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Author Notes:

Corresponding Author: Andrew Taylor, MD, Division of Nuclear Medicine, Emory University Hospital, 1364 Clifton Rd., NE, Atlanta, GA 30322; Email: ataylor@emory.edu

We thank Dr. Patricia A. Marzilli for her invaluable comments during the preparation of the paper.


Research Funding:

This research was supported by the National Institutes of Health grant no. DK38842.


  • 99mTc tricarbonyl
  • lanthionine
  • 99mTc(CO)3(LAN)
  • renal radiopharmaceuticals

First Evaluation of a 99mTc-Tricarbonyl Complex, 99mTc(CO)3(LAN), as a New Renal Radiopharmaceutical in Humans


Journal Title:

Journal of Nuclear Medicine and Radiation Therapy


Volume 47, Number 6


, Pages 1032-1040

Type of Work:

Article | Post-print: After Peer Review


99mTc-mercaptoacetyltriglycine (99mTc-MAG3), 99mTc-dd- and ll-ethylene-di-cysteine (99mTc-EC) and 99mTc-mercaptoacetamide-ethylene-cysteine (99mTc-MAEC) contain N3S or N2S2 ligands designed to accommodate the four ligating sites of the {99mTcO}3+ core; they are all excellent renal imaging agents but have renal clearances less than that of 131I-orthoiodohippurate (131I-OIH). To explore the potential of the newly accessible but less polar {99mTc(CO)3}+ core having three ligating sites, we decided to build on the success of 99mTc-EC with its N2S2 ligand and two dangling carboxylates and have chosen an N2S ligand that also has two dangling carboxyls, lanthionine (LANH2), to form 99mTc(CO)3(LAN), a new renal radiopharmaceutical.Methods Biodistribution studies were performed on Sprague-Dawley rats by using 99mTc(CO)3(LAN) isomers, meso-LAN and dd,ll-LAN (an enantiomeric mixture), coinjected with 131I-OIH. Human studies were also performed by coinjecting each 99mTc product (~74 MBq [~2 mCi]) and 131I-OIH (~ 7.4 MBq [~ 0.2 mCi]) into 3 normal volunteers with dual-isotope imaging performed by using a camera system fitted with a high-energy collimator. Blood samples were obtained from 3 to 90 min after injection, and urine samples were obtained at 30, 90 and 180 min. Results Biodistribution studies in rats revealed a rapid blood clearance as well as rapid renal extraction for both preparations, with the dose in urine at 60 min averaging 88% that of 131I-OIH. In humans, both agents provided excellent renal images, with the plasma clearance averaging 228 mL/min for 99mTc(CO)3(meso-LAN) and 176 mL/min for 99mTc(CO)3(dd,ll-LAN), respectively. At 3 hours, both 99mTc(CO)3(meso-LAN) and 99mTc(CO)3(dd,ll-LAN), showed good renal excretion, averaging 85% and 77% that of 131I-OIH, respectively. Plasma protein binding was minimal (10% and 2%), and red cell uptake was similar (24% and 21%) for 99mTc(CO)3(meso-LAN) and 99mTc(CO)3(dd,ll-LAN), respectively. Conclusion Although the plasma clearance and the rate of renal excretion of the 99mTc(CO)3(LAN) complexes are still less than those of 131I-OIH, the results of this first application of a 99mTc tricarbonyl complex as a renal radiopharmaceutical in humans demonstrate that 99mTc(CO)3(LAN) complexes are excellent renal imaging agents and support continued renal radiopharmaceutical development based on the 99mTc tricarbonyl core.

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© 2006 SNMMI; all rights reserved

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