Russell Mitesh Cerejo, MD

Lyu J, Ma N, Liebeskind DS, Wang DJJ, Ma L, Xu Y, et al. Arterial Spin Labeling Magnetic Resonance Imaging Estimation of Antegrade and Collateral Flow in Unilateral Middle Cerebral Artery Stenosis. Stroke. 2016

The authors in their above titled paper describe a novel way to non-invasively assess for

antegrade and collateral blood flow in intracranial stenosis patients. They evaluated 41 consecutive patients with symptomatic intracranial stenosis of the M1 segment of the middle cerebral artery due to atherosclerosis. These patients underwent three-dimensional pseudo-continuous arterial spin labeling (3D pCASL) with 3.0T MRI. The calculated perfusion on the CBF map of post labeling delay (PLD) 1.5s as early-arriving flow, and perfusion on the CBF map of PLD 2.5s as combination of early-arriving flow, late-arriving antegrade flow and late-arriving retrograde flow. The mean early arriving flow proportion was 78.3%±14.9%. The mean late-arriving retrograde flow proportion was 16.1%±10.2%. Half patients underwent cerebral angiography with calculation of Modified TICI scale and ASITN/SIR collateral grade.

The authors found significant correlations between early-arriving flow and late-arriving flow on two-PLD pCASL with conventional angiographic antegrade and collateral scales, suggesting that the early-arriving flow and late-arriving retrograde flow to the territory supplied by the stenotic MCA may primarily represent antegrade and collateral flow, respectively.

This is an interesting study, which has tried to use a novel non-invasive technique to assess for collaterals that are important not only in chronic stenoses but also acute occlusions.