Accuracy of four-dimensional phase-contrast velocity mapping for blood flow visualizations: a phantom study

Area of Science:

• Medical Imaging
• Biophysics
• Cardiovascular Flow Dynamics

Background:

• Four-dimensional phase-contrast MRI (4D PC-MRI) visualizes dynamic blood flow but is susceptible to phase background effects.
• The impact of these phase offsets on flow visualizations and particle traces remains understudied and experimentally unverified.

Purpose of the Study:

• To quantify background phase offsets in accelerated 4D PC-MRI sequences.
• To assess the impact of these offsets on particle trace visualizations.
• To evaluate the effectiveness of background phase correction methods in reducing visualization errors.

Main Methods:

• Utilized a rotating phantom with a known velocity field to quantify background phase in 4D PC-MRI.
• Investigated sequences accelerated with SENSE and varying k-t BLAST speed-up factors.
• Compared particle trace deviations before and after applying two distinct phase correction techniques.

Main Results:

• Quantified background velocity offsets up to 7 cm/s, increasing with distance from the slice center.
• Observed constant background offsets across different k-t BLAST speed-up factors.
• Found end deviations in particle traces up to 5.3 mm; phase correction reduced deviations by 56% (subtraction) to 78% (polynomial fit).

Conclusions:

• Background phase errors significantly distort pathline visualizations in 4D PC-MRI.
• Robust phase correction methods are essential for accurate blood flow depiction.
• Failure to minimize phase background errors can lead to substantial pathline deviations.