Correlation of pleural effusions’ grayscale sonographic parameters with fluid’s analysis results

Until now, in the sonographic imaging of pleural effusions, the quantitative evaluation of the fluids characteristics was performed indirectly by using other anatomic structures of the thorax as a relative measure of comparison (1). Such quantitative methods are used to assess the fluid’s volume but to the best of our knowledge no method exists for the measurement of the fluids’ density and other qualitative values. The interpretation of the internal echogenicity of a pleural effusion is based upon the subjective observation and evaluation of each operator. According to the internal echogenicity, effusion can be subclassified as anechoic, complex non-septated, complex septated, and homogenously echogenic (2). Additionally, several visual patterns like swirling (3) or sonographic septations (4,5) have been proven useful as diagnostic predictors for pleural effusions (6). We suggest a quantitative method, based on the pixel density of the pleural effusion’s image, in order to evaluate the echogenicity of pleural effusion