Virtual Radiologic (vRad), the country's biggest teleradiology group, said Tuesday it bought Diagnostic Imaging Inc., a 35-year-old private radiology practice operating out of Philadelphia.

vRad said the practice will keep its name and retain its physician leadership, but will be rolled into its vRad Radiology Alliance, a nationwide network of 400 radiologists.

Founded in 1975, Diagnostic Imaging is a 60-radiologist practice, the largest in Philadelphia. It serves 16 hospitals and imaging centers in the Philadelphia metropolitan area and in New Jersey. Dr. Bruce Lehrman serves as president, and Dr. Eli Dweck as medical director.

"We are looking forward to having the DII physicians join our national practice network," Rob Kill, vRad's president and CEO, said in a statement. "We value their on-site presence, and are excited to invest in this Alliance partnership."

The Eden Prairie Minn.-based company has grown immensely over the past year or so. In December, it merged with its rival teleradiology provider, NightHawk Radiology. In March, a 15-radiologist practice in central Illinois, Lakeland Radiology Alliance, joined the group. And New York Radiology Alliance, a 60-radiologist practice which serves 12 hospital and 30 imaging centers in the New York City area, joined in August 2010.

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