Multislice CT and D-dimer test detect pulmonary embolism without ultrasound

Venous ultrasonography may be an extraneous step in the diagnosis of pulmonary embolism. A D-dimer test performed with multislice CT scan is no less sensitive than the two tests performed in combination with venous ultrasound of the leg, according to a study from Switzerland.

Accepted diagnostic methods to detect PE include clinical probability assessment (CPA) followed by sequential diagnostic tests, such as D-dimer, ultrasound, and CT, according to Dr. Marc Righini of the Geneva University Hospital, first author of the study in the April 18 issue of The Lancet.

MSCT is replacing pulmonary angiography as imaging modality of choice for PE because of its ability to visualize the segmental and subsegmental vessels, he said.

Righini and colleagues drew their findings from a randomized controlled trial of 1819 outpatients with clinically suspected PE. The first 903 patients were assessed with CPA combined with D-dimer measurement and MSCT. The second strategy involving 916 patients was the same as the first but included venous ultrasonography of the leg.

Effectiveness of each method was assessed by calculating the three-month risk of recurrent deep vein thrombosis or PE in patients who were left untreated on the basis of having been excluded by either strategy.

The researchers found that the prevalence of PE was 20.6% in both groups: 186 in the D-dimer/CT group, and 189 in the D-dimer/CT/ultrasound group. Analysis of the remaining patients showed that the three-month risk of PE was 0.3% in both groups, again suggesting the two strategies were equally effective.

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