Non-Invasive Characterization of Lower Extremity Deep Vein Thrombosis via Advanced Ultrasound Elastography: A Prospective Pilot Study

Duplex ultrasonography is the preferred non-invasive imaging technique for diagnosing lower extremity deep vein thrombosis (DVT), but considered largely unreliable for determining thrombus-specific features. Elastosonography techniques including real-time strain elastography (RT-SE) are widely used in clinical practice to assess tissue elasticity, but its potential remains largely unrealized in DVT, where RT-SE might provide adjunct information on thrombus biomechanical properties potentially aiding clinical decision-making. This single-center prospective pilot study investigates the use of modern RT-SE imaging enhanced with an advanced quantification software for reconstructive tissue elasticity analysis in patients with symptomatic acute lower-extremity DVT objectively diagnosed within 6 months of enrollment. Between-group differences in median thrombus elasticity, assessed via a newly proposed elasticity biomarker, namely thrombus tissue deformation index, were evaluated using Mann-Whitney U or Kruskal-Wallis tests. Relationships between thrombus elasticity and patient-, DVT- and anticoagulation-related factors were assessed through Spearman's rank-order correlation. Thirty-eight deep venous thrombi were analyzed using advanced RT-SE, in addition to standard duplex ultrasonography (i.e., triplex ultrasonography). Median thrombus elasticity was 25.7% (interquartile range [IQR], 22.1-26.1), 20.8% (IQR, 17.1-22.1), and 3.8% (IQR, 1.3-6.6) in acute, sub-acute, and chronic DVT, respectively (p < 0.001). Thrombus elasticity robustly correlated with the period of DVT diagnosis (i.e., lower elasticity with increasing thrombus chronological age; ρ = -0.70, p < 0.0001). Elasticity of chronic thrombi inversely correlated with dynamic changes in residual vein obstruction (i.e., higher elasticity of thrombi undergoing smaller size reduction over time; ρ = 0.85, p < 0.0001). These findings preliminarily identify modern advanced RT-SE imaging as a viable and easily-implementable tool for enhanced non-invasive thrombus characterization, with the potential to inform thrombus-guided management strategies in patients with DVT.