Performance of⁶⁸Ga-Labeled Fibroblast Activation Protein Inhibitor PET/CT in Evaluation of Erdheim–Chester Disease: A Comparison with¹⁸F-FDG PET/CT

Abstract

Erdheim-Chester disease (ECD) involves multiple organs and tissues and has diverse manifestations, which makes it difficult to distinguish lesions caused by ECD from those caused by other diseases. Variable degrees of fibrosis are present in ECD. Therefore, we conducted a prospective cohort study to explore the ability of 68 Ga fibroblast activation protein inhibitor ( 68 Ga-FAPI) PET/CT to detect lesions in ECD patients. Methods: Fourteen patients diagnosed with ECD, as confirmed by histology, were included in this study. For every patient, 68 Ga-FAPI PET/CT and 18 F-FDG PET/CT were conducted within 1 wk. The positive rate and SUV max of the lesions in the involved organs were compared between the examinations. Results: The most commonly involved organs were bone (100%), heart (57.1%), lung (57.1%), kidney (42.9%), and peritoneum or omentum (35.7%); other common manifestations were intracranial infiltration (50%) and cutaneous infiltration (35.7%). 68 Ga-FAPI PET/CT detected 64 of 67 lesions in 14 patients, whereas 18 F-FDG PET/CT detected 51 of 67 lesions (P 5 0.004). The SUV max for 68 Ga-FAPI PET/CT was significantly higher than the SUV max for 18 F-FDG PET/CT of the heart (4.9 6 2.4 vs. 2.8 6 1.2, respectively;