Scintigraphy
Scintigraphy (Latin scintilla spark, Greek draw γράφειν describe ) is an imaging technique in nuclear medicine diagnostics. The thereby resulting image is also called scintigram. Here radiolabelled substances ( radiopharmaceuticals ) are introduced into the body, which accumulate in the target organ to be examined, and then visualized with a gamma camera, from which the emitted radiation is measured. The method is suitable not only for diagnostic localization example of inflammation in skeletal ( bone scan ). Since the timing of intake and excretion of the radiating substance can be recorded, information on the function of organs, for example in the Nierenfunktionsszintigrafie or Herzszintigrafie let them win. The radiation exposure is usually lower than in the comparable X-ray examinations in these studies. In Germany about 60,000 scintigraphy be performed weekly.
Principle
The imaging is based on the administration of radiopharmaceuticals, i.e. substances that are radioactively labeled. In this case these substances are used, which are particularly well accumulate in the examined tissue. This is known as tracer (indicator).
For the diagnosis of radiopharmaceuticals are used which emit gamma rays. The radionuclides accumulate, depending on the chemical and biological nature, in certain organs of the human being (eg, thyroid, heart, liver, kidney, lung, bone ). When bone scintigraphy for example, bisphosphonates are used, which are installed as a result of bone metabolism in the bone. As a radioactive marker technetium isotope 99m Tc is used here mostly.
With the aid of a scanner or of a gamma camera, the emitted radiation can be determined (detected ), and are transformed into an image farbvisualisiertes. ( The detection is performed using a scintillation crystal, which produces upon impingement of the gamma quanta flashes of light " scintigraphy " comes here from the Latin scintillare and means " twinkle, twinkle ", .. Hence the name " scintigraphy " ) The flashes of light from the crystals in an electronic signal is converted and displayed according to the frequency as pixel in blackening. The representation of the examined organs can be either flat ( planar) or by means of SPECT. When SPECT procedures are made more shots of the same region of the body from different angles and obtained from the data a three dimensional model is calculated, which allows cross-sectional images as in a CT scan.
Application
Common applications for the scintigraphy for example in tumor diagnosis. The radiolabeled tracer is preferably accumulate in tissue that has an increased metabolism and therefore more vascularized ( blood supply ) is ( "hot spot "). This is typical of tumor tissue. In scintigram this tissue parts appear / darker or more different. For questions related to the skeletal system, can be combined with this procedure very quickly gain a comprehensive overview, unclear findings can be clarified. If there is suspicion about a loosened endoprosthesis, the scintigraphy after the safe and closes it out. The activity state and the distribution pattern of a rheumatic disease can be estimated, the question of skeletal metastases can be answered.
It is also possible to diagnose, with this method an increased or reduced metabolism of non-tumor tissue, such as thyroid examination. An example shows the adjacent figure.
Another possible application is to be found in the Child and Adolescent Medicine: If there is in children, especially infants, the suspicion of abuse ( battered child syndrome - common clinical indication ' fall from the changing table " ), you can find increased bone metabolism a scintigraphy, as repair measure of the bone occur. It is thus possible to draw conclusions on the application of external force. These bones do not even need to be broken, even slight bruises can be detected by scintigraphy.
The length of time for the tests is - depending on the underlying physiological processes - some for several hours; in the bone scintigraphy for example can be recognized by the gift of the radiopharmaceutical to finish shooting three to four hours. For the recording itself 10 to 30 minutes, the patient lies, depending on the question and device, still under the gamma camera. Radiation exposure varies depending on the performed investigation and is, for example, for a thyroid scintigraphy in the height of a simple radiograph ( about 0.5 mSv ) for most of the studies below that in a more extensive computer tomography ( about 5 to 20 mSv ), in individual cases, also above. The indication for a nuclear medicine examination is to provide strict in children and adolescents, in pregnant women is an indication usually is not given. It should also be borne in mind that the technology used is based on that the radiation leaves the body. Depending on the isotope used should therefore too close contact with pregnant women, children and young people to be avoided in the first 24 to 48 hours after the examination.
Similar procedures
- Positron emission tomography ( PET)
- Single Photon Emission Computed Tomography ( SPECT)