This pilot study aims at validating 18F-flourodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in the detection and characterization of venous thromboembolism (VTE) in the entire human body, especially deep venous thrombosis (DVT) and pulmonary embolism (PE). On completion of this study the investigators will hopefully be able to demonstrate the importance of functional/molecular imaging technique in managing patients with this common and potentially fatal disorder.

Acute DVT and PE are common and serious conditions. Highly effective treatment (most often anticoagulant agents) is available for acute VTE, but it is associated with potentially dangerous side effects. In addition, DVT and PE are just two manifestations of VTE, which can occur everywhere in the human organism. An underlying disease (i.e. cancer) is often a key factor in developing VTE.

Commonly used diagnostic imaging techniques in DVT and PE have a fair diagnostic accuracy, but do not address other important aspects of the disease. In contrast to this, FDG-PET/CT has the potential to contribute in VTE diagnosis by

• Differentiate between acute and chronic VTE
• Screening of the entire body for VTE (e.g. the pelvis where normal imaging techniques fail)
• Early diagnosis of underlying disease (e.g. cancer, with the possibility of early treatment)

This is a pilot study with the above mentioned objectives, and is part of a larger study addressing other aspects of FDG-PET/CT in VTE.

The investigators believe that their hypothesis that FDG-PET/CT imaging may introduce a new approach for detecting thrombi anywhere in the body, particularly in the venous system including the pelvis and the calves, will add a new dimension in treating patients with suspected PE. This technology will only detect acute thrombi and not chronic thrombi that no longer have activity, which will obviate unnecessary treatment in this population.

Inclusion Criteria:

• Positive or negative diagnosis of VTE (DVT/PE)
• Age ≥ 50 years
• Informed consent obtained
• Symptoms < 1 week

Exclusion Criteria:

• Pregnant or lactating women
• Foreign language patients with a need for an interpreter
• Previous DVT or PE
• Known malignancy

The study population comprises the following patient groups: 10 patients with a positive diagnosis of DVT, 10 patients where clinically suspected DVT was ruled out, 10 patients with a positive diagnosis of PE, and 10 patients where clinically suspected PE was ruled out.