Diagnosis of pulmonary embolism by transthoracic sonography: a comparison of sonography and spiral computed tomography in determining the morphology of pulmonary lesions

Background and objective: Pulmonary embolism often extends to pleural surfa ces, resulting in pleural-based parenchymal lesions. This study was carried out in order to evaluate the clinical value of transthoracic sonography (T S) for the diagnosis of pulmonary embolism. Patients and methods: A prospective study was performed in 45 patients (27 men, 18 women; mean age: 63,4 years; range: 24-88 years) with suspected pul monary embolism. Transthoracic sonography was performed in all patients. In addition, helical computed tomography (CT) was carried out in 40 patients. Other diagnostic procedures included the estimation of D-dimeres, echocard iography, venous duplex sonography of the legs and ventilation/perfusion sc anning. The diagnosis of pulmonary embolism was accepted when an embolus wa s detected on CT or as a conclusive result of the other investigations. Results: Pulmonary embolism was established in 33 patients. Peripheral pare nchymal lesions suspicious of pulmonary embolism were detected by transthor acic sonography in 26 patients (79%). In seven patients with central pulmon ary embolism diagnosed by CT, no peripheral lesions could be detected by so nography. One patient with sonographic signs of pulmonary embolism had a di ffuse bronchogenic adenocarcinoma which was diagnosed on autopsy. The sensi tivity of transthoracic sonography (computed tomography) for pulmonary embo lism was 79% (76%) and the specificity 92% (100%). The positive and negativ e predictive values of transthoracic sonography for the detection of pulmon ary embolism were 96% and 61% (100% and 61%), respectively. The accuracy wa s 82% (82%). Conclusions: A substantial number of pulmonary emboli involve the periphera l lung areas. Transthoracic sonography is a non-invasive technique for diag nosing such parenchymal alterations and may serve as an alternative method in the diagnosis of pulmonary embolism.