THERE ARE certain disease entities involving the liver that are extremely difficult to diagnose accurately by physical examination or by the standard laboratory and roentgenographic studies. In situations where the liver substance has been replaced, in part, by abscess, cyst, benign tumor, primary or metastatic malignant tumor, and so forth, the diagnosis may remain in doubt until large areas of the liver have been destroyed. It has often been noted that patients with fairly widespread metastatic cancer of the liver will have normal liver "profile" tests. A recent study reported that in approximately one-third of autopsy cases of multiple liver metastases the organ was not enlarged. The technique of liver scanning using a radioactive labeled liver dye or colloid has been developed during the past few years. Rose bengal dye (tetrachlor-tetraiodo-fluorescein), which is most often used for liver scanning, was first described in 1923 by Delprat. Several years ago an