title: Accelerated time-resolved 3D contrast-enhanced MR angiography at 3T: clinical experience in 31 patients.
abstract: OBJECTIVE
  To evaluate whether time-resolved 3D MR-angiography at 3T with a net acceleration factor of eight is applicable in clinical routine and to evaluate whether good image quality and a low artifact level can be achieved with a temporal update rate that allows for additional information on pathologies.
  
  
  METHODS
  Thirty-one consecutive patients underwent time-resolved 3D contrast-enhanced MR-angiography on a 3T system. Imaging consisted of accelerated 3D gradient echo sequences combining parallel imaging with an acceleration factor of four, partial Fourier acquisition along phase and slice encoding direction, and twofold temporal acceleration using view sharing. Data volumes representing the arterial and venous contrast phases were independently evaluated by two experienced radiologists by grading of image quality and artifact level on a 0-3 scale.
  
  
  RESULTS
  Time-resolved MR-angiography was successfully performed in all subjects without the need for contrast agent bolus timing. Excellent arterial (average score = 2.65 +/- 0.32) and good venous (average score = 2.56 +/- 0.28) diagnostic image quality and little image degrading due to artifacts (average score = 2.20 +/- 0.16) were confirmed by both independent readers (agreement in 65.2% of all evaluations). In 14 patients vascular pathologies were identified in the arterial phases. In eight examinations temporal resolution and depiction of contrast agent dynamics provided additional information about pathology.
  
  
  CONCLUSIONS
  Without the necessity for additional bolus timing, time-resolved 3D contrast-enhanced MR-angiography with imaging acceleration along both the spatial encoding direction and temporal domain revealed excellent diagnostic image quality in neurovascular and thoracic imaging. Despite the limited spatial resolution as compared to high-resolution imaging of the carotid artery bifurcation, the results demonstrate the applicability of contrast-enhanced MR-angiography in thoracic and abdominal MRA as well as cervical imaging with a temporal update rate allowing for additional information on pathologies. Future studies may include an evaluation of optimal trade-offs between spatial and temporal resolution, different acceleration factors and a comparison to the gold-standard for accuracy.
authors.affiliation: Department of Diagnostic Radiology and Medical Physics, University Hospital Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany. alex.frydrychowicz@uniklinik-freiburg.de
authors.forename: Alex
authors.initials: A
authors.lastname: Frydrychowicz
authors.forename: Thorsten A
authors.initials: TA
authors.lastname: Bley
authors.forename: Jan T
authors.initials: JT
authors.lastname: Winterer
authors.forename: Andreas
authors.initials: A
authors.lastname: Harloff
authors.forename: Mathias
authors.initials: M
authors.lastname: Langer
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hennig
authors.forename: Michael
authors.initials: M
authors.lastname: Markl
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction / Q000379:methods; D003287:Contrast Media / Q000494:pharmacology; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013895:Thoracic Arteries / Q000473:pathology
chemical_list: D003287:Contrast Media