Fig. 3

Illustration of the HET quantitation on two NSCLC studies, with high (top) and low (bottom) heterogeneity. The corresponding scatterplots (right) illustrate the representation of the volumetric tracer uptake (black dots) as a function of radial position within the ideal ellipsoid pattern, from core (left hand side of the x-axis) to the volume boundary (right hand side of the x-axis). The HET variable quantifies the lack of goodness-of-fit of the data-adaptive regression model (red) derived from this representation, thus assessing how well the idealized ellipsoidal pattern describes the observed uptake data