Insurers are increasingly rejecting imaging procedures recommended by U.S. doctors as the companies work to trim $30 billion a year they say is wasted on the tests. With U.S. health costs projected to grow to 25% of the economy in 2025 from 16% now, insurers are turning to so-called radiology benefit managers who can reject scans determined to be unneeded, said representatives from a Washington-based consultant to hospitals. In addition to requiring advance approval, screeners are negotiating discounted fees for scans, requiring imaging facilities to win accreditation, and guiding consumers to cheaper test centers.