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Background: Pretreatment computed tomography perfusion parameter relative cerebral blood volume (rCBV) lesion volume has been shown to predict 90-day modified Rankin Scale score in small-core strokes with Alberta Stroke Program Early Computed Tomography Score ≥5, including those with medium-vessel occlusions (mid and distal M2 segment occlusions). Hence, in this study we aim to assess the performance of different rCBV lesion volume thresholds (rCBV <42%, rCBV <38%, and rCBV <34%) with 90-day modified Rankin Scale score including patients with large core (Alberta Stroke Program Early Computed Tomography Score <5) and strictly including only patients with anterior circulation large-vessel occlusion., Methods and Results: In this retrospective evaluation of our prospectively collected database, inclusion criteria were (1) Computed tomographic angiography confirmed anterior circulation large-vessel occlusion from September 1, 2017, to October 1, 2023; and (2) diagnostic computed tomography perfusion. Student t test, Mann-Whitney U test, and χ 2 test were used in the univariate data analysis. Spearman's rank correlation analysis was used to assess correlations. Outcome measure was dichotomized into good functional outcome (90-day modified Rankin Scale score, 0-2) and poor functional outcome (90-day modified Rankin Scale score, 3-6) for logistic regression and receiver operating characteristic analysis. P ≤0.05 was considered significant. In total, 229 patients met our inclusion criteria. The majority of the patients (n=161) in our cohort had M1 occlusion. All the rCBV thresholds were significantly higher in patients with poor 90-day functional outcomes and were independently associated with the outcome. Spearman's rank correlation analysis revealed a slightly stronger correlation of rCBV <42% (ρ=0.27, P <0.001), as compared with rCBV <38% (ρ=0.25, P <0.001) and rCBV <34% (ρ=0.24, P <0.001) with functional outcome. Receiver operating characteristic analysis revealed that rCBV <42% (area under the curve, 0.67 [95% CI, 0.60-0.74]; P <0.001) performed marginally better than rCBV <38% (area under the curve, 0.66 [95% CI, 0.59-0.73]; P <0.001), and rCBV <34% (area under the curve, 0.65 [95% CI, 0.58-0.72]; P <0.001)., Conclusions: All the rCBV thresholds were independently associated with poor 90-day functional outcome; however, the rCBV <42% marginally outperformed rCBV <38% and rCBV <34% lesion volumes.

Stroke mimics constitute a significant proportion of patients with suspected acute ischemic stroke. These conditions may resemble acute ischemic stroke and demonstrate abnormalities on perfusion imaging sequences. The most common stroke mimics include seizure/epilepsy, migraine with aura, brain tumors, functional disorders, infectious encephalopathies, Wernicke's encephalopathy, and metabolic abnormalities. Brain perfusion imaging techniques, particularly computed tomography perfusion and magnetic resonance perfusion, are being widely used in routine clinical practice for treatment selection in patients presenting with large vessel occlusion. At the same time, the utilization of these imaging modalities enables the opportunity to better diagnose patients with stroke mimics in a time-sensitive setting, leading to appropriate management, decision-making, and resource allocation. In this review, we describe patterns of perfusion abnormalities that could discriminate patients with stroke mimics from those with acute ischemic stroke and provide specific case examples to illustrate these perfusion abnormalities. In addition, we discuss the challenges associated with interpretation of perfusion images in stroke-related pathologies. In general, perfusion imaging can provide additional information in some cases-when used in combination with conventional magnetic resonance imaging and computed tomography-and might help in detecting stroke mimics among patients who present with acute onset focal neurological symptoms., (© 2022 American Society of Neuroimaging.)