Fig. 4

Molecular MRI reveals vascular inflammation in the IA area and predicts the outcome severity. a Schematic representation of the experimental approach. b Representative high-resolution T2*-w images (coronal view) before and after MPIO-αP-selectin intravenous injection in mice at Day 3 post-IA induction. MPIO-αP-selectin–induced hypointense signal in the T2*-w sequence in the vicinity of the IA area. Arrowheads indicate the MPIO-specific hypointensities. P-selectin endothelial activation is increased in the ipsilateral hemisphere and restricted to the IA area. (**P < 0.01; N = 5 mice/group; Mann–Whitney U test). c Representative high-resolution T2*-w images (coronal view) after MPIO-αVCAM-1 intravenous injection in the mice subjected to IA induction, at Day3. Arrowheads indicate the MPIO-specific hypointensities concentrated mainly around the IA area. d Corresponding signal void quantification for the MPIO-αP-selectin (**P < 0.01; N = 5 mice/group; Mann–Whitney U test). e Corresponding signal void quantification for the MPIO-αVCAM-1. VCAM-1 endothelial activation significantly increased in the ipsilateral hemisphere and restricted to the IA area (**P < 0.01; N = 5 mice/per group; Mann–Whitney U test). f Representative three-dimensional reconstruction of MR scans (T2*-w sequence) with MPIO signal voids and their distribution across the brain. g Correlation between the P-selectin signal from the MR scans at Day3 and hemorrhage volumes at Day5 (N = 5, R² = 0.91). h Correlation between the VCAM-1 signal from the MR scans at Day3 and hemorrhage volumes at Day5 (N = 5, R² = 0.85). i Representative images of P-selectin MPIO signal void at earlier time points (Day 3) and the hemorrhage volumes after the IA ruptures (Day 5). A smaller volume of signal void results in a small hemorrhage, whereas a larger volume results in a substantially bigger hemorrhage. j Colocalization of IA location at Day5 and the P-selectin signal from the MR scans at the Day3. Statistical analysis was performed using Mann–Whitney U test; **P < 0.01, ***P < 0.001; NS, not significant. Further detailed information on statistics is provided in the Methods & Materials