title: MR angiography at 3 Tesla to assess proximal internal carotid artery stenoses: contrast-enhanced or 3D time-of-flight MR angiography?
abstract: OBJECTIVE
  The aim of this study was to compare the diagnostic accuracy of 3D time-of-flight (TOF-MRA) and contrast-enhanced (CE-MRA) magnetic resonance angiography at 3 T for detection and quantification of proximal high-grade stenosis using multidetector computed tomography angiography (MDCTA) as reference standard.
  
  
  METHODS
  The institutional ethics committee approved this prospective study. A total of 41 patients suspected of having internal carotid artery (ICA) stenosis underwent both MDCTA and MRA. CE-MRA and TOF-MRA were performed using a 3.0-T imager with a dedicated eight-element cervical coil. ICA stenoses were measured according to the North American Symptomatic Carotid Endarterectomy Trial criteria and categorized as 0-25 % (minimal), 25-50 % (mild), 50-69 % (moderate), 70-99 % (high grade), and 100 % (occlusion). Sensitivity and specificity for the detection of high-grade ICA stenoses (70-99 %) and ICA occlusions were determined. In addition, intermodality agreement was assessed with κ-statistics for detection of high-grade ICA stenoses (70-99 %) and ICA occlusions.
  
  
  RESULTS
  A total of 80 carotid arteries of 41 patients were reviewed. Two previously stented ICAs were excluded from analysis. On MDCTA, 7 ICAs were occluded, 12 ICAs presented with and 63 without a high-grade ICA stenosis (70-99 %). For detecting 70-99 % stenosis, both 3D TOF-MRA and CE-MRA were 91.7 % sensitive and 98.5 % specific, respectively. Both MRA techniques were highly sensitive (100 %), and specific (CE-MRA, 100 %; TOF-MRA, 98.7 %) for the detection of ICA occlusion. However, TOF-MRA misclassified one high-grade stenosis as occlusion. Intermodality agreement for detection of 70-99 % ICA stenoses was excellent between TOF-MRA and CE-MRA [κ = 0.902, 95 % confidence interval (CI) = 0.769-1.000], TOF-MRA and MDCTA (κ = 0.902, 95 % CI = 0.769-1.000), and CE-MRA and MDCTA (κ = 0.902, 95 % CI = 0.769-1.000).
  
  
  CONCLUSIONS
  Both 3D TOF-MRA and CE-MRA at 3 T are reliable tools for detecting high-grade proximal ICA stenoses (70-99 %). 3D TOF-MRA might misclassify pseudo-occlusions as complete occlusions. If there are no contraindications for CE-MRA, CE-MRA is recommended as primary MR imaging modality.
authors.affiliation: Department of Neuroradiology, Neurocentre, University Hospital Freiburg, Breisacher Strasse 64, 79106, Freiburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Weber
authors.forename: P
authors.initials: P
authors.lastname: Veith
authors.forename: B
authors.initials: B
authors.lastname: Jung
authors.forename: G
authors.initials: G
authors.lastname: Ihorst
authors.forename: O
authors.initials: O
authors.lastname: Moske-Eick
authors.forename: S
authors.initials: S
authors.lastname: Meckel
authors.forename: H
authors.initials: H
authors.lastname: Urbach
authors.forename: C A
authors.initials: CA
authors.lastname: Taschner
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016893:Carotid Stenosis / Q000175:diagnosis*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008536:Meglumine / Q000031:analogs & derivatives*; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D009942:Organometallic Compounds; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine