ACCURACY OF THE DIAGNOSIS OF PLEURAL EFFUSION ON SUPINE CHEST-X-RAY

Diagnosis of pleural effusion (PE) on supine chest X-ray (SCXR) is con sidered difficult. This study aimed at evaluating the accuracy of the diagnosis of PE on SCXR and was performed in two phases. At phase 1, a formula for the sonographic estimation of the volume of PE was establ ished by correlating 24 measurements (in 7 patients in whom complete d rainage was achieved) with the drained volumes. At phase two, 112 cons ecutive SCXRs were supplemented by sonography of the chest. The films were evaluated for the presence of PE and for the presence of differen t radiologic signs of PE. Sonography showed PE in 41 right and 30 left hemithoraces. The overall accuracy of the diagnosis of PE on SCXR was 82%. Only one of the undiagnosed PEs had a volume of >300 ml. The mos t accurate signs were increased density of the hemithorax, blunted cos tophrenic angle, and loss of the hemidiaphragm silhouette.