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Objectives Automated CT perfusion mismatch assessment is an established treatment decision tool in acute ischemic stroke. However, the reliability of this method in patients with head motion is unclear. We therefore sought to evaluate the influence of head movement on automated CT perfusion mismatch evaluation. Methods Using a realistic CT brain-perfusion-phantom, 7 perfusion mismatch scenarios were simulated within the left middle cerebral artery territory. Real CT noise and artificial head movement were added. Thereafter, ischemic core, penumbra volumes and mismatch ratios were evaluated using an automated mismatch analysis software (RAPID, iSchemaView) and compared with ground truth simulated values. Results While CT scanner noise alone had only a minor impact on mismatch evaluation, a tendency towards smaller infarct core estimates (mean difference of -5.3 (-14 to 3.5) mL for subtle head movement and -7.0 (-14.7 to 0.7) mL for strong head movement), larger penumbral estimates (+9.9 (-25 to 44) mL and +35 (-14 to 85) mL, respectively) and consequently larger mismatch ratios (+0.8 (-1.5 to 3.0) for subtle head movement and +1.9 (-1.3 to 5.1) for strong head movement) were noted in dependence of patient head movement. Conclusions Motion during CT perfusion acquisition influences automated mismatch evaluation. Potentially treatment- relevant changes in mismatch classifications in dependence of head movement were observed and occurred in favor of mechanical thrombectomy. [ABSTRACT FROM AUTHOR]

Objectives: To develop and validate a quantitative and observer-independent method to evaluate pial collateral circulation by DSC-perfusion MRI and test whether this novel method delivers diagnostic information which is redundant to or independent from conventional penumbra imaging by the mismatch approach.Methods: We retrospectively identified 47 patients with M1 occlusion who underwent MR diffusion/perfusion imaging and mechanical thrombectomy at our facility. By automated registration and segmentation, Tmax delays were attributed specifically to the pial, cortical and parenchymal compartments. The resulting pial volumes at delay were defined as the pial Tmax map-assessed collateral score (TMACS) and correlated with gold standard digital subtraction angiography (DSA). Mismatch ratio was assessed by conventional penumbra defining MRI criteria.Results: Strong correlation was found between TMACS and angiographically assessed collateral score (Pearson ρ = -0.74, p < 0.001). In multiple logistic regression, both good collaterals according to TMACS [OR 4.3 (1.1-19, p = 0.04)] and mismatch ratio ≥ 3.5 [OR 12.3 (1.88-249, p = 0.03)] were independent predictors of favourable clinical outcome.Conclusions: Perfusion delay in the pial compartment, as evaluated by TMACS, closely reflects the extent of pial collaterals in gold-standard DSA. TMACS and mismatch ratio were found to be complementary predictors of a favourable clinical outcome, each adding independent predictive information.Key Points: • MRI-DSC perfusion delay specific in the pial compartment reflects leptomeningeal collateralization. • A novel quantitative- and observer-independent marker of collateral status (TMACS) is introduced. • Quantification of collateral status leads to an independent predictor of neurological outcome. [ABSTRACT FROM AUTHOR]

Purpose Multiple scores have been described for the assessment of collateralization in acute ischemic stroke. Currently, there is no gold standard for collateral assessment by CT angiography (CTA). This study compared four frequently used collateral scores with regard to their correlation with early infarct core and mismatch ratio. Methods 30 consecutive patients with acute occlusion of the M1 segment or terminal carotid artery were reviewed retrospectively. Collaterals were assessed using dynamic and also single-phase CTA according to grading systems by the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR), Alberta Stroke Program Early CT Score (ASPECTS) (on collaterals), Christoforidis et al and Miteff et al. The Christoforidis and ASITN/SIR scores, which were initially designed for conventional angiography, were adapted to be applicable to CTA. The scores were compared with respect to early infarct core and mismatch ratio in perfusion CT estimated by RAPID software using Spearman correlation. Results ASITN/SIR and ASPECTS collateral scores showed good correlation with early infarct core (rho=-0.696, p<0.001 and rho=-0.677, p<0.001) and mismatch ratio (rho=0.609, p<0.001 and rho=0.581, p<0.001). In contrast, the Christoforidis and Miteff scores correlated less well with infarct core (rho=0.245, p=0.191 and rho=-0.272, p=0.145, respectively) and mismatch ratio (rho=-0.329, p=0.075 and rho=0.279, p=0.135, respectively). ASPECTS and ASITN/SIR showed excellent cross-correlation (rho=0.901, p<0.001). Conclusions Compared with the Christoforidis and Miteff scores, the modified ASITN/SIR and ASPECTS collateral scores showed consistently higher correlation with the extent of early infarct core and mismatch volume. This is probably because these scores evaluate the extent and delay of vascular enhancement in the affected territory rather than the backflow of contrast medium to the occlusion. [ABSTRACT FROM AUTHOR]

Background and Purpose: Collaterals are important in large vessel occlusions (LVO), but the role of carotid artery disease (CAD) in this context remains unclear. This study aimed to investigate the impact of CAD on intracranial collateralization and infarct growth after thrombectomy in LVO., Materials and Methods: All patients who underwent thrombectomy due to M1 segment occlusion from 01/2015 to 12/2021 were retrospectively included. Internal carotid artery stenosis according to NASCET was assessed on the affected and nonaffected sides. Collaterals were assessed according to the Tan score. Infarct growth was quantified by comparing ASPECTS on follow-up imaging with baseline ASPECTS., Results: In total, 709 patients were included, 118 (16.6%) of whom presented with CAD (defined as severe stenosis ≥70% or occlusion ipsilaterally), with 42 cases (5.9%) being contralateral. Good collateralization (Tan 3) was present in 56.5% of the patients with ipsilateral CAD and 69.1% of the patients with contralateral CAD. The ipsilateral stenosis grade was an independent predictor of good collateral supply (adjusted OR: 1.01; NASCET point, 95% CI: 1.00-1.01; P  = .009), whereas the contralateral stenosis grade was not ( P  = .34). Patients with ipsilateral stenosis of ≥70% showed less infarct growth (median ASPECTS decay: 1; IQR: 0-2) compared with patients with 0%-69% stenosis (median: 2; IQR: 1-3) ( P  = .005). However, baseline ASPECTS was significantly lower in patients with stenosis of 70%-100% ( P  < .001). The results of a multivariate analysis revealed that increasing ipsilateral stenosis grade (adjusted OR: 1.0; 95% CI: 0.99-1.00; P  = .004) and good collateralization (adjusted OR: 0.5; 95% CI: 0.4-0.62; P  < .001) were associated with less infarct growth., Conclusions: CAD of the ipsilateral ICA is an independent predictor of good collateral supply. Patients with CAD tend to have larger baseline infarct size but less infarct growth., (© 2024 by American Journal of Neuroradiology.)