Imaging experimental osteomyelitis using radiolabeled liposomes

Vibhudutta Awasthi, Beth Goins, Robert Klipper, Rebecca Loredo, Donna Korvick, William T. Phillips

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Abstract

We evaluated radiolabeled liposomes (liposomes labeled both with 99mTc and 111In) for the early detection of osteomyelitis in an experimental model. Methods: Liposomes, containing 5% polyethylene glycol- distearoyl phosphatidylethanolamine with encapsulated glutathione and deferoxamine, were prepared and labeled with 99mTc and 111In by a previously described method. Acute osteomyelitis was induced in male New Zealand rabbits by intramedullary injection of sodium-morrhuate and Staphylococcus aureus in the tibial bone marrow. Serial imaging studies, consisting of radiolabeled liposome imaging (2-4 mCi 699mTc and 75-125 μCi 111In), 99mTc-methylene diphosphonate (MDP) (3-5 mCi) and 67Ga- citrate (500 μCi), were performed starting at the third day after injection. Each radionuclide study was separated by at least 2 days. The animals also underwent radiography of the lower extremities. The animals were then killed and the infected tibia was excised for histopathology. Results: For interpreting relative efficacy of individual radiopharmaceuticals, only animals showing positive histopathological findings (n = 9) were considered. Radiographs (Days 12, 13) were conclusive for osteomyelitis in only 3 rabbits. Radiolabeled liposome imaging (Days 4-6) showed positivity in 8 cases and was equivocal in 1. Though the lesion could be delineated as early as 8 hr postinjection in the 99mTc window, the best target-to-nontarget ratio (T/NT) of 1.86 ± 0.19 was obtained at 48 hr in the 111n window. Three-phase 99mTc-MDP scan (Day 7) was positive in only 5 rabbits with 3 hr T/NT of 1.6 ± 0.23. Galium-67-citrate images (Days 9-11) were positive in 8 cases and equivocal in 1, the mean 48 hr T/NT being 1.74 ± 0.24. These results show liposomes are better than 99mTc-MDP for imaging bone infection. Given the early localization and better quality of the images, radiolabeled liposomes also exhibited advantages over 67Ga-citrate for detection of acute osteomyelitis.

Original languageEnglish (US)
Pages (from-to)1089-1094
Number of pages6
JournalJournal of Nuclear Medicine
Volume39
Issue number6
StatePublished - Jun 1 1998

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Keywords

  • Infection imaging
  • Liposomes
  • Osteomyelitis
  • Technetium-99m

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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