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
Journal of Cardiovascular Magnetic Resonance volume 12, Article number: P81 (2010)
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).
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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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 (Suppl 1), P81 (2010). https://doi.org/10.1186/1532-429X-12-S1-P81