title: Three-dimensional dynamic contrast enhanced imaging of the carotid artery with direct arterial input function measurement.
abstract: OBJECTIVE
  Kinetic analysis using dynamic contrast enhanced MRI to assess neovascularization of carotid plaque requires images with high spatial and temporal resolution. This work demonstrates a new three-dimensional (3D) dynamic contrast enhanced imaging sequence, which directly measures the arterial input function with high temporal resolution yet maintains the high spatial resolution required to identify areas of increased adventitial neovascularity.
  
  
  METHODS
  The sequence consists of multiple rapid acquisitions of a saturation prepared dynamic 3D gradient recalled echo (GRE) sequence temporally interleaved with multiple acquisitions of a 2D slice. The saturation recovery time was adjusted to maintain signal linearity with the very different contrast agent concentrations in the 2D slice and 3D volume. The K(trans) maps were obtained from the 3D dynamic contrast measurements while the 2D slice was used to obtain the arterial input function. Calibration and dynamic studies are presented.
  
  
  RESULTS
  For contrast agent concentrations up to 5 mM, a saturation recovery time for the 2D slice of 20 ms resulted in less than a 10% deviation from the desired linear response of signal intensity with contrast agent concentration. The corresponding saturation recovery time of 83 ms for the 3D volume maintained less than a 10% deviation from the linear response up to contrast agent concentrations of 2 mM while a contrast agent concentration of 5 mM had almost a 30% deviation. There was a significant improvement in signal attenuation (9 ± 3% versus 23 ± 5% at 40 cm/s) when flow compensation was added to the slice select gradients. For patient studies, volume transfer and plasma fraction maps were calculated with data from the proposed sequence.
  
  
  CONCLUSIONS
  This work demonstrated a novel sequence for 3D dynamic contrast enhanced imaging with a simultaneously acquired 2D slice that directly measures the arterial input function with high temporal resolution. Acquisition parameters can be adjusted to accommodate the full range of contrast agent concentration values to be encountered and the kinetic parameters obtained were consistent with expected values.
authors.affiliation: Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Mendes
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Parker
authors.forename: Scott
authors.initials: S
authors.lastname: McNally
authors.forename: Ed
authors.initials: E
authors.lastname: DiBella
authors.forename: Bradley D
authors.initials: BD
authors.lastname: Bolster
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Treiman
mesh_terms: D002340:Carotid Artery Diseases / Q000175:diagnosis*; D003287:Contrast Media / Q000493:pharmacokinetics; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008536:Meglumine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D009389:Neovascularization, Pathologic / Q000175:diagnosis*; D009942:Organometallic Compounds / Q000493:pharmacokinetics; D019047:Phantoms, Imaging
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine
keywords: carotid inflammation; carotid plaque; dynamic contrast enhanced; plaque progression