Basic acoustic parameters are examined in rabbit liver with and without a solid contrast agent used for tumor detection. In normal liver, backscatter, attenuation, and sound speed are found to decrease with increasing water content. The addition of micron-sized particles made from iodipamide ethyl ester (IDE) can increase backscatter and attenuation depending on size and concentration. A discrepancy of the increased backscatter from theoretical predictions based on random scatterers is attributed to the particle's biodistribution in the liver.