ULTRASONIC TISSUE CHARACTERIZATION OF EXPERIMENTAL VENOUS INTIMAL HYPERPLASIA

Ultrasonic tissue characterization (UTC) employing slope and Y-interce pt parameters from the normalized power spectrum of backscattered echo es was employed in vivo to study compositional changes in the walls of pig jugular veins in which thrombi were experimentally induced. Light microscopy revealed these changes to be intimal hyperplasia with an e arly predominance of smooth muscle cells and a later mixture of smooth muscle cells and collagen deposits. UTC distinguished intimal hyperpl asia from previously reported data from luminal thrombosis UTC. Furthe rmore, UTC was able to discriminate between early (predominantly smoot h muscle cells) and older (smooth muscle cells plus collagen deposits) intimal hyperplasia. The study suggests that intimal hyperplasia in t he experimental model used may be organized thrombus and that UTC may be able to follow both the development of wall changes as well as lumi nal changes occurring in venous thrombosis.