Positron emission tomography, or PET, is a non-invasive method for examining the body using a special apparatus. This method is used to scan internal organs.
What are the specifics of diagnosis
PET research - what is it? Positron emission tomography is a branch of nuclear medicine. This direction is associated with the use of pharmaceuticals for the diagnosis and treatment of various ailments. Specially made substances contain a very small amount of radioactive isotopes. Their doses are so small that they do not harm the body at all.
Information on the accumulation of nucleotides in tissues using special software is transformed into a graphic image of the human body and three-dimensional projections of internal systems. Spatial visualization of the body makes it possible to assess the localization of the drug. The negative effects of PET studies were not noted.
Types of tomography
The method of delivery to the affected area of the body of the labeled drug is used not only for diagnosis, but also for treatment. It is known that radiation has a devastating effect on humans. But scientists were able to tame it and turn it for the benefit of people. Very small doses of radiation, targeted to the affected areas, can treat many serious diseases.
Tomography is a visualization of organs and tissues in separate thin layers. Initially, the so-called preparation of biological products for research. Tissue fragments were cut into layers, fixed using special chemicals or frozen, and then photographed.
A bit of history
The predecessor of distance tomography was a traditional x-ray. Today, layered visualization is carried out by using special analog and digital equipment. Tomography uses x-rays. Scientists have tried to overcome the static nature of this method for many years. Moving the X-ray machine along the patient’s still body was the first step towards a layered diagnosis of the body. The creators of the method, Godfrey Hounsfield and Alan Kormak, became laureates of the Nobel Prize in Physiology or Medicine in 1972.
Computed tomography is a very broad term. Today, all non-invasive body checks are performed using hardware and software. In the narrow sense of the word, computed tomography means layer-by-layer study using x-rays.
Another variation of the method is the so-called magnetic resonance imaging (MRI). It is also a way of layer-by-layer remote visualization of internal organs. But it is not based on x-rays, but on the use of the electromagnetic response of atomic nuclei. This is a modern method; it was first tested in 2003 by Peter Mansfield and Paul Lauterbur. For their invention, scientists received the Nobel Prize.
Positron emission scan tasks
Radioactive components tend to accumulate in the affected areas of the body and are able to glow against the background of other tissues. This makes pharmaceuticals very useful in the diagnosis of malignant neoplasms.
Cancer cells quickly divide and accumulate radioactive substances in large quantities. Therefore, the affected areas of the body are clearly visible. Similar non-invasive remote diagnostic methods, such as x-rays or computed tomography, show only tissue damage. A PET study also notes the degree of activity of the cancer process.
In the diagnosis of tumor diseases, radiopharmaceuticals are used for such purposes:
- identification of foci of the oncological process and affected tissues;
- differential diagnosis of malignant neoplasms;
- evaluation of the effectiveness of treatment.
With a full PET examination of the body, the affected areas glow actively, which allows you to determine the degree of tumor invasion in neighboring organs, as well as the presence of metastases. They arise because dangerous cells, moving through the circulatory and lymphatic systems, penetrate tissues that are significantly distant from the primary focus.
Differential diagnosis and treatment effectiveness assessment
In addition to cancer, medicine also knows benign tumors. They do not grow, do not penetrate into neighboring organs and do not give metastases. Their cells are mature, active division is absent. Benign formations do not accumulate radionucleotides and do not glow. PET diagnostics also performs the function of distinguishing tumor processes in the body.
This examination helps evaluate treatment outcomes. If the activity of cell division, as well as their luminosity, has significantly decreased, therapy can be considered successful.
What is the uniqueness of the approach
The inventor of the method is the Hungarian scientist Georg Hevesi. In 1913, he first invented ways to use radiation-labeled drugs in medicine. For this, the scientist received the Nobel Prize in chemistry. The first advanced positron emission tomograph of the modern type was created in 1961 by James Robertson.
A PET study differs from other imaging methods in that it is able to identify tumor processes at the earliest stages. The focus of the disease is still very small, but is already actively absorbing labeled drugs. This examination is able to detect malfunctions of the organ at the cellular level, but poorly displays its structure. Therefore, today the positron emission method is combined with computed tomography, which allows localization of damaged tissue to within a few millimeters.
Cardiovascular Surgery and Pathology of the Nervous System
A PET study is conducted not only to diagnose tumor diseases, but also to check neurological and cardiological disorders. For example, using this method, you can determine the intensity of the organs, a heart attack, and even a heart attack. The device is able to detect areas with impaired or weak blood circulation. This is important for the diagnosis of heart attack and coronary heart disease. With such diseases, doctors need to know whether the circulatory system is completely affected or whether it is supplied with oxygen, albeit poorly. PET will help in this, determining the need for surgical intervention.
