Diagnostic and prognostic computed tomography imaging markers in basilar artery occlusion (Review)

Abstract

Acute ischemic stroke treatment has been revolutionized by the addition of mechanical and aspiration thrombectomy. Randomized controlled trials have proven beyond doubt, the substantial clinical impact of endovascular interventions in anterior circulation territory strokes. Unfortunately, patients with vertebrobasilar ischemic stroke could not be included in these early trials due to inherent clinical, radiological, and prognostic particularities of posterior circulation ischemia; thus, indications for the treatment of posterior fossa strokes and basilar artery occlusion (BAO) are mainly based on retrospective studies and registries. BAO carries high morbidity and mortality, despite the new improvements in endovascular therapy. Identifying patients who will likely benefit from invasive treatment and have a good clinical outcome resides in discovering clinical, biological, or imaging markers, that have prognostic implications. Such imaging markers have been described, especially in the last decade. Hyperdense Basilar Artery Sign (HDBA), Posterior Circulations-Alberta Stroke Program Early CT Score (pc-ASPECTS), Pons-Midbrain Index (PMI), Posterior Circulation Collateral Score (pc-CS), Posterior Circulation CT Angiography Score (pc-CTA), and Basilar Artery on CT Prognostic Score (BATMAN), are computed tomography (CT) markers with properties that can aid the diagnosis of BAO and can independently predict clinical outcome. This paper aims to present a comprehensive review of these imaging signs to have a thorough understanding of their diagnostic and prognostic attributes.

Keywords: acute ischemic stroke; angiography; basilar artery occlusion; computed tomography; imaging markers.

Figure 1

(A and B) Coronal reformated NCCT and CTA images reveal the HDBA sign and the corresponding distal BA thrombus, extending in both posterior cerebral arteries. (C and D) Before and after aspiration thrombectomy: Frontal projection digital subtraction angiography images confirm the BA occlusion, and subsequent recanalization. NCCT, non-contrast computer tomography; CTA, computer tomography angiography; HDBA, hyperdense basilar artery; BA, basilar artery.

Figure 2

Axial non-contrast CT images (A) at the level of the cerebellar hemispheres, (B) pons, (C) midbrain and cerebral peduncles, and (D) thalamus, show the allocation of points to each structure for the calculation of pc-ASPECTS. CT, computed tomography; pc-ASPECTS, pc-ASPECTS, Posterior Circulation Alberta Stroke Program Early CT Score.

Figure 3

(A and B) Digital subtraction angiograms from bilateral internal carotid artery contrast injection show both posterior communicating arteries with a fetal configuration (white arrow) in a patient with basilar artery occlusion. (C and D) Contrast injection in the left vertebral artery reveal the distal basilar occlusion (white arrow) and collateral reconstitution of the superior cerebellar arteries through the posterior inferior cerebellar artery (curved arrow).