A comparative

Area of Science:

• Nuclear Medicine
• Infectious Diseases
• Orthopedics
• Immunology

Background:

• Osteomyelitis diagnosis is critical for treatment success, with increased PD-L1 expression often indicating infection.
• Nuclear imaging, particularly PET, offers non-invasive, whole-body assessment of PD-L1 expression.
• Implant-associated Staphylococcus aureus osteomyelitis (IAOM) presents diagnostic challenges.

Purpose of the Study:

• To compare the efficacy of 18F-FDG and a novel 18F-labeled PD-L1-binding peptide probe (18F-PD-L1P) in PET imaging of IAOM.
• To evaluate the sensitivity and accuracy of 18F-PD-L1P for early detection of S. aureus osteomyelitis.

Main Methods:

• Synthesis of an anti-PD-L1 probe (18F-PD-L1P).
• Comparison of 18F-FDG and 18F-PD-L1P in PET imaging of IAOM in rat tibias at 7 and 21 days post-infection.
• Quantification of probe uptake using %ID/g ratios and correlation with PD-L1 immunohistochemistry (IHC) findings.

Main Results:

• 18F-PD-L1P demonstrated significantly higher %ID/g ratios than 18F-FDG at both 7 and 21 days post-infection (P=0.001 and P=0.028, respectively).
• The uptake intensity of 18F-PD-L1P correlated with pathological changes observed in osteomyelitic bones.
• 18F-PD-L1P provided earlier and more sensitive detection of S. aureus osteomyelitis compared to 18F-FDG.

Conclusions:

• The 18F-PD-L1P probe is a promising radiotracer for the early and accurate diagnosis of S. aureus osteomyelitis.
• This novel probe enhances diagnostic capabilities for infection-induced bone diseases.