Feasibility of 4D Flow MR Imaging of the Brain with Either Cartesian y-z Radial Sampling or k-t SENSE: Comparison with 4D Flow MR Imaging using SENSE

Abstract

Purpose: A drawback of time-resolved 3-dimensional phase contrast magnetic resonance (4D Flow MR) imaging is its lengthy scan time for clinical application in the brain. We assessed the feasibility for flow measurement and visualization of 4D Flow MR imaging using Cartesian y-z radial sampling and that using k-t sensitivity encoding (k-t SENSE) by comparison with the standard scan using SENSE.Materials and Methods: Sixteen volunteers underwent 3 types of 4D Flow MR imaging of the brain using a 3.0-tesla scanner. As the standard scan, 4D Flow MR imaging with SENSE was performed first and then followed by 2 types of acceleration scan-with Cartesian y-z radial sampling and with k-t SENSE. We measured peak systolic velocity (PSV) and blood flow volume (BFV) in 9 arteries, and the percentage of particles arriving from the emitter plane at the target plane in 3 arteries, visually graded image quality in 9 arteries, and compared these quantitative and visual data between the standard scan and each acceleration scan.Results: 4D Flow MR imaging examinations were completed in all but one volunteer, who did not undergo the last examination because of headache. Each acceleration scan reduced scan time by 50% compared with the standard scan. The k-t SENSE imaging underestimated PSV and BFV (P < 0.05). There were significant correlations for PSV and BFV between the standard scan and each acceleration scan (P < 0.01). The percentage of particles reaching the target plane did not differ between the standard scan and each acceleration scan. For visual assessment, y-z radial sampling deteriorated the image quality of the 3 arteries.Conclusion: Cartesian y-z radial sampling is feasible for measuring flow, and k-t SENSE offers sufficient flow visualization; both allow acquisition of 4D Flow MR imaging with shorter scan time.

Applications of lattice QCD techniques for condensed matter systems

“…In three dimensions, probably the simplest theoretical model of topological insulators is the single-particle Wilson-Dirac Hamiltonian on 3D cubic lattice, 70,77,78 which reads in the momentum space representation:…”

“…where α i and β are the Dirac α-and β-matrices, κ is the dimensionful hopping parameter, r is the Wilson parameter which roughly corresponds to SOC in real 3D topological insulators and m0 (with −2r < m 0 < 0) is the topological mass term. 70,77,78 The Hamiltonian (12) can be obtained as a low-energy approximation to the tight-binding models of the real-world topological insulators such as Bi 2 Se 3 , Bi 2 T e 3 and Sb 2 T e 3 . 77 Inter-electron interaction effects in 3D topological insulators and the SOC can be equally important in compounds involving 5d transition metals, and their interplay might result in interesting new topologically insulating phases.…”

Advanced flow MRI: emerging techniques and applications

“…In addition, several advanced acceleration methods for the improvement of spatial resolution and/or reduction of total scan time have been successfully explored including k-t BLAST 226 , k-t GRAPPA, k-t SENSE 227 , radial 227 and spiral 228 sampling schemes as well as compressed sensing approaches 229,230 .…”

4D Flow Preliminary Investigation for Anterior Fossa Dural Arteriovenous Fistula

“…On the left side, selective cannulation of the internal and external carotid arteries failed because of technical difficulties. Flow in the blood vessels was measured using 4-D flow phase-contrast 3.0-T MRI 4 (Fig. 2 and Supplementary Video) (Philips Medical system; 3.0 T-Achieva; TR: 8.7 ms, TE: 5.4 ms, FA: 13°, velocity encoding (VENC): 70 cm/s, voxel size: 1.19 × 1.36 × 1.4 mm).…”