Arterial Spin Labeling Magnetic Resonance Imaging Estimation of Antegrade and Collateral Flow in Unilateral Middle Cerebral Artery Stenosis

Abstract

Background and purpose Three-dimensional pseudo-continuous arterial spin labeling (3D pCASL) with multiple post-labeling delays (PLDs) has been used to assess cerebral blood flow (CBF). We used this modality to estimate antegrade and collateral flow in patients with unilateral middle cerebral artery (MCA) stenosis. Methods Consecutive patients with unilateral MCA 50% to 99% stenosis at two centers underwent pCASL with a PLD of 1.5s and 2.5s. Mean CBF of bilateral MCA territory at the PLD 1.5s and 2.5s were measured. Early-arriving flow proportion was defined as [CBF 1.5s at lesion side/CBF 2.5s at normal side] × 100%. Late-arriving retrograde flow proportion was defined as [(CBF 2.5s minus CBF 1.5s) at lesion side minus (CBF 2.5s minus CBF 1.5s) at normal side]/CBF 2.5s at normal side × 100%. Antegrade and collateral scales were evaluated in patients with conventional angiography. Spearman correlation coefficients were calculated between early-arriving flow and late-arriving retrograde flow proportions on ASL and antegrade and collateral scales on conventional angiography, respectively. Results Forty-one patients (46.0±12.0 years) were enrolled. The mean early-arriving flow proportion was 78.3%±14.9%. The mean late-arriving retrograde flow proportion was 16.1%±10.2%. In 21 patients with conventional angiography, Spearman correlation coefficient was 0.53 (95%CI 0.11–0.79) between antegrade grade and early-arriving flow proportion (p=0.01) and 0.81 (95%CI 0.56–0.92) between collateral grade and late-arriving retrograde flow proportion (p<0.0001). Conclusion Three-dimensional pCASL with two-PLD may provide an empirical approach for estimating antegrade and collateral flow in patients with unilateral MCA stenosis.

Sequential changes of arterial spin-labeling perfusion MR images with dual postlabeling delay following reconstructive surgery for giant internal carotid artery aneurysm

“…Labeled blood that travels via collateral pathways of the circle of Willis exhibit prolonged ATT as long as 1 second. [ 1 6 9 ]…”

“…[ 1 6 ] To resolve this tradeoff between allowing sufficient delay to visualize tissue perfusion and maintaining adequate diagnostic quality, PLDs of 1.5–2.0 seconds are routinely used in daily clinical practice. [ 1 6 7 9 13 15 ]…”

“…In patients with steno-occlusive cerebrovascular disease, including leptomeningeal anastomosis, labeled blood that travels via collateral pathways of the circle of Willis or secondary collateral pathways exhibits prolonged ATT. [ 1 6 9 ] Thus, ASL measurements that employ a conventional single PLD (e.g. 1.5 seconds) lead to underestimation of cerebral blood flow (CBF).…”

Research Status of Three-Dimensional Pseudo-Continuous Arterial Spin Labeling in Ischemic Cerebrovascular Diseases

“…In case of hypoperfusion due to stenosis or occlusion of brain tissue feeding artery, the brain tissue would maintain intracranial hemodynamic stability in a compensatory manner of generating a bypass artery or arterial anastomosis network; the formation of collateral circulation would be of great clinical significance. Studies [17] have shown that there is a significant correlation between the formation of collateral circulation and stroke outcome/prognosis. A nice collateral circulation can always improve the success rate of vascular recanalization treatment, thus promoting tissue reperfusion, reducing infarction volume, reducing the risk of hemorrhagic transformation after infarction, and effectively improving clinical outcome.…”

Clinical usefulness of multiphase arterial spin labeling imaging for evaluating cerebral hemodynamic status in a patient with symptomatic carotid stenosis by comparison with single-photon emission computed tomography: A case study

“…Magnetic resonance (MR) imaging with pulsed arterial spin labeling (ASL) has been used for noninvasive assessment of cerebral perfusion [1] . More recently, multiphase ASL, in which the imaged slices are acquired with various postlabeling delays (PLD), provides temporal information of cerebral perfusion for patients with chronic cerebral ischemia [2] , [3] , [4] , [5] . This technique can offer a noninvasive assessment of cerebral hemodynamics that may not be adequately acquired using single-photon emission computed tomography (SPECT) imaging.…”