Accelerated dual-venc 4D flow MRI with variable high-venc spatial resolution for neurovascular applications

• Published in: Magnetic resonance in medicine 2022-10, Vol.88 (4), p.1643-1658
• Main Authors: Aristova, Maria, Pang, Jianing, Ma, Yue, Ma, Liliana, Berhane, Haben, Rayz, Vitaliy, Markl, Michael, Schnell, Susanne
• Format: Article
• Language: English
• Subjects: Acceleration; Blood Flow Velocity; Cartesian coordinates; Dynamic range; Humans; Imaging, Three-Dimensional - methods; In vivo methods and tests; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Noise reduction; Phantoms, Imaging; Pulsatile Flow; Reproducibility of Results; Spatial discrimination; Spatial resolution; Velocity; Velocity measurement
• ISSN: 0740-3194; 1522-2594; 1522-2594
• DOI: 10.1002/mrm.29306

Dual-velocity encoded (dual-venc or DV) 4D flow MRI achieves wide velocity dynamic range and velocity-to-noise ratio (VNR), enabling accurate neurovascular flow characterization. To reduce scan time, we present interleaved dual-venc 4D Flow with independently prescribed, prospectively undersampled spatial resolution of the high-venc (HV) acquisition: Variable Spatial Resolution Dual Venc (VSRDV). A prototype VSRDV sequence was developed based on a Cartesian acquisition with eight-point phase encoding, combining PEAK-GRAPPA acceleration with zero-filling in phase and partition directions for HV. The VSRDV approach was optimized by varying z, the zero-filling fraction of HV relative to low-venc, between 0%-80% in vitro (realistic neurovascular model with pulsatile flow) and in vivo (n = 10 volunteers). Antialiasing precision, mean and peak velocity quantification accuracy, and test-retest reproducibility were assessed relative to reference images with equal-resolution HV and low venc (z = 0%). In vitro results for all z demonstrated an antialiasing true positive rate at least 95% for  = 2 and 5, with no linear relationship to z (p = 0.62 and 0.13, respectively). Bland-Altman analysis for z = 20%, 40%, 60%, or 80% versus z = 0% in vitro and in vivo demonstrated no bias >1% of venc in mean or peak velocity values at any . In vitro mean and peak velocity, and in vivo peak velocity, had limits of agreement within 15%. VSRDV allows up to 34.8% scan time reduction compared to PEAK-GRAPPA accelerated DV 4D Flow MRI, enabling large spatial coverage and dynamic range while maintaining VNR and velocity measurement accuracy.