False ischaemic penumbras in CT perfusion in patients with carotid artery stenosis and changes following angioplasty and stenting

Abstract Introduction Carotid artery stenosis influences CT perfusion (CTP) studies, sometimes manifesting as a false ischaemic penumbra (FIP). This study aims to estimate the incidence of FIP in patients with carotid artery stenosis, establish their relationship with the degree of stenosis, and measure quantitative and qualitative changes in CTP after carotid angioplasty and stenting (CAS). Methods Between October 2013 and June 2015, we prospectively selected 26 patients with carotid stenosis who underwent CAS, with CTP being performed 2-10 days before and after CAS. Results Sixteen patients had unilateral stenosis (11 in the subgroup displaying C I, 1.7-71.3; P  = .0005). There were statistically significant changes in the parameters CBF, TTP, MTT, and Tmax CTP, which reverted after angioplasty. No significant changes were found in CBV. Conclusions Carotid artery stenosis involves changes in CTP parameters. Patients with ≥90% stenosis carry a high risk of FIP; CTP studies may therefore be misinterpreted in these cases. Changes in CTP parameters are reverted after CAS.