Gadolinium Chelates Necessary?
abstract: With the increasing availability of integrated PET/MR scanners, the utility and need for MR contrast agents for combined scans is questioned. The purpose of our study was to evaluate whether administration of gadolinium chelates is necessary for evaluation of pediatric tumors on (18)F-FDG PET/MR images.
  
  
  METHODS
  First, in 119 pediatric patients with primary and secondary tumors, we used 14 diagnostic criteria to compare the accuracy of several MR sequences: unenhanced T2-weighted fast spin-echo imaging; unenhanced diffusion-weighted imaging; and-before and after gadolinium chelate contrast enhancement-T1-weighted 3-dimensional spoiled gradient echo LAVA (liver acquisition with volume acquisition) imaging. Next, in a subset of 36 patients who had undergone (18)F-FDG PET within 3 wk of MRI, we fused the PET images with the unenhanced T2-weighted MR images (unenhanced (18)F-FDG PET/MRI) and the enhanced T1-weighted MR images (enhanced (18)F-FDG PET/MRI). Using the McNemar test, we compared the accuracy of the two types of fused images using the 14 diagnostic criteria. We also evaluated the concordance between (18)F-FDG avidity and gadolinium chelate enhancement. The standard of reference was histopathologic results, surgical notes, and follow-up imaging.
  
  
  RESULTS
  There was no significant difference in diagnostic accuracy between the unenhanced and enhanced MR images. Accordingly, there was no significant difference in diagnostic accuracy between the unenhanced and enhanced (18)F-FDG PET/MR images. (18)F-FDG avidity and gadolinium chelate enhancement were concordant in 30 of the 36 patients and 106 of their 123 tumors.
  
  
  CONCLUSIONS
  Gadolinium chelate administration is not necessary for accurate diagnostic characterization of most solid pediatric malignancies on (18)F-FDG PET/MR images, with the possible exception of focal liver lesions.
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, and Lucile Packard Children's Hospital, Stanford University, Stanford, California; and.
authors.forename: Christopher
authors.initials: C
authors.lastname: Klenk
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, and Lucile Packard Children's Hospital, Stanford University, Stanford, California; and.
authors.forename: Rakhee
authors.initials: R
authors.lastname: Gawande
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, and Lucile Packard Children's Hospital, Stanford University, Stanford, California; and.
authors.forename: Vy Thao
authors.initials: VT
authors.lastname: Tran
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, and Lucile Packard Children's Hospital, Stanford University, Stanford, California; and.
authors.forename: Jennifer Trinh
authors.initials: JT
authors.lastname: Leung
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, and Lucile Packard Children's Hospital, Stanford University, Stanford, California; and.
authors.forename: Kevin
authors.initials: K
authors.lastname: Chi
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, and Lucile Packard Children's Hospital, Stanford University, Stanford, California; and.
authors.forename: Daniel
authors.initials: D
authors.lastname: Owen
authors.affiliation: Department of Pediatrics, Lucile Packard Children's Hospital, Stanford University, Stanford, California.
authors.forename: Sandra
authors.initials: S
authors.lastname: Luna-Fineman
authors.affiliation: Department of Pediatrics, Lucile Packard Children's Hospital, Stanford University, Stanford, California.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Sakamoto
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, and Lucile Packard Children's Hospital, Stanford University, Stanford, California; and.
authors.forename: Alex
authors.initials: A
authors.lastname: McMillan
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, and Lucile Packard Children's Hospital, Stanford University, Stanford, California; and.
authors.forename: Andy
authors.initials: A
authors.lastname: Quon
authors.affiliation: Department of Radiology, Molecular Imaging Program at Stanford, and Lucile Packard Children's Hospital, Stanford University, Stanford, California; and h.e.daldrup-link@stanford.edu.
authors.forename: Heike E
authors.initials: HE
authors.lastname: Daldrup-Link
mesh_terms: D000293:Adolescent; D002614:Chelating Agents / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media / Q000009:adverse effects*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005682:Gadolinium / Q000737:chemistry*; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D064847:Multimodal Imaging / Q000379:methods*; D009367:Neoplasm Staging; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D002614:Chelating Agents; D003287:Contrast Media; D019788:Fluorodeoxyglucose F18; D005682:Gadolinium
keywords: 18FDG-PET; MR contrast utility; PET-MR fusion; PET/MR; pediatric oncology