To explain the basic physics of arterial spin labeling (ASL) perfusion to radiologists and to point out opportunities for its use in daily clinical practice.

Arterial spin labeling (ASL) is an MR technique that does not require extrinsic administration of contrast media. Instead, spins of flowing arterial blood are labeled as an intrinsic contrast agent. Although the ASL principle was discovered in the early 1990s and was used in MR systems with low field strength, modern high-field MR scanners with an improved signal-to-noise ratio (SNR) and state-of-the-art pulse sequences and multichannel coils have opened up opportunities for widespread use of ASL in neurological and mental diseases. The most important parameter...

There are four main techniques to achieve ASL perfusion: pulsed (PASL), continuous (CASL), pseudo-continuous (PCASL), and velocity-selective (VS-ASL). PASL uses short (2-5 milliseconds) radiofrequency (RF) pulses to label a thick slab of arterial blood spins at a single instance in time proximal to the scanning region, and the imaging is performed after a time long enough for that spatially labeled blood to reach the tissue in the region of interest. After labeling, a post-labeling delay is required, during which tagged blood moves into the scanning...

ASL is a promising MR technique that could challenge established gold-standard methods. In neurovascular diseases, ASL is an alternative tool for CT and bolus tracking MRI for studying the mechanisms and predicting the outcome of stroke. Also, a strong correlation was found between ASL and DSC perfusion in brain tumor investigations. ASL is especially important as a non-invasive MR modality in pediatric patients, as it minimizes exposure to ionizing radiation and traumatic venous cannulation.

A. Lavrova: Nothing to disclose M. Zubkov: Nothing to disclose A. I. Holodny: Nothing to disclose V. Cheremisin: Nothing to disclose

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