The liver contrast effects of
Sonazoid in two ultrasonographic imaging modes, gray-scale conventional and harmonic, were examined as a time-related study in normal rabbits, and evaluated quantitatively and visually with
tumor-model rabbits to estimate the diagnostic potential. Peak enhancement of vessels and parenchyma was observed 1 min after injection in both modes, although signal enhancement in the parenchyma lasted for 120 min compared with rapid decay (5-10 min) in vessels. When
Sonazoid was intravenously injected into metastatic
carcinoma-model (VX-2) rabbits, all hepatic
tumors showed ring enhancement in the early phase followed by clear contrast defects in the delayed phase, because signal enhancement remained only in normal parenchyma. Visual analysis scores for the diagnosis of
tumors were improved by
Sonazoid injection, and the videodensitometric differences between
tumor and normal tissues were significantly greater after injection. Although the harmonic mode tended to show better contrast effects, the conventional mode provided significant contrast enhancement in this hepatic
tumor-model.
Sonazoid might be useful for the detection of undifferentiated
tumors in the liver by making it possible to visualize neovascularity in the early phase and clear contrast defects in the delayed phase, not only in the harmonic but also in the conventional mode.