Purpose
Many sick adults and children are unable to perform long breath-holds required for conventional, Cartesian phase-contrast (PC) sequences. Using a prospectively-triggered spiral PCMR sequence accelerated with sensitivity encoding (SENSE), it should be possible to achieve high resolution PCMR data in a short breath-hold.
The aim of this study was to compare flow volumes measured using: a) reference free-breathing, gated Cartesian PCMR, b) standard breath-hold, gated, Cartesian PCMR, and c) gated, spiral, SENSE, breath-hold PCMR.
Methods
40 consecutive children and adults were enrolled in this study (M:22, F:18, age:21.4±13.8 years). Flow was measured in the:
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Ascending aorta (AAO, N=40)
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Main pulmonary artery (MPA, N=38)
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Right pulmonary artery (RPA, N=22)
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Left pulmonary artery (LPA, N=24)
Flow assessment was performed in each vessel using the three sequences above (parameters shown in Table 1).
Stroke volume and regurgitation fraction were calculated for each patient. Additionally, Qp/Qs (N=38) and RPA/LPA (N=20) ratios were quantified where possible.
Results
Average scan time was 91±17 seconds for the reference free-breathing sequence, 16±3 seconds for the standard breath-hold sequence, and 5±1 seconds for the spiral breath-hold sequence.
Combining all vessels (N=124), there were no statistical differences in mean stroke volume calculated from the reference free-breathing sequence (60.3±27.3 mL), the standard breath-hold sequence (59.8±27.6 mL) and the spiral breath-hold sequence (59.5±27.1 mL). Bland-Altman analyses are shown in Figure 1. There was no clinically significant bias using either breath-hold sequence (spiral breath-hold: -0.7 mL, standard breath-hold: -0.5 mL). However, the limits of agreement were smaller and the correlation better for the spiral breath-hold compared to the standard breath-hold sequence (-4.4 to 2.9 mL vs. -10.3 to 9.3 mL, respectively).
![figure 1](http://media.springernature.com/lw685/springer-static/image/art%3A10.1186%2F1532-429X-13-S1-P380/MediaObjects/12968_2011_Article_1961_Fig1_HTML.jpg)
Figure 1
There was also an excellent agreement in QP/QS and RPA/LPA ratios between all sequences, however the spiral breath-hold sequence was found to be superior to the standard breath-hold sequence in terms of limits of agreement and correlation. There was a small but statistically significant underestimation of regurgitation fraction using the spiral sequence.
Conclusion
Flow volumes can be accurately and reliably quantified using a spiral SENSE PCMR sequence, with high spatio-temporal resolution in a short breath-hold. As the standard method of measuring flow in congenital heart disease is free-breathing, cardiac gated PCMR, this spiral sequence could reduce total flow imaging from ~10 minutes, to <1 minute. This is a marked reduction in total scan time and has implications for patient throughput and compliance for congenital cardiac MR scanning.
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Steeden, J.A., Atkinson, D., Taylor, A.M. et al. Rapid flow assessment of congenital heart disease using high spatio-temporal gated spiral phase-contrast MR. J Cardiovasc Magn Reson 13 (Suppl 1), P380 (2011). https://doi.org/10.1186/1532-429X-13-S1-P380
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DOI: https://doi.org/10.1186/1532-429X-13-S1-P380