Carotid Pseudo-occlusion on CTA in Patients with Acute Ischemic Stroke: a Concerning Observation

Objective: Differentiation between an occluded and a patent extracranial internal carotid artery (ICA) is crucial in the diagnostic workup of patients with acute ischemic stroke; particularly in patients eligible for endovascular treatment. We report neurological and radiological findings of cases in which CTA in the acute phase incorrectly revealed an occlusion of the ICA.

Methods: In our image data base of 54 patients with acute ischemic stroke eligible for endovascular treatment, we searched for patients with an occluded extracranial ICA on CTA whereas DSA proved that this artery was patent. Of these patients, all available images were re-examined to investigate possible causes of these so-called pseudo-occlusions.

Results: We detected 6 patients (11%) with a pseudo-occlusion. The pseudo-occlusions on CTA were associated with reduced flow due to carotid T-occlusions (4 cases) or a combination of a high degree stenosis of the extracranial ICA and MCA occlusion (2 cases).

Conclusion: CTA in the acute phase of ischemic stroke needs to be interpreted with severe caution, and in endovascular treatment decisions we should be aware that an extracranial ICA occlusion may be a false positive finding.