Using the novel FAPI probe 99mTc-HYNIC-FAPI-04 and quantitative SPECT/CT imaging technology, this study investigates the diagnostic efficacy of 99mTc-HYNIC-FAPI-04 quantitative SPECT/CT in patients with common solitary bone lesions in adults, and compares its diagnostic performance with conventional CT, MRI, and 99mTc-MDP bone scintigraphy. Follow-up pathological results of patients post-surgery were analysed to assess the accuracy of 99mTc-HYNIC-FAPI-04 diagnostic outcomes, and its diagnostic value and significance were evaluated.

Inclusion Criteria:

• Benign solitary bone lesions in adults (fibrous cortical defects, fibrous hyperplasia, non-ossifying fibroma, osteoblastoma, osteoid osteoma, osteochondroma, etc.); Malignant solitary bone lesions in adults (osteosarcoma, Ewing's sarcoma, chondrosarcoma, malignant giant cell tumour of bone, etc.); Other fibroblast-rich bone lesions (chordoma, alveolar soft part sarcoma, fibrosarcoma, malignant fibrous histiocytoma, etc.).

Exclusion Criteria:

• Severe liver and kidney dysfunction; Pregnant women and breastfeeding patients; Patients in poor physical condition who cannot tolerate the examination; Patients who cannot cooperate to complete the examination; Patients under the age of 18.