Fluorodeoxyglucose (FDG)-Positron Emission Tomography (PET) in Cancer Associated Venothromboembolism

Study AIM #1 To establish the sensitivity of FDG PET/CT in the diagnosis of acute VTE.

Rationale: We believe that FDG PET/CT can be used to accurately diagnose the presence, extent, and acuity of VTE. It is unrealistic to assume that FDG-PET could or should become the primary imaging modality for evaluating VTE. The cost, compared to Doppler ultrasound, would be prohibitive, and would involve unnecessary radiation of the patient. We intend to establish the value of FDG PET, instead, as an alternative modality for the diagnosis of VTE. Clinical situations where this might prove useful include: 1) the presence of old clot, when the distinction between new and old may be important; 2) evaluation of abdominal, pelvic and thoracic thrombus, where Doppler is difficult-to-impossible because of patient obesity; 3) Complicated anatomy due to the presence of tumor or post-therapeutic changes.

The sensitivity of FDG PET/CT will be established in patients with acute VTE. The accuracy with which sites of abnormal FDG uptake can be related, spatially, to vascular structures will be critical to the success of this study. There is little doubt that this can better be accomplished with PET/CT than with PET alone. PET/CT will be used for all of these studies. Patients with documented acute VTE, will be enrolled. To determine the utility of FDG PET/CT in distinguishing acute from subacute or chronic clot, and to establish the extent of acute clot, the initial whole body PET/CT scan must be performed within 2 weeks of onset of symptoms of DVT, and subsequent limited region PET/CT scans will be performed at 2-3 weeks and at 6 weeks following the initial PET/CT scan. Whenever possible, subjects will be recruited who have unprovoked VTE because the potential benefit to the patient for participating in this study will be greatest for these patients are at a higher risk for harboring an underlying occult malignancy. However, patients with both provoked and unprovoked VTE will be eligible for enrollment under this specific aim.

Inclusion criteria

• Inclusion criteria will include documented acute DVT (+/-PE) by Doppler ultrasound or contrast venography.
• Subjects will be eligible either with provoked or unprovoked DVT.
• To meet the inclusion criteria, patients must be enrolled and the initial PET/CT scan performed within 2 weeks of initial onset of symptoms of VTE.

Exclusion criteria

• Subjects less than 18 years of age,
• Those who are unable to understand and provide signature informed consent
• Pregnant subjects. Any female of childbearing age who has a uterus and functional ovaries will undergo a serum pregnancy test prior to inclusion. 4. Subjects with calf-only blood clot will be excluded, due to the fact that these cases are often complicated by venous stasis disease, post-phlebitic syndrome, and the presence of both acute and chronic clot, which may compromise interpretation.