Purpose: CT angiography (CTA) is a noninvasive technique for evaluating intracranial arterial stenoses and for following up on intracranial stents. We analyzed a series of patients to assess the capabilities of CTA with respect to preinterventional und postinterventional diagnostic imaging for stent-assisted intracranial angioplasty.
Materials and methods: We examined 8 patients with 9 symptomatic intracranial arterial stenoses before and after stent placement with CTA. CT angiographies were compared to the periprocedural conventional angiography with regard to the quality of the visualization as well as the dimensions of the identified stenoses and the implanted stents.
Results: The extent of the preinterventional intracranial stenoses identified with CTA differed between -15% to + 12% from conventional angiography. In any case we were able to assess stent position, expansion, and perfusion with postinterventional CTA. The mean residual stenosis after stent placement was 33% (13 - 48%) measured with conventional angiography and it was accurately estimated with a difference of +/- 15% in 5 of 9 stents by CTA. 4 residual stenoses were underestimated or overestimated between -20% and + 26%. Further CTA controls of several patients showed good visualization of in-stent neointimal hyperplasia.
Conclusion: CTA is useful for stent planning and follow-up of symptomatic intracranial stenoses. Intracranial stents and their lumina are adequately visualized by CTA, especially in vertebrobasilar vessels. However, residual stenosis and restenosis especially in the intracranial internal carotid artery and in the presence of calcified plaques may be incorrectly estimated by CTA. In case of doubt patients must undergo invasive angiography. In summary the use of CTA is a possibility for the primary follow-up of intracranial stents. It cannot generally prevent further diagnostics, but it is a potential method for reducing invasive angiography.