Diagnostic Efficacy of Acoustic Radiation Force Impulse in Staging of Lower Limb Intramuscular Venous Thrombosis

OBJECTIVES: Acoustic radiation force impulse (ARFI) imaging can quantitatively reflect tissue stiffness through shear wave velocity (SWV). In recent years, ARFI technology has been successfully applied in the diagnosis of liver and breast diseases, and has made some progress in the quantitative assessment and staging of femoral vein and popliteal vein thrombosis. However, research on intramuscular venous thrombosis in the lower limbs is still insufficient. This study aims to evaluate the application value of ARFI technology in the staging of lower limb intramuscular venous thrombosis. METHODS: A prospective cohort of 227 patients with 265 intramuscular venous thromboses was included. According to the time of thrombus formation, they were divided into acute (133 cases, 152 thromboses), subacute (52 cases, 65 thromboses), and chronic (42 cases, 48 thromboses) groups. Gray-scale and Doppler ultrasound characteristics were analyzed, and sampling depth and SWV values were compared among groups. Receiver operating characteristic (ROC) curves were plotted to determine optimal cutoff values for distinguishing different stages. RESULTS: Acute-phase thrombi typically appear hypoechoic, avascular, and sharply demarcated from the vessel wall. Subacute thrombi are predominantly isoechoic, usually without detectable blood flow, and show indistinct margins in some cases. Chronic thrombi exhibit heterogeneous echogenicity, often demonstrate intrathrombus flow signals, and consistently display poorly defined borders with the vessel wall. The SWV values for the 3 groups of cases were (1.90 ± 0.26) m/s, (2.35 ± 0.34) m/s, and (2.82 ± 0.43) m/s for the 3 groups respectively. One-way ANOVA showed no significant difference in sampling depth (p = .160) but significant difference in SWV values (p < .05). The ROC curve area for distinguishing acute from subacute thrombi was 86.6% (95% CI: 0.818-0.913, p < .05), with a cutoff SWV of 2.01 m/s, yielding 89.2% sensitivity and 70.4% specificity for acute thrombi diagnosis. For subacute versus chronic thrombi, the ROC area was 82.3% (95% CI: 0.743-0.902, p < .01), with a cutoff SWV of 2.63 m/s, achieving 72.9% sensitivity and 87.7% specificity for subacute thrombi diagnosis. CONCLUSION: ARFI technology shows high diagnostic efficacy for staging lower limb intramuscular venous thrombosis and can be promoted in clinical practice.