A method of segmenting a structure in a volume represented by a 3D digital representation comprising the following steps: - 1. applying a region growing algorithm to said volume starting from a user-defined seed point to generate a mask Mask_final, - 2. evaluating said mask Mask_final by the user to identify (a) region(s) having un-connected structures, - 3. if a region with un-connected structures is found, identifying a new seed point in said region by user-interaction, - 4. applying a region growing algorithm to said new seed point resulting in a new mask Mask_S, - 5. - If said new mask Mask_S intersects with said mask Mask_final, creating a mask as the union of said new and said mask Mask_final, - else, applying a locally adaptive region growing iteration comprising iteratively performing a region growing algorithm to an automatically defined next seed point to generate a new mask Mask_new until said new mask Mask_new intersects said mask Mask_final, characterized in that said locally adaptive region growing iteration comprises - determining a grey value distance between said next seed point and a low threshold value used to generate said mask Mask_S and a grey value distance between said next seed point and a high threshold value used to generate said mask Mask_S, - determining the difference between the two calculated grey value distances, - if said difference is lower than a preset threshold, enlarging the range between said low and said high threshold so as to encompass said next seed point by replacing said low threshold value by minimum of said low threshold value and the grey value of said next seed point and by replacing said high threshold value by the maximum of said high threshold and the gray value of said next seed point, - otherwise replacing said seed point by a new seed point, - applying said region growing algorithm to said volume starting from said new seed point to generate said mask Mask_new. - 1. applying a region growing algorithm to said volume starting from a user-defined seed point to generate a mask Mask_final, - 2. evaluating said mask Mask_final by the user to identify (a) region(s) having un-connected structures, - 3. if a region with un-connected structures is found, identifying a new seed point in said region by user-interaction, - 4. applying a region growing algorithm to said new seed point resulting in a new mask Mask_S, - 5. - If said new mask Mask_S intersects with said mask Mask_final, creating a mask as the union of said new and said mask Mask_final, - else, applying a locally adaptive region growing iteration comprising iteratively performing a region growing algorithm to an automatically defined next seed point to generate a new mask Mask_new until said new mask Mask_new intersects said mask Mask_final, characterized in that said locally adaptive region growing iteration comprises - If said new mask Mask_S intersects with said mask Mask_final, creating a mask as the union of said new and said mask Mask_final, - else, applying a locally adaptive region growing iteration comprising iteratively performing a region growing algorithm to an automatically defined next seed point to generate a new mask Mask_new until said new mask Mask_new intersects said mask Mask_final, characterized in that said locally adaptive region growing iteration comprises - determining a grey value distance between said next seed point and a low threshold value used to generate said mask Mask_S and a grey value distance between said next seed point and a high threshold value used to generate said mask Mask_S, - determining the difference between the two calculated grey value distances, - if said difference is lower than a preset threshold, enlarging the range between said low and said high threshold so as to encompass said next seed point by replacing said low threshold value by minimum of said low threshold value and the grey value of said next seed point and by replacing said high threshold value by the maximum of said high threshold and the gray value of said next seed point, - otherwise replacing said seed point by a new seed point, - applying said region growing algorithm to said volume starting from said new seed point to generate said mask Mask_new.