A 75-year-old woman in Seoul underwent a scan that revealed something her doctors had never been able to see so clearly before: the exact location of multiple blood clots snaking through the deep veins of her left leg, from thigh to calf, and scattered through her right calf as well. The technology behind that breakthrough—a novel PET radiotracer called 18F-GP1—can do something conventional imaging cannot: visualize blood clots directly and in their entirety, detecting clots in both legs and lungs in a single whole-body scan. It's a simple but profound shift from looking for structural signs of a clot to actually seeing the clot itself.
Deep vein thrombosis, the condition where blood clots form in leg veins and sometimes migrate to the lungs as potentially life-threatening pulmonary embolism, affects approximately 900,000 Americans each year. Yet diagnosing it remains fragmented and inefficient. Doctors typically rely on venous ultrasound and CT scans, tools that work indirectly—looking for vein compression or contrast fill defects rather than the clot itself. Some clots, especially in hard-to-reach areas, slip through these nets entirely. This matters urgently, because early detection is critical to prevent the clot from traveling to the lungs, where it can become fatal.
Researchers at Asan Medical Center in Seoul, led by Sangwon Han, MD, Ph.D., tested 18F-GP1 PET/CT on 46 symptomatic patients. Three independent nuclear medicine physicians, unaware of which patients they were reviewing, evaluated each scan. The results were striking: the radiotracer showed high diagnostic accuracy for detecting clots not only in the thigh but also in the calf—areas where conventional ultrasound often struggles. Critically, it also demonstrated a high detection rate for pulmonary embolism occurring alongside deep vein thrombosis. And the patients tolerated the procedure well, with no drug-related adverse events recorded.
What makes this advance so significant is what it means for patients: instead of undergoing separate tests—ultrasound here, CT there, maybe another scan if doctors suspect lung involvement—a person could walk into a clinic, receive a single scan, and get complete information about clots throughout their entire body. "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," Han noted. The convenience matters, but so does the speed and confidence. When every hour counts in preventing complications, a test that answers all the questions at once can be the difference between swift treatment and dangerous delays.
The work was presented at the Society of Nuclear Medicine and Molecular Imaging's 2026 Annual Meeting and has been named the 2026 SNMMI Henry N. Wagner, Jr., Image of the Year—a recognition chosen from nearly 1,500 submitted abstracts and reserved for innovations that demonstrate genuine capacity to improve patient care. Experts see potential well beyond leg clots. Giuseppe Esposito, MD, chair of the SNMMI Scientific Program Committee, envisions this as a platform technology that could detect clots throughout the body and help identify stroke and cardiovascular disease. Already, 18F-GP1 has been evaluated in Phase 2 studies for deep vein thrombosis, embolic stroke, and cardiovascular disease. With validation through larger Phase 3 trials, this radiotracer could enter routine clinical practice within the next five to ten years, transforming how we catch and treat clots before they become emergencies.