Fig. 6.
Scatterplot of the mean normalized voxel intensity within each of the five ventilation level classifications in all 39 subjects (entire population) at each point in time (every 0.5 s). Plotted lines show the linear regression fit within each of the ventilation levels over time. The slopes of the fitted lines (2.35 × 10−7, 1.60 × 10−7, 6.22 × 10−8, −9.99 × 10−8, and −3.59 × 10−7 for ventilation levels 1, 2, 3, 4, and 5, respectively) are each significantly different from all others (P < 0.01).