The PET/CT device provides both metabolic and anatomical information in a single examination. The information obtained by PET / CT has proven to be much more accurate in the evaluation of patients with known or suspected malignant diseases.

Indications for PET/CT examination include, but are not limited to, the following:

Evaluation of an abnormality detected by another imaging method, to determine the level of metabolism and the probability of malignancy;

Location of a primary tumor when metastatic disease is discovered as the first manifestation of cancer; Staging of patients with known malignant diseases;

Monitoring the response to treatment on a known neoplasia;

Metabolic assessment of residual disease that, by conventional imaging methods, presents as tumor or post-treatment inflammation, fibrosis, or necrosis;

Detection of recurrences, especially in the presence of increased tumor markers;

Assessment of lesions difficult to access for biopsy; Radiotherapy planning; Assistance in treatment planning. (IAEA HUMAN HEALTH SERIES No. 9, APPROPRIATE USE OF FDG-PET FOR THE MANAGEMENT OF CANCER PATIENTS) The essence of the method consists in marking some biologically active substances (e.g. glucose, amino acids, ligandoreceptors, etc.) with isotopes that emit positrons (C11 , F18, N13, O15), after which the marked material (tracer) is introduced into the patient’s body, and the image of its distribution will be established. The development of the isotopic trace signaling technique and its clinical use is linked to the name of the Hungarian scientist György Hevesy, awarded in 1943 with the Nobel Prize.

The dosage is generally between 4 – 7 mCi (148 – 259 MBq) in adults and directly proportional to lower body weight and BMI (and at least 1 mCi- 37 MBq) in children. The common feature of the most commonly used PET isotopes is that they have a very short half-life (20-110 minutes), therefore, by using them, patients receive a lower radiation dose compared to other longer half-life medical isotopes.

Theoretically, any molecule that participates in the metabolism of the living organism can be labeled with PET isotopes. However, in practice, there are some limitations, mostly of a chemical nature. With the help of the PET method, almost all biochemical and physiological processes can be visualized, and the distribution of activity in the body can be determined quantitatively.

The most commonly used radiopharmaceutical is fluoro-deoxyglucose (FDG), a glucose analog to which the F18 isotope has been covalently bound. Increased glucose consumption is a feature of most cancers. The diagnosis of oncological conditions with FDG-PET has been a clinical practice for several decades worldwide, without the occurrence of allergic reactions or any other side effects due to the carrier-free nature of the radiopharmaceutical. FDG is not metabolized in the circulation, and the unused portion of it is eliminated by the kidneys in unchanged form (unlike normal glucose).

It is characteristic of the rate of excretion that approximately 90 minutes after FDG injection, about 40% of the activity has already been eliminated in the urine. The tissue distribution of the labeled substance introduced into the body can be detected with the help of the PET camera by recording the radiation related to the positron emission.

Increased glucose consumption is characteristic of most types of cancer. Diagnosing oncological conditions for several decades has been possible without the occurrence of allergic reactions. Apart from the mild complications that rarely occur after the intravenous injection (local reddening of the skin, swelling, light bleeding), there are no other side effects. The specialized literature does not report allergic reactions related to the substance FDG.

In case of hyperglycemia (diabetes), measures will be taken so that until the beginning of the examination, the blood sugar is close to the normal value, but in any case below 144 mg/dl. If the blood sugar does not fall below 8 mmol/l (144mg/dl), the examination must be postponed. Renal failure makes it difficult to eliminate the substance but does not contraindicate the examination. During pregnancy, due to the radiation to which rapidly dividing tissues are subjected, the examination is contraindicated.

Breastfeeding is not a contraindication, because after milking the breasts, breastfeeding can be continued 20 hours after the examination. The examination is performed on an empty stomach; it is prohibited to eat food approximately 6 hours before, but adequate hydration is required. It is recommended to consume 1-1.5 liters of sugar-free liquid (still mineral water).

Rarely, depending on the patient, it may be necessary to take 5 mg of diazepam for muscle relaxation and anxiety reduction, after which, for 12 hours, the patient is prohibited from driving. It is recommended to avoid activities that require physical effort in the 3 days preceding the examination.

Recording of images usually begins 60-120 minutes after injection of the radiotracer and lasts 10-30 minutes (depending on the type of examination). After the examination, the patient can leave and continue daily activities normally.