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Symptoms of DVT may include pain, sudden swelling in the calf or thigh, tenderness, discoloration or redness, and skin that is warm to the touch. Surprisingly, these symptoms are often mistaken for other diseases and as many as half of all DVT episodes produce minimal symptoms or are completely “silent” and remain undiagnosed until they lead to a life threatening pulmonary embolism.

Ultrasound is the most common diagnostic tool for DVT but is not considered particularly accurate below the knee, where many clots begin to form, and it only has approximately 60% sensitivity for asymptomatic DVT. Venography is a painful and much less commonly used procedure where a contrast agent is injected into a vein on top of the foot and X-rays are used to track the solution through the vein of the leg. However, the same type of nuclear medicine procedure that is used today for liver, lung, bone and brain scans may one day help physicians rapidly detect the active clotting process in DVT.

A new diagnostic imaging agent, called Fibrimage®, under development by Canadian-based Draxis Health, aims to make DVT detection quicker and more reliable. Researchers at Draxis Health are investigating whether Fibrimage® can accurately check for newly-forming thrombus (blood clots) in the large, deep veins in the lower limbs. These dangerous clots can be caused by a variety of risk factors and triggered by either increasing age, obesity, cancer or decreased blood flow resulting from restricted mobility following major surgery such as joint replacements.

This innovative diagnostic approach starts with an injection of Fibrimage® in the arm. The active agent in Fibrimage® binds to human fibrin, part of an actively forming blood clot, and within two hours the clot can be seen on a gamma camera. The procedure is expected to allow physicians to distinguish, with a high degree of sensitivity, a new active thrombus from any older and less threatening stabilized clots.

“Most doctors rely on conventional ultrasound scans to make a diagnosis, but ultrasound cannot distinguish whether the clot is an active clot needing urgent attention or a chronic inactive clot,” said Dr. Martin Barkin, CEO of Draxis Health, “Our goal is to develop Fibrimage®, to the point that it can be a reliable diagnostic agent for the early detection of deep venous thrombosis, and recurrent deep venous thrombosis so that life-saving therapy can be targeted at the affected patient in a timely way and long term complications can be minimized.”

A late stage clinical trial of Fibrimage® as a diagnostic agent for deep venous thrombosis is nearing completion in Canada and discussions are on-going with the FDA to conduct an additional late stage trial in the United States.

For more information, log onto www.draximage.com