3D binary mask from both sagittal frontal axial segments

Operating system: windows 10
Slicer version: 4.10.2
Expected behavior: obtain one 3D binary mask
Actual behavior: three 3D masks, each by segment
Imaging Modality: 3D US

What kind of ultrasound images do you work with: cardiovascular, ob/gyn, musculoskeletal? Are they acquired by 3D probe or position-tracked 2D probe? What is the brand/model of your ultrasound system? How did you import the images?

Thank you @lassoan
I got the answer.
These are 3D US kidney volumes. The probe used is a 3D.
According to the expert who did the scans, it’s almost impossible to get complete kidney segmentations on living beings.
3D slicer offers the possibility to transform the 3 very partial segmentations into a single binary volume which is also partial. And that’s all we can do, apparently.