Practical considerations for territorial perfusion mapping in the cerebral circulation using super-selective...

Area of Science:

• Medical Imaging
• Neuroimaging
• Biophysics

Background:

• Super-selective pseudo-continuous arterial spin labeling (psPCASL) is crucial for quantifying territorial perfusion in cerebral circulation.
• Challenges such as off-resonance effects, pulsatility, vessel movement, and label rotation schemes can impact accuracy.
• Improving labeling efficiency is essential for enhancing image quality and perfusion quantification.

Purpose of the Study:

• To investigate challenges affecting psPCASL in cerebral circulation.
• To evaluate methods for maximizing labeling efficiency and image quality.
• To propose a strategy for calculating territorial perfusion fractions.

Main Methods:

• Simulations were used to study off-resonance, label rotation, and vessel movement effects on labeling efficiency.
• In vivo studies in 10 subjects assessed off-resonance compensation (multiphase prescan, field map) and cardiac triggering.
• Territorial perfusion fraction maps were acquired in 2 subjects.

Main Results:

• Multiphase calibration significantly improved labeling efficiency (P = .002) compared to uncompensated acquisition.
• Cardiac triggering qualitatively improved image quality and tissue contrast (P = .010).
• A constant clockwise label rotation scheme yielded the highest labeling efficiency, and significant vessel movement was observed in 50% of subjects.

Conclusions:

• Optimized labeling efficiency enhances image quality and accuracy of territorial perfusion fraction maps.
• Labeling efficiency is critically dependent on off-resonance calibration, cardiac triggering, label rotation, and vessel tracking.
• Accurate territorial perfusion quantification is achievable with optimized psPCASL parameters.