PET CT Second Opinion

PET-CT combines two types of radiological diagnostics. Computed tomography produces high-resolution images of cross-sections of the body. Based on these, the radiologist assesses the anatomy of the body, identifies changes in the organs, and determines their nature.  At the same time, positron emission tomography technology can be used to draw conclusions about certain metabolic processes in the tissues.

Before a PET study, the patient is injected intravenously with a radiopharmaceutical. This is a low-radioactive substance that is distributed throughout the body. It almost never causes allergic reactions. The natural decay of this substance produces low radiation, which allows the doctor to visualize its distribution in the body. With the help of computed tomography, which is performed simultaneously, these metabolic processes can be accurately attributed to specific parts of the body.

The most commonly used PET-CT radiotracer is 18F-FDG, a glucose analog with the positron-emitting radionuclide fluorine-18, which displays cell metabolism. Since many tumor cells have an increased metabolism (e.g., due to their rapid growth), the radiopharmaceutical allows them to be detected.

In other words, it is PET-CT that can simultaneously answer two fundamentally different but very important questions:

- "What does the tissue look like?"

- "What are its biochemical properties?"

It can help, for example, to assess the effectiveness of chemotherapy for malignant diseases. Very often, metabolic changes in tumor foci become visible on PET-CT long before the mass actually shrinks in size. Because chemotherapy disrupts the metabolism of tumor cells, they absorb less radioactively marked glucose. Therefore, the doctor can determine early enough whether chemotherapy is the right choice or whether the treatment plan needs to be changed.

PET-CT interpretation

The scan is only one step in the diagnostic process. The resulting images must be read by a physician. For this purpose, the functional positron emission scan data are combined with anatomical data from a CT scan. The images may show areas with increased metabolic activity, which may indicate the presence of tumor foci or inflammation. The metabolic activity assessment unit is SUV (standardized uptake value).

Computed tomography is used to determine the exact location and size of a lesion.

The final result of PET-CT image analysis is a report. It is prepared by a radiologist and includes a detailed description of anatomical and functional data, including localization and size of areas of pathological metabolic activity.