title: Simultaneous whole-body time-of-flight 18F-FDG PET/MRI: a pilot study comparing SUVmax with PET/CT and assessment of MR image quality.
abstract: OBJECTIVE
  The recent introduction of hybrid PET/MRI scanners in clinical practice has shown promising initial results for several clinical scenarios. However, the first generation of combined PET/MRI lacks time-of-flight (TOF) technology. Here we report the results of the first patients to be scanned on a completely novel fully integrated PET/MRI scanner with TOF.
  
  
  METHODS
  We analyzed data from patients who underwent a clinically indicated F FDG PET/CT, followed by PET/MRI. Maximum standardized uptake values (SUVmax) were measured from F FDG PET/MRI and F FDG PET/CT for lesions, cerebellum, salivary glands, lungs, aortic arch, liver, spleen, skeletal muscle, and fat. Two experienced radiologists independently reviewed the MR data for image quality.
  
  
  RESULTS
  Thirty-six patients (19 men, 17 women, mean [±standard deviation] age of 61 ± 14 years [range: 27-86 years]) with a total of 69 discrete lesions met the inclusion criteria. PET/CT images were acquired at a mean (±standard deviation) of 74 ± 14 minutes (range: 49-100 minutes) after injection of 10 ± 1 mCi (range: 8-12 mCi) of F FDG. PET/MRI scans started at 161 ± 29 minutes (range: 117 - 286 minutes) after the F FDG injection. All lesions identified on PET from PET/CT were also seen on PET from PET/MRI. The mean SUVmax values were higher from PET/MRI than PET/CT for all lesions. No degradation of MR image quality was observed.
  
  
  CONCLUSIONS
  The data obtained so far using this investigational PET/MR system have shown that the TOF PET system is capable of excellent performance during simultaneous PET/MR with routine pulse sequences. MR imaging was not compromised. Comparison of the PET images from PET/CT and PET/MRI show no loss of image quality for the latter. These results support further investigation of this novel fully integrated TOF PET/MRI instrument.
authors.affiliation: From the *Division of Nuclear Medicine and Molecular Imaging, Stanford University Medical Center; †Stanford University Medical Center, Molecular Imaging Program at Stanford (MIPS); ‡Stanford University Medical Center, Department of Radiology; §Stanford University Medical Center, Departments of Radiology, Bioengineering, Materials Science and Engineering, Molecular Imaging Program at Stanford (MIPS), Stanford, CA.
authors.forename: Andrei
authors.initials: A
authors.lastname: Iagaru
authors.forename: Erik
authors.initials: E
authors.lastname: Mittra
authors.forename: Ryogo
authors.initials: R
authors.lastname: Minamimoto
authors.forename: Mehran
authors.initials: M
authors.lastname: Jamali
authors.forename: Craig
authors.initials: C
authors.lastname: Levin
authors.forename: Andrew
authors.initials: A
authors.lastname: Quon
authors.forename: Garry
authors.initials: G
authors.lastname: Gold
authors.forename: Robert
authors.initials: R
authors.lastname: Herfkens
authors.forename: Shreyas
authors.initials: S
authors.lastname: Vasanawala
authors.forename: Sanjiv Sam
authors.initials: SS
authors.lastname: Gambhir
authors.forename: Greg
authors.initials: G
authors.lastname: Zaharchuk
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000493:pharmacokinetics*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18