Fig. 2

Representation of the steps executed by the extended part of the algorithm. a Two cortical interruptions ≥0.41 mm are visualized on a 2D grayscale image as output of the first part of the algorithm. A region of interest (ROI) is obtained by dilating the detected cortical interruptions with 48 voxels (=3.936 mm) and masked with the outer contour (b). Within this ROI, a distance transformation is performed. Only voids that are ≥0.738 mm in diameter are selected (c). These volumes are eroded by 2 voxels to lose connections of ≤0.328 mm and therefore prevent leaking into the trabecular structure (d). The voids that remain connected to a cortical interruption are included (e), dilated to its original size and the originally detected cortical interruptions are added (f)