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Coronary magnetic resonance angiography at 7 Tesla: a quantitative comparison with results at 3 Tesla
Journal of Cardiovascular Magnetic Resonance volume 12, Article number: O88 (2010)
Commercial 7 Tesla(T) systems have recently become available for human use. Our initial results have shown feasibility of right coronary artery(RCA) magnetic resonance angiography(MRA) at 7 T. Since then, we have optimized the RF coil design, resulting in significantly improved image quality at 7 T.
To quantitatively compare same-subject signal-to-noise(S/N), coronary vessel length, vessel sharpness, acquisition time and navigator efficiency of right coronary MRA at 7 T and 3 T.
Eight healthy adult subjects (mean age 23 ± 3 years, 5 men) underwent vector ECG-triggered, navigator gated and corrected free-breathing 3D MRA of the RCA at 7 T and 3 T. At 7 T a quadrature loop-pair (two 15 cm elements) was constructed, and the 2D selective respiratory navigator was localized at the lung-heart interface. At 3 T, a commercial 6-element cardiac receive array was used with body-coil transmit. A 3D segmented k-space gradient echo technique was combined with spectrally selective adiabatic inversion-recovery magnetization fat saturation. At 3 T, coronary MRA were obtained with the navigator localized at the lung-heart interface and at the lung-liver interface, respectively. The scan parameters at both field strengths were as similar as possible (Table 1). The S/N in the bloodpool of the aortic root near the RCA offspring, coronary vessel length, vessel sharpness, acquisition time and navigator efficiency were compared using Wilcoxon matched-pairs test. For visualization, reformatting with the 'Soapbubble'-tool was utilized.
In Figure 1, RCAs obtained in the same subject at 7 T(Figure 1a) and 3 T (Figure 1b) are shown. The corresponding quantitative findings averaged over all subjects are listed in Table 2. The S/N was very similar at both field strengths and visible RCA vessel length was slightly lower at 7 T, but not statistically significant. Vessel sharpness obtained at 7 T was significantly higher compared to that at 3 T (p < 0.03). The scanning time for all 3D acquisitions was identical. There was a tendency for reduced navigator efficiency at 7 T which was not statistically significant, however. These findings apply for both the diaphragmatic navigator as well as for that localized at the heart with a trend for a lower S/N at 3 T for the navigator localized at the lung-heart interface.
Using a quadrature transmit/receive coil at 7 T, it was shown that 7 T coronary MRA image quality has already begun to approach that at 3 T while vessel sharpness is already significantly improved. With future incorporation of technology such as larger transmit arrays we anticipate that the image quality at 7 T will continue to improve at rapid pace.
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van Elderen, S.G., Versluis, M.J., Westenberg, J.J. et al. Coronary magnetic resonance angiography at 7 Tesla: a quantitative comparison with results at 3 Tesla. J Cardiovasc Magn Reson 12, O88 (2010). https://doi.org/10.1186/1532-429X-12-S1-O88
- Magnetic Resonance Angiography
- Right Coronary Artery
- Coil Design
- Magnetic Resonance Angiography Image
- Healthy Adult Subject