PET, Primary Sjögren Syndrome
Conditions
Brief summary
Primary Sjögren's syndrome (pSS) is a chronic autoimmune exocrinopathy characterized by lymphocytic infiltration, progressive destruction of salivary gland acini, and varying degrees of functional impairment and fibrosis. Conventional imaging provides limited ability to simultaneously evaluate glandular function and inflammatory activity, leading to challenges in disease staging and treatment decision-making. This study explores a conceptual dual-tracer imaging framework using PSMA PET and FAPI PET to delineate complementary biological processes in pSS.
Detailed description
Based on current evidence, salivary gland acinar cells physiologically express PSMA; thus, reduced PSMA uptake may reflect loss of functional parenchyma in patients with pSS. In contrast, activated fibroblasts markedly express FAP, and increased FAPI uptake correlates with ongoing inflammation and fibroblast-driven remodeling. We hypothesize that within the same gland, functional decline (PSMA↓) and inflammatory activity (FAPI↑) may coexist and exhibit a negative correlation, forming a paired imaging biomarker that captures both pathological dimensions. By integrating these two signals into a combined PSMA/FAPI Index, this approach may enable more precise characterization of the "function-inflammation" spectrum in pSS, providing a noninvasive tool for disease staging, monitoring, and potentially predicting therapeutic response.
Interventions
DIAGNOSTIC_TEST⁶⁸Ga-PSMA PET/CT
PSMA PET imaging performed for clinical evaluation in prostate cancer patients, used as a comparator for physiologic salivary gland PSMA uptake.
DIAGNOSTIC_TEST⁶⁸Ga-FAPI PET/CT
FAPI PET imaging to assess inflammatory activity (FAPI) in patients with primary Sjögren's syndrome.
Sponsors
Peking Union Medical College Hospital
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
DIAGNOSTIC
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
* Age 18-80 years; * Fulfillment of the 2016 ACR-EULAR Classification Criteria for pSS at enrollment. OR diagnosis of a solid tumor scheduled for FAPI PET imaging
Exclusion criteria
* Combined with tumors or other connective tissue diseases (for SS group); * Patients who are currently using hormones/biological agents (for both groups)； * Pregnancy or lactation
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Difference in Salivary Gland PSMA Uptake Across Groups | Baseline | Quantitative comparison of PSMA PET uptake parameters (SUVmax, SUVmean) of the parotid glands among three groups: pSS patients, individuals with normal salivary glands, and prostate cancer patients. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Multiglandular PSMA Uptake Comparison | Baseline | Evaluation of PSMA PET uptake (SUVmax, SUVmean) in the parotid, submandibular, and lacrimal glands across the same study groups. |
| Correlation Between PSMA Uptake and Clinical Indicators | Baseline | Correlation of salivary gland PSMA SUV values with clinical, immunological, and functional markers of pSS, including ESR, CRP, IgG, RF, anti-SSA/SSB titers, unstimulated whole salivary flow rate, sialography findings, ESSDAI, and ESSPRI scores. |
| Quantitative and Spatial Relationship Between PSMA and FAPI Uptake Definition | Baseline | 1. Quantitative correlation: Association between PSMA SUV and FAPI SUV in the same glands. 2. Spatial co-localization: Overlap or complementarity of low-PSMA and high-FAPI regions within individual glands using image fusion and voxel-based analysis (e.g., Dice coefficient). |
Countries
China
Contacts
CONTACTZhaohui Zhu, MD
CONTACTJiarou Wang, MD
Outcome results
None listed