Increased SNR efficiency in velocity selective arterial spin labeling using multiple velocity selective saturation...

Area of Science:

• Magnetic Resonance Imaging
• Cerebrovascular Physiology
• Medical Physics

Background:

• Velocity-selective arterial spin labeling (VSASL) is theoretically robust against transit delay (TD) but suffers from lower signal-to-noise ratio (SNR) due to saturation instead of inversion.
• Improving SNR in VSASL is crucial for its clinical applicability, particularly in scenarios requiring longer post-labeling delays.

Purpose of the Study:

• To enhance the signal-to-noise ratio (SNR) efficiency of velocity-selective arterial spin labeling (VSASL).
• To investigate the use of multiple velocity-selective saturation (VSS) modules in VSASL (mm-VSASL) for improved SNR performance.

Main Methods:

• Simulations were performed to calculate theoretical SNR efficiency improvements and optimize parameters for multi-module VSASL (mm-VSASL).
• A VSASL sequence with two VSS modules (VSASL-2VSS) was implemented for in vivo cerebral blood flow measurements.
• Comparisons were made against conventional VSASL (VSASL-1VSS), pulsed ASL (PASL), and pseudo-continuous ASL (PCASL), measuring transit delays (TDs) and bolus durations (BDs).

Main Results:

• VSASL-2VSS demonstrated a significant in vivo SNR improvement of 22.1 ± 1.9% compared to VSASL-1VSS, aligning with simulation predictions.
• The SNR achieved with VSASL-2VSS was comparable to or higher than that of pseudo-continuous ASL (PCASL), particularly in gray matter.
• Experimental validation confirmed that VSASL exhibits minimal sensitivity to transit delay effects.

Conclusions:

• Employing multiple VSS modules effectively boosts the SNR efficiency of VSASL.
• Multi-module VSASL (mm-VSASL) presents a promising alternative, potentially offering superior or equivalent SNR to PCASL in applications necessitating extended post-labeling delays.