Thu, 08/20/2015 - 2:30pm
Greg Watry, Digital Reporter
The whole body of a rat can be imaged for blood clots with one PET scan (which is overlaid here on an MRI image) using the FBP8 probe. Arrow points to a blood clot. Image: Peter Caravan, PhDEach year, 795,000 Americans experience a stroke, according to the Centers for Disease Control and Prevention (CDC). Nearly 185,000 of those people have had a previous stroke. It’s estimated strokes cost the U.S. $34 billion in health care services, medications and missed days of work.
According to Peter Caravan, of Massachusetts General Hospital, strokes are caused when a blood clot somewhere in the body breaks off and travels to the brain.
“Blood clots are associated with the leading causes of death and morbidity,” he said at the 250th National Meeting & Exposition of the American Chemical Society. Heart attack, stroke, pulmonary embolism and deep vein thrombosis all occur because of blood clots in the coronary arteries, brain, lungs or legs. “There’s an urgent need to find these clots when they occur,” he said.
Physicians employ multiple methods to detect blood clots, including ultrasounds on carotid arteries or legs, magnetic resonance imaging to scan the heart and computed tomography for the lungs. But Caravan and his team have developed a new method to detect blood clots with a single scan.
“In my lab, we’ve invented a new molecular probe that, upon injection into a vein, will go travel through the body and find blood clots wherever they’re occurring,” Caravan said.
Called positron emission tomography, the method utilizes a fibrin binding probe, containing copper-64, to search the body for the clot. Caravan called it a “convenient” but “expensive” test, simply involving a puncture of a vein to deliver the probe. “It can replace multiple tests and that’s where we believe there is real value,” said Caravan.
“The cost of the test is appropriate to the clinical decision that is occurring,” he said.
With a half-life of 12.7 hrs, copper-64 clears through the kidneys and whatever remains decays in the body, according to Caravan. A human dosage would be 100 micrograms.
After identifying a clot, different strategies can be employed for clearance, including a thrombectomy, breakdown via a tissue plasminogen activator or prescribing and antithrombotic.
Currently, “we’re compiling the regulatory documents that will allow us to use this probe in (human) patients,” said Caravan. Clinical trials are slated to begin by the end of 2015 or early 2016.
Tested on rodents, the new method yielded results of 97% accuracy.