Quantitative d-dimer levels and the extent of venous thromboembolism in CT angiography and lower limb ultrasonography.
BACKGROUND
We evaluated the diagnostic yield of multidetector-row CT angiography and determined the clot burden within pulmonary vasculature as a measure of pulmonary embolism (PE) severity at different d-dimer levels and pretest clinical probabilities.


METHODS
254 consecutive patients referred to CT pulmonary angiography for suspected PE after d-dimer testing were grouped into clinical probability classes using Wells' score, and the frequency of PE was determined. A score representing clot burden within pulmonary vasculature was calculated from the number of obstructed segmental arteries in CT scans in a partly differing group of 96 PE positive patients.


RESULTS
The prevalence of PE increases with the d-dimer level (7% at d-dimer levels of 0.5-1 microg/ml, reaching 90% at d-dimer levels > 9 microg/ml; p < 0.001). D-dimer levels above 4 microg/ml are associated with a significantly higher clot burden in pulmonary arteries (median score 11 versus 5, and 53% versus 16% of patients in the subgroup with a score > 10 points; p < 0.001), and thrombus in a main pulmonary artery was detected more frequently (37% versus 9%, p = 0.003). Similar results were obtained for distal versus proximal deep venous thromboses, detected by ultrasonography of the lower limb in a separate group of 44 patients.


CONCLUSIONS
High d-dimer levels are associated with an increased prevalence of CT radiographic findings indicating extended clinically severe PE or lower limb venous thrombosis.
Hochuli
M
M
Department of Internal Medicine, Division of Angiology, Institute of Radiology Kantonsspital Frauenfeld, Switzerland.
Duewell
S
S
Frauchiger
B
B
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis*; D012189:Retrospective Studies; D012307:Risk Factors; D036542:Tomography, Spiral Computed; D018616:Ultrasonography, Doppler, Duplex; D054556:Venous Thromboembolism / Q000097:blood / Q000175:diagnosis*
D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D