Retrospective Study of FAPI Imaging in Bone Metastases: Diagnostic Utility and Therapeutic Relevance Across Cancer Types in a Single-Center Real-World Cohort

Bone metastases frequently occur in advanced-stage malignancies, contributing to diminished quality of life and unfavorable prognoses. However, conventional imaging modalities for diagnosing bone metastases exhibit inherent limitations. This study aimed to evaluate the diagnostic utility of fibroblast activation protein inhibitor (FAPI) imaging using [99mTc]Tc-H7ND for detecting bone metastases (BM). From June 2021 to September 2023, 564 patients with malignancies underwent FAPI imaging were screened. Eighty patients with confirmed or suspected BM were included. FAPI SPECT/CT was compared with CT, MRI, bone scintigraphy (BS), and [¹⁸F]FDG PET/CT for diagnostic efficacy. The uptake values in different components of BM were assessed, alongside discussions on potential of FAPI imaging in evaluating treatment response. Eighty patients (median age: 60 years; range: 23–79 years; 48 men) with confirmed or suspected BM were included, of these, 64 were confirmed BM. FAPI SPECT/CT demonstrated superior sensitivity (96.5