A new synthetic method for 99mTc labeled N-pyridoxyl-5-methyltryptophan as a hepatoma imaging agent.
N-Pyridoxyl-5-methyltryptophan (5-PMT) was synthesized by a simplified method using sodium borohydride for the reduction of a Schiff base of pyridoxal and 5-methyltryptophan. Lyophilized kits containing 5-PMT, stannous chloride and L-(+)-ascorbic acid were prepared and labeled to afford 99mTc-5-PMT with 96% or higher radiochemical purity analysed by two thin-layer chromatographic solvent systems. 99mTc-5-PMT showed a rapid blood clearance, a faster hepatobiliary transit and a lower renal retention in comparison with 99mTc-5-EHIDA in rats. Eleven (61%) of 18 patients with histologically confirmed hepatocellular carcinoma showed positive images at 2 to 5 h after i.v. injection. The smallest tumor that could be identified was 2 cm in diameter with the best tumor/liver ratio of 4. In conclusion, 99mTc-5-PMT synthesized by sodium borohydride reduction shows great promise as a useful hepatoma imaging agent.
Zhou
Y G
YG
Shanghai Medical University, China.
Zhu
T
T
Zhao
H Y
HY
Wu
Z M
ZM
Shi
Q X
QX
Liang
F H
FH
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D007202:Indicators and Reagents; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D015609:Organotechnetium Compounds; D011730:Pyridoxal / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000493:pharmacokinetics; D011877:Radionuclide Imaging; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000493:pharmacokinetics
D007202:Indicators and Reagents; D009942:Organometallic Compounds; D015609:Organotechnetium Compounds; C038081:technetium Tc 99m pyridoxyl-5-methyltryptophan; D011730:Pyridoxal; D014364:Tryptophan