Study objectives: Despite the widespread use of lung scanning and angiography, pulmonary embolisms (PEs) remain undiagnosed in the majority of patients, suggesting the need for alternative diagnostic approaches. The present study investigates the clinical utility of transthoracic sonography (TS) for the diagnosis of PE and compares the data obtained with the technique to those obtained by spiral CT (sCT) scanning.
Design: This prospective study was performed using 69 patients with suspected PEs. TS was performed in all patients. In addition, sCT scanning was carried out in 62 patients. Other diagnostic procedures included the estimation of d-dimers, echocardiography, venous duplex sonography of the legs, pulmonary angiography, and ventilation/perfusion scanning. The diagnosis of PE was accepted when there was a conclusive result of these investigations or when an embolus could be visualized on a CT scan.
Setting: The Department of Pneumology in Friedrich-Schiller-University Hospital (Jena, Germany).
Patients: Sixty-nine patients (27 women and 42 men) with suspected PEs.
Results: A diagnosis of PE was established in 44 patients. Ninety-one peripheral parenchymal lesions (mean, 2.6 lesions per patient; range 1 to 9 lesions per patient) that are associated with PE were detected by TS in 35 patients (80%). Multiple, triangular, hypoechoic, and pleural-based parenchymal lesions with a localized and/or basal effusion were typical of the PEs as shown by TS. In nine patients with central PEs that had been diagnosed by CT scanning, no peripheral lesions could be detected by sonography. One patient with sonographic signs of PEs had a diffuse bronchogenic adenocarcinoma that was diagnosed at autopsy. In another patient with parenchymal lesions, pneumonia was diagnosed by CT scanning. The sensitivity of TS for detecting PEs was 80% (sensitivity of CT scanning, 82%), and the specificity of TS for detecting pulmonary lesions was 92% (specificity of CT scanning, 100%). The positive and negative predictive values of TS for the detection of PEs were 95% and 72%, respectively (positive predictive value for CT scanning, 100%; negative predictive value for CT scanning, 77%). The accuracy of TS was 84% (accuracy of CT scanning, 89%).
Conclusions: TS is a noninvasive technique that is used for diagnosing parenchymal alterations, and it may serve as an additional method in the strategy for diagnosing PE.