Neuhaus, Ain

Background Identifying eloquent regions associated with poor outcomes based on CT perfusion (CTP) may help inform personalized decisions on selection for endovascular therapy (EVT) in patients with large vessel occlusion (LVO) ischemic stroke. This study aimed to characterize the relationship between CTP-defined hypoperfusion and National Institutes of Health Stroke Scale (NIHSS) subitem deficits. Methods Patients with anterior circulation LVO, baseline CTP, itemized NIHSS at presentation and 24 hours were included. CTP was analyzed using e-CTP (Brainomix, UK). Time to maximal contrast (Tmax) prolongation was defined as >6 s, and penumbra as the difference between Tmax and ischemic core (relative cerebral blood flow<30%). Voxel-lesion-symptom mapping was performed using sparse canonical correlation analysis. For each NIHSS subitem, and total NIHSS, the associations were plotted between Tmax voxels with baseline NIHSS, and penumbra voxels with delta NIHSS (24 hours minus baseline). Results This study included 171 patients. Total NIHSS was predicted by hypoperfusion in left frontal cortex and subcortical white matter tracts. Voxels associated with neurological recovery were symmetrical and subcortical. Limb deficits were associated with respective motor cortex regions and descending motor tracts, with negative correlation within the contralateral hemispheres. A similar but smaller cluster of voxels within the penumbra was associated with NIHSS improvement. Language impairment correlated with left frontal cortex and superior temporal gyrus voxels. With the exception of dysarthria, significant associations were observed and more diffusely distributed in all other NIHSS subitems. Conclusions These results demonstrate the feasibility of hypoperfusion-to-symptom mapping in LVO. Symptom-based mapping from presenting imaging could refine treatment decisions targeting specific neurological deficits.

Introduction: Selection criteria for endovascular thrombectomy (EVT) for emergent large-vessel occlusion (ELVO) stroke increasingly rely on CT perfusion (CTP) findings at presentation. While perfusion imaging is used to estimate the likelihood of deriving long-term functional benefit from EVT, there is comparatively little data on how perfusion deficits relate to domains of neurological function. Here, we investigated region-specific hypoperfusion as a driver of neurological dysfunction through correspondence between NIHSS items and CTP. Methods: We included 169 patients with ELVO presenting to Mayo Clinic Rochester or Jacksonville, who had baseline CTP and itemised NIHSS data. Perfusion was quantified as mean transit time using e-CTP (Brainomix Ltd., Oxford, UK) and thresholded to ≥5 s for lesion masking. Voxel-wise lesion-symptom mapping (VLSM) was performed using sparse canonical correlations analysis (Lesymap package, R). Results: Total NIHSS was most strongly predicted by left MCA territory hypoperfusion, corresponding to language-eloquent cortical areas and dominant hemisphere motor tracts (figure 1). Contralateral limb motor deficits (NIHSS 5 and 6) were mainly associated with subcortical and white matter hypoperfusion; there was an additional strong signal for left frontal cortex in language function (NIHSS 9). The remaining NIHSS items were less well localised. Conclusions: Expanding on previous pilot data, our results provide further evidence for the feasibility of hypoperfusion-to-symptom mapping in ELVO. This could allow for more nuanced clinical-imaging mismatch determination, and selection of patients based on specific neurological deficits that may be reversible.

Background and purpose The Alberta Stroke Program Early CT Score (ASPECTS) is a commonly used scoring system to select patients with stroke for endovascular treatment (EVT). However, the inter- and intra-reader variability is high. Objective To determine whether the inter- and intra-reader variability is different for various regions of the ASPECTS scoring system by evaluating the interobserver variability of ASPECTS between different readers in a per-region analysis. Materials and methods All patients with acute ischemic stroke who proceeded to EVT in our institutions over a 4-year period were retrospectively identified from a prospectively maintained database. Images were reviewed by two experienced neuroradiologists, who recalculated the ASPECTS independently. We examined each region of the ASPECTS system to evaluate agreement between the raters in each area. Results 375 patients were included. The median total ASPECTS was 9 (IQR 8–9). The most common region showing ischemic change was the insula, with the M6 region being least commonly affected. Overall interobserver agreement for ASPECTS using Cohen’s κ was 0.56 (95% CI 0.51 to 0.61). The region with the highest agreement was the insula (κ=0.56; 0.48 to 0.64). The region with the lowest agreement was M3 (κ=0.34; 0.12 to 0.56). Agreement was relatively good when ASPECTS were dichotomized into 0–5 versus 6–10 (κ=0.66; 0.49 to 0.84). Conclusions Substantial interobserver variability is found when calculating ASPECTS. This variability is region dependent, and practitioners should take this into account when using ASPECTS for treatment decisions in patients with acute stroke.