Velocity-selective-inversion prepared arterial spin labeling.

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging Techniques
• Physiology

Background:

• Arterial spin labeling (ASL) is a non-invasive MRI technique for quantifying cerebral blood flow (CBF).
• Velocity-selective ASL (VSASL) enhances ASL specificity by labeling spins within a defined velocity range.
• Improving the robustness and performance of VSASL labeling modules is crucial for accurate CBF measurements.

Purpose of the Study:

• To develop and validate a novel Fourier-transform based velocity-selective inversion (FT-VSI) pulse train for VSASL.
• To assess the robustness of the FT-VSI pulse train to common MRI imperfections.

Main Methods:

• A new FT-VSI pulse train incorporating paired and phase-cycled refocusing pulses was designed.
• Simulations and phantom studies were conducted to evaluate the pulse train's sensitivity to B0/B1 inhomogeneity and gradient imperfections.
• Cerebral blood flow (CBF) was quantified using FT-VSI prepared VSASL at 3 Tesla and compared with conventional VSASL and pseudocontinuous ASL (PCASL) in eight healthy volunteers.

Main Results:

• The FT-VSI pulse train demonstrated excellent robustness to B0/B1 field inhomogeneity and eddy currents in simulations and phantom studies.
• Estimated gray matter and white matter CBF values were 49.5 ± 7.5 and 14.8 ± 2.4 mL/100 g/min, respectively.
• FT-VSI prepared VSASL showed excellent correlation with conventional VSASL and PCASL, with a 39% higher signal-to-noise ratio (SNR) in gray matter compared to conventional VSASL.

Conclusions:

• The novel FT-VSI pulse train is a suitable labeling module for VSASL, offering robustness to field inhomogeneity and gradient imperfections.
• FT-VSI prepared VSASL yields consistent CBF maps with improved SNR compared to conventional VSASL.
• This technique enhances the reliability and performance of velocity-selective ASL for CBF quantification.