Background and aims: Symptomatic carotid stenosis is associated with an increased risk of early stroke recurrence. Severity of the stenosis, current basis of revascularization, explains only the cerebral ischemic mechanism of regional hypoperfusion. Plaque inflammation, the initiating event for plaque rupture and thromboembolism (artery-to-artery embolism), is not evaluated routinely. Using 18F-fluorodeoxyglucose positron-emission tomography (FDG-PET)/computed tomography (CT) and high resolution magnetic resonance imaging (HR-MRI), we investigated the role of plaque imaging and stroke recurrence in our cohort of stroke patients with recently symptomatic carotid stenosis.
Methods: This ongoing prospective study included consecutive patients within 30-days of recent stroke and ipsilateral carotid stenosis (≥50%). FDG uptake was quantified as mean standardized uptake values (SUV, g/ml). The ratio of T1 hyperintensity of carotid plaque to the ipsilateral sternocleidomastoid muscle (SCM) was recorded on T1-weighted fat suppressed images. Patients were followed prospectively for stroke recurrence within 90-days. Embolic potential of carotid plaque is estimated by presence of spontaneous microembolic signals (MES) on extended transcranial Doppler monitoring of ipsilateral middle cerebral artery.
Results: Of the 33 patients included in the study, 6 (18%) suffered from recurrent cerebral ischemic event in the same vascular territory within 90-days. Compared to patients without subsequent cerebral ischemic events, patients with recurrent cerebral ischemia showed higher mean T1 carotid-SCM ratio (2.49 versus 1.53; p<0.0001) and higher mean SUV value in the carotid plaque (3.52g/ml versus 1.51g/ml; p<0.0001). Higher T1 carotid-SCM ratio on HR-MRI (OR 4.249, 95%CI 1.818-5.18; p<0.0001), higher mean SUV on FDG-PET (OR 3.050, 95%CI 5.586-28.571; p=0.005) and MES on TCD (OR 2.186, 95%CI 1.652-47.619;p=0.037) were independent predictors of recurrent cerebral ischemia.
Conclusions: FDG-PET/CT and HR-MRI imaging of carotid stenosis helps in identification of patients at higher risk of subsequent cerebral ischemic events and may aid in better therapeutic decision-making.