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

Abstract

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.