Flow artifacts in steady-state free precession cine imaging.

Area of Science:

• Medical Imaging
• Magnetic Resonance Imaging Physics

Background:

• Steady-state free precession (SSFP) cardiac cine imaging is susceptible to dark flow artifacts.
• These artifacts often degrade image quality but can typically be resolved through scanner adjustments.

Purpose of the Study:

• To provide a theoretical explanation for dark flow artifacts in SSFP cardiac cine imaging.
• To validate the theory using phantom experiments and in vivo observations.
• To identify the likely cause of these artifacts in clinical settings.

Main Methods:

• Developing a theoretical model for dark flow artifacts based on off-resonance spin behavior.
• Conducting phantom experiments to replicate and validate the theoretical predictions.
• In vivo experiments involving controlled detuning of the scanner's center frequency.

Main Results:

• The theoretical model successfully explains dark flow artifacts as spins traversing off-resonant magnetic field points.
• Phantom experiments validated the theoretical predictions.
• In vivo artifacts were reproducible by detuning the center frequency by approximately half the inverse repetition time (TR).
• This detuning magnitude is comparable to the water-lipid frequency difference, suggesting mistuning to the lipid peak.

Conclusions:

• Dark flow artifacts in SSFP cardiac imaging arise from spins encountering off-resonant magnetic fields.
• Incorrectly tuning the scanner's center frequency to the lipid peak instead of the water peak is a probable cause of these artifacts in vivo.
• Proper scanner tuning is crucial for artifact-free cardiac cine imaging.