The PET tracers F-18-FDG and F-18-FLT are used to detect tumor diseases in general and not just specific tumors.

Tumors are malignant tissue growths that proliferate uncontrollably. This results in increased metabolic activity of tumor cells, which primarily require glucose as an energy source. F-18-FDG behaves similarly to glucose and is taken up and metabolized by the cells. However, unlike glucose, F-18-FDG is modified in such a way that it cannot be further broken down or excreted from the cell. Therefore, it accumulates in tumor cells due to their heightened glucose metabolism, and the emitted radiation allows for precise imaging of the tumor.

In addition to metabolic activity, the production of genetic material also increases significantly, which is necessary before cells can divide and proliferate. Cells require nucleotide bases as building blocks for DNA, which are processed more intensively by the cell. F-18-FLT behaves similarly to the nucleotide bases. It is incorporated into the DNA in the same way as the nucleotide bases, but due to the fact that it is possible to make use

Principle

Using the weakly radioactive substance Ga-68-DOTATOC, it is possible to detect primarily neuroendocrine tumors and a specific type of thyroid carcinoma, as well as some other tumors. The radioactively labeled substance binds to somatostatin receptors, which are abundant on the surface of tumor cells. The radiation emitted by Ga-68 can then be detected in PET scans. This allows for a precise depiction of the distribution of somatostatin receptors and thus of the tumor.

The examination is often performed to determine whether treatment of the tumor with a similar radioactive substance (Lu-177-DOTATOC), which we also offer at our facility, is feasible.

Principle

Using the weakly radioactive substance Ga-68-PSMA, it is possible to visualize prostate cancer and its spread in the body. Prostate cancer is a tumor disease of the prostate gland. PSMA (Prostate-Specific Membrane Antigen) is a surface molecule commonly found on prostate tumors and serves as a receptor. Ga-68 is coupled to a binding molecule that can specifically bind to PSMA after injection. By detecting the radiation emitted by Ga-68, the tumor can be precisely visualized and localized.

This examination is often performed to determine whether treatment of the tumor disease with a similar radioactive substance (Lu-177-PSMA), which we also offer at our facility, is feasible.

Principle

Using the weakly radioactive substance F18-FET, the amino acid metabolism of brain tumors can be visualized, and the tumors can be precisely localized. Brain tumors are cell proliferations in the brain and spinal cord. There are different types of brain tumors, each characterized by the type of degenerated cells, tumor type, and potentially affected brain areas. A common type of brain tumor is glioma, which represents about half of all primary brain tumors. These tumors originate from glial cells, which form the supportive tissue of the brain. Brain tumors exhibit a significantly increased amino acid metabolism compared to surrounding normal brain tissue. This characteristic is utilized in diagnostics using radioactively labeled amino acids. Additionally, following chemotherapy or radiation therapy, treatment response can be evaluated and therapy adjusted if necessary. F18-FET is taken up by tumor cells and incorporated into the amino acid metabolism, enabling precise visualization of these tumors.

When is a brain tumor PET performed?

• Assessment of the malignancy of a brain tumor
• Planning of a biopsy in suspected cases of brain tumor
• Determination of tumor extent and localization for planning surgical removal
• Investigation of tumor recurrence

F-18-FDG, a weakly radioactive substance, can be used in brain diagnostics to detect and differentiate various forms of dementia. In dementia, certain areas of the brain consume less sugar compared to normal brain tissue. F-18-FDG, a radioactively labeled sugar, is taken up by cells but not metabolized, allowing these regions with reduced metabolism to be visualized.

In addition, an Amyloid-PET scan can also be performed. Amyloid is a protein complex that accumulates in the brain in increased amounts in certain forms of dementia and can be visualized.

Principle

Using the weakly radioactive F-18-FDG, areas of reduced blood flow in the heart can be specifically visualized in cardiac diagnostics, highlighting regions that are functionally intact but may benefit from restored blood flow.

During reduced blood flow, the heart muscle can reduce its energy metabolism to adapt to the diminished nutrient supply. These areas are known as hibernating myocardium. Heart muscle cells predominantly utilize fatty acids but also sugars in their metabolism. Administration of a radioactively labeled sugar (F-18-FDG) allows uptake into cells without subsequent breakdown, thereby depicting metabolic activity. Prior glucose administration encourages the heart muscle to shift its metabolism towards sugar uptake to enhance sugar uptake.

By combining this with measurement of heart blood flow using Tc-99m-MIBI, comparison can be made to identify areas with reduced blood flow that still exhibit metabolic activity and are functionally intact.

Radiation Exposure: F-18-FDG (370 MBq) approximately 10 mSv Tc-99m-MIBI (740-1110 MBq) 4-7 mSv

When is cardiac viability diagnostics with F-18-FDG-PET performed?

• High-risk patients with reduced blood flow and impaired heart function

Principle

Using the weakly radioactive F-18-FDG, inflammations in the body can be specifically visualized.

In areas of inflammation in the body, there is an increased metabolism and thus an enhanced consumption of sugar. Areas where more sugar is consumed compared to normal body tissue can be visualized using a radioactively labeled sugar (F-18-FDG), which is taken up by cells but not broken down.

This examination is primarily used when there is inflammation in the body whose origin has not yet been identified. This is particularly the case when there is prolonged fever of unknown origin or when inflammatory markers in the blood are elevated for unclear reasons.