Value of contrast-enhanced ultrasound in diagnosis of thrombus in inferior vena cava filter

Objective To evaluate the diagnostic value of contrast-enhanced ultrasound (CEUS) in assessing thrombus of inferior vena cava filters before filters removal. Methods We analyzed 127 patients who scheduled for inferior vena cava filter extraction from June to November 2023, 53 of which underwent CEUS examination. The enhancement of contrast agent signal within and around the filter was observed under CEUS mode. The thrombus was classified based on the signal loss of contrast agent and then compared with digital subtraction angiography(DSA). Results In the CEUS mode, the contrast agent was visualized within the inferior vena cava, clearly revealing signal loss for the thrombus location. Based on the size and location of the thrombus, filter thrombus was categorized into four groups: 41 cases of type 0, 8 cases of type Ⅰ, 3 cases of type Ⅱ, and 1 case of type Ⅲ. No significant difference in thrombus classification was observed between CEUS and DSA (P>0.05). According to the classification of filter thrombus, different extraction schemes were applied to 53 patients with inferior vena cava filters. There were no major bleeding events or symptomatic pulmonary embolism happened. Conclusions CEUS is valuable for evaluating filter thrombus prior to removal, providing a basis for preoperative assessment of surgical risks, selection of treatment plans, and prevention of complications.