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Segmentation of 3D Tubular Tree Structures in Medical Images ...

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3.4. Experiments 61<br />

junction with the stenotic area (Fig. 3.8). Krissian’s multi-scale TDF was <strong>in</strong>fluenced<br />

by the calcification and thus the result<strong>in</strong>g centerl<strong>in</strong>e moved far away from the desired<br />

position. The GVF-based TDFs on the other hand are not sensitive to such k<strong>in</strong>ds <strong>of</strong><br />

disturbances. In proximity <strong>of</strong> the stenosis where the TDF filter was not able to identify<br />

a tubular structure, the GVF-based group<strong>in</strong>g/l<strong>in</strong>kage was able to extract a medial curve<br />

that stayed centered with a quality comparable to that <strong>of</strong> the skeletonization approaches.<br />

The simpler structure-based group<strong>in</strong>g/l<strong>in</strong>kage methods on the other hand closed the gap<br />

between the tubular structures along a straight l<strong>in</strong>e, show<strong>in</strong>g a large deviation from a<br />

high quality skeleton. The skeletonization approaches <strong>of</strong> Bouix and Palagyi showed some<br />

sensitivity to surface noise <strong>in</strong> the gold standard segmentation and produced additional<br />

centerl<strong>in</strong>es. The authors themselves mention this behavior and these spurious branches<br />

can be removed by appropriate prun<strong>in</strong>g strategies.<br />

(a) GVF-based group<strong>in</strong>g<br />

and l<strong>in</strong>kage (Section 3.3).<br />

(b) Structure based<br />

group<strong>in</strong>g and l<strong>in</strong>kage<br />

(Section 3.2).<br />

(c) Mutliscale tube detection<br />

and simple l<strong>in</strong>kage.<br />

(d) Hassouna’s skeletonization<br />

approach.<br />

(e) Bouix’s skeletonization<br />

approach.<br />

(f) Palagyi’s skeletonization<br />

approach.<br />

Figure 3.8: Enlarged subw<strong>in</strong>dow show<strong>in</strong>g curve skeletons <strong>of</strong> an aorta conta<strong>in</strong><strong>in</strong>g a severe<br />

stenosis due to calcification. Green: Result <strong>of</strong> GVF-based group<strong>in</strong>g and l<strong>in</strong>kage (Section<br />

3.3). Red: Other approaches.

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