Magnetic resonance imaging


What is magnetic resonance imaging?

Magnetic resonance imaging (MRI) is a diagnostic imaging technique that uses radio frequency magnetic fields and electromagnetic waves to provide detailed images of the human body.

The MRT, also known as nuclear magnetic resonance tomography (NMR) or nuclear spin tomography, shows both the skeleton and the internal organs.
The examination is absolutely painless and does not involve any risks.

With this method, cross-sectional images of the body are generated, which are processed with the help of a computer; the radio pulses are converted into anatomical images and these are displayed on a screen.

The sectional images can be created in all three spatial planes, which enables a virtual, three-dimensional representation of the body.

The advantage of this procedure is that it is easy to distinguish between different tissue structures, such as the liver and spleen (which have the same transparency on an X-ray ), and that healthy tissue can be clearly distinguished from injuries.
Magnetic resonance imaging means time savings and an accurate, reliable diagnosis.

MRI is preferable to computed tomography (CT) if particularly high spatial resolution is not required because the patient is not exposed to ionizing radiation.

Because despite the term “nuclear”, nuclear magnetic resonance tomography does not use any radioactive substances or harmful radiation, but uses very strong magnetic fields and radio frequency waves such as those used for radio and television.
Even without X-rays, this imaging technique is usually associated with radiology because it creates images of the patient’s internal structures.

With the current state of research, there is no reason to assume that an MRI examination could be harmful to health; an exception are pregnant women and those cases in which the magnetic field interferes with metal parts present in the body, eg cardiac pacemakers or artery clamps.
Negative effects cannot be ruled out here and the MRI should only be carried out after a thorough assessment of the individual case.
The only disadvantage of magnetic resonance imaging is the high cost of the device and the maintenance effort.

How is an MRI scan done?

After all objects containing metal and clothing have been removed, the patient lies down on a couch, which is pushed into the examination tube by remote control until it is between the magnetic poles. During the examination, the patient does not have to do anything other than lie quietly and – if there are problems – call the staff.
For this purpose, the MRT machine is equipped with loudspeakers and microphones in order to be able to communicate with the doctors and assistants.
During the examination, sounds of various intensities and lengths are generated.
The device produces different sounds in some areas depending on the sequence used.

This method is thus characterized by a series of noises and pauses.
In order to protect the patient from the sometimes very unpleasant noise, earplugs are usually given to him.
The examination usually lasts 20 to 30 minutes, although technical developments make the recording times increasingly shorter.

In some cases, the doctor can inject a contrast agent (gadolinium) that has no side effects to improve the image quality and ensure a reliable diagnosis.
Magnetic resonance imaging requires a prescription.
The results are available a few days after the examination.

What can an MRI detect?

Today, MRI plays a key role in the detection of numerous diseases, because it enables accurate and reliable diagnosis and has practically no negative side effects.

Magnetic resonance imaging is mainly used in medicine for diagnostic purposes and can in fact be used to detect various pathologies affecting organs and tissues of the human body.
The quality of the results reveals details that other imaging methods do not show.
With the help of an MRI, it is possible, for example, to examine the blood flow in the tissues, the hydration of the intervertebral discs, the state of health of the joints and to diagnose neurological diseases and certain types of tumors very precisely.
Damage to the soft tissue that is not shown on the X-ray can be easily recognized, such as meniscus lesions , rupture of the cruciate ligaments andCollateral ligaments of the knee, herniated disc , rotator cuff tendon injuries, etc.
This examination method is useful in diagnosing diseases of the brain, spine, abdomen and pelvis (liver and uterus), large blood vessels and the musculoskeletal system (joints, bones , soft tissue). This imaging diagnostic method is particularly popular
when there is a suspected change in the spine because it provides information about the condition of the intervertebral discs.
Usually used only in patients suffering from chronic and severe back painsuffer, a nuclear spin tomography is carried out, because in 90% of the cases the back pain disappears of its own accord within 30 days, this examination method is not advisable in the acute phase, i.e. in the first week.
MRI can also be used in sports medicine to examine: total body fat, thickness of the subcutaneous fat layer, and amount of visceral and intra-abdominal fat.
However, the use of magnetic resonance in this area is quite limited due to the low availability and high equipment costs.

What preparation is necessary?

In the days before a magnetic resonance imaging, no preparation is necessary: ​​the patient can eat normally and continue to take all medication as before.
If an allergic reaction to the contrast medium is feared, preventive treatment can be carried out.

Usually the patient is asked to undress (the underwear can be left on as long as it does not contain any metal parts). Jewelry and piercings, hair clips, belts, glasses and watches must be removed beforehand, as must contact lenses, hearing aids, removable dentures, corsets and wigs.
Cell phones, credit cards and other cards with a magnetic stripe, which could interfere with the examination device, are not allowed on board.

The duration of an MRI scan depends on which part of the body is being scanned: the larger the area, the longer the scan will take (it can take up to 40-45 minutes).
For the recordings to be successful, it is important to lie still; many patients have difficulties with this; they may ask to stretch a little between each sequence.
Except in special cases, there is no observation time after the end of the examination: the patient is allowed to get dressed and go home.

What are the disadvantages and side effects of MRI?

This examination method should be avoided during pregnancy or should only be used in emergencies, especially in the first 12 weeks.
If injections of contrast medium are planned, breastfeeding mothers should express milk beforehand and store it to cover the first 24 hours after the examination; it is advisable to use the bottle so that the contrast medium cannot be ingested by the baby.
Women who use contraceptives such as the spiral should later have their gynecologist check whether this has been displaced by the influence of the magnetic fields.

Patients with cardiac pacemakers or neurostimulators must not undergo MRI, the magnetic fields generated could impair their functionality.
Anyone who has metal structures in their body (prostheses, nails, screws, heart valves), especially in the vicinity of vital organs, must not be exposed to magnetic resonance imaging because there is a risk that the magnetic field will move them to other regions.
New materials are increasingly being used in surgery, often based on titanium, which do not constitute a contraindication to MRI.

No type of assistance is required during and after the examination, the patient can leave the practice immediately and drive a car himself.
The examination is painless, apart from a small puncture if contrast medium is injected.

Only the following side effects can be mentioned as disturbing: the loud noises that the machine makes and the feeling of claustrophobia (claustrophobia) when the patient is locked in the examination tube.

For the noise, the patient is usually offered earplugs or headphones; As far as the uncomfortable narrowness is concerned, the devices are now much more spacious and open than they used to be.
If you have problems and suffer from severe claustrophobia, epilepsy or mental health problems, you should definitely tell the staff before the examination.
If necessary, a mild sedative can be given, which is also used with children, to keep them calm for the duration of the somewhat lengthy examination.

It is normal for some parts of the body to feel warm during the examination; however, if this feeling becomes excessive, staff should be informed.
It is also possible that the magnetic field generated by the machine, by stimulating nerve cells, causes unwanted muscle contraction or makes some muscles in different parts of the body pulsate.
Whatever happens, the staff monitors the patient throughout the examination and can intervene at critical moments at any time.

If the above rules are observed, the only risk factor in magnetic resonance imaging is an allergic reaction to the contrast agent; the doctor should therefore be informed if critical situations of this kind have already occurred or if severe kidney disease is present.
An allergy can manifest itself through mild symptoms such as itching , nausea , vomiting ; only rarely do more severe symptoms occur. Tattoos can irritate the skin, especially when they are beautifully aged, as they used to be made using metallic pigments.

Otherwise, magnetic resonance tomography is a safe and harmless examination method for humans.
Since there is no ionizing radiation, it can be repeated after a short time.

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