Characterizing IgG4-RD 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 it might be more sensitive than FDG in detecting a certain type of inflammations according to our preliminary research.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 IgG4-related disease.

Detailed Description
-----------------
Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory condition that is capable of affecting multiple organs. Common forms of presentation include:Type 1 (IgG4-related) autoimmune pancreatitis (AIP)，IgG4-related sclerosing cholangitis, major salivary gland enlargement or sclerosing sialadenitis; Orbital disease, often with proptosis and retroperitoneal fibrosis. The involved organs share a number of core pathologic features and striking clinical and serologic similarities, including tumor-like swelling of involved organs, a lymphoplasmacytic infiltrate enriched in IgG4-positive plasma cells, and a variable degree of fibrosis that has a characteristic storiform pattern. 68Ga-FAPI has been developed as a tumor-targeting agent as fibroblast activation protein is overexpressed in cancer-associated fibroblasts and it might be a pan-tumor PET agent. Recently we have reported a case of IgG4-related disease revealed by 68Ga-FAPI and 18F-FDG PET/CT which showed FAPI was not more tumor-specific than FDG, furthermore,it might be more sensitive than FDG in detecting a certain type of inflammations-like the pancreatic lesion. 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 IgG4-related disease.

Official Title
-----------------
Characterizing IgG4-related Disease With 68Ga-FAPI PET/CT

Conditions
-----------------
IgG4-related Disease

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


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: suspected or confirmed untreated IgG4-RD 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 IgG4-RD 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 |
| --- | --- | --- |
| Metabolic parameters | Total Lesion Glycolysis (TLG) of focal lesions are measured on 68Ga-FAPI PET/CT. | through study completion, an average of 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diagnostic value | Diagnostic value of 68Ga-FAPI PET/CT for IgG4-RD in comparison with 18F-FDG PET/CT. | through study completion, an average of 1 year | 
| adverse events | Number of participants and kind of adverse events as a measure of safety. | through study completion, an average of 1 year | 
| Disease burden assessement | Correlation between disease burden assessed on 68Ga-FAPI PET/CT and clinical parameters for IgG4-RD. | 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 | 
| Prediction value | Prediction value of 68Ga-FAPI PET/CT for IgG4-RD in therapy response assessment | through study completion, an average of 1 year |