Phase contrast MRI with minimized background phase errors.

Area of Science:

• Medical Imaging
• Biophysics
• Magnetic Resonance Imaging

Background:

• Phase contrast MRI (PC-MRI) measures bodily velocities.
• Magnetic field imperfections cause background phase errors, limiting PC-MRI accuracy.
• Accurate velocity measurements are crucial for clinical utility.

Purpose of the Study:

• Minimize systematic background phase errors in PC-MRI.
• Maximize the accuracy of velocity measurements in PC-MRI.

Main Methods:

• Modeled MRI scanner background phase errors using the gradient impulse response function (GIRF).
• Optimized gradient waveforms numerically using the GIRF to minimize background phase errors.
• Tested optimized pulse sequences in phantoms and human subjects, comparing results to conventional PC-MRI.

Main Results:

• Optimized waveforms reduced background phase by 78.8%.
• Predicted background phase closely matched measured phase in a static phantom (0.6 mm/s difference).
• Achieved excellent agreement for in vivo blood flow values (agreement $$ = 0.96).

Conclusions:

• GIRF modeling and optimized gradients effectively minimize PC-MRI background phase errors.
• This method enhances PC-MRI accuracy efficiently.
• The methodology is adaptable to other MRI sequences affected by magnetic field errors.