[Echohistograms of circumscribed liver lesions]

The term focal liver changes usually applies to benign and malignant primary and secondary tumours. However, according to echotomographic findings, tumour-like diseases, such as focal nodular hyperplasia and diseases caused by bacteria, fungi, protozoa and parasites may also be included. Improvement in echotomographic technique and use of echohistogram have recently enabled provision of data determining the aetiology, i.e. pathohistological structure of changes with computerized analysis. The study included 178 patients with circumscribed liver lesions: thirty patients had primary carcinoma, 39 had secondary carcinoma, 41 had cystic disease, 35 hemangioma, 10 focal steatosis, 23 had other circumscribed lesions, as well as 175 subjects with healthy liver. The examinations were performed using the real-time ulstrasound apparatus (Toshiba SA 100 A). Echohistograms were obtained by placing certain amount of liver tissue onto X and Y axes, to be processed and graphically presented by the apparatus. X axis showed the number of particles (N) of liver tissue on certain surface, while Y axis showed the average value (M) and maximal value (Max) of particles. Analysis of echohistographic parameters evidenced the following: mean distribution values of M, Max and N differed in different pathological conditions (Tables 1 and 2). Correlation analysis of the studied parameters revealed different values among the studied groups of patients (Table 3, Figure 1). Analysis of echohistograms and their parameters revealed differences between the tissues of the "healthy" and "affected" liver which may be significant in diagnosis of circumscribed liver changes. N/Max:N/M ratio was higher in normal liver when compared to the studied groups of patients (except for N/M subration in focal changes). Our study, as well as the studies performed by aforementioned authors, evidenced close correlation of the appearance of echohistograms and parameter ratio with density, homogenicity and greatly with vascularization of the studied tissue. It has also been evidenced that the interrelations between the echosistographic parameters are in a complexly interwoven, and partly in aetiology, or it is better to say in relations between the healthy tissue and pathological liver changes. However, it must be concluded that the series of the described cases is small to enable establishment of diagnostic criteria exclusively based on echohistograms. Similar analysis of echohistograms in circumscribed liver diseases was not evidenced in the referential literature published so far. We consider the method useful and believe that the future development of computerized ultrasound extensions will enable differentiation of lesions.