Advances in arterial spin labelling MRI methods for measuring perfusion and collateral flow

Area of Science:

• Medical Imaging
• Neuroimaging
• Magnetic Resonance Imaging

Background:

• Arterial Spin Labelling MRI (ASL) development has matured since the 2015 consensus statement.
• ASL is poised for clinical implementation in various settings.

Purpose of the Study:

• Review new developments in ASL for clinical use.
• Discuss challenges and advancements in ASL quantification and perfusion imaging.
• Highlight new ASL technologies for flow territory mapping.

Main Methods:

• Review of recent technological advancements in ASL MRI.
• Focus on quantification methods and challenges in pseudo-continuous ASL (pCASL).
• Evaluation of new ASL techniques like time-encoded pCASL and combined 4D-angiography.

Main Results:

• Key challenges for quantitative cerebral blood flow (CBF) include labelling efficiency and arterial transit time artifacts.
• New ASL developments enable time-efficient dynamic imaging and richer information content.
• Vessel-encoded and super-selective pCASL provide clinical flow territory mapping comparable to digital subtraction angiography (DSA).

Conclusions:

• ASL MRI is ready for clinical prime-time, particularly for perfusion imaging and flow territory mapping.
• Despite remaining quantification challenges, new ASL methodologies offer significant clinical utility.
• Advanced ASL techniques are comparable to current clinical standards like DSA and ready for adoption.