Characterizing SAPHO With 68Ga-FAPI PET/CT

Study Overview
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Brief Summary
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68Ga-FAPI has been developed as a tumor-targeting agent as fibroblast activation protein is overexpressed in cancer-associated fibroblasts and some inflammation. Thus this prospective study is going to investigate whether 68Ga-FAPI PET/CT may be superior for diagnosis, therapy response assessment and follow-up of SAPHO than 18F-FDG PET/CT.

Detailed Description
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Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a spectrum of heterogeneous diseases characterized by osteoarticular and dermatological manifestations. Inflammatory osteitis with hyperostosis is the central feature of the syndrome, typically affecting multiple areas and possibly progressing to irreversible osteoarticular damage. Owing to the relapsing-remitting disease course, the goal of management is to improve clinical symptoms and prevent disease progression. Therefore, it's meaningful to seek appropriate methods to evaluate current osteroarticular lesions. 68Ga-FAPI that targets fibroblast activation protein (FAP) is introduced in tumor imaging. However, FAP was also shown to be expressed in rheumatoid arthritis, bone lesions with acute to chronic inflammation, fibrosis and ischemic heart tissue after myocardial infarction, thus the investigators speculate that it is possible for SAPHO to be imaged with 68Ga-FAPI. The aim of this study is to evaluate the performance of 68Ga-FAPI PET/CT in SAPHO and to compare it with the performance of 18F-FDG PET/CT.

Official Title
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Characterizing Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis (SAPHO) With 68Ga-FAPI PET/CT

Conditions
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SAPHO Syndrome

Intervention / Treatment
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* Drug: 68Ga-FAPI


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: suspected or confirmed untreated SAPHO patients; 18F-FDG PET/CT within two weeks; signed written consent. Exclusion Criteria: pregnancy; breastfeeding; known allergy against FAPI any medical condition that in the opinion of the investigator may significantly interfere with study compliance.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 68Ga-FAPI PET/CT<br>Inject 68Ga-FAPI and then perform PET/CT scan. | Drug: 68Ga-FAPI<br>* Intravenous injection of one dosage of 74-148 MBq (2-4 mCi) 68Ga-FAPI. Tracer doses of 68Ga-FAPI will be used to image lesions of SAPHO by PET/CT.<br>* Other names: 68Ga-fibroblast activating protein inhibitors;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diagnostic value | Sensitivity and Specificity of 68Ga-FAPI PET/CT for SAPHO in comparison with 18F-FDG PET/CT | through study completion, an average of 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Metabolic parameters | Total Lesion Glycolysis (TLG) of SAPHO lesions are measured on 68Ga-FAPI PET/CT. | through study completion, an average of 1 year | 
| FAPI expression and SUV | Correlation between FAPI expression and SUV in PET | through study completion, an average of 1 year | 
| Disease burden assessement | Correlation between Total Lesion Glycolysis (TLG) of bone lesions assessed on 68Ga-FAPI PET/CT and clinical parameters for SAPHO | through study completion, an average of 1 year |