What is nuclear magnetic resonance?
Nuclear magnetic resonance (NMR) is a method that uses magnetic waves, radio waves and a computer to produce some interior images of the body.
One can see the skeleton and the internal organs.
The examination is absolutely painless and risk free.
This type of examination provides images of sections of the body that are processed with the help of a computer that transforms radio waves into anatomical images and displays them using a computer monitor.
Sections can be obtained in all three planes of space, thus creating a virtual three-dimensional view of the body.
The advantage of this examination is to distinguish, for example, a liver tissue and a spleen (which on the radiograph have the same transparency) to show the difference between healthy and damaged tissues.
The use of magnetic resonance imaging is time-consuming and allows for a more accurate and accurate diagnosis .
Magnetic resonance imaging is preferred over computed tomography because the patient does not absorb ionizing radiation.
In fact, despite the word “nuclear”, NMR does not use any ionizing radiation or radioactive substances, but uses high-intensity magnetic fields similar to large magnets and radiofrequency waves, such as those used for radio and television.
Although not using x-rays, this test is usually considered part of Radiology because it generates images related to the patient’s internal structures.
In the current state of knowledge, there is no reason to consider magnetic resonance imaging harmful, except for those cases in which the magnetic field interacts with metal implants that are present in the patient’s body, such as pacemaker, vascular clips and in the case of women pregnant women.
In these cases, the examination can be harmful.
The only limit to its continued disclosure is the high cost of equipment and maintenance.
During the examination, the patient should do nothing except relax and warn the technical staff with special tools in case of difficulties. The devices are equipped with microphones and speakers to communicate with your doctor or nurse.
Various types of noise of varying duration and intensity can be heard during playback.
Some parts of the machine produce a different sound depending on the type of sequence that is used.
The exam is characterized by alternating noise and short breaks because there are several sequences.
The noise is very strong because of the emission of radio waves, so ear protectors are provided to the patient.
The average duration of the examination is usually between twenty and thirty minutes, although more modern techniques can reduce detection time.
To improve image quality and for a safer diagnosis, in some cases your doctor may inject a contrast medium (gadolinium) that is usually free of side effects.
A medical prescription is required to complete the test.
Usually the report can be delivered to the patient within 3-5 days after the examination.
Magnetic resonance imaging
Today, magnetic resonance imaging plays an important role in the diagnosis of many diseases because of its extreme accuracy and almost total absence of side effects.
Magnetic resonance imaging is used in medicine for diagnostic purposes, it can be used for the diagnosis of a variety of pathological conditions that affect the organs and tissues of the body.
The quality of the results allows us to appreciate undetectable details with other diagnostic techniques.
Just to mention a few examples, it is possible to study the vascularization of the tissues, the state of hydration of the intervertebral discs, consider the health of the joints, diagnose neurological diseases with extreme precision and some forms of cancer.
It is useful in case of damage to soft tissues that are undetectable by radiography such as meniscus injury , knee lateral ligament injury, crusades , disc herniation , rotator cuff tendon injury, etc.
This method is useful for the diagnosis of diseases of the brain, spine, abdomen and pelvis ( liverand uterus), the great vessels and the musculoskeletal system ( joints , bones , soft tissues).
Especially in case of suspected spinal changesthis diagnostic procedure is often used because it can provide information about the conditions of the intervertebral discs. Patients suffering from chronic and incapacitating back pain
are usually submitted to MRI , considering that more than 90% of cases of spinal pain return spontaneously within thirty days, it is not recommended to undergo this examination in the acute phase or in the first week.
This technique can also be used in the field of sports medicine to assess: the total amount of body fat, the subcutaneous fat thickness and the amount of visceral or intra-abdominal adipose tissue. However, due to the low availability and high cost of instrumentation, the use of magnetic resonance imaging in this field is quite limited.
What kind of preparation should be done?
In the days leading up to performing an MRI there is no need for any preparation or any special precaution: you can eat normally and take all the medications you take regularly.
Preventive treatment may be necessary to avoid dangerous reactions in people with allergies who must be tested with contrast medium or other specific cases.
Usually the patient will be asked to remove all clothing except intimate parts (if they do not contain metal parts) and wear a hospital gown and disposable hosiery (provided by the staff).
The patient obviously must remove all jewelry and piercings, hair clips and belts, glasses and watches, but also contact lenses, dental prostheses, corsets and wigs.
It is not allowed to bring cell, c artão credit card or other magnetic storage which can interfere with the MRI machine.
The duration of an MRI varies depending on the part of the body being examined: the longer, the longer the examination (it may take 40-45 minutes).
Many people find it difficult to stay immobile so they can ask to move a little between one sequence and another.
Except in special cases indicated by the technical team, a period of observation is not necessary at the end of the examination: the patient can dress immediately and go home.
What are the contraindications and side effects?
During pregnancy the test is contraindicated and should be performed only in cases of absolute necessity, especially during the first 12 weeks.
If the doctor has to inject a contrast medium before the examination, women who are breastfeeding should collect the necessary milk for 24 hours after the MRI, then they can breastfeed the baby with a bottle.
Women with contraceptive means, such as the IUD, should consult their gynecologist to make sure that the device does not move under the influence of magnetic fields.
It is also not possible to perform an MRI cardiac pacemaker or neuro-stimulation because the magnetic field generated can affect its operation.
Who has metal structures of various types in the body (implants, nails, screws, metallic heart valves) after major surgery, especially if near vital organs, can not undergo NMR to prevent the magnetic field from causing a movement in an area different.
In surgery with new materials, these are generally made of titanium and do not have contraindications with MRI.
For the exam does not need any assistance, neither during nor then to return home, even driving, without any type of limitation.
Performing an MRI does not cause pain, in addition to a small puncture needed to inject the contrast liquid.
The only discomfort that can occur during the examination is the high noise caused by the machine and the feeling of claustrophobia felt inside a large cylinder during the examination.
To avoid hearing the machine noise, the doctor supplies the patient with headphones.
The discomfort you feel inside the machine is less when using larger, open equipment.
In any case, it is necessary that those who suffer from severe claustrophobia, epilepsy or psychiatric disorders signal the issue to the operators.
Possibly to be more relaxed, the patient can take a mild sedative, often used to keep the children immobile for some time.
During the examination it is normal to feel a sensation of warmth in some parts of the body. If it becomes excessive, the patient must inform the operators.
It is possible that the magnetic field generated by the machine causes an involuntary contraction or pulsating sensation in some muscles of the body because it stimulates the patient’s nerve cells.
In any case, whoever performs an examination has the patient under control, so he can always intervene if necessary.
Respecting the rules mentioned above, the only risk of MRI is an allergic reaction to the substance used as a contrast medium.
It is necessary to alert the staff if the patient has had an allergic reaction to the liquid or in case of severe renal dysfunction.
The allergymay occur with mild symptoms, such as itching , nausea and vomiting , only in some cases more rare manifestations have stronger symptoms.
Tattoos with the use of metallic pigments can create skin irritations.
The absence of ionizing radiation also allows for repetition after a short period of time.