Accelerated dual-venc 4D flow MRI for neurovascular applications

Area of Science:

• Medical Imaging
• Cardiovascular Imaging
• Magnetic Resonance Imaging

Background:

• 4D flow MRI is crucial for assessing hemodynamics but faces challenges with velocity-to-noise ratio (VNR) and dynamic velocity range.
• Improving VNR and dynamic range is essential for accurate quantification of blood flow in various clinical applications.

Purpose of the Study:

• To enhance the VNR and dynamic velocity range of 4D flow MRI.
• To develop and validate a dual-velocity encoding (dual-venc) technique combined with k-t GRAPPA acceleration.

Main Methods:

• Developed a dual-venc 4D flow MRI sequence with k-t GRAPPA acceleration, utilizing a shared reference scan and low-/high-venc scans.
• Employed high-venc data to correct aliasing in low-venc data, creating a single dataset with improved VNR.
• Validated the sequence in phantom experiments and applied it to 16 volunteers for intracranial hemodynamics assessment.

Main Results:

• The dual-venc sequence successfully acquired 4D flow MRI data with reduced acquisition time.
• Phantom and volunteer studies demonstrated significantly reduced image noise (51.4% and 54.6% lower, respectively) in dual-venc compared to high-venc.
• In vivo assessments showed improved image quality, including fewer artifacts, enhanced vessel conspicuity, and reduced noise.

Conclusions:

• Dual-venc 4D flow MRI effectively combines the superior VNR of low-venc acquisitions with the ability to capture both low- and high-velocity flows.
• The technique offers improved flow visualization, image quality, and reduced noise in both in vitro and in vivo settings.
• This advancement holds promise for more accurate and reliable hemodynamic assessments.