Abstract
Introduction: 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 (PE).
Methods: Pleural ultrasound (US) was performed in 30 patients with pleural effusion. Five consequent images of the pleural effusion were retrieved through axial view and one from the 10th rib through coronal view and converted into the high-resolution tagged image file format. All images were further processed with a widespread imaging analysis program. Pleural effusion echogenicity was measured with histogram analysis. The mean echo levels of all pixels of the pleural effusion and of the 10th rib were counted, and the hypoechogenicity index (HI) was calculated according to the following formula: HI = mean echo level of all pixels of the rib/mean echo levels of all pixels of pleural effusion. HI greater than 1 indicates (PE) hypoechogenicity. Diagnostic thoracocentesis was performed in all patients and biochemical markers were measured.
Results: HI index was calculated in all patients. A strong correlation between HI and fluid LDH was found (r=-0.726, p<0.001). A weak correlation between HI and total number of fluid cells was also found (r= -0.385, p=0.104).
Conclusion: This study demonstrated HI as new index which could indicate the inflammation density of PE. Moreover, when used in combination with classical biomarkers, such as fluid LDH and cell counts, HI might be a useful adjunct for the discrimination of pleural transudate. More studies are needed in order to investigate further this quantitative method.
- Copyright ©ERS 2015