Vital Images Inc. (Nasdaq: VTAL) shares rallied 31.5% to $18.65 in morning trading Thursday, after Toshiba Medical Systems Co. said late Wednesday that it would acquire the provider of image-visualization software to the medical industry for $273 million. Volume for the stock was 3.7 million shares, overwhelming a daily average of 52,000.

Under the terms of the agreement, which has been unanimously approved by each of Vital Images’ and TMSC’s boards of directors, Vital Images’ shareholders will receive $18.75 in cash for each outstanding share of Vital Images common stock they own. This represents a 39% premium over the volume-weighted average Vital Images share price for the past 30 days.

Toshiba Medical Systems Co. CEO Satoshi Tsunakawa commented, “After a decade-long successful partnership spanning more than 50 countries, TMSC is taking the partnership to the next level. We have enormous respect for Vital Images’ products, pipeline and people, and look forward to working with their highly skilled team to enhance clinical value for patients throughout the world.”

Chief Executive Officer of Vital Images, Michael Carrel also commented on the developments, “TMSC has been our largest customer for a decade, as well as a strategic development partner. We will combine forces to enhance the multi-modality platform we have been marketing to hospitals in the U.S. and overseas. This transaction means we can now accelerate our global presence with the strength and backing of TMSC.”

Minneapolis-based Vital Images, Inc. is a leading provider of advanced visualization and analysis software for physicians and healthcare specialists.