Role of Duplex Imaging in Intermnediate Category Ventilation Peffusion Scans

Abstract

Clinical diagnosis of pulmonary embolus (PE) is difficult. Pulmonary angiography is still the gold standard for diagnosing PE, and ventilation perfusion (VQ) lung scans are used as a screening test. With normal VQ scans, PE can be ruled out. High probability VQ scans have high positive accuracy. The authors conducted a retrospective analysis of 45 patients who underwent intermediate VQ scans. Of the 45 patients who had intermediate VQ scans performed, 37 (82%) had venous duplex imaging (VDI) conducted, with 7 found to be positive for deep vein thrombosis. Of the 45 patients who had intermediate VQ scans performed, 12 (27%) had pulmonary angiograms performed, 7 (58%) of which were positive for PE. Six of these seven patients also had VDI conducted, all of which were negative. In total, of the 22 patients found to have a clinical discharge diagnosis of PE, 13 had either VDI studies or pulmonary angiographies positive for PE. These results indicate that a positive VDI study substantiates a diagnosis of PE. However, negative VDI study does not rule out pulmonary embolus.

Keywords

pulmonary embolism venous duplex imaging

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