Abstract: Objective:To explore the radionuclide distribution characteristics of ^99mTc-MDP bone imaging of bone tumors or tumor-like lesions in extremities, to clarify the application value of radionuclide distribution characteristics of ^99mTc-MDP bone imaging of bone tumor and tumor-like lesions with different pathological types in the differential diagnosis, and to provide the clues for clinical diagnosis. Methods:A total of 76 patients with abnormal radionuclide distribution characterics of exetremities showed in ^99mTc-MDP bone imaging were selected. The results of ^99mTc-MDP bone imaging were compared with the results of the final clinica diagnosis.The differences in the age, lesion location, radienuclide distribution characteristics of the patients with different pathological types were analyzed. Semi quantitative method (T/N) was used to detect the degree of radioactivity and the differences in T/N between benign and malignant lesions groups. Results:① Among 76 patients with bone tumors and tumor-like lesions,the pathological benign findings were in 24 cases and the malignant findings were in 52 cases.②The age of the patients with giant cell tumor of bone around knee joint was (42.1 ±17.4)years old,and the age of the patients with fibrous dysplasia in proximal femur was (48.0±17.1) years old. In malignant lesions,the age of the patients with metastatic carcinoma located in femoral shaft was (64.0 ±14.2)years old; the age of the patients with osteosarcoma around epiphysis end was (30.3±15.3) years old; the age of the patient with Ewing's sarcoma located in femur was (49.2 ±4.7) years old; the age of patients with fibrosarcoma in long bone was (39.5 ±17.2)years old; the age of patients with chondrosarcoma occurred in long bone was (63.0±14.8)years old. ③The radionuclide distribution characteristics of giant cell tumor, osteosarcoma, Ewing's sarcoma, chondrosarcoma and fibrosarcoma were "wedge" or "lumpy";the radiological defect of giant cell tumor was greater than Ewing's sarcoma and fibrosarcoma, while osteosarcoma and chondrosarcoma rarely had center defects; the radionuclide distribution characteristics of fibrous dysplasia and metastasis were "strip-type",and the metastases involving bilateral cortical bone had the radioactive defect in the central region, but fibrous dysplasia distributed uniformly along with the unilateral cortical bone. ④ The average value of T/N in malignant lesions (3.38±1.95) was higher than that in benign lesions (1.43±0.51)(t=-11.35, P<0.01). Conclusion:The pathological types of lesions can be preliminarily speculated according to the characteristics of ^99mTc-MDP bone imaging of bone tumors and tumor-like lesions of extremities, which can provide a reliable reference for clinical diagnosis and differential diagnosis.

Key words: ^99mTc-methylene diphosphonate, bone neoplasms, tumor-like lesions, extremities, bone imaging