Clinical evaluation of sup(99m)Tc-N-pyridoxyl-5-methyltryptophan hepatobiliary scintigraphy in hepatocellular carcinoma

We have assessed the diagnostic value of sup(99m)Tc-N-pyridoxyl-5-methyltryptophan (sup(99m)Tc-PMT) hepatobiliary scintigraphy in 28 patients with hepatocellular carcinoma (HCC) who had obvious filling defects on sup(99m)Tc-phytate liver scintigram. Uptake of sup(99m)Tc-PMT in obvious defects on sup(99m)Tc-phytate liver scintigram was observed in 16 out of 28 patients (57.1 %). Most of HCC with sup(99m)Tc-PMT uptake were histologically well-differenciated. However, well-differenciated HCC did not always take up sup(99m)Tc-PMT. No correlation was observed between sup(99m)Tc-PMT uptake in the tumor and levels of serum alpha-fetoprotein. Patients with high alpha-fetoprotein level (>3000 ng/ml) were only 9 patients (32.1 %) in our study. By the combined results of sup(99m)Tc-PMT hepatobiliary scintigraphy and alpha-fetoprotein level (>3000 ng/ml), diagnostic rate for HCC was markedly elevated up to 75 %. Therefore, it is considered that sup(99m)Tc-PMT hepatobiliary scintigraphy is clinically useful for specific diagnosis of HCC. Furthermore, it provides the information for invasion of HCC into the bile duct. (author)