Fujifilm Holdings Corp. said Thursday it plans to acquire all outstanding shares in SonoSite Inc., a leading U.S. maker of hand-carried ultrasound diagnostic devices, through a friendly tender offer to reinforce its medical equipment business.

Fujifilm will spend up to $995 million to buy SonoSite shares for $54 each, a 28 percent premium to SonoSite's shares closing market price of $42.24 on Wednesday. Fujifilm will conduct the tender offer over 21 business days, starting within 20 business days from Friday in the United States, according to the leading maker of photographic products and graphics-related systems.

SonoSite, based in Bothell, Washington, booked an operating profit of $27 million on sales of $275 million in financial 2010. With a workforce of 878 as of last Dec. 31, the company operates in the U.S., Japan and seven other countries, including Australia, Britain and France.

The global market for ultrasound diagnostic devices, used to visualize internal organs, is worth nearly ¥500 billion in annual sales, with sales of hand-carried machines growing at a yearly rate of more than 10 percent, Fujifilm said.