Dependence of tissue characterization features on region of interest (ROI) size: studies on phantoms and simulations

In our previous work on prostate tissue, we noted an apparent dependence of the computed tissue characterization features and the size of the ROI chosen. We are studying this effect in a systematic fashion by computing feature values for ROI of different size in both phantoms and simulations. As expected, most features exhibited larger variance when small ROI were used. Most features exhibited a dependence on ROI size although some features were strongly dependent on ROI size only for small ROI sizes. The nature of the ROI size dependence varied widely for different features.