New PET radiotracer shows high accuracy for detecting clots in the legs and lungs

A novel PET radiotracer can accurately detect deep vein thrombosis in the legs and reveal whether clots have migrated to the lungs. By enabling whole‑body imaging of blood clots in a single scan, the approach may support faster and more efficient diagnosis -- particularly for patients who also require evaluation for potentially life‑threatening pulmonary embolism. This research was presented at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2026 Annual Meeting, and the collection of images showcasing the visualization of blood clots in the legs and in the lungs, has been selected as the 2026 SNMMI Henry N. Wagner, Jr., Image of the Year.

Each year, SNMMI chooses an image that best exemplifies the most promising advances in the field of nuclear medicine and molecular imaging. The state-of-the-art technologies captured in these images demonstrate the capacity to improve patient care by detecting disease, aiding diagnosis, improving clinical confidence, and providing a means of selecting appropriate treatments. This year, the SNMMI Image of the Year was chosen from nearly 1,500 abstracts submitted for the meeting.

Deep vein thrombosis is a common disease in which blood clots form in the legs, and in some cases, travel to the lungs as a pulmonary embolism. It affects approximately 900,000 Americans a year according to the Centers for Disease Control and Prevention. Early detection is critical to ensure prompt treatment.

Conventional imaging techniques, such as venous ultrasound and CT, rely on indirect structural changes -- like vein compressibility or contrast filling defects rather than directly visualizing the clot itself. ¹⁸F-GP1 PET/CT is a thrombus-specific imaging that selectively targets activated platelets, allowing blood clots to be visualized directly even in areas that may be difficult to assess with conventional imaging."

Sangwon Han, MD, PhD, clinical assistant professor, Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

In the study, researchers assessed the diagnostic accuracy and tolerability of a novel radiotracer, ¹⁸F-GP1 PET/CT, for identifying acute lower extremity deep vein thrombosis. Forty-six symptomatic patients underwent ¹⁸F-GP1 PET/CT imaging, with scans independently evaluated by three blinded nuclear medicine physicians. Diagnostic performance for identifying clots in the thighs was compared with venous ultrasound; accuracy for detecting calf clots and detection rate for lung clots was also evaluated. Radiotracer safety was assessed throughout the study.

¹⁸F-GP1 PET/CT showed high diagnostic accuracy for detecting clots not only in the thigh but also in the calf. It also demonstrated a high detection rate of pulmonary embolism occurring together with deep vein thrombosis. ¹⁸F-GP1 PET/CT was well tolerated, with no drug-related adverse events.

"These findings suggest that a single whole-body PET scan could accurately evaluate clots in both the legs and lungs at the same time, potentially reducing the need for multiple tests while improving patient convenience," said Han.

Giuseppe Esposito, MD, SNMMI Scientific Program Committee chair, see the potential for this radiotracer to transform the detection of acute thrombus beyond deep vein thrombosis. "This approach could serve as a platform technology for detecting clots throughout the body and even help to detect stroke or cardiovascular disease, he said. These images show just how powerful molecular imaging can be."

¹⁸F-GP1 PET/CT has already been evaluated in Phase 2 studies for deep vein thrombosis, as well as in conditions such as embolic stroke and cardiovascular disease. With further validation through larger, multicenter Phase 3 trials, this radiotracer could become part of routine clinical practice within the next five to 10 years.