title: Comparison of blood flow velocity quantification by 4D flow MR imaging with ultrasound at the carotid bifurcation.
abstract: OBJECTIVE
  4D flow MR imaging is an emerging technique that allows visualization and quantification of 3D blood flow in vivo. However, representative studies evaluating its accuracy are lacking. Therefore, we compared blood flow quantification by using 4D flow MR imaging with US within the carotid bifurcation.
  
  
  METHODS
  Thirty-two healthy volunteers (age 25.3 ± 3.4 years) and 20 patients with ≥50% ICA stenosis (age 67.7 ± 7.4 years) were examined preoperatively and postoperatively by use of 4D flow MR imaging, with complete coverage of the left and right carotid bifurcation. Blood flow velocities were assessed with standardized 2D analysis planes distributed along the CCA and the ICA and were compared with US at baseline and postoperatively in patients. In addition, we tested reproducibility and interobserver agreement of 4D MR imaging in 10 volunteers.
  
  
  RESULTS
  Overall, 101 CCAs and 79 ICAs were available for comparison. MR imaging underestimated (P < .05) systolic CCA and ICA blood flow velocity by 26% (0.79 ± 0.29 m/s vs 1.06 ± 0.31 m/s) and 19% (0.72 ± 0.21 m/s vs 0.89 ± 0.27 m/s) compared with US. Diastolic blood flow velocities were similar for MR imaging and US (differences, 9% and 3%, respectively; not significant). Reproducibility and interobserver agreement of 4D flow MR imaging was excellent.
  
  
  CONCLUSIONS
  4D flow MR imaging allowed for an accurate measurement of blood flow velocities in the carotid bifurcation of both volunteers and patients with only moderate underestimation compared with US. Thus, 4D flow MR imaging seems promising for a future combination with MRA to comprehensively assess ICA stenosis and related hemodynamic changes.
authors: Department of Neurology, University Hospital, Freiburg, Germany. andreas.harloff@uniklinik-freiburg.de
authors: A
authors: A
authors: Harloff
authors: T
authors: T
authors: Zech
authors: F
authors: F
authors: Wegent
authors: C
authors: C
authors: Strecker
authors: C
authors: C
authors: Weiller
authors: M
authors: M
authors: Markl
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000473:pathology; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000473:pathology; D016893:Carotid Stenosis / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000601:surgery; D003287:Contrast Media; D003971:Diastole / Q000502:physiology; D016894:Endarterectomy, Carotid / Q000379:methods; D057510:Endovascular Procedures / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D015588:Observer Variation; D010100:Oxygen / Q000097:blood; D015203:Reproducibility of Results; D015607:Stents; D013599:Systole / Q000502:physiology; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D010100:Oxygen