99mTc-alafosfalin: an antibiotic peptide infection imaging agent

Nucl Med Biol. 2003 Feb;30(2):169-75. doi: 10.1016/s0969-8051(02)00348-7.


The radiolabeled antibiotic peptide (99m)Tc-alafosfalin was assessed as an infection imaging agent in a rat model by comparison with (99m)Tc-DTPA and (99m)Tc-leukocytes. (99m)Tc-alafosfalin was prepared via an instant cold kit and (99m)Tc-leukocytes were prepared using (99m)Tc-stannous fluoride colloid in an ex vivo labeling procedure of whole blood. In separate experiments, the three radiotracers were administered to rats infected with staphylococcus aureus. Quantitative biodistribution studies were performed as well as scintigraphic images and histopathology. (99m)Tc-alafosfalin is a stable product, obtained in high radiochemical purity (>95%). This agent was mainly renally excreted, with low liver, spleen and bone uptake, and resulted in a mean ratio of infected/non-infected thighs of 4.3/1.0 at 4 hr post radiotracer injection. (99m)Tc-DTPA gave a corresponding ratio of 1.9/1.0 and (99m)Tc-leukocytes gave 20.0/1.0 at the same time point. An in vitro assay found the level of (99m)Tc-alafosfalin binding to staphylococcus aureas higher than (99m)Tc-DTPA (10% versus 1% respectively). (99m)Tc-alafosfalin accumulates at sites of infection in a rat model better than the perfusion molecule (99m)Tc-DTPA, yet less than (99m)Tc-leukocytes. The distribution characteristics of this (99m)Tc-antibiotic peptide would be an advantage in imaging abdominal and soft tissue infection.

Publication types

  • Comparative Study
  • Evaluation Study
  • Validation Study

MeSH terms

  • Alanine / analogs & derivatives
  • Alanine / pharmacokinetics*
  • Animals
  • Anti-Bacterial Agents / pharmacokinetics
  • Bacterial Infections / blood
  • Bacterial Infections / diagnostic imaging
  • Bacterial Infections / metabolism
  • Bacterial Infections / pathology
  • Female
  • Leukocytes / diagnostic imaging
  • Myositis / blood
  • Myositis / diagnostic imaging
  • Myositis / metabolism
  • Myositis / pathology
  • Organ Specificity
  • Organotechnetium Compounds / pharmacokinetics*
  • Peptides / pharmacokinetics
  • Radionuclide Imaging
  • Radiopharmaceuticals / pharmacokinetics
  • Rats
  • Rats, Sprague-Dawley
  • Staphylococcal Infections / blood
  • Staphylococcal Infections / diagnostic imaging*
  • Staphylococcal Infections / metabolism*
  • Staphylococcal Infections / pathology
  • Technetium / pharmacokinetics
  • Technetium Tc 99m Pentetate / pharmacokinetics
  • Tissue Distribution
  • Whole-Body Counting


  • Anti-Bacterial Agents
  • Organotechnetium Compounds
  • Peptides
  • Radiopharmaceuticals
  • technetium 99m alafosfalin
  • Technetium
  • Alanine
  • Technetium Tc 99m Pentetate