CT scan of extremities

CT examination of the extremities is an imaging technique for bone, joint, muscle and soft tissue lesions of the extremities. Prone position. The body is placed in the middle of the bed, lifted on both hands, the palms are up, and the elbow joints on both sides are close together to narrow the scanning field. The head is advanced. According to the positioning piece, including the entire elbow joint. Check the process with the doctor's password to do the action, do not arbitrarily move to ensure the clarity of the angiography. Basic Information Specialist Category: Inspection Category: CT Applicable gender: whether men and women apply fasting: not fasting Reminder: Before the examination, you must inform the CT doctor of the detailed medical history and various examination results. If you have your own X-ray films, magnetic resonance films and previous CT films, please submit them to CT doctor for reference. Normal value Normal bone and joint, muscle density is uniform, no abscess and destruction. Clinical significance Abnormal result I. Bone and joint diseases CT shows cross-sectional images of cortex, cancellous bone, bone marrow cavity, articular cartilage and adjacent muscles, fat and tendons. X-ray examination of bone and joint trauma can make a diagnosis. Only deep or anatomical complex areas, such as hip joint trauma, can be examined by CT. CT can show fractures, dislocations, intra-articular free bodies and soft tissue hematoma that are not found on X-ray films. CT can diagnose infectious diseases of bone and joint. Acute suppurative osteomyelitis, CT can be seen bone destruction, increased bone marrow density and small dead bone. When X-ray films are difficult to identify for inflammation and tumors, such as CT findings of the above changes and abscess in soft tissue, it is helpful for the diagnosis of osteomyelitis. Second, for bone tumors, CT can show the size, shape, contour, internal structure, relationship with surrounding tissues and understanding the extent of tumor invasion in the bone marrow cavity and invasion of extra-soft tissues. The detection of bone marrow by tumor infiltration has a high value, but CT is still difficult to identify the benign and malignant tumors and to determine the tumor properties. It should be considered in combination with clinical data. Third, soft tissue disease CT can show muscle separation of the limbs and large blood vessels and nerve structures, therefore, CT can be used to observe soft tissue diseases, determine the extent and nature of the lesion. The density of soft tissue tumors is generally lower than that of normal muscles. Enhanced scanning can increase the density difference between lesions and normal muscles. Most benign tumors have clear or enveloped boundaries and uniform texture, but there are limits to qualitative diagnosis. Lipomas are characterized by typical fat density. Cavernous hemangioma can be seen in the small circular venous stone in the mass, and the tumor is obviously strengthened after contrast-enhanced scanning, which has certain characteristics. Soft tissue malignant tumors are generally unclear, uneven in texture or patchy. Necrosis, edema, and hemorrhage often occur in tumors that grow rapidly, making the lesion density more uneven. When the adjacent bone tissue or organ is invaded by the tumor, the tumor is confirmed to be malignant. CT can not judge the nature of most soft tissue tumors, and sometimes it is difficult to distinguish from hematoma or abscess. Under CT guidance, percutaneous transthoracic biopsy can obtain correct histological results. Patients in need of examination for patients with bones, joints, muscles and soft tissue lesions or injuries. Precautions Taboo before inspection: 1. Before the examination, the CT doctor should be informed of the detailed medical history and various examination results. If you have your own saved X-ray film, magnetic resonance film and previous CT film, you need to submit it to CT doctor for reference. 2. For enhanced scanners, prepare according to the requirements for use of iodine-containing contrast agents. Fasting 4 hours before the test. 3, remove the inspection site clothing including underwear with metal materials and various items: such as headwear, hairpins, earrings, necklaces, jade, coins, belts and keys. 4, if CT enhanced scan or children, unconscious, need to be accompanied by healthy people. 5, CT enhanced scan If you use ion contrast agent, you need to do intravenous injection of contrast agent iodine allergy test, no response after 20 minutes, before you can check. 