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

Department of Radiology, University of Bonn, Bonn, Germany.
Journal of Magnetic Resonance Imaging (Impact Factor: 3.21). 06/2008; 27(6):1455-60. DOI: 10.1002/jmri.21354
Source: PubMed


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.
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).
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.
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.

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    • "Time-resolved MRA (TR-MRA) is an alternative MRA technique which uses a keyhole imaging approach to sample the center of k-space more frequently compared with high-spatial-frequency information peripherally to obtain MRA images with high temporal resolution, such as 4D time-resolved MRA with keyhole (4D-TRAK), time-resolved imaging with stochastic trajectories (TWIST), time-resolved echo-shared angiography technique (TREAT), time-resolved imaging of contrast kinetics (TRICKS) [8,10-13]. 4D-TRAK with a combination of parallel imaging and CENTRA at high field strength has demonstrated its wide clinical potential in the characterization of multiple vascular lesions because of the high temporal and spatial resolution obtained simultaneously in previous studies [6-9]. Most ruptured CAs in clinical are ≥ 3 mm in diameter. "
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