Chest ultrasound in diagnosis of pulmonary embolism in comparison to helical CT

To many people die because of undiagnosed pulmonary embolism. Common pulmonary embolism is the most unexpected mortal event in necropsy, antemortem correctly diagnosed in 18-39%. The diagnostic value of chest ultrasound (CUS) has been investigated.

117 (68 women, 49 men) patients with clinical suspicion of pulmonary embolism underwent chest sonography and spiral computed tomography (CT). Final diagnosis has been made by CT respective with echo-cardiography, venous duplex sonography and fibrin dimer tests.

Finally, 70 patients suffered from pulmonary embolism. The chest sonograms showed averaged 1.5 x 2.8 cm (0.5-8.5) large triangular or rounded hypoechoic lesions, mean 2.6 pro patient, similar in form and size as in CT. Fresh reperfusionable infarcts were homogenous and hypoechoic. Older infarcts were well demarcated, mainly wedge shaped. A hyperechoic reflex in the center corresponds to the bronchiole: a sign of segmental involvement. The sensitivity of chest ultrasound was 94%, the specificity 87%, positive predictive value 92%, negative predictive value 91%, accuracy 91%. Overall 61 patients had PE in CT, in 47 (67%) cases a direct emboli detection was possible. 14 patients had peripheral lung consolidations without detectable emboli, but fibrin-dimer tests were positive in all cases, there was deep vein thrombosis diagnosed and they showed signs of PE in echocardiography. Spiral CT showed a sensitivity of 85%, a specificity and a positive predictive value of 100%, a negative predictive value of 83% and an accuracy of 92%.

CUS can improve diagnosis of pulmonary embolism. Sonography also reveals small infarcts which remain undetected with other imaging procedure such as helical CT.