1-phase skeletal scintigraphy is a diagnostic nuclear medicine procedure used to visualize bone areas based on bone metabolism. The field of application of 1-phase skeletal scintigraphy is primarily in the evaluation of bone tumors or osseous metastases (bone metastases; daughter tumors), since these are associated with a change in bone metabolism. With 1-phase skeletal scintigraphy, there is the possibility of two-dimensional imaging of bone metabolism. Furthermore, with the help of the procedure, topographic imaging and assignment of changes in bone metabolism also becomes feasible.
Indications (areas of application)
- Staging (determination of the degree of spread of a malignant tumor) and therapy monitoring – scintigraphy is very well suited for performing a staging examination because the procedure has excellent sensitivity (percentage of diseased patients in whom the disease is detected by the use of the procedure, i.e., a positive finding occurs). The skeletal system is a common target area for osseous metastases (bone metastases; Daughter tumors) – breast carcinoma, prostate carcinoma, bronchial carcinoma, renal cell carcinoma, thyroid carcinoma, pancreatic carcinoma, colorectal carcinoma, gastric carcinoma, hepatocellular carcinoma, ovarian carcinoma (listing in decreasing frequency) – so precise examination is necessary to assess both metastasis and therapy.
- Diagnosis of primary bone tumors – the use of 1-phase skeletal scintigraphy in the diagnosis of primary bone tumors is useful because the procedure provides highly accurate imaging of bone metabolism. In conjunction with other diagnostic procedures, a very good sensitivity and specificity can be achieved (specificity: probability that actually healthy people who do not suffer from the disease in question, are also detected as healthy by the procedure).
- Clarification of unclear bone pain – unclear bone pain can occur as a result of various pathological (pathological) processes. Both primary bone tumors (eg, osteosarcoma) and osseous metastases (see above) as well as manifest osteoporosis (bone loss) can be crucial for the occurrence of pain in the bone area. However, multiphase skeletal scintigraphy is preferable to 1-phase skeletal scintigraphy for imaging inflammatory processes.
- Bone metabolism disorders – in the context of primary hyperparathyroidism (parathyroid hyperfunction; pathologically increased release of parathyroid hormone), there is increased degradation of bone due to increased release of parathyroid hormone. By the parathyroid hormone calcium is mobilized from the bone, so that the calcium content in the blood serum can be normalized.
- Vitality diagnostics – after the implementation of a transplantation (loosening of implanted endoprostheses, e.g. hip joint or knee joint prostheses) or in the presence of bone necrosis, 1-phase skeletal scintigraphy can be used to assess bone metabolism and thus the vitality of the bone.
Contraindications
Relative contraindications
- Lactation phase (breastfeeding phase) – breastfeeding must be interrupted for 48 hours to prevent risk to the child.
- Repeat examination – no repeat scintigraphy should be performed within three months due to radiation exposure.
Absolute contraindications
- Gravidity (pregnancy)
Before the examination
- Application of the radiopharmaceutical – Radioactively labeled diphosphonates are used to perform skeletal scintigraphy. The use of 99mTechnetium-labeled hydroxy-methylene diphosphonate is particularly common. The application of the radiopharmaceutical is intravenous.
- Performance of other diagnostic procedures – before performing 1-phase skeletal scintigraphy, additional nuclear medicine procedures such as sonography (ultrasound) are performed.
- Bladder emptying – after application, the patient should be encouraged to take in fluids and empty the bladder frequently so that the amount of radiopharmaceutical that has not been deposited in the bone can be quickly eliminated from the body.
The procedure
Of crucial importance for the functional principle of skeletal scintigraphy is the high affinity of the applied radiopharmacon to the bone matrix. Because of this, an attachment of the radiopharmaceutical to the surface of the hydroxyapatite occurs, which is also referred to as adsorption. The process of adsorption depends on the one hand on the bone thickness, and on the other hand on the regional blood supply and bone metabolism. After two to four hours, adsorption is complete, so that subsequently the actitvity distribution of the administered radiopharmaceutical can be measured with a gamma camera and subsequently imaged.
After the examination
At the end of the examination, patients should continue to consume plenty of fluids to achieve adequate elimination of the radiopharmaceutical and thus minimize radiation exposure.
Potential complications
- Intravenous application of radiopharmaceutical may result in local vascular and nerve lesions (injuries).
- Radiation exposure from the radionuclide used is rather low. Nevertheless, the theoretical risk of radiation-induced late malignancy (leukemia or carcinoma) is increased, so that a risk-benefit assessment should be performed.
