Is there anything similar in Slicer to Smart Brush found in BrainLab elements contouring?
Yes. The corresponding tool in 3D Slicer is Grow from seeds:
It is as fast as the Smart Brush and much more powerful, as it allows segmentation of any number of structures at once, allows specifying intensity range, can even restrict growing to remain inside an arbitrary region, allows editing in 3D, etc.
Thank you. Thats great. Will try it out.