How common are calcified fat lumps after fat grafting to breasts and how can they be avoided?

I am getting fat grafted to my breasts next month and my only concern is about fat cells dying, calcifying and leaving lumps. Are there techniques that MD's can use to avoid this from happening and/or things I can do before or after surgery to help? My surgeon says he plans to inject 400cc's to each breast that will be taken from my abdomen and flanks. He says he injects it with an 18g needle in thousands of rows of fat throughout rather than large clusters and expects 150-200 to be permanent.