Quantitative 4D flow accelerated with SENSE at 3 T accurately measured stroke volume compared to 2D-flow (96.7 vs 97.3 ml, p=0.86), whereas k-t BLAST significantly underestimated flow velocities.
Observational (n=13)
Single-blind
Random order
No
Does 4D-flow MRI accelerated with SENSE or k-t BLAST accurately quantify and visualize cardiovascular flow compared to standard 2D-flow in healthy volunteers?
4D-flow MRI accelerated with SENSE at 3 T provides accurate quantitative flow assessment, while k-t BLAST is currently limited to qualitative visualization due to velocity underestimation.
Absolute Event Rate: 96.7% vs 97.3%
p-value: p=0.86
BACKGROUND: Three-dimensional time-resolved (4D) phase-contrast (PC) CMR can visualize and quantify cardiovascular flow but is hampered by long acquisition times. Acceleration with SENSE or k-t BLAST are two possibilities but results on validation are lacking, especially at 3 T. The aim of this study was therefore to validate quantitative in vivo cardiac 4D-acquisitions accelerated with parallel imaging and k-t BLAST at 1.5 T and 3 T with 2D-flow as the reference and to investigate if field strengths and type of acceleration have major effects on intracardiac flow visualization. METHODS: The local ethical committee approved the study. 13 healthy volunteers were scanned at both 1.5 T and 3 T in random order with 2D-flow of the aorta and main pulmonary artery and two 4D-flow sequences of the heart accelerated with SENSE and k-t BLAST respectively. 2D-image planes were reconstructed at the aortic and pulmonary outflow. Flow curves were calculated and peak flows and stroke volumes (SV) compared to the results from 2D-flow acquisitions. Intra-cardiac flow was visualized using particle tracing and image quality based on the flow patterns of the particles was graded using a four-point scale. RESULTS: Good accuracy of SV quantification was found using 3 T 4D-SENSE (r2 = 0.86, -0.7 ± 7.6%) and although a larger bias was found on 1.5 T (r2 = 0.71, -3.6 ± 14.8%), the difference was not significant (p = 0.46). Accuracy of 4D k-t BLAST for SV was lower (p < 0.01) on 1.5 T (r2 = 0.65, -15.6 ± 13.7%) compared to 3 T (r2 = 0.64, -4.6 ± 10.0%). Peak flow was lower with 4D-SENSE at both 3 T and 1.5 T compared to 2D-flow (p < 0.01) and even lower with 4D k-t BLAST at both scanners (p < 0.01). Intracardiac flow visualization did not differ between 1.5 T and 3 T (p = 0.09) or between 4D-SENSE or 4D k-t BLAST (p = 0.85). CONCLUSIONS: The present study showed that quantitative 4D flow accelerated with SENSE has good accuracy at 3 T and compares favourably to 1.5 T. 4D flow accelerated with k-t BLAST underestimate flow velocities and thereby yield too high bias for intra-cardiac quantitative in vivo use at the present time. For intra-cardiac 4D-flow visualization, however, 1.5 T and 3 T as well as SENSE or k-t BLAST can be used with similar quality.
Carlsson et al. (2011) conducted an observational in Healthy volunteers (n=13). 4D-flow accelerated with SENSE vs. 2D-flow was evaluated on Stroke volume on 3 T 4D-SENSE (p=0.86). Quantitative 4D flow accelerated with SENSE at 3 T accurately measured stroke volume compared to 2D-flow (96.7 vs 97.3 ml, p=0.86), whereas k-t BLAST significantly underestimated flow velocities.