We present an effective and intuitive visualization of the macro-vasculature of a selected nodule or tumor in three-dimensional
image data (e.g. CT, MR, US). For the differential diagnosis of nodules the possible distortion of adjacent
vessels is one important clinical criterion.
Surface renderings of vessel- and tumor-segmentations depend critically on the chosen parameter- and threshold-values
for the underlying segmentation. Therefore we use rotating Maximum Intensity Projections (MIPs) of a volume of
interests (VOI) around the selected tumor. The MIP does not require specific parameters, and allows much quicker
visual inspection in comparison to slicewise navigation, while the rotation gives depth cues to the viewer. Of the vessel
network within the VOI, however, not all vessels are connected to the selected tumor, and it is tedious to sort out which
adjacent vessels are in fact connected and which are overlaid only by projection. Therefore we suggest a simple
transformation of the original image values into connectivity values. In the derived connectedness-image each voxel
value corresponds to the lowest image value encountered on the highest possible pathway from the tumor to the voxel.
The advantage of the visualization is that no implicit binary decision is made whether a certain vessel is connected to
the tumor or not, but rather the degree of connectedness is visualized as the brightness of the vessel. Non-connected
structures disappear, feebly connected structures appear faint, and strongly connected structures remain in their original
brightness. The visualization does not depend on delicate threshold values. Promising results have been achieved for
pulmonary nodules in CT.