Inclusion Criteria:  Men and women Diagnosis of a first episode of acute proximal leg DVT within 4 weeks of initial DVT diagnosis and without symptomatic pulmonary embolism (PE) Must have ECOG performance status ≤ 2 Expected life expectancy of >2 years Before initiation of anticoagulation, must have adequate platelet count: Platelet count > 100 x 10^9/L, Before initiation of anticoagulation, must have adequate hemoglobin (Hgb) count: Hgb > 9 mg/DL Before initiation of anticoagulation, must have normal INR and PTT: INR ≤ 1.5 and aPTT≤40  Exclusion Criteria:  Concurrent participation in another therapeutic clinical trial History of prior DVT in the previous 2 years Recurrent deep vein thrombosis (DVT) Established post thrombotic syndrome (PTS) Limb-threatening circulatory compromise Pulmonary embolism with hemodynamic compromise Deranged baseline coagulation profile before initiation of anticoagulation: INR > 1.5 or aPTT prolonged >40 Active bleeding within last 3 months Anemia with Hemoglobin<9 mg/dL Thrombocytopenia with platelets < 100,000/ml Previously documented hypersensitivity to either the drug or excipients Any contraindication to anticoagulation or allergy to factor V inhibitors or ferumoxytol Any contraindication to magnetic resonance imaging (MRI) including metal implants or claustrophobia Severe hepatic impairment as defined by Childs-Pugh Class B or C Severe renal impairment with CrCl<30 ml/min, Taking any P-GP or strong CYP3A4 inhibitors or inducers History of major bleeding including history of gastrointestinal bleeding or intracranial bleeding Known history of bleeding diathesis History of chronic atrial fibrillation or stroke History of active cancer or malignancy within 1 year, Life expectancy <2 years. Patients requiring emergent or urgent surgery or procedures within the first 3 months of the study that cannot be postponed will be excluded. Patients who are breastfeeding or anticipate pregnancy Participant is pregnant or breastfeeding Participant is a prisoner (protected population)