Skeletal scintigraphy with technetium-99m-tetraphenyl porphyrin sulfonate for the detection and determination of osteomyelitis in an animal model

This article explores the accumulation of ^99mTc-tetraphenyl porphyrin sulfonate (TPPS₄) at inflammatory sites, especially osteomyelitis, and compares the results with ¹¹¹In Cl₃ and ¹¹¹In-WBC in an animal model. Methods: Osteomyelitis was induced in 12 New Zealand white rabbits by injecting staphylococcus aureus in the left tibia. Three weeks later, radiographs confirmed the disease. Two hours later, after injection of 74 MBq ^99mTc-TPPS₄, scintiphotos of the lower extremities were acquired and repeat scintiphotos were obtained 24 hr after injection of 5.55 MBq ¹¹¹In Cl₃. After these studies, 24- and 48-hr scintiphotos of the lower extremities were acquired after injecting 5.55 MBq ¹¹¹In-labeled WBC. Results: The left tibia averaged three times the uptake with ^99mTc-TPPS₄ compared with right tibia; with ¹¹¹In Cl₃ and ¹¹¹In WBC the ratios are two times. These three radiopharmaceuticals reveal positive images, but the image quality using ^99mTc-TPPS₄ is better, as would be expected from the more favorable physical characteristics of ^99mTc and the higher uptake. Conclusion: The traditional combination of three-phase bone and ⁶⁷Ga- citrate scintigraphy can be replaced by a single injection of ^99mTc- TPPS₄ with imaging as early as 2 hr. Finally, the use ^99mTc-TPPS₄ should result in a substantial reduction in radiopharmaceutical cost.