Contrast-Enhanced Sonography for Differential Diagnosis of Pleurisy and Focal Pleural Lesions of Unknown Cause

Abstract

Ultrasound enables the visualization of pleural-based lesions with a poor correlation to specific pathology. At this time, there are no data about the diagnostic value of contrast-enhanced sonography (CES) in pleural lesions. From August 2004 to January 2005, 25 consecutive patients with clinical symptoms of pleurisy and focal pleural lesions of unknown origin seen on B-mode ultrasonography were prospectively studied by CES. The lesions were diagnosed as pleuropneumonia (n = 12), pulmonary embolism/infarction (n = 7), malignant lymphoma (n = 2), pleural metastasis (n = 2), granuloma (n = 1), and unknown cause (n = 1). The diagnosis of the lesions was confirmed by contrast-enhanced CT scanning (n = 20), scintigraphy (n = 3), and follow-up (n = 2). Time to the enhancement of the contrast agent was determined. The CES patterns were evaluated during the arterial phase (ie, 2 to 30 s) and the parenchymal phase (ie, 1 to 5 min). The extent of the enhancement of pleural lesions was classified using normal liver tissue as an in vivo reference (absent, hypoechoic, isoechoic, hyperrechoic, or mixed echogenicity). In 20 patients, an enhancement of the pleural lesion was seen. All 12 patients with pleuropneumonia had a short time to enhancement (between 1 and 6 s), and a marked enhancement (isoechoic/hyperechoic) during the arterial and parenchymal phase. In the remaining 13 patients with other diagnoses than pleuropneumonia, 5 patients had no enhancement and 8 patients had a delayed time to enhancement (> 6 s). The extent of the enhancement was reduced (hypoechoic/anechoic) in 12 of 13 patients during the arterial and parenchymal phases. In patients with pleurisy and pleural lesions of unknown cause that were found sonographically, CES enables the diagnosis or exclusion of pleuropneumonia.