Characterizing Rheumatoid Arthritis With 68Ga-FAPI PET/CT

Study Overview
=================
Brief Summary
-----------------
68Ga-FAPI has been developed as a tumor-targeting agent as fibroblast activation protein is overexpressed in cancer-associated fibroblasts and some inflammation, such as IgG4-related disease and inflammatory bowel disease. Some researches identified FAP expression in synovial samples taken from both rheumatoid arthritis and osteoarthritis patients.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 arthritis than 18F-FDG PET/CT.

Detailed Description
-----------------
Arthritis is a term used to mean any disorder that affects the joints. The two most common forms of arthritis are osteoarthritis and rheumatoid arthritis.Rheumatoid arthritis is an autoimmune chronic inflammatory disease of unknown etiology and is characterized by chronic inflammation of the joint capsule's synovial membrane. This chronic inflammation ultimately destroys the underlying cartilage and bone. Activated fibroblast-like synoviocytes (FLS) line the synovial membrane and are a prominent cell type responsible for inflammation and joint destruction. Osteoarthritis is characterized by degradation of joint cartilage. Studies demonstrate chondrocytes expressed FAP and that chondrocyte FAP expression was elevated in patients with osteoarthritis. Other researches identified FAP expression in synovial samples taken from both rheumatoid arthritis and osteoarthritis patients. However, FAP expression was greater in samples taken from refractory rheumatoid arthritis patients in comparison to end-stage osteoarthritis patients.68Ga-FAPI has been developed as a tumor-targeting agent as fibroblast activation protein is overexpressed in cancer-associated fibroblasts and some inflammation, such as IgG4-related disease and inflammatory bowel disease. Recently the investigators have published an article of the application of 68Ga-FAPI in IgG4-related disease which showed it was more sensitive than FDG in detecting a certain type of inflammations. 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 arthritis than 18F-FDG PET/CT.

Official Title
-----------------
Characterizing Rheumatoid Arthritis With 68Ga-FAPI PET/CT

Conditions
-----------------
Arthritis

Intervention / Treatment
-----------------
* Drug: 68Ga-FAPI


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: suspected or confirmed untreated arthritis 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
-----------------
Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

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 arthritis by PET/CT.<br>* Other names: 68Ga-fibroblast activating protein inhibitors;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diagnostic value | Sensitivity and Specificity of 68Ga-FAPI PET/CT for IgG4-RD 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 focal lesions are measured on 68Ga-FAPI PET/CT. | Time Frame: through study completion, an average of 1 year | 
| Disease burden assessement | whether Total Lesion Glycolysis (TLG) assessed on 68Ga-FAPI PET/CT was correlated with clinical parameters for arthritis using correlation coefficients analysis | 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 | 
| Therapy response | Change of Total Lesion Glycolysis (TLG) on 68Ga-FAPI PET/CT after therapy | through study completion, an average of 1 year |