Scintigraphic imaging using technetium-99m-labeled ceftizoxime in an experimental model of acute osteomyelitis in rats.

PURPOSE: To investigate inflammatory (zymosan) and infectious (Staphylococcus aureus) processes in experimental models in rats using technetium-99m-labeled ceftizoxime (CFT).

METHODS

Male Wistar rats were used for the development of the inflammatory (zymosan) and infectious (S. aureus) processes in the medullary cavity of the left tibia. Sterile saline was used for the control group. At 48 h after induction of the processes, the animals were anesthetized and scintigraphic images were acquired at 1, 2, 4, and 6 h after intravenous injection of 0.1 ml of 99mTc-CFT (55 MBq). Quantitative analysis of the scintigraphic images was performed by counting the radioactivity in the regions of interest. Samples of tibia were taken for histopathological examination.

RESULTS

The images showed that 99mTc-CFT presented higher tropism to infectious foci than with the inflammatory site. The average value of the target/nontarget ratio of the 99mTc-CFT was significantly higher in the infected (2.40+/-0.22) than in the inflamed tibia (1.50+/-0.05) and the control group (1.05+/-0.04) for all of the investigated times. The histological data showed a similar inflammatory response for both the S. aureus and zymosan groups.

CONCLUSION

The 99mTc-CFT presented a high tropism and retention for an infected region in this model of osteomyelitis, thereby constituting an interesting strategy to distinguish aseptic from septic sites.