PLEURAL EFFUSIONS - PATTERNS ON VENTILATION-PERFUSION LUNG SCANS

Perfusion and ventilation abnormalities created by pleural effusions c an interfere with the interpretation of the lung scan. This retrospect ive study identified and evaluated the specificity of scintigraphic pa tterns for pleural effusion. Ninety-two ventilation-perfusion lung sca ns were analyzed for the following signs of pleural effusion: presence of fissures, straightened or concave lung borders, costophrenic angle blunting, and attenuation of lung activity by interposed fluid. The f indings later were correlated with chest radiographs. Of 25 pleural ef fusions detected by chest radiography, scintigraphy predicted 14 (spec ificity, 86%). In all of these cases, there was agreement with the che st radiograph (specificity, 100%). The fissure sign and the straight- concave border sign were equally reliable for the prediction of pleura l fluid. Costophrenic angle blunting was never seen as the sole indica tor of pleural fluid, and attenuation was seen alone in only one case. Another finding observed during this evaluation was absent ventilatio n at the lung base with preserved perfusion. Scintigraphic patterns ma y not be reliable in obstructive lung disorders and diseases with alte red lung compliance. The recognition of scintigraphic patterns of pleu ral effusions on ventilation-perfusion scans can improve the clinical value of lung scintigraphy by reducing the number of indeterminate rea dings.