Risk of pulmonary embolism after negative MDCT pulmonary angiography findings

OBJECTIVE. The purpose of our study was to determine the risk of pulmonary embolism in patients who have negative MDCT pulmonary angiography findings. SUBJECTS AND METHODS. In this prospective study, one hundred two consecutive patients with suspected pulmonary embolism underwent MDCT pulmonary angiography. Scans were reviewed jointly by two observers and findings recorded by consensus. Observers noted whether pulmonary embolism or other disease was present. No pulmonary embolism was seen in 85 patients (52 men and 33 women; age range, 20-94 years; mean age, 60 years) who were followed up for a mean of 9 months (range, 4-13 months) for evidence of subsequent pulmonary embolism. RESULTS. One patient had a diagnosis of pulmonary embolism made within 3 weeks of undergoing MDCT pulmonary angiography. MDCT pulmonary angiography showed additional potentially significant findings in 76% of patients; 47% of these findings were not suspected on chest radiography. CONCLUSION. The risk of pulmonary embolism at a mean of 9 months after negative MDCT pulmonary angiography findings is 1%. In our study of patients without pulmonary embolism, MDCT pulmonary angiography revealed other causes for individual patients' signs or symptoms in most cases.