Arjen Lindenholz

167 MRI Vessel Wall Imaging after Intra-Arterial Treatment for Acute Ischemic Stroke 7 without IAT (IAT-group vs. non-IAT group, p-value 0.04). In the IAT-group, there were more foci of vessel wall enhancement ipsilateral ( n = 18.5; 86%) to the treated artery compared with the contralateral side ( n = 3; 14%) (p = 0.005). In the non- IAT group there was no difference in the number of enhancing foci between the ipsilateral ( n = 18; 60%) and the contralateral sides ( n = 12; 40%) (p = 0.47). In the IAT-group, vessel wall enhancement was more often concentric on the ipsilateral side ( n = 8) compared with contralateral side ( n = 0) (p = 0.01). In the non-IAT group there was no significant difference in concentric enhancement between the ipsilateral ( n = 7) and the contralateral side ( n = 5) (p = 0.14). No differences were found between eccentric enhancing foci ipsilateral-versus-contralateral side and IAT-group versus non-IAT group. The locations of all enhancing foci are shown in Table 2 and Supplemental table 1 and all statistical analyses are shown in Table 3 . The degree of movement calculated over all patients was 0.77 ± 0.51 (standard deviation; SD) degrees for Δ Rotation and 0.81 ± 0.59 millimeters for Δ Translation. Table 3. Comparison of enhancing foci between IAT-group and non-IAT group and between ipsilateral and contralateral side. IAT-group non-IAT group p-value Total number of enhancing foci 21.5 30 0.04* Total number of ipsilateral enhancing foci 18.5 18.0 0.003* Total number of contralateral enhancing foci 3.0 12.0 0.74* Total number of concentric ipsilateral foci 9.0 8.5 0.02* Total number of eccentric ipsilateral foci 9.5 9.5 0.07* (proportion); p-value (proportion); p-value Total number of enhancing foci ipsilateral vs. contralateral (18.5 vs. 3.0); 0.005 † (18.0 vs. 12.0); 0.47 † Total number of concentric enhancing foci ipsilateral vs. contralateral (9.0 vs. 0.0); 0.011 † (8.5 vs. 3.0); 0.14 † Total number of eccentric enhancing foci ipsilateral vs. contralateral (9.5 vs 3.0); 0.06 † (9.5 vs. 9.0); 0.97 † Table 3. IAT: intra-arterial treatment; *, Mann-Whitney U test; † , Wilcoxon Signed Rank test