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Objectives: Large vessel occlusion (LVO) stroke patients routinely undergo interhospital transfer to endovascular thrombectomy capable centers. Imaging is often repeated with residual intravenous (IV) iodine contrast at post-transfer assessment. We determined imaging findings and the impact of residual contrast on secondary imaging. Anterior circulation LVO stroke patients were selected out of a consecutive cohort. Directly admitted patients were contrast naïve, and transferred patients had previously received IV iodine contrast for stroke assessment at the referring hospital. Two independent readers rated the visibility of residual contrast on non-contrast computed tomography (CT) after transfer and assessed the hyperdense vessel sign. Multivariate linear regression analysis was used to investigate the association of the Alberta Stroke Program Early CT score (ASPECTS) with prior contrast administration, time from symptom onset (TFSO), and CTP ischemic core volume in both directly admitted and transferred patients. Results: We included 161 patients, with 62 (39%) transferred and 99 (62%) directly admitted patients. Compared between these groups, transferred patients had a longer TFSO-to-imaging at our institution (median: 212 vs. 75 min, p < 0.001) and lower ASPECTS (median: 8 vs. 9, p < 0.001). Regression analysis presented an independent association of ASPECTS with prior contrast administration (ß = -0.25, p = 0.004) but not with TFSO (ß = -0.03, p = 0.65). Intergroup comparison between transferred and directly admitted patients pointed toward a stronger association between ASPECTS and CTP ischemic core volume in transferred patients (ß = -0.39 vs. ß = -0.58, p = 0.06). Detectability of the hyperdense vessel sign was substantially lower after transfer (66 vs. 10%, p < 0.001). Conclusion: Imaging alterations due to residual IV contrast are frequent in clinical practice and render the hyperdense vessel sign largely indetectable. Larger studies are needed to clarify the influence on the association between ASPECTS and ischemic core.
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BACKGROUND: To study hippocampus subfield volumes in patients after microsurgical clipping (MC) and/or endovascular coiling (EC) of intracranial aneurysms. METHODS: Hippocampus subfield volumetry was performed using FreeSurfer v6.0 in 51 patients (35 females, mean age 54.9 ± 11.9 years, range 24-78 years). Visual inspection of image and segmentation quality was performed prior to statistical analyses. Multiple regression analysis, controlled for age, sex, and side of treatment, was used to assess the impact of prior MC and history of subarachnoid haemorrhage (SAH) on hippocampus subfield volumes (cornu ammonis (CA)-2/3, CA-4, subiculum). Partial correlation analyses were used to assess effect of multiple treatments on hippocampus subfield volumes. RESULTS: Prior MC was significantly associated with lower hippocampal subfield volumes in MC patients for right and left CA-2/3 (ß = -22.32 [-40.18, -4.45]; p = 0.016 and ß = -20.03 [-39.38, -0.68]; p = 0.043) and right CA-4 (ß = -17.00 [-33.86, 0.12]; p = 0.048). History of SAH was not significantly associated with hippocampal subfield volumes. We observed a higher disease burden in the MC cohort. The number of aneurysms correlated with right-sided hippocampal subfield volumes while the number of treatment interventions did not. CONCLUSION: In this explorative study, we found that history of MC was significantly associated with lower volumes in distinct hippocampal subfields, which may be a consequence of a more extensive treatment. This could indicate specific atrophy of CA-2/3 after MC and should motivate hippocampal subfield assessment in larger cohorts.
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Background and Purpose- Intracranial thrombi can be characterized according to their permeability as measured by contrast agent penetration. Thrombus composition and its associated pathogenesis are important factors affecting treatment and secondary prevention. We aimed to explore the histopathologic factors explaining the heterogeneity of thrombus permeability measures and evaluated potential correlations with stroke pathogenesis. Methods- Thrombus densities were measured in thin-slice noncontrast computed tomography and automatically aligned computed tomographic angiography images of 133 patients with large-vessel occlusions of the middle cerebral artery. Change in thrombus attenuation (Δt) and corrected void fraction (ε; attenuation increase corrected for contralateral artery densities) were calculated. First, these thrombus perviousness measures were correlated with histological thrombus components (especially fractions of fibrin-platelet accumulation and red blood cells) and stroke pathogenesis (n=32). For validation, an association between perviousness and pathogenesis was assessed in a second, independent cohort (n=101). Results- Thrombus perviousness estimates were correlated with both fibrin/platelets fractions (Δt: r=0.43, P=0.016/ε: r=0.45, P=0.01) and inversely with red blood cells counts (Δt: r=-0.46, P=0.01/ε: r=-0.49, P=0.006). In the first cohort, Δt was substantially higher in samples from patients with cardioembolic stroke pathogenesis as compared with noncardioembolic-derived thrombi ( P=0.026). In the validation cohort, thrombus perviousness measures differed significantly between cardioembolic (Δt: median [ interquartile range]=12.53 [8.70-17.90]; ε: median [interquartile range]=0.054 [0.036-0.082]) and noncardioembolic thrombi (Δt: median [interquartile range]=3.2 [2.17-6.44], P<0.001; ε: median [interquartile range]=0.020 [0.011-0.027], P<0.001) and were associated with pathogenesis (Δt: ß=0.45, P=0.016/ε: ß=83.6, P=0.013) in a binary logistic regression model. Conclusions- Permeable thrombi showed a strong correlation with lower fractions of red blood cells counts and more fibrin/platelets conglomerations, concurrent with an association with cardioembolic origin. This novel information about thrombus perviousness may be valuable as a new and simple to acquire imaging marker for identifying stroke pathogenesis using early and readily available imaging.