Can arterial spin labeling detect white matter perfusion signal?

Can arterial spin labeling detect white matter perfusion signal?

Since the invention of arterial spin labeling (ASL) it has been acknowledged that ASL does not allow reliable detection of a white matter (WM) perfusion signal. However, recent developments such as pseudo-continuous labeling and background suppression have improved the quality.

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 arterial spin labeling perfusion?

Arterial spin labeling ( ASL ) is a magnetic resonance (MR) imaging technique that enables the measurement of brain perfusion noninvasively at the tissue level. Benefiting from the contrast of inflowing magnetically labeled blood, ASL obviates an exogenous contrast agent.

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].

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 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.

What is perfusion rate?

Perfusion is measured as the rate at which blood is delivered to tissue, or volume of blood per unit time (blood flow) per unit tissue mass. The SI unit is m3/(s·kg), although for human organs perfusion is typically reported in ml/min/g. There are more than one hundred thousand perfusion procedures annually.

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 bold signal fMRI?

The blood-oxygen-level-dependent (BOLD) signal, detected in fMRI, reflects changes in deoxyhemoglobin driven by localized changes in brain blood flow and blood oxygenation, which are coupled to underlying neuronal activity by a process termed neurovascular coupling.

What does couching mean in ASL?

Scaffolding
Couching/Scaffolding – A series of signs are grouped together to form a concept. This technique can include several of the expansions; 3D space, explaining by example, contrasting or just explaining the concept.

What if Pi is high in oximeter?

A higher PI value, therefore, indicates a stronger pulsatile signal and better peripheral circulation at the sensor site.

What is arterial spin labeling (ASL)?

Arterial spin labeling (ASL) is a magnetic resonance (MR) imaging technique used to assess cerebral blood flow noninvasively by magnetically labeling inflowing blood. In this article, the main labeling techniques, notably pulsed and pseudocontinuous ASL, as well as emerging clinical applications wil …

What is ASL MR perfusion?

Arterial spin labeling (ASL) MR perfusion is an MR perfusion technique which does not require intravenous administration of contrast (unlike DSC perfusion and DCE perfusion ). Instead it exploits the ability of MRI to magnetically label arterial blood below the imaging slab.

How is arterial blood water magnetically labeled?

First, arterial blood water is magnetically labeled just below the region (slice) of interest by applying a 180 degree radiofrequency (RF) inversion pulse. The result of this pulse is inversion of the net magnetization of the blood water. In other words, the water molecules within the arterial blood are labeled magnetically.

How is arterial blood water labeled in ASL?

In ASL, arterial blood water is magnetically labeled then imaged. First, arterial blood water is magnetically labeled just below the region (slice) of interest by applying a 180 degree radiofrequency (RF) inversion pulse. The result of this pulse is inversion of the net magnetization of the blood water.