Gray scale ultrasound and isotope scanning: complementary techniques for imaging the liver.

Technical advances in gray scale ultrasound have led to better signal-to-noise ratios and improved resolution. A display of the texture of the liver is now possible, making ultrasound an important complementary technique to radioisotope scanning. In the positive radioisotope scan, ultrasound permits differentiation of isotopically cold areas into neoplasms, benign cysts, and abscesses. In addition, when the radioisotope scan is equivocal, ultrasound is invaluable in differentiating normal variants from disease states. Dilated intrahepatic ducts can also be identified. Examples of the use of ultrasound in defining radioisotope abnormalities are presented.