Optimal flip angle for high contrast balanced SSFP cardiac cine imaging

Area of Science:

• Cardiovascular Magnetic Resonance Imaging
• Biomedical Engineering
• Medical Imaging Physics

Background:

• Cardiac cine imaging is crucial for assessing heart function.
• Optimizing imaging parameters like flip angle (FA) is essential for maximizing signal and contrast.
• Blood-myocardium contrast is vital for accurate diagnosis and monitoring.

Purpose of the Study:

• To determine the optimal flip angle (FA) for cardiac cine imaging.
• To maximize myocardial signal and blood-myocardium contrast.
• To compare simulation data with in vivo measurements.

Main Methods:

• Bloch equation simulations were performed for stationary myocardium and flowing blood.
• In vivo measurements of signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were acquired.
• Studies included healthy subjects and patients across various cardiac views (short-axis, four-chamber, three-chamber).

Main Results:

• Blood and blood-myocardium contrast increased with FA up to ~105° in the short-axis view.
• Significant SNR differences between left and right ventricular blood were observed for FA > 75°.
• Flow dynamics (in-plane vs. through-plane) influenced SNR and CNR in different views.

Conclusions:

• Optimal FA for high blood-myocardium CNR is ~105° (short-axis) and ~75° (three/four-chamber views).
• Reduced through-plane flow, common in certain patient conditions, may require limiting FA to ~75°.
• The findings provide guidance for optimizing cardiac cine MRI acquisition parameters.