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Background and purposeCurrently, there is neither a standard protocol for vessel wall MR imaging of intracranial atherosclerotic disease (ICAD) nor a gold standard phantom to compare MR sequences. In this study, a plaque phantom is developed and characterized that provides a platform for establishing a uniform imaging approach for ICAD.Materials and methodsA patient specific injection mold was 3D printed to construct a geometrically accurate ICAD phantom. Polyvinyl alcohol hydrogel was infused into the core shell mold to form the stenotic artery. The ICAD phantom incorporated materials mimicking a stenotic vessel and plaque components, including fibrous cap and lipid core. Two phantoms were scanned using high resolution cone beam CT and compared with four different 3 T MRI systems across eight different sites over a period of 18 months. Inter-phantom variability was assessed by lumen dimensions and contrast to noise ratio (CNR).ResultsQuantitative evaluation of the minimum lumen radius in the stenosis showed that the radius was on average 0.80 mm (95% CI 0.77 to 0.82 mm) in model 1 and 0.77 mm (95% CI 0.74 to 0.81 mm) in model 2. The highest CNRs were observed for comparisons between lipid and vessel wall. To evaluate manufacturing reproducibility, the CNR variability between the two models had an average absolute difference of 4.31 (95% CI 3.82 to 5.78). Variation in CNR between the images from the same scanner separated by 7 months was 2.5–6.2, showing reproducible phantom durability.ConclusionsA plaque phantom composed of a stenotic vessel wall and plaque components was successfully constructed for multicenter high resolution MRI standardization.

Background Traditional treatment in acute ischemic stroke is based on time criteria when administering intravenous and intra-arterial therapies. However, recent evidence suggests that image-based criteria may be useful for selecting patients for intra-arterial interventions. The use of CT perfusion (CTP)-based criteria, regardless of time from symptom onset, in patient selection for intra-arterial treatment of ischemic stroke was assessed. Methods Patients with ischemic stroke who presented to the emergency department at the Medical University of South Carolina with a National Institute of Health Stroke Scale score of ≥ 8, regardless of time from symptom onset, were assessed retrospectively. CTP maps were qualitatively assessed for the presence of penumbra and infarction. Selected patients underwent mechanical aspiration of their occlusion using the Penumbra system. Functional outcome was then recorded using the modified Rankin scale (mRS) at 90 days or the closest follow-up to 90 days. Results 53 patients were included in the study. The median time from symptom onset to groin vascular access was 6.3 h. Eight patients (15%) had bleeding complications including subarachnoid hemorrhage, parenchymal hemorrhage and intraventricular hemorrhage. After CTP-based selection, the patients were divided into two groups for analysis: ≤6 h and >6 h from symptom onset to endovascular procedure. No difference was found in functional outcome between the two groups (38.5% and 40.7% achieved 90-day mRS ≤2, respectively (p=1.0) and 57.7% and 51.9% achieved 90-day mRS ≤3, respectively (p=0.785)). There was no difference in the rate of intracranial hemorrhage between the two groups (11.5 vs 18.5, p=0.704). Conclusion This study demonstrated similar rates of good functional outcome and intracranial hemorrhage in patients with ischemic stroke when endovascular treatment was performed based on CTP selection rather than time-guided selection. These findings suggest that endovascular reperfusion in ischemic stroke may be effective and safe, and may allow patient selection not solely based on time from symptom onset.