Magnetic resonance direct thrombus imaging differentiates acute recurrent ipsilateral deep vein thrombosis from residual thrombosis

Accurate diagnostic assessment of suspected ipsilateral recurrent deep vein thrombosis (DVT) is a major clinical challenge since differentiating between acute recurrent thrombosis and residual thrombosis is difficult with compression ultrasonography (CUS). We aimed to evaluate non-invasive Magnetic Resonance Direct Thrombus Imaging (MRDTI) in this setting. This was a prospective study of 39 patients with symptomatic recurrent ipsilateral DVT (incompressibility of a different proximal venous segment than at the prior DVT), and 42 asymptomatic patients with at least 6-month-old chronic residual thrombi, and normal D-dimer levels. All patients were subjected to MRDTI. MRDTI images were judged by two independent radiologists blinded for the presence of acute DVT, and a third in case of disagreement. The sensitivity, specificity and inter-observer reliability of MRDTI were determined. MRDTI demonstrated acute recurrent ipsilateral DVT in 37 of 39 patients and was normal in all 42 patients without symptomatic recurrent disease, for a sensitivity of 95% (95%CI 83-99%) and a specificity of 100% (95%CI 92-100%). Inter-observer agreement was excellent (kappa-statistic 0.98). MRDTI images were adequate for interpretation in 95% of them. MRDTI is a sensitive and reproducible method for distinguishing acute ipsilateral recurrent DVT from 6-month-old chronic residual thrombi in the leg veins.