PET cancer testing

Cancer diagnosis main methods

What is known as part of the usual repertoire of terms for physicians is incomprehensible technical jargon to some laymen. What exactly is behind the acronym ‘CT’? This is very clear: it describes a diagnostic procedure that is worth considering, even by medical experts, because it has become a turning point in modern methods of medical examination.

Perspective Diagnostic Procedure – Computed Tomography (CT)

ct skeniranje

Further development of X-rays

Those who still do not understand what ‘CT’ is will guess what is meant by the term ‘computed tomography.’ CT was developed in the 1970s by its discoverers, scientists Cormack and Hounsfield, for which they received the Nobel Prize in Medicine. Since its introduction, CT has been steadily improving, especially in image quality and continuous examination time (e.g., spiral CT). It is nothing but a computerized form of X-ray examination.

CT works that way

Routine X-rays and CT scans are “imaging procedures” that give an image of the inside of the body from a medical point of view. Different structures (e.g., fat, bone, muscle, etc.) are also differently permeable to X-rays due to their density. These differences can be registered and, e.g., can be displayed on film at inappropriate levels of gray. In CT, this is done with the help of a computer.

Lying on the table, the patient pushes through a tX-ray tube opening, a modern spiral CT constantly rotating around him in a spiral. With fine, mostly fan-shaped air, the area under examination is scanned several times in a short time. The measuring heads register the energy passed through the body, the light that different structures have attenuated to different degrees, and transmit information to the computer as electrical impulses. This creates a millimeter-by-millimeter display of the body area. This creates cross-sections, then longitudinal and oblique cross-sectional images (tomography), which can be combined, ultimately in the form of a multidimensional image, instead of individual shades of gray, which appear visible on the monitor.

Advantages and disadvantages of CT examination

Unlike normal X-ray examinations, CT as an uncomplicated, painless method ensures that minimal differences in density are observed, e.g., in or between organs. Therefore, among other things, it is used to localize minor and major tissue changes – especially in the brain, chest, abdomen, and pelvis. CT is also reasonably used in cancer progression and subsequent diagnosis.

It is often the first more sophisticated method for diagnosing acute internal diseases, e.g., bleeding. Additionally, applied contrast media, which are mostly iodine-containing and usually well-tolerated, support the review’s informative value. It is estimated that radiation exposure carries a shallow health risk based on studies. You should follow the rules of conduct prescribed by your doctor (e.g., fasting with bowel CT, breathing during admission, etc.).

Importance of CT scanners

CT has in no way replaced conventional X-rays, although, unlike them, it can image organs without superposition and in multiple dimensions. In some reviews, it is more useful, e.g., when taking tissue samples because the puncture needle can give accurate images of the point to be punctured here. On the other hand, in bone fractures, conventional X-rays are still preferred because they also provide a more accurate bone image due to better spatial resolution.

Magnetic resonance imaging – MRI

MRI magnetna rezonanca

Anyone who wants to get to the heart of the disease in the true sense of the word is in good hands with the diagnostic method of “magnetic resonance imaging” (MRT), also known as “nuclear spin tomography” or “magnetic resonance imaging” (MRI). As the name suggests, this type of modern medical imaging method is based on the nuclear magnetic or proton resonance of individual atoms. MRI is, therefore, often more differentiated than any other diagnostic technique and is usually used only when other methods have achieved little.

Functional principle of MRI

MRT was discovered in the 1940s by scientists Bloch and Purcell and used in physics and chemistry. Lauterbur and Mansfield made it interesting for medicine in the 1970s. Like their predecessors, they received the Nobel Prize for their achievement.

The method works with the nuclei of hydrogen atoms, of which there are many in the body, but depending on the organ or tissue, also in different densities and bonds with other atoms. If the patient is pushed into a narrow, tubular MRI machine on a mobile basis, as in computed tomography (CT), a strong magnetic field causes the movement of otherwise disturbing protons in a certain direction. Radio waves through a radio coil placed around the body can deviate from this position.

These impulses of excitation can be heard through loud knocking sounds. If you turn off the radio waves again, they return to the previous position (relaxation). Depending on the tissue, this releases energy in different ways and transmits it to the computer via fine antennas in electrical impulses. This calculates and creates cross-sectional images of the inside of the body in any direction without the patient having to change position in the tube.

Precise magnetic resonance imaging

MRI cross-sectional images are even more accurate and differentiated than images of other methods, especially water-enriched structures. Optimal procedure for soft tissues, for the brain, vessels, spinal cord, e.g., but less suitable for bone and air-rich structures like the lungs. The smallest foci of inflammation can be detected just as well by MRI as, e.g., Strokes that are localized and analyzed in the shortest possible time.

