Arjen Lindenholz

163 MRI Vessel Wall Imaging after Intra-Arterial Treatment for Acute Ischemic Stroke 7 Statistical analysis SPSS version 21.0 for Windows (IBM, Armonk, New York) was used for statistical analysis. Descriptive statisticswere used for the frequency of intracranial dissection or stenosis. Counts are given in proportions (percentages) including their 95% confidence intervals (CI). The intraclass correlation coefficient (ICC) using a two- way mixed, average measurement, consistency model and the Dice similarity coefficient (DSC) to correct for the location of the enhancement were calculated to evaluate the interrater agreement. A Wilcoxon signed-rank test was used for comparison between the number of enhancing foci ipsilateral and contralateral to the ischemic site as seen on the vessel wall images. A Mann-Whitney U test was performed to compare the number of enhancing foci between the IAT-group and non-IAT group. A two-sided p-value < 0.05 was considered statistically significant. Results Patients and treatment Between December 2009 and October 2017, forty-nine patients were included in this study. A flowchart of the study inclusion is shown in Figure 1 . Baseline characteristics for both patient groups can be found in the Table 1 . Figure 1 . Flowchart of study inclusion. IAT: intra-arterial treatment.