The Brush Sign Is Associated with a More Severe Oxygen Metabolic Impairment of the Ischemic Penumbra: An MRI-Based Study in Patients with Acute Stroke

In acute stroke, the brush sign has been linked to an increased risk of hemorrhagic transformation. We aimed to assess the oxygen metabolic abnormalities occurring in patients with acute ischemic stroke (AIS) exhibiting the brush sign on admission MRI and its prognostic value at follow-up. We retrospectively analyzed data from the Cohort of Patients to Identify Biological and Imaging Markers of Cardiovascular Outcomes in Stroke cohort (NCT: 03149705), a single-center observational study that enrolled patients treated with thrombectomy from 2016 to 2022. DSC-MRI was used to generate cerebral metabolic rate of oxygen (CMRO2) and oxygen extraction fraction maps. These maps were coregistered with apparent diffusion coefficient maps to extract values within the ischemic core and penumbra and expressed as relative changes. We included 204 of 321 (63.6%) participants enrolled in the cohort (114 men, median age 69.0 years and median NIHSS score 14.0). Of these 204 patients, 70 (34.3%) exhibited the brush sign. They had higher baseline NIHSS score (median: 15.5 versus 13.0, P = .007), larger ischemic core (median: 24.5 mL versus 12.4 mL, P = .002), and larger ischemic penumbra (median: 15.0 mL versus 8.9 mL, P < .001). These patients showed more severe CMRO2 impairment in both the ischemic core (-52.9% versus -44.1%, P = .002) and penumbra (-31.0% versus -13.8%, P < .001). Multivariable analysis indicated that the brush sign was associated with greater CMRO2 impairment (OR = 0.5, 95% CI: 0.4-0.6, P < .001). At follow-up, the brush sign was associated with a higher risk of not achieving functional independence (OR = 1.8, 95% CI: 1.3-3.4, P = .04). The brush sign on admission MRI was associated with a more severe reduction in CMRO2 within the ischemic penumbra and poorer clinical outcomes at 3 months in patients with AIS treated with mechanical thrombectomy.