Disorders that occur in Parkinson's disease or epilepsy can also be identified. A PET scan of the brain helps in the earliest stages to identify malfunctions leading to senile dementia. For example, when there are no symptoms yet, but certain parts of the organ are already affected. PET can easily identify foci of epileptic disease that can be affected by therapy.
How does the scan go?
Before the examination, the patient is injected intravenously with a solution of glucose with radioactive drugs. After a while (about an hour), when the bloodstream distributes the labeled atoms throughout the body, a person fits on a special couch attached to the scanner. In the waiting period, it is advisable not to move and completely relax. The drug accumulates in the working muscles, which may adversely affect the results of the study. The couch with the patient moves through the scanner, and in the meantime, special detectors identify foci of active absorption of the substance and display data on a computer monitor.
The software visualizes layers of organs and systems with the indication of luminous zones. The specialist studies the results of the test and forms a medical report, which is provided to the patient along with tomography printouts. The minimum scan time is half an hour.
What should be told to the doctor
In the diagnosis of cancer, a PET scan may show what are called false positives. The drug is able to accumulate not only in tumor foci, but also in inflammatory processes in one or another organ. Therefore, you should not do PET immediately after surgery or chemotherapy. How much time should pass in each case, the doctor will tell.
The radio product is excreted from the body during the day. This study is completely safe. The only contraindication is pregnancy. However, the patient must inform the doctor about all chronic diseases, including allergic reactions, before undergoing a PET examination.
Reviews about the procedure are positive. It is effective and safe. You should tell the doctor about all the medications, vitamins, nutritional supplements and decoctions of herbs taken. If a woman is breast-feeding a baby, she must also report it. Usually, after eliminating harmful substances from the body , breastfeeding can be restored. Before research, it is necessary to remove all jewelry and objects containing metal, such as a hearing aid. Tell your doctor if you have dentures (including dentures) or implants. Tell me about the presence of tattoos. They may contain metal dyes.
How to prepare
PET diagnostics require special preliminary steps. If the procedure is scheduled for the morning, a minimum of light food should be consumed in the evening. After that, you can’t eat anymore. You can only drink water. For people with diabetes, a special procedure for preparing for the study is provided. The doctor will tell you about it.
There are practically no complications during the PET scan. This can also be said about side effects and unpleasant consequences. Sometimes patients feel weak and lightly dizzy. But these symptoms can be caused by starvation in preparation for the study. They pass quickly. It should be noted that during the procedure the patient has to lie still. This can cause discomfort, back pain and a feeling of heaviness in the neck. But complete peace is very important for true scan results.
Observe Precautions
Preparation for a PET examination involves arrival at a medical institution 15 minutes before the appointed time. Do not bring children or pregnant women with you; they should be kept as far away as possible from radiation sources. Take the results of all previous examinations, extracts from medical records, medical records. After the procedure, you must carefully follow the rules of personal hygiene. In order for radiopharmaceuticals to be more quickly excreted from the body, heavy drinking is recommended.
Medical centers and institutions
Where to do a pet test? This question is of concern to most patients. To date, there are not very many medical centers in which you can undergo positron emission tomography. In Moscow, you can make a diagnosis in such institutions:
- Scientific Center for Vascular Surgery Bakuleva.
- Center for Radiosurgery Berezina.
- Central Regional Clinical Hospital.
- Central Clinical Hospital No. 1.
- Institute of Clinical Radiology.
- Russian Cancer Research Center named after Flea.
A Kashirka PET study is conducted in confidence. The branch was opened recently, in 2013. It has already received high marks from specialists and positive feedback from patients.
In St. Petersburg, examination can be done in the following institutions:
- Human Brain Institute.
- Military Medical Academy named after Kirov.
- Central Research Institute of Radiology in the village of Pesochny.
Also positron emission tomography can be done in Chelyabinsk and Tyumen oncology clinics. There are two specialized medical institutions in Kazan:
- Cancer Center of the Republic of Tatarstan.
- Republican Clinical Oncology Center.
Conclusion
Combined PET / CT devices are by no means in all the institutions mentioned above. Some centers have in their arsenal only a positron emission tomograph. When examining, it is better to give preference to combined CT and PET. Reviews about them are extremely positive. Such tomographs are reliable and safe. The presence of combined devices, the price and the schedule of the institution should be checked with the administrator.
Conditions for the comfort of patients are created in all medical centers. They have comfortable lounges for people waiting for the procedure to begin. The cafeteria serves healthy and tasty dishes. After returning home, it is recommended that you sleep a little.