PET/CT imaging agent could improve acute venous thromboembolism diagnosis

Charlotte Edwards 18 February 2019 (Last Updated February 18th, 2019 17:50)

Researchers based at the University of Ulsan College of Medicine in the Republic of Korea have found that the positron emission tomography/computed tomography (PET/CT) tracer 18F-GP1 results in high image quality and a high detection rate for acute venous thromboembolism (VTE).

PET/CT imaging agent could improve acute venous thromboembolism diagnosis
18F-GP1 PET/CT and CT images of 55-y-old man with DVT and PE. Credit: Kim C, Lee JS, Han Y, et al.

Researchers based at the University of Ulsan College of Medicine in the Republic of Korea have found that the positron emission tomography/computed tomography (PET/CT) tracer 18F-GP1 results in high image quality and a high detection rate for acute venous thromboembolism (VTE).

The study has been published in the latest issue of The Journal of Nuclear Medicine and details how 18F-GP1 can also identify blood clots in distal veins of the leg below the knee, an area where conventional imaging is said to have limitations.

Acute VTE is a disease that includes deep-vein thrombosis of the leg or pelvis and its potentially fatal complication, pulmonary embolism. Signs and symptoms of VTE are highly variable and nonspecific, which often results in a delayed or inaccurate diagnosis.

Asan Medical Center professor Dr Dae Hyuk Moon said: “Conventional imaging with ultrasonography, CT venography or CT pulmonary angiography is typically unable to distinguish old thromboemboli from new and potentially unstable thromboemboli.

“The 18F-GP1 tracer used in this study offers the unique ability to detect, characterise and track newly formed thrombi that have a high risk for embolisation and further complication.”

The researchers conducted a prospective study to acquire clinical proof-of-concept for thrombus PET imaging with 18F-GP1. They assessed the safety and diagnostic performance of 18F-GP1 PET/CT in 20 patient participants who had acute deep-vein thrombosis or pulmonary embolism. Each patient already had signs or symptoms of VTE and had one or more VTE foci confirmed by standard imaging.

When reviewing the images taken during the study, the researchers found that they could easily distinguish 18F-GP1 uptake in thromboemboli from the blood pool. A positive correlation was also observed between 18F-GP1 uptake and P-selectin expression on circulating platelets, which shows the presence of activated platelets and acute VTE.

The imaging tracer showed an increased uptake in the distal veins of the leg in 12 patients that had not been detected with conventional imaging. Thromboembolic foci was also detected by 18F-GP1 PET/CT in all 20 of the participants.

Moon added: “Incorrect diagnosis of VTE commits the patient to unnecessary anticoagulation and results in higher risk and costs, whereas incorrectly concluding that VTE is absent places the patient at high risk of potentially fatal pulmonary embolism.

“Although the current studies are preliminary, 18F-GP1 PET/CT may provide not only more accurate anatomic localisation, but also information on the risk of the clot growth or embolisation. This may lead to changes in clinical intervention to the individual patient.”