Abstract 164: Comparison Between Transcranial Doppler and Functional MRI With Breath Holding Test for Cerebral Vasoreactivity Assessment in Patients with Carotid Stenosis

Background: Impaired cerebral vasoreactivity (CVR) detected by Transcranial Doppler (TCD) is predictive of stroke in patients with carotid stenosis. Functional MRI (fMRI) can evaluate CVR either. Few studies have compared both methods for CVR assessment already. However, none of them used breath holding test (BHT) as the vasodilatory stimulus. Objectives: To assess CVR through BHT using TCD and fMRI in patients with carotid stenosis and controls in order to verify whether fMRI can detect any difference on BOLD-signal intensities between these groups. Additionally, we aimed to verify if fMRI can discriminate correctly any subject with impaired CVR as compared to TCD. Methods: Fifteen patients with carotid stenosis defined as stenosis ≥50% by angiography or ≥70% by ultrasound or ≥70% by CTA or MRA (11men;52-90yo;mean:67.7yo) and 7 matched-controls (5men:51-85yo;mean:64.6yo) performed BHT during TCD. Impaired CVR was diagnosed if mean percentage increase of MCA velocities ≤31% on 3-consecutive intervals of 3...