The iCoCooN: Integration of Cobweb Charts with Parallel Coordinates for Visual Analysis of DCE-MRI Modeling Variations

Efficacy of radiotherapy treatment depends on the specific characteristics of tumorous tissues. For the determination of these characteristics, clinical practice uses Dynamic Contrast Enhanced (DCE) Magnetic Resonance Imaging (MRI). DCE-MRI data is acquired and modeled using pharmacokinetic modeling, to derive per voxel a set of parameters, indicative of tissue properties. Different pharmacokinetic modeling approaches make different assumptions, resulting in parameters with different distributions. A priori, it is not known whether there are significant differences between modeling assumptions and which assumption is best to apply. Therefore, clinical researchers need to know at least how different choices in modeling affect the resulting pharmacokinetic parameters and also where parameter variations appear. In this paper, we introduce iCoCooN: a visualization application for the exploration and analysis of model-induced variations in pharmacokinetic parameters. We designed a visual representation, the Cocoon, by integrating perpendicularly Parallel Coordinate Plots (PCPs) with Cobweb Charts (CCs). PCPs display the variations in each parameter between modeling choices, while CCs present the relations in a whole parameter set for each modeling choice. The Cocoon is equipped with interactive features to support the exploration of all data aspects in a single combined view. Additionally, interactive brushing allows to link the observations from the Cocoon to the anatomy. We conducted evaluations with experts and also general users. The clinical experts judged that the Cocoon in combination with its features facilitates the exploration of all significant information and, especially, enables them to find anatomical correspondences. The results of the evaluation with general users indicate that the Cocoon produces more accurate results compared to independent multiples.