Semiautomatic Cochleostomy Target and Insertion Trajectory Planning for Minimally Invasive Cochlear Implantation

Figure 2

Illustration of the automatic cochleostomy target/insertion trajectory computation algorithm. (a) Based on the landmarks (black circles), a local cochlear coordinate system is computed. As an assumption, the 𝑥- 𝑦 plane is defined as the location of the basilar membrane. The surface model of the cochlea is truncated to the first half turn of the ST. (b) Radial cross sections are computed starting at the RW (0° reference). The center of gravity is estimated (red circles) based on the extracted vertices (black dots) for each cross section. (c) The centroid line (red line) is fitted with the data points, representing the mid-scala course of ST. For a specified range, the tangents of the centroid line are computed, defining the optimal insertion trajectories (blue lines) and the corresponding cochleostomy targets (diamonds) at the angular position 𝜃_𝐶.