Heart auto segmentation in CT images

Hi 3D slicer experts:
I want to segment the heart in CT images automatically , but I don’t know any thing about it. could you guide me about this?
thanks

See detailed, step-by-step video tutorial here:

Other tutorials can be found here: https://www.slicer.org/wiki/Documentation/Nightly/Training#Slicer4_Image_Segmentation