Magnetic resonance velocity imaging using a fast spiral phase contrast sequence

Area of Science:

• Medical Imaging
• Biophysics
• Cardiovascular Science

Background:

• Magnetic resonance (MR) phase contrast (PC) imaging offers quantitative in vivo flow measurements.
• Conventional spin-warp sequences for PC imaging result in long scan times.
• Respiratory motion in abdominal and thoracic imaging complicates conventional PC techniques.

Purpose of the Study:

• To develop a rapid phase contrast sequence for time-resolved, three-direction velocity imaging.
• To enable flow measurements within a single breath-hold, reducing motion artifacts.
• To assess the clinical applicability of the rapid sequence in various vascular regions.

Main Methods:

• Implementation of a rapid phase contrast sequence utilizing interleaved spiral k-space data acquisition.
• Acquisition of time-resolved, three-direction velocity data within a single breath-hold.
• Validation using steady and pulsatile flow phantom experiments with in-line ultrasound comparison.

Main Results:

• The rapid sequence achieved time-resolved, three-direction velocity imaging within a breath-hold.
• Phantom experiments showed excellent agreement between the novel technique and ultrasound flow measurements.
• Successful application in normal volunteers for imaging carotids, renal arteries, and the heart.

Conclusions:

• The presented rapid phase contrast sequence significantly reduces scan time for quantitative flow imaging.
• This technique overcomes limitations of conventional methods, particularly in the presence of respiratory motion.
• The method is validated and shows promise for clinical application in diverse vascular territories.