T₁ -FLAIR imaging during continuous head motion: Combining PROPELLER with an intelligent marker

Area of Science:

• Medical Imaging
• Biophysics

Background:

• Motion artifacts significantly degrade the quality of Magnetic Resonance Imaging (MRI) scans, particularly in neurological applications.
• Existing motion correction techniques, such as PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction), have limitations in handling substantial head motion.

Purpose of the Study:

• To describe a T1-weighted FLAIR sequence incorporating prospective and retrospective motion correction to produce sharp MRI images during head motion.
• To evaluate the efficacy of combining prospective and retrospective motion correction strategies within a PROPELLER sequence.

Main Methods:

• The study integrated prospective motion correction using an intelligent marker-navigator with the retrospective capabilities of the PROPELLER sequence.
• Three methods for incorporating the marker-navigator into the PROPELLER sequence were assessed.
• A variable refocusing flip-angle scheme was employed to reduce specific absorption rate and scan time for the T1-weighted FLAIR PROPELLER sequence.
• Motion correction performance was evaluated in 4 volunteers experiencing various head motions.

Main Results:

• Prospective motion correction demonstrated superior performance over retrospective correction during out-of-plane motion.
• The combination of retrospective and prospective correction yielded the sharpest images, even with continuous, large head movements.
• Retrospective PROPELLER correction showed comparable results to prospective correction during minimal out-of-plane movement.

Conclusions:

• Prospective motion correction integrated with a PROPELLER sequence effectively manages continuous, large, and high-speed head motions.
• This combined approach allows for MRI acquisition with only minor reductions in image quality, enhancing diagnostic utility in moving subjects.