Functional perfusion imaging using pseudocontinuous arterial spin labeling with low-flip-angle segmented 3D spiral...

Area of Science:

• Neuroimaging
• Biomedical Engineering
• Radiology

Background:

• Arterial spin labeling (ASL) offers quantitative cerebral blood flow (CBF) measurement for functional MRI (fMRI).
• Existing ASL fMRI protocols (2D multislice, 3D spin-echo) face limitations like low signal-to-noise ratio (SNR) or blurring.
• 3D ASL with segmented readouts can enhance SNR efficiency but may be sensitive to temporal signal fluctuations.

Purpose of the Study:

• To characterize the temporal SNR of a segmented 3D spiral ASL sequence.
• To investigate the impact of radiofrequency (RF) phase cycling and flip-angle schedules on image properties.
• To optimize a 3D ASL protocol for improved fMRI performance.

Main Methods:

• Characterization of temporal SNR for a segmented 3D spiral ASL sequence.
• Evaluation of RF phase cycling schemes and flip-angle schedules.
• Comparison of the optimized 3D ASL protocol against 2D multislice ASL.

Main Results:

• Radiofrequency spoiling was identified as crucial for segmented 3D spiral ASL.
• The optimized 3D ASL protocol achieved a 2-fold improvement in temporal SNR compared to 2D multislice.
• The protocol demonstrated excellent visual cortex activation in fMRI experiments.

Conclusions:

• Optimized segmented 3D spiral ASL provides superior temporal SNR for fMRI.
• This technique overcomes limitations of previous ASL fMRI protocols.
• The improved SNR enables more robust detection of functional brain activity.