Content
Magnetic resonance imaging (MRI), also known as nuclear magnetic resonance imaging (NMR), is an image exam capable of showing the internal structures of the organs with definition, being important to diagnose various health problems, such as aneurysms, tumors, joint changes or other injuries to internal organs.
To perform the exam, a large machine is used, which creates high-definition images of the internal organs through the use of a magnetic field, which causes the body's molecules to be agitated, captured by the device and transferred to a computer. The exam lasts about 15 to 30 minutes and, normally, no preparation is necessary, although it may be necessary to use a contrast, in some cases, through the injection of the medication through the vein.
MRI machine
Magnetic resonance image of the skull
What is it for
Magnetic resonance imaging is indicated in the following cases:
- Identify neurological diseases, such as Alzheimer's, brain tumor, multiple sclerosis or stroke, for example;
- Observe inflammation or infections in the brain, nerves or joints;
- Diagnose musculoskeletal injuries, such as tendonitis, ligament injuries, cysts, such as Tarlov's cyst or herniated discs, for example;
- Identify masses or tumors in the body's organs;
- Observe changes in blood vessels, such as aneurysms or clots.
It is necessary to take some precautions before performing this exam, as there cannot be any type of metallic material close to the magnetic field of the device, such as hairpins, glasses or clothing details, thus preventing accidents. For this same reason, this test is contraindicated for people who have any type of prosthesis, pacemakers or metallic pins implanted in the body.
In addition to the good quality of the images formed by magnetic resonance, another advantage is the non-use of ionizing radiation to obtain the results, differently from computed tomography. Understand what it is for and when a CT scan is needed.
How it is done
Magnetic resonance imaging usually lasts between 15 to 30 minutes, and can last up to 2 hours depending on the area to be examined. For this, it is necessary to remain inside the device that emits the magnetic field, and it does not hurt, however, it is very important not to move during this period, since any movement can alter the quality of the exam.
In people who are unable to stand still, such as children, people with claustrophobia, dementia or schizophrenia, for example, it may be necessary to perform the test with sedation to induce sleep, otherwise the test may not be effective.
In addition, in some cases, it may be necessary to apply a contrast to the patient's vein, such as Gallium, as it is a way of causing greater definition of the images, mainly to visualize organs or blood vessels.
Types of MRI
The types of MRIs depend on the affected site, the most common of which include:
- Magnetic resonance imaging of the pelvis, abdomen or chest: it serves to diagnose tumors or masses in organs such as the uterus, intestine, ovaries, prostate, bladder, pancreas, or heart, for example;
- Magnetic resonance imaging of the skull: helps to assess brain malformations, internal bleeding, cerebral thrombosis, brain tumors and other changes or infections in the brain or its vessels;
- Magnetic resonance imaging of the spine: helps to diagnose problems in the spine and spinal cord, such as tumors, calcifications, hernias or bone fragments, after fractures - See how to identify spinal arthrosis, for example;
- Magnetic resonance imaging of joints, such as the shoulder, knee or ankle: serves to assess soft tissues within the joint, such as the bursa, tendons and ligaments.
Magnetic resonance imaging is, therefore, an excellent exam to observe the soft parts of the body, however, it is not usually indicated to observe lesions in rigid regions, such as bones, being, in these cases, exams such as x-ray or computed tomography , for example.
Created by: Tua Saúde Editorial Team
Bibliography>
- Adilson Prando, Fernando Moreira. FUNDAMENTALS OF RADIOLOGY AND DIAGNOSIS BY IMAGE. 2. ed. Rio de Janeiro: Elsevier, 2014.