Assessment of Leptomeningeal Collaterals Using Dynamic CT Angiography in Patients with Acute Ischemic Stroke

Abstract

Whole-brain dynamic time-resolved computed tomography angiography (CTA) is a technique developed on the new 320-detector row CT scanner capable of generating time-resolved cerebral angiograms from skull base to vertex. Unlike a conventional cerebral angiogram, this technique visualizes pial arterial filling in all vascular territories, thereby providing additional hemodynamic information. Ours was a retrospective study of consecutive patients with ischemic stroke and M1 middle cerebral artery þ / À intracranial internal carotid artery occlusions presenting to our center from June 2010 and undergoing dynamic timeresolved CTA and perfusion CT within 6 hours of symptom onset. Leptomeningeal collateral status was assessed by determining relative prominence of pial arteries in the ischemic region, rate and extent of retrograde flow, and various topographical patterns of pial arterial filling. Twenty-five patients were included in the study. We demonstrate the existence of the following novel properties of leptomeningeal collaterals in humans: (a) posterior (posterior cerebral artery (PCA)-MCA) dominant collateralization, (b) intraterritorial 'within MCA region' leptomeningeal collaterals, and (c) significant variability in size, extent, and retrograde filling time in pial arteries. We also describe a simple and reliable collateral grading template that, for the first time on dynamic CTA, incorporates back-filling time as well as size and extent of collateral filling.

4D-CTA in Neurovascular Disease: A Review

“…In case of proximal vascular stenotic or occlusive disease, 4D-CTA can be used to study altered flow dynamics of the intracranial vasculature, for example, to evaluate collateral flow via the circle of Willis. In a retrospective study with 25 patients with proximal vessel occlusion, Menon et al 53 could differentiate distinct patterns of collaterals. These patterns consisted of posterior cerebral artery-MCA dominant collateralization, intratentorial leptomeningeal collaterals, and variability in size, extent, and retrograde filling time in pial arteries.…”

CTA Collateral Status and Response to Recanalization in Patients with Acute Ischemic Stroke

“…1,2 During an acute stroke, ischemic brain depends on blood flow from these collaterals to survive until the occluded artery is opened. [3][4][5][6][7][8] This collateral circulation is highly variable and potentially influences the rate at which an infarct grows. 4,[8][9][10] Collateral status at baseline is an independent determinant of clinical outcome among patients with acute ischemic stroke.…”

“…[3][4][5][6][7][8] This collateral circulation is highly variable and potentially influences the rate at which an infarct grows. 4,[8][9][10] Collateral status at baseline is an independent determinant of clinical outcome among patients with acute ischemic stroke. 3,5,7,8,11 Nonetheless, "effect modification" by collateral status measured noninvasively by use of CTA of the relationship between recanalization and clinical outcome has not been demonstrated before.…”

Relative Filling Time Delay Based on CT Perfusion Source Imaging: A Simple Method to Predict Outcome in Acute Ischemic Stroke

“…There are more sophisticated methods to assess collateral flow by using whole-brain CTP. 22 However, these require 320-slice CT, which would limit their applicability. In contrast, rFTD assessment can be performed by using any CT scanner technology and is simple and robust in clinical practice.…”