title: Simultaneous PET/MR imaging of the brain: feasibility of cerebral blood flow measurements with FAIR-TrueFISP arterial spin labeling MRI.
abstract: BACKGROUND
  Hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) with simultaneous data acquisition promises a comprehensive evaluation of cerebral pathophysiology on a molecular, anatomical, and functional level. Considering the necessary changes to the MR scanner design the feasibility of arterial spin labeling (ASL) is unclear.
  
  
  OBJECTIVE
  To evaluate whether cerebral blood flow imaging with ASL is feasible using a prototype PET/MRI device.
  
  
  METHODS
  ASL imaging of the brain with Flow-sensitive Alternating Inversion Recovery (FAIR) spin preparation and true fast imaging in steady precession (TrueFISP) data readout was performed in eight healthy volunteers sequentially on a prototype PET/MRI and a stand-alone MR scanner with 128 × 128 and 192 × 192 matrix sizes. Cerebral blood flow values for gray matter, signal-to-noise and contrast-to-noise ratios, and relative signal change were compared. Additionally, the feasibility of ASL as part of a clinical hybrid PET/MRI protocol was demonstrated in five patients with intracerebral tumors.
  
  
  RESULTS
  Blood flow maps showed good delineation of gray and white matter with no discernible artifacts. The mean blood flow values of the eight volunteers on the PET/MR system were 51 ± 9 and 51 ± 7 mL/100 g/min for the 128 × 128 and 192 × 192 matrices (stand-alone MR, 57 ± 2 and 55 ± 5, not significant). The value for signal-to-noise (SNR) was significantly higher for the PET/MRI system using the 192 × 192 matrix size (P < 0.01), the relative signal change (δS) was significantly lower for the 192 × 192 matrix size (P = 0.02). ASL imaging as part of a clinical hybrid PET/MRI protocol could successfully be accomplished in all patients in diagnostic image quality.
  
  
  CONCLUSIONS
  ASL brain imaging is feasible with a prototype hybrid PET/MRI scanner, thus adding to the value of this novel imaging technique.
authors.affiliation: Department of Radiology, Diagnostic and Interventional Radiology, Eberhard Karls University Tübingen, Tübingen, Germany. stegger@uni-muenster.de
authors.forename: Lars
authors.initials: L
authors.lastname: Stegger
authors.forename: Petros
authors.initials: P
authors.lastname: Martirosian
authors.forename: Nina
authors.initials: N
authors.lastname: Schwenzer
authors.forename: Sotirios
authors.initials: S
authors.lastname: Bisdas
authors.forename: Armin
authors.initials: A
authors.lastname: Kolb
authors.forename: Christina
authors.initials: C
authors.lastname: Pfannenberg
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Bernd
authors.initials: B
authors.lastname: Pichler
authors.forename: Fritz
authors.initials: F
authors.lastname: Schick
authors.forename: Andreas
authors.initials: A
authors.lastname: Boss
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000098:blood supply*; D002560:Cerebrovascular Circulation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D059629:Signal-To-Noise Ratio; D013113:Spin Labels; D018709:Statistics, Nonparametric
chemical_list: D013113:Spin Labels