If the capsule is normal (thin) it is likely that all the forms of radiographic imaging you mentioned will not detect a specific capsule (as opposed to "post surgical changes"). On the other hand, if the capsule is thickened and/or calcified, a distinct layer may be identifiable on the imaging scans you noted mentioned. I hope this helps.
Leaving a capsule behind is preferred if it is thin and pliable. If there are calcific components, or silicone granulomatous material, or if the capsule is deforming the breast tissue, then removal of the capsule may be warranted. If the capsule is left behind, the body will break down and remodel the scar tissue on its own.Kenneth Hughes, MD, ABPS Board Certified Plastic SurgeonLos Angeles, CA