Imaging Findings of Multiphase CT Angiography of Acute Internal Carotid Artery Occlusion Within 6-Hour Time-Window After Thrombectomy and Its Clinical Implication

Background: Intra-arterial thrombectomy (IAT) is one of the mainstream treatments for acute ischemic stroke. As relatively little evidence on extracranial internal carotid artery (ICA) occlusions exists in the literature, we share our experiences after using IAT for intracranial and extracranial ICA occlusions. We further clarify the imaging characteristics of multiphase computed tomography angiography (CTA) and share the experience of balloon angioplasty in acute ICA occlusion. Objectives: To investigate the imaging findings of multiphase CTA and the clinical conditions and outcomes of acute ICA occlusions at different segments after IAT. Patients and Methods: All participants receiving IAT for acute stroke with isolated ICA occlusions were included, obtained from three hospitals between June 2016 and November 2018. An imaging review for non-enhanced computed tomography (CT), multiphase CTA, and angiography was conducted. Epidemiological and clinical data were reviewed. Further comparisons were evaluated between the occlusion side from the C6 to C7 segments and C1 to C5 segments of the ICA. Results: The average age of the patients was 73.0 years, and the initial National Institutes of Health Stroke scale (NIHSS) score was 18.6. Nineteen percent of cases had good outcomes. Good reperfusion results were achieved in 50% of cases. Compared to the group with occlusion from C6-C7, the group with occlusion from C1-C5 had a relatively good Alberta Stroke Program Early CT score (ASPECTS) in the A1 phase of the multiphase CTA, and more patients had a good collateral. Three cases received a balloon angioplasty for a concurrent proximal cervical ICA tight stenosis, and all cases had good reperfusion results. Conclusion: Distal occlusion of the ICA demonstrates lower ASPECTS and a worse collateral on multiphase CTA. A multiphase CTA with an extended scan range in the A2 and A3 phases is able to exclude pseudo-occlusion of the ICA. Balloon angioplasty is helpful for concurrent proximal cervical ICA tight stenosis.