"Siemens Healthineers will acquire all fully diluted shares of Corindus for $4.28 per share in cash or $1.1 billion in total," the Munich-based group said in a statement.

Massachusets-based Corindus builds robots to assist surgeons with operations on veins and arteries.

It says its machines help doctors place implants like stents more accurately and without exposure to radiation from the scanners used in the operating theatre.

Healthineers, which Siemens partially floated on Germany's MDax medium-sized businesses index last year, has until now mainly focused on building scanners.

""With this acquisition, we are opening up a new field for our image-guided therapies business," chief executive Bernd Montag said.

The company added that it hopes to seal the deal by the end of 2019.

Shares in Siemens Healthineers fell back slightly early Thursday, shedding almost one percent to trade at 36.09 euros by 09:25 am in Frankfurt (0725 GMT) while Siemens gained 0.4 percent to 89.69 euros, in line with the DAX blue-chip index.