A virtual anatomical structure can be analyzed to determine enclosing
three-dimensional boundaries of features therein. Various techniques can
be used to determine tissue types in the virtual anatomical structure.
For example, tissue types can be determined via an iso-boundary between
lumen and air in the virtual anatomical structure and a fuzzy clustering
approach. Based on the tissue type determination, a deformable model
approach can be used to determine an enclosing three-dimensional boundary
of a feature in the virtual anatomical structure. The enclosing
three-dimensional boundary can be used to determine characteristics of
the feature and classify it as of interest or not of interest.