Yaping Luo 1 2, Qingqing Pan 1 2, Huaxia Yang 3, Linyi Peng 3, Wen Zhang 3, Fang Li 4 2

Abstract: IgG4-related disease (RD) is characterized by lymphoplasmacytic infiltration enriched in IgG4-positive plasma cells and variable degrees of fibrosis with a characteristic storiform pattern. Since fibrosis is an important feature of IgG4-RD, we performed a prospective cohort study to evaluate the performance of 68Ga-fibroblast activation protein inhibitor (FAPI), a recently introduced PET agent targeting fibroblast activation protein, in IgG4-RD.

Methods: Twenty-six patients with IgG4-RD were recruited. All patients underwent both 68Ga-FAPI and 18F-FDG PET/CT. The positive rates of the PET/CT scans in the involved organs and the uptake values were compared.

Results: In a total of 136 involved organs in the 26 patients, 68Ga-FAPI PET/CT additionally detected 18 (13.2%) involved organs in 13 (50.0%) patients, compared with 18F-FDG PET/CT. 68Ga-FAPI PET/CT had a higher positive rate than 18F-FDG PET/CT in detecting involvement in the pancreas, bile duct/liver, and lacrimal gland. 68Ga-FAPI also demonstrated significantly higher uptake than 18F-FDG in the matched disease in the pancreas, bile duct/liver, and salivary gland (P < 0.01). However, lymph node involvement with flip-flop uptake of 18F-FDG did not accumulate 68Ga-FAPI.

Conclusion: 68Ga-FAPI might be a promising imaging agent for the assessment of IgG4-RD.

Affiliations:

  1. Department of Nuclear Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College Hospital, Beijing, China.
  2. Beijing Key Laboratory of Molecular Targeted Diagnosis and Therapy in Nuclear Medicine, Beijing, China; and.
  3. Department of Rheumatology, Chinese Academy of Medical Sciences and Peking Union Medical College Hospital, Beijing, China.
  4. Department of Nuclear Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College Hospital, Beijing, China lifang@pumch.cn.