Comparison of ¹³¹I-Tetracycline and ⁶⁷Ga-Citrate as Abscess Localizing Agents

Summary

Previous studies have shown that radiolabeled tetracyclines tend to accumulate in infarcts and necrotic tumors. These results suggested that radiolabeled tetracyclines might also accumulate in necrotic abscesses or areas of inflammation. In order to develop a better abscess scanning agent, we compared the efficiency of ^13II-tetracycline with ⁶⁷Ga-citrate in labeling experimentally induced staphylococcal aureus abscesses in rats 24 and 72 hours after injection. In addition to evaluating ¹³¹I-tetracycline as an abscess scanning agent, we hoped to obtain data which might clarify the controversy regarding early versus late gallium scanning in suspected infection.

¹³¹I-tetracycline was chosen over ^99mTc-tetracycline because the longer half-life of ¹³¹I would allow 72 hour imaging. Absolute concentrations of gallium in the abscess contents and in the surrounding areas of inflammation were significantly greater than the concentration of ¹³¹I-tetracycline at both 24 and 72 hours. With the exception of blood, muscle, and bone, the abscess-to-tissue activity ratios for gallium and ¹³¹I-tetracycline were similar; however, the ratio of gallium activity in the inflammed tissue to other tissues was greater than that of 131I-tetracycline for every tissue examined at both time periods. The data suggest that 131I-tetracycline has little potential as a general abscess scanning agent. The gallium tissue concentrations and tissue ratios suggest that abscesses which can be imaged at 72 hours can probably be imaged at 24 hours, thus allowing earlier initiation of appropriate therapy. Because of the higher lesion-toblood ratio at 72 hours, a 72-hour scan would appear to be indicated before a scan is interpreted as normal.

• References

• 1 Chauncey D. M, Halpern S. E, Hagan P. L. et al. Tumor model studies of I-131. tetracycline and other compounds. J. Nucl. Med 1976; 17: 274-281.
• 2 Dewanjee M. K. Autoradiography of live and dead mammalian cells with ^99mTc-tetracycline. J. Nucl. Med 1975; 16: 315-317.
• 3 Dewanjee M. K, Prince E. W. Cellular necrosis model in tissue culture: uptake of ^99mTc-tetracycline and the pertechne-tate ion. J. Nucl. Med 1974; 15: 577-581.
• 4 Duran-Reynals F. Studies on the localization of dyes and foreign proteins in normal and malignant tissues. Amer. J. Cancer 1939; 35: 98-107.
• 5 Duszynski D. O, Kuhn J. P, Afshani E, Riddlesber-ger M. M. Early radionuclide diagnosis of acute osteomyelitis. Radiology 1975; 117: 337-340.
• 6 Handmaker H, Leonards R. The bone scan in inflammatory osseous disease. Sem. nucl. med 1976; VI: 95-106.
• 7 Holman B. L, Dewanjee M. K, Idoine J. et al. Detection and localization of experimental myocardial infarction with ^99mTc-tetracycline. J. Nucl. Med 1973; 14: 595-599.
• 8 Holman B. L, Kaplan W. D, Dewanjee M. K. et al. Tumor detection with ^99mTc-tetracycline. Radiology 1974; 112: 147-153.
• 9 Hopkins G. B, Kan M, Mende C. W. Early ⁶⁷Ga scintigraphy for the localization of abdominal abscesses. J. Nucl. Med 1975; 16: 990-992.
• 10 Hopkins G. B, Mende C. W. Gallium-67 and subphrenic abscesses - is delayed scintigraphy necessary? J. Nucl. Med 1975; 16: 609-611.
• 11 Littenberg R. L, Taketa R. M, Alazraki N. P. et al. Gallium-67 for localization of septic lesions. Ann. Intern. Med 1973; 79: 403-406.
• 12 Ludford R. The vital staining of normal and malignant cells. Proc. R. Soc. Lond. (Biol) 1929; 104: 493-512.
• 13 Taylor A, Hagan P. L, Alazraki N. P. et al. Tissue distribution of lead 203 acetate and its comparison with gallium-67 citrate as an abscess localizing agent. J. Nucl. Med 1976; 17: 470-472.
• 14 Vassar P, Saunders A, Culling C. Tetracycline fluorescence in malignant tumors and benign ulcers. Arch. Pathol 1960; 69: 613-616.