Figure 1.

Schematic of histogram-based approach methods. (A) Statistical histogram-based segmentation consists of measuring the percentiles in increments of 10% plus 25th, 75th, and 95th percentiles. (B) Physiological histogram-based segmentation consists of measuring the tumor volume fraction with low rCBV (2 SD less than the mean of white matter), medium rCBV, or high rCBV (approximately 2 SD greater than the mean in gray matter) values. (C) Serial rCBV maps undergo digital image post-processing and analysis that involves registration of images before and during treatment. Once spatially aligned, individual voxels within the tumor are presented using a three-color overlay and are classified as unchanged (green), increased (red), or decreased (blue) rCBV following treatment initiation. These data can also be presented in a scatterplot and quantified over the entire tumor volume by summing all voxels within a classification and normalizing by the total tumor volume to generate relative volumes for each class.