Magnetic resonance imaging (MRI) is one of the most informative methods for examining internal organs in modern medicine. In its diagnostic value, it is significantly superior to x-ray examination. What is the essence of the technique, and what does MRI angiography of cerebral vessels show? This, as well as many other things that you should know about MRI diagnostics, is described later in the article.
The essence of the method
What is an MRI scan of cerebral vessels? With its help, you can see in detail the cerebral arteries, their shape, size, attitude to the surrounding brain tissue.
All this is possible due to the fact that the tomograph emits electromagnetic waves of different frequencies. They lead to the vibration of hydrogen atoms, which are found in large numbers in all tissues of the body. Different concentrations of these atoms in individual parts of the brain are displayed on the screen. It is because of this that brain tissue is visible in its intensity.
Separately, MRI angiography of cerebral vessels with contrast is isolated. Its essence lies in the introduction of a special substance that stains the cerebral arteries. It is more informative than conventional MRI.
What diseases can be diagnosed with MRI?
With the help of MRI angiography of cerebral vessels, an accurate diagnosis can be made. Moreover, not only the nature of the circulatory disturbance is determined, but also its exact localization. You can also find out how long this adverse event has occurred.
The diagnostic value of the method is increased when using a contrast medium. But this method is more expensive than classical magnetic resonance imaging, so sometimes you have to refuse it.
What does MRI angiography of cerebral vessels show without contrast?
- The volume of hematoma in the brain, the extent of hemorrhage.
- The focus of ischemia in the brain due to blockage of the vessel by a thrombus or embolus.
- Neoplasms and cysts of the brain.
That is, the use of MRI without the introduction of contrast allows you to see brain tissue and a violation of the structure of the brain, if any.
With the help of contrast MRI angiography, an accurate diagnosis of a much wider range of diseases is possible:
- cerebral vessel aneurysm - bag-shaped protrusion of its thinned wall;
- exact localization of a blood clot or embolus with ischemic stroke;
- anomalies in the structure of blood vessels;
- exact localization and volume of tumors, as blood supply at the tumor site is significantly increased;
- slowing or accelerating blood flow in the vessels.
Indications for MRI
MRI in the mode of angiography of cerebral vessels is carried out only in the direction of a doctor to confirm the presence of such diseases:
- cerebral atherosclerosis - the deposition of fatty plaques on the walls of cerebral vessels;
- vasculitis - inflammation of the vascular wall;
- ischemic or hemorrhagic strokes;
- vascular malformations - anomalies in the structure of the vessel;
- stenosis of the carotid or cerebral arteries - a decrease in the diameter of their lumen;
- consequences of traumatic brain injury;
- venous sinus thrombosis in the brain.
Also, this method is addressed if the patient has prolonged headaches, the cause of which could not be determined using other diagnostic methods.
Survey preparation
Before undergoing a routine MRI scan of cerebral angiography, no specific preparation is required. And in the case when the doctor prescribes an MRI with contrast, before the examination you need to adhere to some rules:
- You should refuse to eat at least 10 hours before the start of the examination, since the contrast agent causes unpleasant symptoms in the form of nausea and vomiting.
- The patient should warn the doctor about the presence of an allergy to contrast.
- If kidney disease is present, it is also necessary to tell the doctor about this.
Immediately before the administration of the contrast medium, an allergic test is performed. For this, a small amount of solution is administered subcutaneously to the patient. After which the doctor monitors the skin reaction. If rashes, itching, redness or swelling appear, you must refuse to perform contrasting or replace the substance.
Before any magnetic resonance imaging, regardless of the presence of contrast, the patient must remove jewelry, metal products. Also in the cabinet you can not take plastic cards, glasses in a frame of metal, electronics.
How is an MRI angiography performed?
After all the preparatory stages are behind, the patient lies on the table of the tomograph. Throughout the examination, he should lie absolutely still, so his arms, legs and head are fixed with straps to the table.
If contrast is applied, the nurse introduces it in advance, even before the patient lies down on the table.
After the table is automatically retracted into the tomograph, and the image is scanned. Often at this time, patients experience an attack of panic and claustrophobia. The tomograph is quite dark, and the machine itself emits an unpleasant rattle. Therefore, the doctor should consult each patient before the examination and answer all his questions.
If it is necessary to introduce contrast, a catheter is inserted into the peripheral vein. The desired amount of solution is introduced through the catheter. He quickly paints the vascular network of the brain. This allows you to see changes in blood flow, blood vessels, areas of increased blood supply. At the time of administration of the contrast medium, a feeling of slight discomfort is possible.
Nearby is another office with a computer system, which is seated by a diagnostician and operator. Here on the monitors is a layer-by-layer display of brain tissue and its vessels. As a rule, the whole procedure takes up to 40 minutes.
Magnetic resonance imaging is absolutely painless, perhaps only a feeling of inconvenience due to a prolonged stationary state. Sometimes there is heat in the study area and a slight tingling sensation.
Contraindications
Answering the question that this is an MRI angiography of the arteries of the brain, it becomes obvious that the essence of the method is to create an electromagnetic field. That is why the main contraindication for MRI is the presence of any metal objects in the body (pacemaker, joint prostheses, insulin pump, dentures, vascular clips). If, however, an MRI is nevertheless performed, it is possible not only a deterioration in image quality, but also a device breakdown.
Other conditions where MRI angiography of cerebral vessels is contraindicated are presented below:
- age up to 7 years;
- pregnancy period;
- mental illness;
- neurological diseases that are accompanied by hyperkinesis (involuntary body movements);
- claustrophobia - a condition in which a person is afraid to be in a confined space;
- a serious condition of the patient, because of which he cannot be transported to the diagnostic room;
- severe kidney disease - a contraindication to contrast MRI.
Breastfeeding is not a contraindication to the examination. But if the introduction of contrast is provided, lactation must be canceled for a few days after that, since the solution can pass into the baby along with breast milk.
Advantages of the method
The main advantage of MRI angiography of cerebral vessels is the high accuracy and informativeness of the examination. Only this method allows you to see structures covered with bone tissue.
In addition, vascular examination with MRI is much safer than cerebral angiography using x-ray radiation.
The contrast of gadolinium, which is used in magnetic resonance imaging, is absolutely safe and rarely causes allergic reactions.
MRI angiography allows you to make a diagnosis already in the early stages of the disease, when changes in the brain tissue are minimal. This makes it possible to prescribe treatment as soon as possible and increases the chances of a successful rehabilitation.
Disadvantages of the method
Despite the many advantages, MRI angiography of cerebral vessels has several disadvantages:
- To obtain an accurate image, a person must lie still for more than half an hour.
- The study is contraindicated in people with any metal objects in the body.
- Although small, there is a chance of anaphylactic reaction to contrast.
The cumbersomeness of the design scares many patients. Therefore, the doctor must explain to the patient that the tomograph is absolutely safe.
Doctors consultation
The diagnostician who performed the examination does not make a final diagnosis. He only describes what he sees in the image. Interpretation of the results, comparing them with the clinic and objective examination data is carried out by a qualified specialist. For help, the patient can contact the doctors of such specialties:
- neuropathologist;
- neurosurgeon;
- phlebologist;
- angiosurgeon.
As can be seen from the story that this is an MRI scan of the vessels of the brain and neck, this study is a really effective method for the diagnosis of vascular pathology, the advantages of which significantly exceed the disadvantages.