PET Fibrin Imaging of DVT and PE

Inclusion Criteria: * 18 years of age or older with a clinically significant pulmonary embolus (PE) confirmed by a filling defect in CT angiography (CTA), and * Subjects must receive the radiotracer injection within 72 hours of their diagnosis. Exclusion Criteria: * Subjects \< 18 years of age * Time of expected radiotracer injection \> 72 hours from the time of a positive venous duplex ultrasound or CT- angiogram * Women subjects of childbearing potential who are pregnant, seeking to become pregnant, or have a positive serum pregnancy (beta-HCG) test * Unable to lie flat for 45 minutes as assessed by physical examination and medical history (e.g. back pain, arthritis, dyspnea), * Weight that exceeds the PET camera table limit (300 kg) * The subject will not be enrolled in the study if the radiation exposure for research studies during the prior 12 months, combined with the exposure from this study would exceed 50 mSv (millisievert). * Due to the radiation exposure from imaging studies, all women of childbearing potential will be required to have a negative serum pregnancy test performed prior to any imaging procedures on the same day (if not already done that day). Patients with a positive serum pregnancy test will be excluded. Breast feeding women will also be excluded. * A pre-existing condition or use of a medication including vasopressors and tPA (tissue Plasminogen Activator) that in the opinion of the investigator may place the subject at a substantially increased risk * Hemodynamic instability, including requiring escalating doses of vasopressor medication. * No groups designated as "special vulnerable populations" will be studied. * No exclusions will be made based on race, sex, or ethnic origin. * 64Cu-FBP8 (Copper-64 labeled fibrin binding probe 8) is cleared by the kidneys, patients with eGFR (estimated Glomerular Filtration Rate ) \< 30 will be excluded.