Accurate volumetric measurements of anatomical cavities

Objectives: The volumetric assessment of anatomical cavities is of high relevance for various applications in medicine. Based on 3D scanning (i.e., CT) of theses cavities, the volume can be determined by counting the volume elements of a segmentation of that cavity. Unfortunately, elements on the boundary of the segmentation require special treatment to obtain accurate volumetric measurements. In this paper, we propose a novel technique that in particular increases the accuracy of the volume estimation for the boundary elements of segmented anatomical objects. Methods: Based on a 3D segmentation of an anatomical cavity, we recursively subdivide boundary volume elements into a set of simple situations, where the volume can be estimated easily. Results: We performed volumetric measurements on seven datasets of phantom models made of plexiglass (see Fig. 1) scanned by a biplane angiography unit and assessed the quality of our method by comparing the measured volume by our novel method and by the fluid required to fill the phantom cavities. Conclusions: Our method calculates a significantly more accurate volume of the segmented cavities than previous methods. Nevertheless, it is only slightly more computationally expensive.