IP06 - Longitudinal Shear Wave Elastography Identifies Distinct Phenotypes of Thrombus Evolution in Acute Deep Vein Thrombosis

Objectives: Accurate determination of thrombus biological behavior in deep vein thrombosis (DVT) remains challenging using conventional ultrasonography. This study aimed to evaluate longitudinal changes in thrombus stiffness measured by shear wave elastography (SWE) and to determine whether longitudinal stiffness trajectories—rather than symptom duration or baseline echogenicity— identify distinct thrombus evolution phenotypes during anticoagulation.

Methods: This prospective, longitudinal, single-center study included patients with a first episode of acute lower-extremity DVT receiving standard anticoagulant therapy. SWE was performed at diagnosis (D0) and during follow-up at 30 (D30) and 90 days (D90). Thrombus stiffness was quantified in kilopascals (kPa). Multivariable generalized linear models evaluated predictors of total recanalization at D30 and D90. Longitudinal stiffness trajectories were analyzed using generalized estimating equations, assessing interactions with echogenicity and symptom duration.

Results: A total of 57 patients were prospectively followed. At baseline (D0), thrombus stiffness did not differ according to symptom duration or echogenicity. In multivariable analysis, lower baseline stiffness independently predicted total recanalization at 30 days (OR 0.87; 95% CI, 0.51–0.97; p < 0.05), together with symptom duration (OR 1.13; 95% CI, 1.13–1.41; p < 0.05). At 90 days, both baseline stiffness (OR 0.79; 95% CI, 0.57–0.97; p < 0.05) and stiffness at D30 (OR 0.87; 95% CI, 0.72–1.00; p < 0.05) independently predicted recanalization.
Longitudinal analysis demonstrated distinct stiffness trajectories. A significant interaction between time and echogenicity was observed (p < 0.001). Echolucent thrombi exhibited a marked reduction in stiffness from D0 to D90 (mean difference 11.31 kPa; 95% CI, 3.91–18.71), whereas echogenic thrombi showed no significant change over time (Figure 1). Similarly, thrombi with 7–30 days of symptoms demonstrated a significant stiffness reduction between D0 and D90 (mean difference 12.11 kPa; 95% CI, 3.05–22.85), with lower stiffness at D90 compared with thrombi presenting within 7 days (Figure 2).

Conclusions: Longitudinal SWE reveals distinct phenotypes of thrombus evolution in acute DVT based on stiffness behavior over time. Thrombus stiffness is a dynamic biomarker of biological responsiveness to anticoagulation and an independent predictor of recanalization, outperforming symptom duration and baseline echogenicity at diagnosis. Incorporating longitudinal elastographic assessment may refine risk stratification by distinguishing thrombi prone to recanalization from those predisposed to early organization and chronic sequelae.