Intracranial Nonstenosing Atherosclerotic Plaques Assessed With Vessel Wall MRI in Patients With Embolic Stroke of Undetermined Source

Artery-to-artery embolization from vulnerable intracranial nonstenosing atherosclerotic plaques (vNSPs) has been proposed as a major contributor to embolic stroke of undetermined source (ESUS). Vessel wall MRI (VWMRI) offers the potential to identify culprit vNSPs, yet prospective studies in ESUS populations are lacking. This study aimed to assess the role of vNSPs in single-territory ESUS and to evaluate the utility of intracranial VWMRI in the diagnostic workup. Consecutive patients admitted to the Stroke Unit of the IRCCS Mondino Foundation (Pavia, Italy) with a confirmed ESUS diagnosis after a complete etiologic workup were prospectively enrolled in the study. Patients with multiterritorial ischemic lesions, complicated aortic arch atherosclerosis, or a probable patent foramen ovale-associated stroke were excluded. Intracranial VWMRI at 3-T was performed within 1 month of the index event. Atherosclerotic lesions were considered culprit if demonstrating postcontrast enhancement on T1-weighted images and a location consistent with ischemic lesions' distribution. Quantitative radiologic features of vNSPs were also analyzed. A total of 80 patients (mean age 65.6 years, 34 [42.5%] women) were included. VWMRI identified a potentially culprit vNSP in 23 of 80 patients (28.8%, 95% CI 20-39.5). Patients with symptomatic vNSPs were older (72.7 vs 62.8 years, p = 0.002) and more frequently current (43.5 vs 35.1%) or former (30.4 vs 8.8%) smokers (p = 0.014). In a multivariable logistic regression model including major risk factors of intracranial atherosclerosis (age, smoking, hypertension, diabetes, and dyslipidemia), both age (adjusted odds ratio [aOR] 1.12, 95% CI 1.05-1.22, p = 0.002) and smoking status (active smokers: aOR 7.99, 95% CI 1.81-47.8, p = 0.011; former smokers: aOR 8.79, 95% CI 1.73-55.0, p = 0.012) were significantly associated with symptomatic vNSP. Intracranial vNSPs may represent a significant underlying cause of single-territory ESUS, and VWMRI could provide an added value in the diagnostic workup of these patients. Older age and smoking exposure were found to be independently associated with the presence of culprit intracranial vNSPs. Further studies are needed to confirm our findings because of the relatively small and monocentric cohort. This study provides Class IV evidence that VWMRI improves the identification of culprit vNSPs in patients with ESUS.