Echocardiographic tissue characterization and range-gated Doppler ultrasound for the diagnosis of pulmonary embolism

Abstract

We evaluate reflection and absorption indexes of ultrasound as well as Doppler estimates of intrapulmonary blood flow for diagnosing pulmonary embolism. The pulmonary reflection coefficient (PRC), coefficient of tissue attenuation (alpha R) and range-gated blood Doppler signals were studied in 25 patients with pulmonary embolism, 19 with pneumonia, nine with atelectasis, 20 with congestive heart failure, 20 with chronic obstructive lung disease and 10 normal subjects. The PRC was significantly diminished in pulmonary embolism, pneumonia and atelectasis, but was not altered by underlying chronic obstructive lung disease or congestive heart failure. The alpha R in pulmonary embolism was 1.03 ± 0.04 db/MHz cm, significantly lower that that for pneumonia, 1.48 ± 0.03 db/MHz cm (p < 0.001), but not significantly different from that for atelectasis, 0.95 ± 0.05 db/MHz cm. Doppler signals indicating blood flow in the affected area of lung were present in only two of 25 patients with pulmonary embolism, compared with seven of nine with atelectasis and 17 of 19 with pneumonia. The combined use of PRC, alpha R and blood Doppler signals correctly diagnosed pulmonary embolism in 23 of 25 patients. Thus, ultrasound offers a reliable noninvasive method for diagnosis of pulmonary embolism.