Aims: To compare the results of gray scale ultrasound with those of color Doppler ultrasound in order to evaluate the minimal pleural effusion and to differentiate the minimal pleural effusion from pleural thickening.
Patients and methods: We prospectively analyzed 86 patients who, according to their chest radiographs, were suspected of having minimal pleural effusion. All patients were examined by ultrasonography on gray scale and color Doppler and the presence or absence of pleural effusion was confirmed by thorax CT. Using the color Doppler examination we analyzed the fluid color sign of pleural effusion.
Results: In our study, the ultrasonography on gray scale in real time detected pleural effusion with 60% specificity, 100% sensitivity and 88.37% accuracy. By applying the color Doppler the specificity of the method is higher (specificity 100%, sensitivity 96.72% and accuracy 97.57%).
Conclusions: The evidence of pleural effusion on grayscale ultrasound has a greater sensitivity than that of color Doppler ultrasound, but has a smaller specificity. Therefore, color Doppler ultrasound proved to be a useful diagnostic aid in gray-scale ultrasound for the assessment of minimal effusion, having the highest accuracy.