The diagnosis of recurrent ipsilateral DVT is challenging because of persistent intravascular abnormalities after previous DVT.
The incidence of VTE recurrence after negative MRDTI was low and MRDTI proved to be a feasible and reproducible diagnostic test.
Background: The diagnosis of recurrent ipsilateral deep vein thrombosis (DVT) is challenging because persistent intravascular abnormalities after previous DVT often hinder a diagnosis by compression ultrasonography. Magnetic resonance direct thrombus imaging (MRDTI), a technique without intravenous contrast and with a 10-minute acquisition time, has been shown to accurately distinguish acute recurrent DVT from chronic thrombotic remains. We have evaluated the safety of MRDTI as sole test for excluding recurrent ipsilateral DVT. Methods: The Theia study was a prospective international multicenter diagnostic management study involving patients with clinically suspected acute recurrent ipsilateral DVT (NCT02262052). Patients were managed according to the MRDTI result, performed within 24 hours of study inclusion. The primary outcome was the 3-month incidence of venous thromboembolism (VTE) after MRDTI negative for DVT. The secondary outcome was the interobserver agreement of MRDTI readings. An independent committee adjudicated all endpoints. Results: 305 patients were included. The baseline prevalence of recurrent DVT was 38%; superficial thrombophlebitis was diagnosed in 4.6%. The primary outcome occurred in 2 of 119 (1.7%; 95%CI 0.20-5.9) patients with MRDTI negative for DVT and thrombophlebitis, who were not treated with any anticoagulant during follow-up; neither of these recurrences was fatal. The incidence of recurrent VTE in all patients with MRDTI negative for DVT was 1.1% (95%CI 0.13-3.8%). The agreement between initial local and post-hoc central reading of the MRDTI images was excellent (kappa statistic 0.91). Conclusions: The incidence of VTE recurrence after negative MRDTI was low and MRDTI proved to be a feasible and reproducible diagnostic test.