(Reuters) - Philips (PHG.AS) will acquire Volcano Corp (VOLC.O), a U.S.-based medical device maker, for $1.2 billion including debt, to expand in the image-guided therapy market.

Philips will offer $18 per share for Volcano, the companies said in a statement on Wednesday.

The offer is at a premium of about 57 percent to Volcano's closing price on the Nasdaq on Tuesday.

The deal is expected to add to Philips' earnings per share by 2017, according to the statement.

Volcano makes imaging catheters used in the diagnoses of coronary and peripheral artery disease.

(Reporting by Supriya Kurane in Bengaluru; Editing by Gopakumar Warrier)