What does ASL measure?
Arterial spin labeling (ASL) is a non-invasive MRI technique to measure cerebral blood flow (CBF). This review provides a practical guide and overview of the clinical applications of ASL of the brain, as well its potential pitfalls. The technical and physiological background is also addressed.
What does arterial spin labeling measure?
Arterial spin labeling (ASL) is a non-ionizing and completely non-invasive MRI technique for measuring tissue perfusion (blood flow), which uses magnetically labeled arterial blood water protons as an endogenous tracer[3,4].
How does arterial spin labelling work?
Arterial spin labelling utilizes the water molecules circulating with the brain, and using a radiofrequency pulse, tracks the blood water as it circulates throughout the brain. After a period of time in microseconds (enough to allow the blood to circulate through the brain), a ‘label’ image is captured.
What is pCASL?
In 2008 Dai et al proposed a hybrid method between CASL and PASL named pCASL (Pseudo-Continuous Arterial Spin Labeling). pCASL uses a narrow labeling plane (similar to CASL) through which flow-related adiabatic inversion of arterial spins occurs.
What is ASL sequence?
Arterial spin labeling (ASL) will soon be available as a routine clinical perfusion imaging sequence for a significant number of MRI scanners. The ASL perfusion technique offers similar information as conventional dynamic susceptibility sequences; however, it does not require intravenous contrast and can be quantified.
What is pseudo continuous arterial spin labeling?
More recently a hybrid form has been developed, pCASL (pseudo-Continuous Arterial Spin Labeling), that uses a long series of short RF-pulses together with a strong slice-selection gradient. pCASL thus combines favorable features of CASL (high signal-to-noise) with those of PASL (lower energy deposition).
What is ASL perfusion?
Arterial spin labeling (ASL) perfusion is a MRI technique to quantify tissue blood flow. ASL is a non-invasive technique that labels the protons in the arterial blood by radiofrequency pulses, without the exogenous injection of contrast media.
What is MRI spectroscopy used for?
Magnetic resonance (MR) spectroscopy is a noninvasive diagnostic test for measuring biochemical changes in the brain, especially the presence of tumors.
What is pseudo continuous ASL?
Pseudo-continuous ASL (pcASL) is a pulse sequence strategy that can achieve continuous labeling without special hardware. 12. Before describing pcASL, it is helpful to have some intuition for the basic principle of flow-driven adiabatic inversion.
What is an ASL sequence on MRI?
What is pseudo continuous data?
Pseudo continuous data as the name suggests is pseudo continuous i.e. it is actually not continuous (or discrete) but it considered as continuous. Advantages. 1. More powerful analytical tools can be used on the data. 2.
What is faceting in ASL?
Faceting – Describes a feature where several different signs are sequentially to express one idea more clearly. Although several signs are used, this feature actually narrows a concept to a more exact or specific image. Usually used with adjectives or adverbs.