Background and aim: (99m)Tc-depreotide is a (99m)Tc-labelled somatostatin analogue, with high affinity for the 2, 3 and 5 subtypes of somatostatin receptors. These particular receptors are over-expressed on the surface of activated leucocytes, which mediate inflammatory response. Based on this property this study tried to investigate whether (99m)Tc-depreotide scintigraphy could be a useful complementary method in the investigation of bone infection and inflammation.
Methods: Twenty-three patients, who were investigated for probable osteomyelitis, underwent three-phase bone scintigraphy followed by (99m)Tc-depreotide scintigraphy. Clinical and laboratory findings, complementary imaging procedures, clinical follow-up and bone biopsy established the final diagnosis. (99m)Tc-depreotide scintigraphy was performed 3 h after the intravenous administration of 555-740 MBq of the radiopharmaceutical. Scintigraphic images were, at first, blindly interpreted alone and then in comparative assessment with bone scans.
Results: (99m)Tc-depreotide was positive in 12/12 cases of active osteomyelitis, one case of recent femoral head osteonecrosis and 6/9 rheumatoid arthritis sites. Negative (99m)Tc-depreotide scans were acquired in five cases of 'no-inflammation' (an uncomplicated fracture, an aseptic loosening of prosthesis, an old osteonecrosis, a healed and a successfully treated osteomyelitis), as well as in 14/14 total sites of degenerative arthritis-osteoarthropathy. In five cases (septic arthritis, periodontal and soft tissue infections) (99m)Tc-depreotide was positive, though spatially discordant with bone scintigraphy, delineating precisely the focus of infection.
Conclusion: (99m)Tc-depreotide can be a useful complementary imaging method in the evaluation of bone infection and inflammation. Its combination with three-phase bone scintigraphy seems to be accurate in localizing the infection foci and determining the activity of the inflammatory processes.