Comparison of three techniques for evaluation of de novo asymptomatic pulmonary arterial thrombosis following deep vein thrombosis in total knee arthroplasty

PurposeDeep venous thrombosis (DVT) following total knee arthroplasty (TKA) frequently results in pulmonary arterial thrombosis (PAT). Using multislice-CT (MSCT), we evaluated the incidence of de novo asymptomatic PAT following DVT in subjects undergoing TKA and compared these results by ventilation–perfusion (VP) lung scintigram and ultrasonography of the lower extremities.Materials and methodsTwenty-five asymptomatic subjects (5 males, 53–82 years old, receiving anticoagulant therapy) underwent enhanced MSCT, VP lung scintigram, and ultrasonography of the lower extremities before and 7 days after TKA.ResultsAmong 25 subjects, 2 were found to have asymptomatic PAT and DVT, respectively, by pre-TKA MSCT. In the remaining 23 subjects, the post-TKA MSCT detected PAT in 7 subjects (30.4%) and DVT in 6 (26.1%). Those 16 subjects without evidence of PAT on the post-TKA MSCT also had no VP mismatches on their VP lung scintigrams. Additionally, all subjects without evidence of DVT on the post-TKA MSCT also showed no evidence of DVT by ultrasonography. Of the 7 subjects in whom PAT was detected by post-TKA MSCT, VP mismatch was shown by lung scintigraphy in 2 and DVT was confirmed by MSCT in both. No patient had VP mismatch without PAT, and 2 subjects with PAT and VP mismatch had DVT. Conversely, DVT was not revealed by ultrasonography among the 6 subjects (26.1%) in whom DVT was detected in the lower extremities by post-TKA MSCT. However, blood flow abnormalities were shown by ultrasonography of the lower extremities in 4 of the 6 subjects (17.4%).ConclusionMSCT was the most sensitive of the 3 methods and could simultaneously evaluate PAT and DVT. The apparent discrepancy between these techniques may be due to MSCT's ability to detect thrombi that do not interfere with blood flow.