Skeletal Scintigraphy: Treatment, Effects & Risks

Skeletal scintigraphy, or bone scintigraphy, is used to detect active changes in bones. Normal, healthy bones are constantly being remodeled. In particular, where heavy stresses are placed on the bone, calcium phosphate is incessantly incorporated and removed. This phosphate metabolism can be visualized with skeletal scintigraphy so that pathological changes in the bone can be detected at an early stage.

What is skeletal scintigraphy?

Skeletal scintigraphy, or bone scintigraphy, is used to detect active changes in the bones. Skeletal scintigraphy, also called bone scintigram, is an examination method used to detect areas that are subject to increased bone metabolism. In diseases such as metastases of various malignant tumors, fractures (bone fractures), inflammatory changes and also arthrosis, there is increased activity in the affected areas, which can be made visible by means of skeletal scintigraphy. The principle of skeletal scintigraphy is based on the fact that radioactively labeled phosphates are deposited on bone surfaces with increased metabolic activity. In this way, the complete skeletal system of the body can be visualized with a low radiation exposure and the entire body can be examined for pathologically increased bone remodeling. This is a tremendous advantage that skeletal scintigraphy has over X-ray examination, which only images individual sections of the skeleton.

Function, effect, and goals

Applications of skeletal scintigraphy include detection or exclusion of tumors of the bone, metastases of the skeleton, undetected fractures, and inflammation of bones or joints. Skeletal scintigraphy is also used in cases of suspected loosening of prostheses (hip or knee joint endoprosthesis), postoperative and post-traumatic complications as well as in cases of unclear bone or joint pain. Prior to the actual skeletal scintigraphy, it is necessary to administer a low-level radioactive agent to the patient. This is usually done through a cannula in the arm vein. After administration, this agent first accumulates in the soft tissues and then gradually attaches to the bone. The agent is absorbed to varying degrees depending on the type of tissue or change. Depending on the task at hand, the time it takes to achieve optimal imaging during skeletal scintigraphy also varies. In most cases, the first images can be taken after about two hours and the late images after another one to two hours. In the case of 2-phase or 3-phase skeletal scintigrams, the images are taken immediately after injection of the agent. The patient should move as little as possible during the skeletal scintigraphy. If necessary, breaks are taken. A recording device, e.g. a gamma camera, registers the radioactive rays, from which the image is then generated. Areas in which a lot of contrast substance was recorded are displayed differently than areas with less enrichment. Often a two-dimensional image is sufficient, but after processing by computer it is also possible to generate a three-dimensional image or a series of slice images. Enhancement of skeletal scintigraphy is usually not necessary. Since skeletal scintigraphy shows very accurate examination results, changes in the bones are revealed even when an X-ray examination does not yet reveal any findings. In this way, tumor metastases occurring in the skeleton of cancer patients can be detected at an early stage. Likewise, in the case of inflammation, it is possible to differentiate the location, type, and intensity of the inflammatory foci by means of skeletal scintigraphy.

Risks, side effects, and hazards

The radiation exposure during skeletal scintigraphy is not increased compared with an X-ray examination or a computer tomography. After only a short time, the radioactive material decays and is excreted from the body in the urine. The exposure itself does not produce radiation, only the radiation produced by the agent is collected. Since the examination, apart from the puncture during injection, is painless and the radiation exposure is low, skeletal scintigraphy can also be useful in children. In pregnant women, however, it is performed only if there are no diagnostic alternatives.Since the radioactivity of the contrast agent given during skeletal scintigraphy is low, no higher radiation exposure occurs. It corresponds approximately to the exposure to natural radioactivity within a year. The risk of suffering radiation damage from skeletal scintigraphy is extremely low, but cannot be completely ruled out. For this reason, these examinations are not used as routine examinations, but only in very specific cases. In rare cases, infections, nerve damage or scarring can occur at the injection site for the radioactive substance. Allergic reactions to the injected agent are also possible with skeletal scintigraphy. However, these are rarely severe enough to result in serious complications.