title: 4D time-resolved MR angiography with keyhole (4D-TRAK): more than 60 times accelerated MRA using a combination of CENTRA, keyhole, and SENSE at 3.0T.
abstract: OBJECTIVE
  To present a new 4D method that is designed to provide high spatial resolution MR angiograms at subsecond temporal resolution by combining different techniques of view sharing with parallel imaging at 3.0T.
  
  
  METHODS
  In the keyhole-based method, a central elliptical cylinder in k-space is repeated n times (keyhole) with a random acquisition (CENTRA), and followed by the readout of the periphery of k-space. 4D-MR angiography with CENTRA keyhole (4D-TRAK) was combined with parallel imaging (SENSE) and partial Fourier imaging. In total, a speed-up factor of 66.5 (6.25 [CENTRA keyhole] x 8 [SENSE] x 1.33 [partial Fourier imaging]) was achieved yielding a temporal resolution of 608 ms and a spatial resolution of (1.1 x 1.4 x 1.1) mm(3) with whole-brain coverage 4D-TRAK was applied to five patients and compared with digital subtraction angiography (DSA).
  
  
  RESULTS
  4D-TRAK was successfully completed with an acceleration factor of 66.5 in all five patients. Sharp images were acquired without any artifacts possibly created by the transition of the central cylinder and the reference dataset. MRA findings were concordant with DSA.
  
  
  CONCLUSIONS
  4D time-resolved MRA with keyhole (4D-TRAK) is feasible using a combination of CENTRA, keyhole, and SENSE at 3.0T and allows for more than 60 times accelerated MRA with high spatial resolution.
authors.affiliation: Department of Radiology, University of Bonn, Bonn, Germany. winfried.willinek@ukb.uni-bonn.de
authors.forename: Winfried A
authors.initials: WA
authors.lastname: Willinek
authors.forename: Dariusch R
authors.initials: DR
authors.lastname: Hadizadeh
authors.forename: Marcus
authors.initials: M
authors.lastname: von Falkenhausen
authors.forename: Horst
authors.initials: H
authors.lastname: Urbach
authors.forename: R
authors.initials: R
authors.lastname: Hoogeveen
authors.forename: Hans H
authors.initials: HH
authors.lastname: Schild
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gieseke
mesh_terms: D000328:Adult; D000465:Algorithms; D015901:Angiography, Digital Subtraction / Q000379:methods; D003287:Contrast Media / Q000008:administration & dosage; D005240:Feasibility Studies; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis*; D007472:Iohexol / Q000031:analogs & derivatives; D018810:Magnetic Resonance Angiography / Q000295:instrumentation / Q000379:methods*; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D013997:Time Factors
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide; D019786:Gadolinium DTPA