Because deviations in tissues on MRI appear visible through altered structures and processes in elementary particles, this method is also in the first place in the more differentiated diagnosis and treatment of cancer. In this way, e.g., feature detection can be provided tumor cells – extended scope of application of the newer MRT method. Also, metabolic disorders can be detected and, e.g., Causes of epilepsy. MRT, therefore, serves a wide field and is used where much cannot be done in a simpler form.

What should be considered with magnetic resonance imaging?

Unlike X-rays or CT, this examination does not involve any radiation exposure. However, since patients are exposed to a magnetic field in the tube, there should be no metal parts in or on the body. There should also be no electronic items or chip cards, as they can interfere with the magnetic field or become unusable as a result. E.g., People with pacemakers or metal heart valves should refrain from magnetic resonance imaging at all. During the examination, the patient must be as calm as possible and even breathe. The headphones protect it from loud knocking sounds. He can also ring and interrupt the examination at any time. It is sometimes injected with a generally well-tolerated contrast medium to highlight the tomography results. The MRI lasts about half an hour and is divided into sequences with individual measurement breaks of up to ten minutes.

Positron emission tomography – PET

Pozitronska emisiona tomografija - PET

The patient uses a PET scanner

PET – Huge advances in cancer diagnosis

One of the most important prerequisites for treating the disease is the diagnosis, ie. Accurate description of the clinical picture using all medical knowledge and possibilities. Medicine uses different methods. The turning point in the view of the human body “without a scalpel” was the discovery of X-rays Wilhelm Conrad Röntgen, who received the Nobel Prize in 1901 for that. Years.

One of the most important diagnostic areas in tumor diagnostics. Here, in addition to laboratory and endoscopic in recent years, there are test methods. Examination of body cavities and hollow organs is often combined with tissue removal (biopsy), computed tomography (CT), and magnetic resonance imaging (MRI).

Currently, one of the most modern and at the same time the most accurate testing methods in tumor diagnosis is positron emission tomography (PET). It was mainly used in brain examinations in the late 1980s, and it is considered the most important diagnostic component in the search for a large number of tumors.

What is the difference between PET and CT and MRI?

Dr. Eveline Korman (EC): “With this screening technique, we can identify a malignant tumor as such and distinguish scars from active carcinogenic tissue. So we can tell in a non-invasive way (red: without opening the body) whether the cancer is still alive. One of the benefits of PET is that in one examination, the whole body is examined, i.e., we detect any metastases (red: daughter tumors). “

Where is PET used?

Leading nuclear medicine specialists have used the applications in recent years, and clinicians in Germany based on consensus conferences and internationally proven classification procedures in various classified non-classes. The highest level is known as an indication “1a”. These include, e.g., pancreatic, lymphatic, thyroid cancer, black skin cancer (melanoma), and lung nodules in high-risk patients.

How does PET manage to provide such accurate knifeless test results?

Let’s stay with the lungs. Here PET saves the patient the effort of general anesthesia and surgery. This saves high costs. PET takes advantage of the fact that cancer tumors have a significantly higher metabolism rate than healthy tissue and therefore convert more glucose (sugar). One hour before the examination, we inject the patient with a liquid in a vein in his arm with special weakly radiolabeled traces, a sugar solution called F 18-FDG. After the absorption of this substance into the tumor tissue, the marked sugar is not broken down, but stored and the tumor becomes more recognizable. Then the affected tissue can be cleared to be localized. Therefore, it is usually possible to state whether it is a benign (benign) or malignant (malignant) tumor.

The result of your examination is therapy in the form of surgery, radiation or well-known chemotherapy. Does PET help after that?

That. After treatment, PET can prove whether it has been effective and whether it will be continued or must be changed.

How about accuracy compared to other examinations, for example CT?

Just a representative example published in the mid-1990s.

Do health facilities cover the costs of the examination?

Private patients can use the procedure because PET has been recognized since 1995. It is anchored in GOÄ (Order: Fee for doctors). Patients with statutory health insurance require a special permit. The decision on whether to bear the costs is made by the competent legal insurance company, which usually adheres to the recommendations of the medical health insurance service. ZZ discretionary decisions are made on a case-by-case basis, which can be positive for the so-called indication la. I have often pointed out regret that this is being addressed very differently across the country. I hope, however, that in the future, health insurance patients and their doctors will be able to use PET more often for more accurate diagnoses and thus be able to carry out the best possible treatment.
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