AJR Am J Roentgenol 2000 Dec;175(6):1525-31
Evaluation of the lower extremity veins in patients with suspected
pulmonary embolism: A retrospective comparison of helical CT venography and sonography.
Duwe KM, Shiau M, Budorick NE, Austin JH, Berkmen YM
OBJECTIVE. In patients undergoing a combined CT angiographic and CT venographic protocol,
the accuracy of helical CT venography for the detection of deep venous thrombosis was
compared with that of lower extremity sonography. MATERIALS AND METHODS. Patients who had
undergone a combined CT angiographic and CT venographic protocol and sonography of the
lower extremities within 1 week were identified. The final reports were evaluated for the
presence or absence of deep venous thrombosis. Statistical measures for the identification
of deep venous thrombosis with helical CT venography were calculated. In each
true-positive case, the location of the thrombus identified with both techniques was
compared. All false-positive and false-negative cases were reviewed to identify the
reasons for the discrepancies. RESULTS. Seventy-four patients were included. There were
eight patients (11%) with true-positive findings, 61 patients (82%) with true-negative
findings, four patients (5%) with false-positive findings, and one patient (1%) with a
false-negative finding. When comparing helical CT venography with sonography for the
detection of lower extremity deep venous thrombosis, the sensitivity measured 89%;
specificity, 94%; positive predictive value, 67%; negative predictive value, 98%; and
accuracy, 93%. Of the eight true-positive cases, five had sites of thrombus that were in
agreement on both CT venography and sonography. Of the five discordant cases, four were
false-positives and one was a false-negative. Possible explanations for all discrepancies
were identified. CONCLUSION. Compared with sonography, CT venography had a 93% accuracy in
identifying deep venous thrombosis. However, the positive predictive value of only 67% for
CT venography suggests that sonography should be used to confirm the presence of isolated
deep venous thrombosis before anticoagulation is initiated. In addition, interpretation of
CT venography should be performed with knowledge of certain pitfalls.
PMID: 11090368, UI: 20544687
