Scintigraphy of the bones
Bone scintigraphy (also known as skeletal scintigraphy) can be used to visualize bone metabolism and identify areas of increased activity. Our bones are not lifeless scaffolds, but are subject to constant build-up and breakdown. For the scintigraphy of the bones, radioactively marked components of bone metabolism are used (diphosphonates).
After injection of the substance, it is distributed throughout the body and is incorporated into the bones after only a few minutes. The higher the metabolic activity, the more radioactive particles are incorporated and the more clearly a bone stands out in the image captured by the gamma camera. This can be used for various questions that justify a skeletal scintigraphy.
On the one hand, inflammatory processes and changes in the bones can be investigated, for example in rheumatism or osteomalacia (softening of the bones). If it is suspected that a joint prosthesis has loosened, the scintigraphy can provide information. If normal imaging (e.g. x-rays) does not allow a reliable statement to be made, it is still possible to investigate whether a bone is broken or not.
Likewise, in patients with cancer, the question can be investigated whether the tumor has spread into the bone. However, the following must always be taken into account in the evaluation: The scintigraphy of the bones is very sensitive, which means that even small increases in metabolic activity can be reliably detected. On the other hand, the examination is not very specific, which means that no reliable statement can be made about the cause of an abnormality in the scintigram.
As an example, a cancer patient can be used to examine whether malignant cells have scattered into the bones. If the scintigram is inconspicuous, scattering is also rather unlikely. However, if there are areas that are conspicuous on the scintigraphy, they do not necessarily have to be metastases (descendants of cancer).
It can also be a more harmless cause, such as the consequence of a contusion. Therefore, the assessment of the skeletal scintigraphy must always be made individually in connection with other findings and circumstances of the patient. In addition to a scintigraphy of the entire skeleton, only a part of the bones, for example the hands, can be examined in isolation.
In patients with a rheumatic disease, a scintigraphy of the bones can be used to examine whether inflammatory changes are present. This examination also makes it possible to differentiate between pathological joint changes and whether or not they are inflammatory. It is one of many possible examination methods for assessing the activity of the disease. However, scintigraphy is not suitable for the diagnosis of rheumatism, as it is too unspecific. This means that although changes in the bones due to increased metabolic activity can be reliably detected, what causes them cannot be determined by scintigraphy alone.