Multiphase segmented k-space velocity mapping in pulsatile flow waveforms

Area of Science:

• Cardiovascular Imaging
• Magnetic Resonance Imaging (MRI)
• Flow Quantification

Background:

• Respiratory motion degrades image quality in abdominal and cardiothoracic MRI.
• Segmented k-space acquisition shortens imaging time, enabling single breath-holds.
• Breath-hold cine flow imaging allows evaluation of flow in various thoracic and abdominal regions, including coronary arteries.

Purpose of the Study:

• To determine the precision of flow measurement using breath-hold segmented k-space flow sequences.
• To assess the impact of varying lines per segment (LPS) on flow measurement accuracy.
• To establish the clinical relevance of different LPS values for coronary flow assessment.

Main Methods:

• Pulsatile flow in a phantom tube was studied using segmented k-space flow sequences.
• The number of k-space ky-lines per segment (LPS) was systematically varied.
• Velocity curves and flow correlations were analyzed as a function of LPS.

Main Results:

• Velocity curves exhibited a time shift that was linearly dependent on LPS.
• Mean velocity (Vmean) remained constant (40.1 ± 2.9 cm/s).
• Correlation between theoretical and experimental flow curves showed a linear decrease with increasing LPS (C = -0.977 * LPS).

Conclusions:

• Velocity curves shift and smooth with increasing LPS in breath-hold velocity mapping.
• Higher LPS values result in more inaccurate flow measurements.
• LPS values of 7 or greater are not considered clinically relevant for accurate flow quantification.