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Fig. 3 | Critical Care

Fig. 3

From: Brain BOLD MRI O2 and CO2 stress testing: implications for perioperative neurocognitive disorder following surgery

Fig. 3

a–c BOLD response to the O2 ramp with the ETCO2 tension clamped at ~ 43 mmHg. The expected response to the ramp stimulus is depicted by orange voxels. A diffuse response is seen. The scale is t scores based on fit to the GLM from SPM first-level analysis. The blue voxels depict the inverse response. The t score had to exceed 3.11 (p = 0.001) to be colorized. b The response of one voxel to the O2 ramp. The incremental and rapid increase with the step change in O2 (gray scale) is seen by the red dots representing the BOLD scan signal intensity at that moment in time. c The inverse response of one voxel to the O2 ramp. The incremental and rapid decrease with the step change in O2 (gray scale) is seen by the red dots representing the BOLD scan signal intensity at that moment in time. These data are from subject 3

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