Abstract
Detailed knowledge of the relation between tissue-specific acoustic properties and histologic features is essential to achieve highly accurate quantitative ultrasonography results. This study evaluated the relation between acoustic properties and microscopic histologic features, especially focusing on acoustic impedance and speed of sound in rat livers of four histologic types: healthy livers, fatty livers, livers with non-alcoholic steatohepatitis (NASH), fibrotic livers. An 80-MHz center frequency transducer (resolution 20 μm) equipped with a scanning acoustic microscopy system was employed. Statistical analysis showed that both acoustic impedance and speed of sound were slightly lower in lipid-rich tissue (i.e., fatty and NASH liver) than in healthy rat liver and were both higher in fibrotic liver than in the other types (p<0.01). This tendency suggests that these two parameters (impedance, speed of sound) indicated the presence of tissue degeneration caused by lipid deposits or fibrosis. It is thus possible to use them to distinguish an unhealthy from a healthy liver.
