[Gray-level histogram analysis in the sonographic diagnosis of diffuse parenchymal liver disease].

Increased echogenicity is one of the major diagnostic criteria for the subjective evaluation of liver echograms. In our approach to ultrasonic tissue characterisation by B-scan image analysis echogenicity is expressed by parameters deriving from the grey-level histogram. In this study the grey level histograms of a group of normals and patients with diffuse parenchymal liver disease are analysed. When employing the two parameters mean grey level (G) and standard deviation of grey levels (SG) the diagnostic accuracy was 90% (specificity 95%, sensitivity 85%). For subjective evaluation the liver echograms of a randomly selected sub-group of normals and patients were blindly evaluated by three observers who positively correlated the finding of increased echogenicity with the diagnosis of a pathological liver echogram. As demonstrated by our results the two-parameter analysis of the grey-level histogram leads to a quantification of the subjective diagnostic criterion of echogenicity, thus providing useful information for image interpretation.