Novel PET/CT tracer safe, effective for diagnosing acute venous thromboembolism

A novel PET/CT imaging agent—18F-GP1—produced a high quality image and yielded a high detection rate for diagnosing acute venous thromboembolism (VTE), reported researchers of a study featured in the February issue of The Journal of Nuclear Medicine.

In the proof-of-concept study the novel agent was tested in 20 patients with acute deep-vein thrombosis or pulmonary embolism. Overall, the PET agent was well-tolerated and identified blood clots in distal veins of the leg below the knee—an area where traditional imaging falls short.

“Conventional imaging with ultrasonography, CT venography or CT pulmonary angiography is typically unable to distinguish old thromboemboli from new and potentially unstable thromboemboli,” said Dae Hyuk Moon, MD, of Asan Medical Center at the University of Ulsan College of Medicine in the Republic of Korea, in a prepared statement. “The 18F-GP1 tracer used in this study offers the unique ability to detect, characterize and track newly formed thrombi that have a high risk for embolization and further complication.”

Complications from acute VTE include pulmonary embolism, which can be fatal. The variable and nonspecific symptoms of VTE often result in delayed or inaccurate diagnosis, making early and accurate identification of the disease a top priority and central for initiating effective therapeutic treatment.

After review, the team found 18F-GP1 uptake in thromboemboli easily distinguishable from the blood pool. The radiotracer showed increased uptake in 32 vessels that weren’t detected by conventional imaging. Of those, 25 were located in distal veins of the lower extremity in 12 patients.

Additionally, a positive correlation between 18F-GP1 uptake and P-selectin expression on circulating platelets was revealed, demonstrating the presence of activated platelets and acute VTE, according to the authors.

“A positive correlation between 18F-GP1 uptake and P-selectin–positive platelets suggests that 18F-GP1 PET/CT may be helpful in differentiating acute VTE from chronic VTE,” Moon and colleagues concluded. “Taken together, the findings of this study indicate that 18F-GP1 PET/CT may provide an opportunity to overcome the limitations of current diagnostic strategies for acute VTE.”