6, do not take heavy metal drugs within 1 week, do not do gastrointestinal tincture examination. Patients who have been tested for expectorant need to wait for the sputum to empty; if they are eager to have a CT examination, they should be treated with a cleansing enema or oral laxative to sputum. Requirements for inspection: 1, the inspection process with the doctor's password to do the action, do not arbitrarily move to ensure the clarity of the angiography. 2. The CT machine is equipped with a walkie-talkie. If there is any discomfort during the examination or an abnormal situation occurs, the doctor should be informed immediately. Inspection process (1) flat scan Elbow joint Position and range: prone position. The body is placed in the middle of the bed, lifted on both hands, the palms are up, and the elbow joints on both sides are close together to narrow the scanning field. The head is advanced. According to the positioning piece, including the entire elbow joint. Scanning baseline: Continuous scanning of cross sections. Layer thickness and layer spacing: scanning layer thickness: 3 ~ 5mm; layer spacing 3 ~ 5mm. Window width and window position: soft tissue window, window position L: 30 ~ 50HU, window width W: 200 ~ 400HU. Bone window, window position L: 250 ~ 500HU, window width W: 1000 ~ 1600HU. s Position and range: prone position. Place your body in the middle of the bed, lift your hands on both hands, and lower your palms. Keep your hands as close as possible to narrow the scanning field. The head is advanced. According to the positioning piece, including the entire wrist joint. Scanning baseline: Continuous scanning of cross sections. Layer thickness and layer spacing: scanning layer thickness: 3 ~ 5mm; layer spacing 3 ~ 5mm. Window width and window position: soft tissue window, window position L: 30 ~ 50HU, window width W: 200 ~ 400HU. Bone window, window position L: 250 ~ 500HU, window width W: 1000 ~ 1600HU. hip joint Position and range: supine position. The body is placed in the middle of the bed, the two arms are lifted, the thighs are twisted inside, and the two toes are close together. The head is advanced. Continuous scanning from the upper 1 cm above the medulla, including the entire hip joint. Scanning baseline: Continuous scanning of cross sections. Layer thickness and layer spacing: scanning layer thickness: 3 ~ 5mm; layer spacing 3 ~ 5mm. Window width and window position: soft tissue window, window position L: 30 ~ 50HU, window width W: 200 ~ 400HU. Bone window, window position L: 250 ~ 500HU, window width W: 1000 ~ 1600HU. pelvis Position and range: supine position. The body is placed in the middle of the bed, the two arms are lifted, the thighs are twisted inside, and the two toes are close together. The head is advanced. Continuously scan down to the lower part of the ischial bone, including the entire pelvis. Scanning baseline: Continuous scanning of cross sections. Layer thickness and layer spacing: scanning layer thickness: 3 ~ 5mm; layer spacing 3 ~ 5mm. Window width and window position: soft tissue window, window position L: 30 ~ 50HU, window width W: 200 ~ 400HU. Bone window, window position L: 250 ~ 500HU, window width W: 1000 ~ 1600HU. Ankle joint Position and range: supine position. The body is placed in the middle of the bed, the two arms are lifted, the thighs are twisted inside, and the two toes are close together. The head is advanced. Continuously scan down to the large hole of the ischial bone. Scanning baseline: Continuous scanning of cross sections. Layer thickness and layer spacing: scanning layer thickness: 3 ~ 5mm; layer spacing 3 ~ 5mm. Window width and window position: soft tissue window, window position L: 30 ~ 50HU, window width W: 200 ~ 400HU. Bone window, window position L: 250 ~ 500HU, window width W: 1000 ~ 1600HU. Knee joint Position and range: supine position. The body is placed in the middle of the bed, holding the head on both hands, and the knees are slightly raised under the knees to make the joints slightly curved. Advanced. According to the positioning piece, including the entire knee joint. Scanning baseline: Continuous scanning of cross sections. Layer thickness and layer spacing: scanning layer thickness: 3 ~ 5mm; layer spacing 3 ~ 5mm. Window width and window position: soft tissue window, window position L: 30 ~ 50HU, window width W: 200 ~ 400HU. Bone window, window position L: 250 ~ 500HU, window width W: 1000 ~ 1600HU. (2), enhanced scanning Contrast agent: 80 ~ 100ml ion or non-ionic iodine contrast agent. Injection method: intravenous injection of pressure syringe, fractional bolus or pressurized fast hand push bolus, divided group bolus, 2 ~ 3ml / s. Scanning time: continuous scanning is started after 60-80 ml injection, and delayed scanning is performed 3 to 5 minutes after injection of contrast agent if necessary. Scanner: The parameters are the same as the sweep.