Evaluation of different subvolume visualizations in CT-Fluoroscopy guided RF Liver Ablation

In this paper we present four visualization modes based on piecewise and global registration. These visualization modes are evaluated by two interventional radiologists. We are using three routinely acquired datasets from three patients who underwent RF Liver Ablation procedure. Piecewise 2D-3D registration is applied to define a subvolume in the preinterventional dataset that compensates for tissue deformation. The liver in the CT-Fluoroscopy (CT-Fluoro) slice is respectively divided into four and six rectangles. Every single rectangle is independently registered and the intersection of the resulting planes, define a subvolume. This subvolume is minimally traversed in an animation sequence. The visualizations are evaluated qualitatively with regard to the information displayed. Two alternative visualization approaches are also evaluated. The first alternative approach is to display axial slices around the global registered slice, since the interventional radiologists are used to evaluate axial slices. The second alternative approach is to define two envelope planes of the previously defined subvolume and display this envelope volume. The evaluation results show that the visualization of the minimum volume comprised in the registered four and six planes is preferred over the axial visualization or the envelope planes since it shows the lesion from different angles and follows the breathing movement. The interventional radiologists also appreciated the facilitated assessment of the neighborhood of the lesion.