Imagen de resonancia magnética (IRM) para la esclerosis múltiple

Qué esperar al someterse a esta prueba.

La resonancia magnética (IRM) es un procedimiento no invasivo que desempeña un papel clave en el diagnóstico y monitoreo de la esclerosis múltiple (EM) . De hecho, los investigadores y los profesionales médicos consideran que la RM es uno de los mayores avances en el campo de la esclerosis múltiple, ya que permite ver lesiones en el cerebro y la médula espinal que indican la enfermedad que de otro modo requeriría una cirugía para ver.

Si se está sometiendo a una MRI (también conocida como imagen de resonancia magnética nuclear o NMRI) para saber si tiene EM, o si le han diagnosticado y se realizará la prueba para evaluar la progresión de su enfermedad, es posible que esté nervioso. Saber qué esperar de las pruebas de resonancia magnética de principio a fin puede ayudar.

Propósito de la Prueba

La RM se usa de tres maneras para la esclerosis múltiple. Como tal, puede tener varios a lo largo de los años por cualquiera de estas razones.

Diagnóstico

Cuando una persona tiene síntomas que sugieren EM , la prueba de resonancia magnética es uno de los varios procedimientos que se utilizan para confirmar si la enfermedad es el problema al revelar la presencia de lesiones, en áreas en las que el cuerpo atacó y dañó por error la capa protectora de mielina que rodea los nervios. En el cerebro y / o médula espinal.

Monitoreo de enfermedades

Debido a que la esclerosis múltiple es una afección progresiva, las IRM regulares pueden ayudar a rastrear el desarrollo de nuevas lesiones. Las IRM regulares también pueden proporcionar una indicación de qué tan bien está respondiendo a la terapia modificadora de la enfermedad de la EM . Muchos neurólogos recomiendan que los pacientes con EM tengan IRM cada año aproximadamente.

Detección de recaída

Una resonancia magnética puede determinar si una recaída está causando nuevos síntomas neurológicos . Esto se logra utilizando el agente de contraste gadolinio, que causa que las nuevas lesiones se “iluminen”, lo que indica una inflamación activa dentro del sistema nervioso central.

Las lesiones que no se iluminan en una IRM con gadolinio probablemente tengan al menos uno o dos meses de edad.Tipos de resonancias magnéticas utilizadas para la EM

Riesgos y contraindicaciones

Para la mayoría de las personas con EM, las imágenes de resonancia magnética son seguras.

Sin embargo, de acuerdo con la Sociedad Nacional de Esclerosis Múltiple(NMSS), existen dos riesgos potenciales asociados con el uso de agentes de contraste basados ​​en gadolinio (GBCA), incluso para personas con buena salud.

  • Fibrosis sistémica nefrogénica (NSF, por sus siglas en inglés): esta es una condición rara que se sabe que ocurre en personas con insuficiencia renal. Causa engrosamiento de la piel y daño a los órganos internos.
  • Retención de GBCA: se han encontrado depósitos de material de contraste en el cerebro y otros tejidos corporales de algunas personas. Aunque no se sabe si estos depósitos son dañinos, la Administración de Drogas y Alimentos de los Estados Unidos (FDA, por sus siglas en inglés) ha tomado varias medidas de seguridad , incluida la publicación de recomendaciones para los tipos de gadolinio que tienen menos probabilidades de ser retenidos en el cuerpo.

Seguridad de los tintes de contraste utilizados en la resonancia magnética

Consideraciones de seguridad

Besides attracting metal objects outside of the body, such as jewelry, the powerful magnetic field in an MRI machine can affect objects inside the body. As such, the test may not be safe for people who have certain medical implants, medicine pumps, or aneurysm clips, for example.

Tattoos made from inks that contain metallic elements also may be a disqualifying factor for MRI.

Before the Test

Often scans of both the brain and the spinal cord are necessary, especially for an initial MRI for diagnosing MS. If your neurologist orders both, you may be asked if you want to do the scans in one session or in two separate appointments. Getting it done all at once is convenient, but time-consuming. Opting for two sessions means each will be shorter, but if gadolinium is being used, you’ll receive it twice, which may be a consideration worth weighing.

Timing

The length of an MRI for multiple sclerosis will depend on the purpose of the test. For instance, it will take longer to do scans of both the brain and spinal cord than it will to scan one or the other structure.

Other factors that will impact the length of an MRI appointment include whether or not contrast material will be administered and if a sedative or anesthesia will be necessary. In general, an appointment for an MRI for any reason can take anywhere from 45 minutes to four hours.An Overview of Magnetic Resonance Imaging

Location

Magnetic resonance imaging typically takes place at freestanding imaging centers or at hospitals equipped with MRI equipment and technicians trained to perform scans.

In either case, the actual test is done in two conjoined rooms: In one is the actual scanner, in the other is the computer that will operate the machine and where the MRI technician will oversee the scan.

You will be able to communicate with each other while in separate rooms via an intercom system.

What to Wear

Because MRI relies on powerful magnets, anything that is metal or has metal parts—jewelry, watches, eyeglasses, hearing aids, dentures, body piercings, and even underwire bras—isn’t allowed inside of scanners. Leave as many of these items at home as you can to reduce the risk of losing them since you’ll have to remove them anyway.

Some MRI centers allow you to wear your own clothes instead of a hospital gown during the scan as long as there are no metal buttons, snaps, or zippers. If this is the case, wear soft, comfortable clothing. A T-shirt and elastic waist pants or shorts (plus a sports bra for women) are ideal. It can get hot in an MRI machine, so err on the side of choosing lightweight clothing; you can always ask for a blanket if you find the scanning room to be chilly.

