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Intracardiac cardiovascular magnetic resonance velocity mapping: comparison of k-t BLAST and SENSE accelerated 4D acquisitions with 2D-flow at 1.5 T and 3 T


Three-dimensional time-resolved (4D) cardiac flow can be visualized and quantified with velocity encoded phase contrast (PC) MRI, but requires a long scanning time. k-tBLAST is an efficient technique to reduce scan time, but has not been validated for in vivo 4D-flow applications.


To quantitatively compare flow using k-t BLAST and SENSE 4D-acquisitions with standard 2D-flow at 1.5 T and 3 T.


Cardiac 4D-flow with k-tBLAST and SENSE and non-accelerated 2D-flow measurements of the aorta and pulmonary trunk were obtained from 7 healthy volunteers (36 ± 15 years, 5 males) in a 1.5 T and 3 T Philips MRI Scanner. Typical 4D-flow parameters for k-t BLAST were: speedup factor 5, 15 time phases, TE/TR/flip: 3.7/7.6 ms/8°, and for SENSE: parallel imaging factor 2, 40 time phases, TE/TR/flip: 3.7/6.3 ms/8°. The voxel size was 3 × 3 × 3 mm3. 2D-flow was acquired with a PC-FFE sequence with TE/TR/flip: 5.3/8.6 ms/15°. 2D-flow was acquired with 35 time phases and voxel size 1.2 × 1.2 × 6 mm3. The different sequences for each volunteer were acquired in a random order during a single session. From the 4D datasets, 2D-images perpendicular to the aorta and pulmonary artery were reconstructed using in-house developed software. Flow was measured by outlining the aorta and pulmonary trunk in the velocity encoded 2D-images and these contours were transferred to the reconstructed 4D-images. Stroke volumes (SV) and flow were compared using Wilcoxon's test, linear regression and Bland-Altman analysis.


2D-flow measurements of the aorta and pulmonary artery showed a strong correlation (r2 = 0.94) and low bias (2.8 ± 6.1%). 4D-flow scan time was reduced using k-tBLAST from >45 min to<10 min. One k-tBLAST 4D data set was excluded from the 3 T because of suboptimal image quality. Flow from 4D-SENSE showed similar flow curves compared to 2D-flow (Figure 1) but peak flow was lower on both 1.5 T and 3 T (p < 0.05). Peak flow on 4D k-t BLAST was lower than 2D and 4D SENSE flow (p < 0.05). The comparison of SV measurements on the 2D- and 4D-flow sequences from both scanners is shown in Table 1. The measurements of SV on 4D-SENSE was not significantly different from 2D on either scanner (p = 0.33 on 1.5 T and p = 0.36 on 3 T). SV quantified on 4D k-tBLAST was lower compared to 2D on 1.5 T scanners (p < 0.001) but not on 3 T (p = 0.47).

Table 1 Comparison of 4D vs. 2D. Peak flow with 2D at 1.5 T: 431 ± 93 and 3 T: 445 ± 101 ml/s

Figure 1


Quantitative analysis of flow from 4D-PC-MRI is accurate and reproducible with SENSE. Speed up with k-tBLAST yields lower stroke volumes, peak flows and a weaker correlation compared with 2D-acquisitions.

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Correspondence to Carl Crussell.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Crussell, C., Carlsson, M., Toger, J. et al. Intracardiac cardiovascular magnetic resonance velocity mapping: comparison of k-t BLAST and SENSE accelerated 4D acquisitions with 2D-flow at 1.5 T and 3 T. J Cardiovasc Magn Reson 12, P81 (2010).

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  • Stroke Volume
  • Cardiovascular Magnetic Resonance
  • Peak Flow
  • Time Phasis
  • Pulmonary Trunk