The clinical significance of arterial transit artifact on arterial spin labeling in patients with acute ischemic stroke

Background and Objectives: Determining the occlusion site and collateral blood flow is important in acute ischemic stroke. The purpose of the current study was to test whether arterial spin labeling (ASL) magnetic resonance imaging (MRI) could be used to identify the occlusion site and collateral perfusion, using digital subtraction angiography (DSA) as a gold standard. Method: Data from 521 consecutive patients who presented with acute ischemic stroke at our institution from January 2012 to September 2014 were retrospectively reviewed. Image data were included in this study if: (1) the patient presented symptoms of acute ischemic stroke; (2) MRI was performed within 24 h of symptom onset; and (3) DSA following MRI was performed (n = 32 patients). We defined proximal intra-arterial sign (IAS) on ASL as enlarged circular or linear bright hyperintense signal within the occluded artery and distal IAS as enlarged circular or linear bright hyperintense signals within arteries inside or surrounding the affected region. The presence or absence of the proximal IAS and distal IAS were assessed, along with their inter-rater agreement and consistency with the presence of occlusion site and collateral flow on DSA images. Results: The sensitivity and specificity for identifying occlusion site with ASL were 82.8 and 100%, respectively. Those for identifying collateral flow with ASL were 96.7 and 50%, respectively. The inter-rater reliability was excellent for proximal IAS (κ = 0.92; 95% CI 0.76–1.00) and substantial for distal IAS detection (κ = 0.78; 95% CI 0.38–1.00). Conclusions: Proximal IAS and distal IAS on ASL imaging can provide important diagnostic clues for the detection of arterial occlusion sites and collateral perfusion in patients with acute ischemic stroke.

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Abstract WP48: Relationship of Cerebral Blood Flow by Pseudo-continuous Arterial Spin Labeling and Stenosis in Middle Cerebral Artery Territory in Patients Evaluated for Acute Ischemic Stroke

Stroke ◽

10.1161/str.48.suppl_1.wp48 ◽

2017 ◽

Vol 48 (suppl_1) ◽

Author(s):

Eric Lai ◽

Raja Rizal Azman Raja Aman ◽

Hui Zhang ◽

Pui-Wai Chiu ◽

Queenie Chan ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Ischemic Stroke ◽

Middle Cerebral Artery ◽

Acute Ischemic Stroke ◽

Cerebral Artery ◽

Arterial Spin Labeling ◽

Spin Labeling ◽

Arterial Stenosis ◽

Vascular Territory

Purpose: Correlation of arterial stenosis with cortical and subcortical cerebral blood flow (CBF) in the middle cerebral artery (MCA) territory. Methods: 126 patients with acute cerebrovascular symptoms from March to June 2015 underwent MRI and MR Angiography (MRA) in a University hospital using a 3.0 Tesla scanner. Sequences included T1W, T2W, FLAIR, DWI, MRA, Pseudocontinuous Arterial Spin Labeling (pcASL, post-labeling delay 1.525 s). 13 patients (corrupted pcASL data) were excluded, with 113 patients (mean age: 67.74±14.19) evaluated (61 acute ischemic stroke, 52 patients transient ischemic attack). Institutionally developed software was used to determine CBF. MCA stenosis was graded into 4 categories by a neuroradiologist: 0 (no stenosis), 1 (mild <50%), 2 (moderate 50-70%) and 3 (severe >70%). Mean and standard deviation of MCA categories (leptomeningeal and perforating) CBF and corresponding degree of MCA stenosis were measured. Spearman correlation coefficients between CBF of cortical and subcortical regions and degree of MCA stenoses were calculated using SPSS (version 23.0). Results: The table showed the descriptive statistics. There was significant correlation between CBF of cortical region of MCA vascular territory and degree of stenosis of MCA in both left (r s = -0.296, p =0.001) and right (r s = -0.306, p =0.001) side. In the contrary, there was no correlation between subcortical CBF of MCA vascular territory and degree of stenosis of MCA in both sides. Conclusion: pcASL is a feasible non-invasive method to measure CBF in clinical setting. In MCA territory, the cortical blood flow correlated (fairly) with large vessel stenosis but not subcortical flow. We conclude that cortical CBF correlated with large artery stenosis, though being attenuated by collateral blood supply. No such relationship in subcortical CBF might be due to differential grey and white matter CBF flow, variable MCA stenotic location, and perforators originating from other territories.

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