What is MRI and How do you prepare for it

Magnetic resonance imaging, which is the official name, is one of the so-called radiological or radio diagnostic tests. In these tests, radiation is used to see our interior. It may include MRI for arm and elbow which can be very helpful for doctors to take a closer look at the interior of your body.

One or the other is chosen (X-ray, MRI, CT or ultrasound), depending on what you want to see, since there is no perfect and infallible system. They all have their pros and cons.


MRI uses a large magnet and radio waves that pass through our body and provide very precise images of our interior. The magnet makes our molecules vibrate and can be photographed.

  • Unlike the other tests, it does not use X-rays and is therefore, in this sense, harmless.

It is especially useful for scanning the brain and spinal cord. But it is also used to diagnose bone fractures and soft tissue injuries (organs that do not have bone).

An X-ray shows you the calcium in the bone and if there is a break, but the MRI gives you a better view of the interior of the bone, the nerves and the ligaments”,


Although it does not involve risks, and therefore, it is one of the most advisable methods, resonance cannot always be used or it is not convenient to do so.

  • You don’t see everything. It does not offer good vision in some areas of the body because they are in continuous movements, such as the lungs or the heart.
  • The test is long. On average you can be between 30 and 40 minutes without moving. Sometimes you have to be in awkward positions, sideways. It is painless but somewhat exhausting for the patient.
  • Your cost. Both in terms of time and personnel. In emergencies, which have to have an immediate diagnosis, they cannot be waiting and with personnel always aware of the device. That is why sometimes you have to resort to other systems with X-rays.
  • The apparatus imposes. It is a tube and can cause some claustrophobia. In addition, the noise caused by the machine with a continuous tapping is not reassuring, especially if we take into account that the patient may be distressed for fear of having a wrong diagnosis confirmed.


The more up-to-date the equipment, the better images are obtained and therefore the final result is more reliable.

“It’s like a camera, the more perfect it is, the better the image quality”, explains the doctor. The latest models are three teslas (which is the quality measurement system).

In hospitals there may be more or less modern models. Depending on the need for image precision required, the doctor will request one or the other.

Unfortunately, the economic factor also influences. They are very expensive devices and not all centers can have them. An MRI device can cost almost two million euros.


To perform the MRI, the patient cannot wear anything metal that interferes and heats up. That’s why earrings, insulin pumps, etc. are removed.

  • It does not require anesthesia, but since it requires being very still, it is necessary for small children to be sedated and this option can also be chosen if a person has claustrophobia.


When you want to see if blood enters a lesion, for example, because it is a tumor or an inflammation, and thus differentiate it from a stain that could be an old scar or fibrosis, you have to put a substance that allows you to see the blood.

That liquid is commonly known as a contrast. It could be considered the only “risk” of this test since this liquid sometimes causes an uncomfortable sensation of heat or discomfort.

  • In specific cases it can also give allergic reactions. That is why it is important that, when contrast is applied, in addition to the technician who operates the MRI machine, there is a doctor who controls the patient.


The other techniques, radiography and CT, use ionizing radiation (X-rays). The ions can be harmful and even cause cancer in cases of very continuous use. Therefore, it is not advisable to do them in excess or if it is not totally necessary.

  • In contrast, ultrasound does not use radiation, but rather sound waves. It is not harmful at all and that is why it is used in the control of pregnancies.

MRI is especially useful in cancer detection. But it should not be associated only with that. It is also the best option, among others, in knee problems, if you want to know if the injuries, for example, are in the tendons, in the meniscus or elsewhere and if they are recent or due to wear.

Tristram Shandy