Extraskeletal masses are chondrosarcomas. Central chondrosarcoma is a chondrosarcoma that originates from within the bone. The main symptom is deep pain that is not intense and non-persistent. In the progressive stage of the tumor, large spherical extraosseous masses may form. There are distinct sites of predilection, in order of predilection, for the femur (especially proximal), pelvis, proximal humerus, scapula, and proximal tibia. The other bones of the trunk, the radius, the ulna, the foot, and the hand are the less frequent sites of softness (chondromas are common in the hand and less common in the trunk bones). CT examination of bone, joint and soft tissue CT examination of bone, joint and soft tissue is a method to examine bone, joint and soft tissue by CT. It is mainly for injuries and diseases of bones, joints and soft tissues. It is suitable for patients with bone, joint and soft tissue diseases. CT examination of bone, joint and soft tissue can understand the lesions of bone, joint and soft tissue, and has diagnostic significance for bone, joint and soft tissue diseases. Bone, joint and soft tissue CT examination procedure: 1. Intravenous injection of drugs: Different imaging agents are used according to the purpose of the examination. After injection, please rest quietly, do not talk to others, and avoid tense body position. The waiting time after injection is different for different examination items (basically more than 40 minutes). 2.Empty urine before PET/CT examination (for tumor screening) to avoid urine contamination of body surface and clothing. 3.During the PET/CT examination of the body, both arms need to be raised, and the examination time is usually about 20 minutes; for the brain examination, both arms do not need to be raised, and the examination time is usually about 10 minutes. Usually, family members are not allowed to enter the scanning room during the scanning process. 4. When the examination is completed, the doctor on duty will observe whether the image quality meets the requirements and notify the patient to leave after approval; depending on the condition, some patients may need to undergo delayed imaging or CT-enhanced scanning, and sign the informed consent form before CT-enhanced examination. Bone imaging Bone imaging can diagnose bone tumor and bone metastasis 3-6 months earlier than X-ray examination, but it should be noted that this method is highly sensitive and low specificity. Bone imaging can diagnose bone tumor and bone metastasis 3-6 months earlier than X-ray examination, according to the specific analysis of bone imaging. Bone imaging procedure: 1. Conventional bone imaging: it is a static bone imaging of the whole body or local area 2-3 hours after intravenous injection of bone imaging agent. Intravenous injection of imaging agent, static 2-3 hours, at this time, most of the imaging agent has not entered the bone tissue has been excreted from the kidneys, blood radioactivity as the background has been significantly reduced, the bone image is clear. 2.Because the bone imaging agent is not uniformly distributed in the bones of normal people, the method of comparing the radioactivity of symmetrical parts on the left and right sides is used to identify the lesion and normal bone tissue. 3, dynamic bone imaging: refers to the three-time phase bone imaging technology, three-time phase imaging technology is in the intravenous injection of bone imaging agent at different times for multiple imaging, respectively, to collect blood flow, blood pool and delayed (static) bone imaging data, Tc-MDP “bullet” intravenous injection immediately after the speed of 2 seconds a frame continuous acquisition of one minute The arterial perfusion series of the lesion site and its symmetrical parts were obtained, at which time the large arteries and secondary arteries were visualized one after another, followed by the gradual display of the soft tissue contours.