Usefulness of 2-[18F]-fluoro-2-deoxy- d-glucose-Positron Emission Tomography/Computed Tomography for Staging and Evaluation of Treatment Response in IgG4-Related Disease: A Retrospective Multicenter Study.

Objective To evaluate the usefulness of 2-[¹⁸F]-fluoro-2-deoxy- d-glucose-positron emission tomography/computed tomography (FDG-PET/CT) in IgG4-related disease (IgG4-RD) for the staging of the disease and the followup under treatment. Methods All patients included in the French IgG4-RD registry who underwent ≥1 FDG-PET/CT scan were included in the study. Clinical, biologic, pathologic, radiologic, and FDG-PET/CT qualitative and quantitative findings were retrospectively collected and analyzed. Results Twenty-one patients were included in the study and 46 FDG-PET/CT examinations were evaluated. At either diagnosis or relapse, all evaluated patients presented abnormal ¹⁸F-FDG uptake in typical IgG4-RD localizations. In most cases, FDG-PET/CT was more sensitive than conventional imaging to detect organ involvement, especially in arteries, salivary glands, and lymph nodes. In few cases (small-sized lesions and brain or kidney contiguous lesions), false-negative results were noted. Evaluation before and after treatment showed in most cases a good correlation of FDG-PET/CT results with treatment response and disease activity. Conclusion This large retrospective study shows that FDG-PET/CT imaging is useful for the staging of IgG4-RD. Moreover, FDG-PET/CT is useful to assess the response to treatment during followup. [ABSTRACT FROM AUTHOR]