Comparison of delayed hepatobiliary imaging using 99mTc-Sn-N-pyridoxyl-5-methyltryptophan and 67Ga-citrate imaging for diagnosis of hepatocellular carcinoma

Images were obtained both with a biliary agent, ^99mTc-Sn-N-pyridoxyl-5-methyltryptophan (^99mTc-PMT), and with ⁶⁷Ga-citrate in 40 cases of hepatocellular carcinoma and in 43 cases of other hepatic diseases and results were compared. Positive results were obtained by delayed ^99mTc-PMT imaging in 25 (63%) of 40 cases of hepatoma: the hepatic tumor showed increased uptake in 18 cases (45%) and equilibrated uptake in 7 cases (18%). Positive ⁶⁷Ga-citrate imaging was found in 28 (70%) of the 40 cases of hepatoma: increased uptake was seen in 24 cases (60%) and equilibrated uptake in 4 cases (10%). Of 15 cases of hepatoma giving negative results in the ^99mTc-PMT study, 7 cases (47%) took up ⁶⁷Ga-citrate, and 6 of these showed increased ⁶⁷Ga-citrate uptake by the hepatic tumors. A certain relation existed between the degree of histological differentiation of hepatomas and the intensity of ^99mTc-PMT uptake by those tumors, while such a histological correlation was denied for ⁶⁷Ga-citrate uptake by the tumors. Delayed ^99mTc-PMT imaging is preferable to ⁶⁷Ga-citrate imaging for increasing the specificity of diagnosis of hepatoma. ⁶⁷Ga-citrate should be used in those cases that do not give positive results with ^99mTc-PMT.