Impact of Global Mean Normalization on Regional Glucose Metabolism in the Human Brain

Figure 3

Spatial distributions of metabolic variations in patients with disorders of consciousness (i.e., UWS, MCS, and EMCS in Figure 2(c)) versus the control group (i.e., HAEC in Figure 2(a)), shown with respect to unthresholded Student’s -maps using (a) qCMR_glc images and (b) GMN images. (a) For the UWS, MCS, and EMCS groups, the unthresholded -maps with qCMR_glc indicated globally unidirectional metabolic decreases in patients with disorders of consciousness. (b) But the unthresholded -maps with GMN demonstrated the presence of regionally bidirectional metabolic changes in disorders of consciousness. Based on validation of qCMR_glc to aCMR_glc-HYD (Figures 1 and 2; Table 2), without GMN the global decreases corresponded to about 0.15 μmol/g/min (UWS < MCS ≈ EMCS) and with GMN the global changes were diminished to put overemphasis on the regional differences. See Figure S3 for thresholded maps (Table 4).