Arterial Spin Labeling technique and clinical applications of the intracranial compartment in stroke and stroke mimics - A case-based review

Abstract

Magnetic resonance imaging perfusion (MRP) techniques can improve the selection of acute ischemic stroke patients for treatment by estimating the salvageable area of decreased perfusion, that is, penumbra. Arterial spin labeling (ASL) is a noncontrast MRP technique that is used to assess cerebral blood flow without the use of intravenous gadolinium contrast. Thus, ASL is of particular interest in stroke imaging. This article will review clinical applications of ASL in stroke such as assessment of the core infarct and penumbra, localization of the vascular occlusion, and collateral status. Given the nonspecific symptoms that patients can present with, differentiating between stroke and a stroke mimic is a diagnostic dilemma. ASL not only helps in differentiating stroke from stroke mimic but also can be used to specify the exact mimic when used in conjunction with the symptomatology and structural imaging. In addition to a case-based overview of clinical applications of the ASL in stroke and stroke mimics in this article, the more commonly used ASL labeling techniques as well as emerging ASL techniques, future developments, and limitations will be reviewed.

Arterial Spin Labeling in Migraine: A Review of Migraine Categories and Mimics

“…While DWI and FLAIR sequences are helpful in estimating the infarct core, ASL can estimate the surrounding salvageable tissue ie, penumbra, thereby helping select patients for endovascular revascularization procedures. 61 Furthermore, ASL can often help localize the site of vascular occlusion, when used in conjunction with SWI sequences. An intraluminal thrombus manifests as a focus of high signal on ASL, due to the trapped, labeled arterial spins, with a corresponding focus of increased susceptibility on SWI.…”

Clinical application of brain perfusion imaging in detecting stroke mimics: A review

“…Viral encephalitis does not always present with the classical signs and symptoms of fever, headache, or altered mental status 90 . In some cases, sudden‐onset focal neurological deficits may be the presenting manifestation, resembling acute stroke.…”

Clinical applications of arterial spin labeling of the intracranial compartment in vascular anomalies—A case-based review

“…Arterial spin labeling (ASL) is a noninvasive neuroimaging technique that can be used to diagnose various conditions based on quantification of cerebral blood flow (CBF). [1][2][3] In this technique, arterial blood water is labeled by a radiofrequency pulse proximal to a region of interest (ROI), a postlabeling delay is applied, and an image is acquired. [1][2][3] Control images of the ROI are captured, and the two images are subtracted from the ASL images.…”

“…Numerous applications of ASL have been described in the literature, particularly in the diagnosis of strokes and intracranial tumors. [1][2][3] Apart from strokes and tumors, ASL can aid in diagnosing vascular abnormalities and pathologies. For example, ASL can add value to conventional MR sequences by showing specific perfusion-related signal intensity patterns depending on the type of anomaly.…”

“…[1][2][3] In this technique, arterial blood water is labeled by a radiofrequency pulse proximal to a region of interest (ROI), a postlabeling delay is applied, and an image is acquired. [1][2][3] Control images of the ROI are captured, and the two images are subtracted from the ASL images. This process allows for the measurement of relative CBF, and specific changes in CBF correlate to differences in ASL signal intensity that can be used to aid in the diagnosis of various conditions.…”