In the past 29 years, Alpha Imaging, of Willoughby, Ohio, has developed ongoing relationships with more than 500 accounts representing 1,100-plus health-care facilities throughout the Midwest, mid-Atlantic and Southeast U.S. regions. Centerfield Capital Partners sold its stake in the transaction. The firm led the recapitalization of AXS Imaging in 2008 and later provided additional subordinated debt and equity in support of its merger with Alpha Imaging, according to a Centerfield news release. (LBO Wire is a daily newsletter with comprehensive analysis of all the investments, deals, fundraisings and personnel moves involving private equity firms. For a two-week trial, visit http://on.wsj.com/DJPEVCNews,...