Food and Drink

Typically, there are no restrictions as to what can be ingested before an MRI, including medications. One exception: If for any reason you will need to receive anesthesia or a sedative for your test—because you have claustrophobia that is severe enough to make it impossible to lie still and not panic, for example—you may receive instructions about what and when you can eat or drink the day before and the morning of your scan.

Tip

Take a ​cough suppressant if you think you’ll need one. Coughing during an MRI may cause movements that require starting over. Just make sure your doctor says it’s OK to do so.

Cost and Health Insurance

Magnetic resonance imaging can be expensive—anywhere from $400 to $3,500. If you have health insurance, your MRI likely will be covered, although you may be responsible for a co-pay and/or coinsurance. You also may need pre-authorization for an MRI; check with your insurance carrier to be on the safe side.

If you don’t have health insurance, you may be eligible for a discount. Talk to the business or accounting office at the hospital or imaging center to learn about their policies.6 Free or Low-Cost Health Insurance Options

What to Bring

You shouldn’t need to bring much to your scan, but do be sure to have:

  • A photo ID
  • Your insurance card (if you have one)
  • Printed information about any medical device or implant you have
  • Someone to drive you home after your MRI if you will be sedated or have anesthesia

During the Test

You will be interacting with a radiology technician during your MRI.

Pre-Test

Before you prepare for your scan, you may need to fill out a safety screening questionnaire and/or a consent form, go over your health history, and have your heart rate, temperature, and blood pressure checked. You’ll remove your jewelry, glasses, and other such items.

You then will lie down on a moveable table that slides in and out of the MRI scanner, a large cylinder-shaped tube surrounded by a circular magnet. The technologist may use straps or bolsters to help you stay still comfortably. If you’re having a brain MRI, a device may be used to keep your head still.

If you’ll be having a T-1 weighted MRI with a gadolinium contrast agent, an IV will be placed in a vein in your hand or arm to administer the dye. The IV also may be used if you’ll be receiving intravenous sedation.

Some people experience a cold feeling as contrast dye enters the bloodstream or get a metallic taste in their mouth. Both sensations are temporary and normal.

Very rarely, contrast dye causes an allergic reaction (mild hives and itchy eyes and/or skin). Tell the technician if this happens to you; note that the symptoms will probably go away within a few minutes after the dye is administered.

Throughout the Test

Once you’re in position, the table will slide into the tube and the technologist will leave the room. The two-way intercom will allow you to tell him or her if you’re experiencing claustrophobia, anxiety, or pain.

To get the best quality images, you’ll be asked to hold as still as you can during the scan. This may be unpleasant, but it’s the closest thing to discomfort you should experience. You may feel some warmth in the area of your body that’s being scanned, but this is normal.

Post-Test

When the scan is complete, the technician will slide the table out of the machine, remove your IV (if you had one), and help you up.

At this point, you can get dressed, collect any valuables you removed, and go home. If you had anesthesia, you will be taken to a recovery room where you will be woken up and allowed to recover before you go home with a family member or friend.

After the Test

There’s little you should need to do after having an MRI. Side effects are rare and are most likely to occur if contrast dye was used.

If you did receive a contrast dye, drink lots of water to help speed up the process of your kidneys flushing the agent out of your system.

Some people experience headache, nausea, and dizziness for a few hours after receiving contrast dye. The site of an IV may bruise and swell slightly, but this shouldn’t last more than a day or two. If it doesn’t get better, call your doctor.

Interpreting Results

It likely will take a few days for your neurologist to receive the results of your MRI, at which point he or she will contact you to discuss them and talk about any next steps that might be necessary.

What you will learn from your MRI will depend on which type was done and its intention.

Type of MRI What It Reveals
T-1 weighted MRI without gadolinium Diagnosis of MS based on presence of lesions
T-1 weighted MRI with gadolinium Active disease based on lesions that “light up”
T-2 weighted MRI without gadolinium Evaluation of MS based on old and new lesions
Spinal cord MRI MS diagnosis or evaluation lesions on spinal cord

Follow-Up

Likewise, what happens after you receive the results of an MRI for multiple sclerosis will depend on the specific findings.

If lesions that confirm you have multiple sclerosis are revealed, further testing may be needed to fine-tune your treatment. And even if your MRI doesn’t show lesions but you have symptoms that seem to point to MS, your neurologist may have you undergo other types of MS diagnostic tests.

Around 5 percent of people with MS have normal results—no lesions—at the time they first are scanned, so other measures such as blood tests, spinal taps, and evoked potential tests may be needed to definitively confirm a diagnosis.

The results of an MRI scan to evaluate MS in someone who already is living with the disease will show how it’s progressing (or not).

For example, according to the McDonald Criteria, which is used to determine if you have or don’t have MS, MRI is one of the diagnostic methods typically used. (The others are a neurological exam, spinal fluid, and evoked potential testing.)

Use our Doctor Discussion Guide below to help start the conversation with your doctor about interpreting your results.

Bone Marrow Transplantation at | 832-533-3765 | [email protected] | Website

I am Dr. Christopher Loynes and I specialize in Bone Marrow Transplantation, Hematologic Neoplasms, and Leukemia. I graduated from the American University of Beirut, Beirut. I work at New York Bone Marrow Transplantation
Hospital and Hematologic Neoplasms. I am also the Faculty of Medicine at the American University of New York.