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

Background: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.Methods: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).Results: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.Conclusion:In patients with pleurisy and pleural lesions of unknown cause that were found sonographically, CES enables the diagnosis or exclusion of pleuropneumonia.