Shear wave elastography for lower extremity deep vein thrombosis

Abstract

Aim. To evaluate the potential of shear wave elastography to determine the duration of lower extremity deep vein thrombosis, the effectiveness of direct anticoagulation and patient management strategy.Material and methods. Duplex lower extremity vein scanning, supplemented by shear wave elastography with determination of the average, minimum and maximum Young's modulus, was performed in 98 patients with acute, subacute and chronic thrombosis of the iliac and femoral veins on days 1, 3 and 6 of hospitalization. Based on the coefficient of determination (R2) of the median Young's modulus of a venous thrombus at different stages of thrombosis, the significance of its changes was assessed. Diagnostic information content of Young's modulus was calculated by comparing with the histological data of 17 blood clots removed during surgery.Results. As the age of both iliac and femoral vein thrombus increased, the median of the maximum, average and minimum Young's modulus at all stages of thrombosis steadily increased (R2=0,99). The median of the average Young's modulus at the acute stage was determined to be <17 kPa; at the subacute stage — in the range of 17-32 kPa and chronic — >32 kPa. According to shear wave elastography, in patients with acute and subacute stages of thrombosis, by the 6th day of anticoagulant therapy, the thrombus stiffness increased (R2=0,91-0,96), while in the chronic thrombosis group only a tendency to decrease was observed. The diagnostic information value of studying a thrombus using shear wave elastography relative to its histological examination turned out to be sufficient for use in clinical practice. In acute femoral vein thrombosis, the indication for radical treatment was the average Young's modulus ≤8,1 kPa, the minimum Young's modulus ≤1,7 kPa (sensitivity, specificity, positive and negative predictive values varied in the range of 64,3-88,9%); in subacute — ≤23,0 kPa and ≤11,3 kPa, respectively (55,6-100%).Conclusion. The results indicate that the diagnostic information value of shear wave elastography indicators is sufficient to determine the stage of lower extremity deep vein thrombosis in clinical practice.