The role of FDG PET/CT imaging in the assessment and diagnosis of venous thromboembolic disorders.

1133 Objectives: - Highlight the importance of medical imaging in making the proper diagnosis of venous thromboembolic (VTE) disorders such as deep vein thrombosis (DVT) and pulmonary embolism (PE) - Discuss the limitations of conventional diagnostic imaging techniques - Present FDG PET/CT as a potential imaging modality in assessing and diagnosing DVT and PE Methods: Venous thromboembolic disorders (VTE), specifically deep vein thrombosis (DVT) and pulmonary embolism (PE), are potentially life-threatening disorders that affect approximately 300,000 to 600,000 people every year in the United States. The clinical symptoms of VTE are non-specific and diffuse, and therefore the diagnosis is notoriously difficult. In addition, the side effects of available anticoagulant treatment strategies pose significant risks to the patient. In the US, an estimated $1.5 billion is spent annually for the treatment of VTE and its associated complications. Thus, medical imaging plays a critical role in the proper diagnostic workup of VTE disorders. However, currently established diagnostic modalities such as ultrasound and venography have certain limitations and are inapplicable in many cases in the evaluation of VTE. FDG PET/CT imaging has shown promise with acceptable sensitivity in early and pre-symptomatic patients but also in several other important aspects of VTE imaging not sufficiently covered with standard imaging modalities: 1) it is able to detect thrombosis in patients suspected of having DVT not only in the lower extremities but throughout the venous vasculature. 2) it can differentiate acute and chronic thrombi, avoiding any unnecessary treatment in patients with previous DVT and suspected recurrence. 3) it may be able to help differentiate tumor thrombosis from conventional bland thrombosis, although this is still controversial. 4) it may locate underlying malignancies in patients with unprovoked VTE. Results: Through accurate quantification of FDG tracer uptake in patients with VTE, we can assess the level of inflammation in whole body fused PET/CT scans of patients with DVT and PE and monitor response to treatment. FDG uptake can be quantified using SUVmean and SUVmax after determining the appropriate region of interest (ROI). Conclusions: Proper assessment and timely diagnosis of VTE is clinically challenging but vital to ensure appropriate and cost-effective treatment. Conventional diagnostic imaging techniques have various limitations such as being unable to differentiate acute from chronic VTE and identify underlying causes for VTE (e.g. cancer). FDG PET/CT imaging can potentially play a significant role in the detection and assessment of VTE in selected cases.