Optimal flip angle for high contrast balanced SSFP cardiac cine imaging

• Published in: Magnetic resonance in medicine Vol. 73; no. 3; pp. 1095 - 1103
• Main Authors: Srinivasan, Subashini, Ennis, Daniel B.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01-03-2015; Wiley Subscription Services, Inc
• Subjects: Adult; Algorithms; balanced steady state free precession (bSSFP); cardiac cine imaging; Female; Heart - anatomy & histology; Humans; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; Magnetic Resonance Imaging, Cine - methods; maximum blood-myocardium contrast; optimal flip angle; Reproducibility of Results; Sensitivity and Specificity; balanced steady state free precession (bSSFP); optimal flip angle; maximum blood-myocardium contrast; cardiac cine imaging
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.25228

Purpose
To determine the optimal flip angle (FA) for cardiac cine imaging that maximizes myocardial signal and blood‐myocardium contrast.
Methods
Bloch equation simulations of stationary myocardium and flowing blood with an imperfect slice profile were compared to in vivo measurements of blood and myocardium signal‐to‐noise ratio (SNR) and blood‐myocardium contrast‐to‐noise ratio (CNR) in healthy subjects (N = 10) in the short‐axis and four‐chamber views and in patients (N = 7) in the three‐chamber imaging plane.
Results
Left ventricular (LV) and right ventricular (RV) blood SNR and blood‐myocardium CNR increases with increasing FA up to ≈105° in the short‐axis view. A similar trend is seen in the RV four‐chamber view, but a marked SNR difference between the LV and RV blood appears for FA>75°, especially during systole. Notable RV and LV SNR and CNR differences are also evident in the three‐chamber view due to the predominant LV in‐plane flow versus RV through‐plane flow.
Conclusion
Very high blood‐myocardium CNR can be obtained with a FA of ≈105° in the short‐axis plane and ≈75° in the three‐chamber and four‐chamber imaging planes. However, if through‐plane flow is limited, as may occur for patients with low ejection fraction or low heart rates, then the FA may be limited to ≈ 75°. Magn Reson Med 73:1095–1103, 2015. © 2014 Wiley Periodicals, Inc.