Bone scintigraphy is a nuclear medicine imaging technique that involves injecting a radioactive tracer isotope and using specialized cameras to scan the entire skeletal system. Its primary purpose is to detect metabolic abnormalities in bones, facilitating early identification of fractures, tumor metastases, infections, or inflammatory conditions. This examination provides more sensitive lesion localization than X-rays, especially for micro-lesions or hidden injuries.
Clinically, bone scintigraphy is commonly used for monitoring bone metastases in cancer patients, precise diagnosis of sports injuries, and analyzing causes of chronic skeletal pain. Its non-invasive nature makes it a popular tool among multidisciplinary physicians for assessing bone health.
Bone scintigraphy mainly falls into two categories: "Whole-Body Bone Scan" and "Three-Phase Bone Scan." The former involves comprehensive scanning of the entire skeleton, while the latter tracks the dynamic metabolic process of the tracer in bones in stages. During the procedure, patients receive an intravenous injection of a radioactive isotope (such as technetium-99m).
The tracer binds to areas of active bone metabolism. The camera detects gamma-ray signals to generate images. Normal bone tissue maintains stable metabolism, whereas lesions with active osteoblasts appear as "hot spots" or "cold spots." This metabolic imaging principle allows detection of early lesions before structural damage occurs.
Suitable for evaluating metabolic bone diseases such as osteoporosis-related fractures and Paget’s disease, as well as assessing bone integration before joint replacement. After confirming bone metastasis, it can help evaluate treatment response and disease progression.
The procedure involves two phases: injection and scanning:
In special cases, the injection dose can be adjusted, such as based on body weight in pediatric patients. Repeated scans should be spaced at least one week apart to allow complete tracer metabolism.
Compared to other imaging techniques, its accuracy in diagnosing bone metastases exceeds 90%. The three-phase scan can differentiate infections from tumors, providing diagnostic information on lesion nature.
Possible local redness or itching at the injection site, with an incidence below 1%. The theoretical risks of radioactive substances include:
A very small number of patients may require prophylactic medication for allergic reactions, though cases of anaphylactic shock are extremely rare. Post-procedure, drinking plenty of water is recommended to accelerate metabolism.
Before the scan, inform your doctor about pregnancy potential, allergies, and current medications. Diabetic patients should control blood sugar levels, as hyperglycemia may affect imaging results.
Relation to other imaging examinations:
Avoid using bisphosphonate drugs within 24 hours before and after the scan, as they may affect metabolic imaging results. The radioactive tracer has no pharmacological interactions with other medications.
In diagnosing bone metastases, bone scintigraphy has a sensitivity of 95% in patients with primary tumors, especially superior to X-ray in detecting multiple lesions. A 2019 systematic review showed a specificity of 87% for diagnosing osteomyelitis.
Studies confirm that bone scintigraphy is 40% more accurate than conventional X-ray in diagnosing delayed fractures (e.g., stress fractures). The three-phase scan achieves over 90% accuracy in differentiating infection from tumor.
Alternative examinations include:
If radiation exposure is a concern, MRI or ultrasound can be options. However, for detecting metabolic abnormalities, bone scintigraphy remains irreplaceable.
Generally, fasting is not required before the scan, but inform your doctor about medications you are taking (such as calcium supplements or diuretics), as some drugs may affect imaging results. If contrast agents are used, medical staff will provide specific instructions.
Will there be residual radiation after the scan? Are daily activities affected?The radioactive tracer used will be naturally eliminated from the body within 24 to 48 hours. It is recommended to drink plenty of water post-scan to accelerate metabolism. Normal activities such as working and exercising are usually unaffected, but breastfeeding women should suspend nursing for about 12 hours to avoid infant exposure to trace radiation.
Does an abnormal bone scan necessarily indicate cancer metastasis?Abnormal results can be caused by various factors, such as osteoporosis, fracture healing, or inflammatory reactions, and are not always malignant. Physicians will interpret results in conjunction with clinical symptoms and other tests (e.g., MRI or biopsy) to determine the specific cause.
Can patients undergoing chemotherapy or radiotherapy have a bone scan?Patients receiving cancer treatment can still undergo bone scintigraphy, but should inform their treatment schedule and medications in advance. Some chemotherapies may affect bone marrow activity; doctors will adjust interpretation standards based on treatment stage to ensure accuracy.
How soon can I get the report after a bone scan? Do abnormal results require immediate treatment?The report is usually completed within 2-3 working days after analysis by a radiologist. Whether immediate treatment is needed depends on the severity of the abnormality and clinical symptoms. Some benign lesions may only require regular follow-up, while serious conditions might need further diagnosis or surgery, which should be discussed with your physician.
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