Figure 2.

Echo planar imaging (EPI) ${\mathrm{T}}_2^{\ast }$ signal time course during ischemia (A), and following reperfusion (B), mean ${\mathrm{T}}_2^{\ast }$ percentage signal change from baseline for regions of interest (ROIs) during ischemia (C) and following reperfusion (D). (A, B) Positive ${\mathrm{T}}_2^{\ast }$ signal changes were recorded during oxygen challenge (OC) in contralateral caudate nucleus and cortex, the DWI/PWI mismatch, and the ${\mathrm{T}}_2^{\ast }$ OC-defined penumbra. All data were normalized to the average signal over the 4 minutes before OC from eight animals. The blue box represents the period of 100% oxygen inhalation (OC). (C, D) Horizontal lines represent means. **P < 0.01, relative to contralateral cortex ROI. ^#P < 0.05, relative to contralateral caudate nucleus.