TUCSON, AZ, April 12, 2005 – ImaRx Therapeutics, Inc. announced today that the first patient has been treated in a Phase I/II clinical trial evaluating the safety and efficacy of SonoLysis™ for the treatment of peripheral arterial occlusive disease (PAOD). SonoLysis, which combines external ultrasound and ImaRx’s proprietary nanobubbles, is designed to clear blood clots quickly and without the use of invasive surgery or potentially dangerous lytic drugs.

In this 12 patient, multicenter trial, six patients will receive a sixty-minute treatment of SonoLysis (nanobubbles and ultrasound), while the remaining six will receive SonoLysis in conjunction with a small bolus of t-PA, a lytic agent that is typically administered to dissolve the blood clots that cause PAOD.

“Patients receiving the currently approved t-PA therapy for peripheral arterial occlusions are routinely exposed to an infusion of t-PA or other lytic drugs for up to 24 hours. This long infusion time places the patient at risk for bleeding and other complications,” said Dr. Kenneth Ouriel, Chairman of the Department of Vascular Surgery at the Cleveland Clinic and National Study Director for the ImaRx trial. “SonoLysis represents a potentially important advance in treating vascular diseases such as PAOD as it may increase safety and reduce treatment times by limiting the use of a lytic drug.”

“We believe this expansion of our SonoLysis clinical program demonstrates our commitment to building a cardiovascular franchise across multiple indications,” said Evan Unger, M.D., President and CEO of ImaRx. “In addition to our PAOD study, SonoLysis trials are ongoing in acute ischemic stroke and deep vein thrombosis.”

About Peripheral Arterial Occlusive Disease

Peripheral arterial occlusive disease (PAOD) is caused by the formation of blood clots that narrow the arteries outside of the heart and brain. PAOD can lead to insufficient oxygenation of leg muscles resulting in pain, tissue damage and even gangrene. According to the American Heart Association, 8-12 million Americans are directly affected by peripheral arterial disease, a common form of PAOD. Almost 20% of Americans over the age of 70 have peripheral arterial disease, a disease that becomes more common with age.

About ImaRx and NanoInvasive Medicine

ImaRx, a privately-held biopharmaceutical company, develops NanoInvasive™ therapies for the treatment of cardiovascular and CNS diseases and cancers. The Company’s lead product, SonoLysis™, combines the power of ultrasound with proprietary nanobubbles to locally dissolve blood clots without the use of invasive surgery or potentially dangerous lytic drugs. SonoLysis is currently in a Phase II study for stroke, a Phase I/II study for deep vein thrombosis and a Phase I/II study for peripheral arterial occlusive disease. For more information, please visit www.imarx.com.

Courtney Plotnick Associate Director, Business Development

ImaRx Therapeutics, Inc.

1635 East 18th Street

Tucson, AZ 85749

520.770.1259 ext 193

cplotnick@imarx.com

www.imarx.com