Although there isn't a single, specific test that can diagnose multiple sclerosis with 100% accuracy, laboratory tests and imaging are very important to aid in the diagnosis process.
Among these tests, the most important is MRI. Although for many it is a harmless exam (not as bad as an injection), for me, not so much, I am claustrophobic. So, turns out to be a real torture to have to submit myself to the dreaded "magnetic machine" for about half an hour and having to remain completely still, just listening to the sound it makes. But this is the most important test for the diagnosis and management of multiple sclerosis and therefore decided to understand it better and maybe lose the fear.
Magnetic resonance imaging was developed in the '30s, however, only in the 80s came to be used in hospitals. Today it is an essential tool for physicians, particularly when it comes to diseases such as multiple sclerosis, affecting the central nervous system. The structural details of the brain and spinal cord are seen much more clearly with MRI than with x-rays and computed tomography, and unlike these image options, MRI does not involve radiation.
The advent of MRI, in fact, revolutionized the diagnosis and control of multiple sclerosis, which traditionally had been diagnosed by clinical criteria and analysis of cerebrospinal fluid. Thus, since poorly detected by computed tomography, MS was one of the main diseases responsible for spreading the acceptance and use of magnetic resonance imaging.
HOW DOES MRI WORKS
The machine in which the examination is made of a tube surrounded by a large magnet, into which is produced a powerful magnetic field. The MRI machines make use of the ability of the nucleus of hydrogen atoms to absorb and emit electromagnetic waves that are transformed into images.
The hydrogen atoms are present in all cells of the body, but in greater quantity in the soft tissues, because it contains more water. Through resonance, a magnetic field aligns the hydrogen atoms of the part to be displayed. Soon after, this stimulus of attraction is switched off and the atoms return to their places. Depending on the weather and how these hydrogen atoms return to their place of origin, the device identifies whether the body is normal or not. In inflammation and lesions caused by MS, for example, hydrogen atoms return more quickly than in healthy tissues.
Usually the exam requires no previous preparation (sometimes, depending on the test, it is normal for the doctor to ask you to fast for 4 to 6 hours) and as soon as the procedure is finished, the patient can resume normal activities. It is not necessary to stop any medications the patient is taking.
A person doing MRI lies on a stretcher and is oriented to lie still while sliding inside of the machine.Since it is impossible to capture sharp images if the patient is moving, children and patients who can't control themselves need to be sedated before the exam.
MRI does not use radiation, but since the appliance generates a potent magnetic field (10,000 times greater than the Earth's magnetic field), the patient and the tech need to be careful and take some precautions. Small magnetic objects can become projectiles when they are attracted by the magnetic resonance field. Even large and heavy objects such as bookcases and banks present in the examination room, can be drawn. Being subjected to this magnetic field does not cause any biological damage to humans, but the technician or physician performing MRI should give patients detailed instructions, including:
The patient should go to the bathroom before the exam not to experience any urgency for the same, which can last a long time (about half an hour to an hour).
The patient should not move during the test, but can communicate with the doctor to ask for or receive instructionsand to report what you are experiencing.
Resonance is a noisy procedure. The patient should wear protective ear plugs or headphone, usually offered by the institution that makes the exam.
Some patients with phobic profile, may feel uncomfortable inside the MRI tube or even refuse to enter it. In more severe cases, it may opt for a clamping device or be submitted to a rapid sedation, although this means introducing a further complication in a relatively innocuous technique.
Pins, hairpins, metal zipper may distort images of MRI and should be removed. Appliances and objects such as credit cards, watches, eyeglasses, hearing aids, cell phones, mobile orthodontic implants and piercings should be removed but fixed orthodontic appliances do not pose risks to the patient, although they may impair the quality of the images.
Before the exam the patient should informe the doctor, so he decides on whether or not the examination, if using clips for cerebral aneurysms, pacemakers, cochlear implants, metal fragments in the body, lens implants, etc.
Other devices such as IUDs, clips gallbladder surgeries, brain valves, orthopedic implants and vascular stents implanted more than six weeks prior may be admitted without problems.
For safety, pregnant women should not undergo the examination after the 12th week of pregnancy. Harm to the mother or the fetus, even in the resonances made before this time are not known.
The weight limit for the exam is 160 pounds. In some tests the application of an innocuous venous contrast is required (gadolinium contrast).
THE MS DIAGNOSTIC AND MRI
Our nerves have a protective covering called myelin. In MS, the body's immune system mistakenly attacks the myelin, causing inflammation and damage (demyelination). The resulting scar tissue is called injury. Some lesions are inactive and do not cause any symptoms. The active lesions and the ones just forming or expanding, can cause a variety of symptoms, depending on where they are located and their sizes. The name "multiple sclerosis" means "multiple injuries." It is important to mention, however, that not always the number of injuries may be related to the severity of symptoms.
Diagnosis of MS lesions requires to be identified in different parts of the central nervous system (spread in space) and at different periods of time (spreading in time). To identify lesions spread in time with the use of contrast agent is necessary. In a single resonance examination at least one injury must show increase with contrast, indicating active inflammation (new), and one that remains unchanged, indicating previous inflammation.
Historically, diagnoses were based solely on the patient's history and physical examination. Although these are still very important, doctors began to make more use of magnetic resonance imaging, allowing early diagnosis of Multiple Sclerosis. Thus, formal criteria were created for that MRI could be used to show the dissemination of lesions in time and space, allowing doctors to diagnose multiple sclerosis in patients with a clinical event (outbreak).
MONITORING CHANGES WITH A RESONANCE
Therefore it's impossible to dispute the importance of MRI in the diagnosis of MS and the detection of active inflammation. Most neurologists will also request a new MRI every 6 to 12 months to see if new lesions are developing in the absence of clinical symptoms. If there are significant changes in the results of MRI, it is possible that a change in treatment is performed, rather than waiting until the patient has a new outbreak.
Probably, the strongest correlation between how the patient looks clinically and the results of his MRI is not the number of injuries that the patient has (active or inactive), but the volume of brain tissue, where the axons and myelin were destroyed . These areas appear as dark spaces in resonance and are labeled as "black holes". These can take years to develop and often are not evident in newly diagnosed patients. When visible in newly diagnosed patients, it is an indication that the patient already had the disease for many years without clinical symptoms. The resonance to the right, the red arrows indicate areas of brain tissue permanently destroyed, or "black holes".
Certainly the use of magnetic resonance imaging has significantly changed the way the diagnosis and even prognosis of MS is performed, showing a real ally of other clinical and laboratory tests should still be performed, such as blood tests , liquor, visual evoked potential, besides, of course, the clinical history and examination. Unfortunately, to date, Multiple Sclerosis, to be diagnosed is based on the clinical manifestation of symptoms (arising from one or more attacks), which brings the suspicion of demyelinating disease, asking a battery of tests that, according to medical interpretation, eliminate other illnesses and close the diagnosis of Multiple Sclerosis.
The video below explains a simple, straightforward operation of magnetic resonance form: