NORCROSS,Novoste has called off a proposed $20 million merger with ONI Medical Systems after its shareholders failed to approve the deal.

Novoste (Nasdaq: NOVT) said Monday that shareholders “failed to approve” the issuance of shares needed for the deal.

Novoste said on May 18 it would issue $20 million in shares to acquire ONI, a developer of magnetic resonance imaging technology.

ONI is based in Wilmington, MA.

“The merger, which is subject to the completion of all conditions contained in the merger agreement, will result in a complete change in the nature of Novoste’s business and operations,” Novoste said in announcing the deal.

Novoste is focused on vascular brachytherapy which is radiation therapy delivered inside an artery to prevent it from re-closing (restenosis).