Should you drive home after a MRI?
Magnetic resonance imaging (MRI) is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body.
An MRI scanner is a large tube that contains powerful magnets. You lie inside the tube during the scan.
An MRI scan can be used to examine any part of the body.
The results of an MRI scan can be used to:
- help diagnose conditions
- plan treatments
- assess how effective previous treatment has been
Before an MRI scan
On the day of your MRI scan, you should be able to eat, drink and take any medication as usual, unless you’re advised otherwise.
In some cases, you may be asked not to eat or drink anything for up to 4 hours before the scan. Other patients may be asked to drink quite a large amount of water beforehand. This depends on the area being scanned.
When you arrive for your scan, you’ll be asked to fill in and sign a questionnaire about your health and medical history. This helps to ensure that it’s safe for you to have the scan.
As the MRI scanner uses strong magnetic fields, it’s important to remove any metal objects from your body. These include:
- jewellery, like earrings and necklaces
- piercings, like ear, nipple and nose rings
- dentures (false teeth)
- hearing aids
- wigs (some wigs contain traces of metal)
- medicine patches (like nicotine or hormone patches)
- glucose monitors
- tethered or patch insulin pumps
You should avoid bringing valuables along with you to your MRI scan. However, any valuables you do bring can usually be stored in a secure locker.
Depending on which part of your body is being scanned, you may need to wear a hospital gown during the procedure.
If you don’t need to wear a gown, you should wear clothes without metal zips, fasteners, buttons, underwire (bras), belts or buckles.
Is an MRI scan safe?
An MRI scan is a painless and safe procedure. Extensive research has been carried out into whether the magnetic fields and radio waves used during MRI scans may pose a risk to the human body. No evidence has been found to suggest there’s a risk, which means MRI scans are one of the safest medical procedures available.
Some patients occasionally experience a tingling sensation or feel hot from being in the MRI scanner. These effects only last a short while and should ease as soon as the scan is over.
You’re given a squeeze alarm which can alert the Radiographers if you have any concerns during your scan.
MRI scans may not be recommended for patients with certain implants or foreign bodies. If you have any metal in your body, you should tell the person referring you for the scan,. This can then be looked into before your scan.
Some MRI scans involve having an injection of a contrast agent. This makes certain tissues and blood vessels show up more clearly and in greater detail.
Sometimes the contrast agent can cause side effects, like:
- feeling or being sick
- a skin rash
- a headache
These side effects are usually mild and don’t last very long.
It’s also possible for contrast agents to cause tissue and organ damage in people with severe kidney disease. You may be given a blood test to determine how well your kidneys are functioning and whether it’s safe to go ahead with the scan.
You should let the staff know if you have a history of allergic reactions or any blood clotting problems before having the injection.
Anaesthesia and sedatives
An MRI scan is a painless procedure, so anaesthesia (painkilling medication) isn’t usually needed.
If you’re claustrophobic, you can ask for a mild sedative to help you relax. You should ask your GP or consultant well before having the scan.
If you decide to have a sedative during the scan, you’ll need to arrange for a friend or family member to drive you home afterwards, as you won’t be able to drive for 24 hours.
Babies and young children may be given a general anaesthetic before having an MRI scan. This is because it’s very important to stay still during the scan, which babies and young children are often unable to do when they’re awake.
What happens during an MRI scan?
An MRI scanner is a short cylinder that’s open at both ends. You’ll lie on a flat motorised bed that moves inside the scanner.
In some cases, a frame may be placed over the body part being scanned, like the head or chest. This frame contains receivers that pick up the signals sent out by your body during the scan. This can help to create a better quality image.
Depending on the part of your body being scanned, you’ll be moved into the scanner either head or feet first.
Who operates an MRI scanner?
The MRI scanner is normally operated by a Radiographer, who is trained in carrying out imaging investigations. They control the scanner using a computer. This is in a different room to keep it away from the magnetic field generated by the scanner.
You’ll be able to talk to the Radiographer through an intercom. They’ll also be able to see you throughout the scan via a television monitor and a viewing window.
During the scan
At certain times during the scan, the scanner will make loud tapping noises. This is the electric current in the scanner coils being turned on and off. It can be extremely loud and patients have often compared it to standing immediately next to roadworks.
You’ll be given earplugs or headphones to wear to help you feel more comfortable.
You’re usually able to listen to music through headphones during the scan if you want to, and in some cases you can bring your own CD.
To avoid the images being blurred, it’s very important to keep your whole body still throughout the entire scan.
Modern MRI scanners have a wider tunnel, which helps reduce claustrophobia. If you’re claustrophobic you should tell the Radiographer. They’ll be able to support you during your scan. Going into the scanner feet first may be easier for claustrophobic patients, although this isn’t always possible.
How long does an MRI scan take?
A single scan may take a few seconds or 3 to 8 minutes. You may be asked to hold your breath during short scans.
The total scan lasts 15 to 90 minutes, depending on the size of the area being scanned and how many images are needed.
You’ll be moved out of the scanner when your scan is over.
After the scan
An MRI scan is usually carried out as an outpatient procedure. This means you won’t need to stay in hospital overnight.
After the scan, you can resume normal activities immediately. If you have had a sedative, a friend or relative will need to take you home and stay with you for the first 24 hours.
It’s not safe to drive, operate heavy machinery or drink alcohol for 24 hours after having a sedative.
Getting your MRI scan results
Your MRI scan needs to be studied by a Radiologist (a doctor trained in interpreting scans and X-rays). It may also need to be discussed with other specialists. This means it’s unlikely you’ll get the results of your scan immediately.
The Radiologist will send a report to the doctor who arranged the scan. They’ll discuss the results with you.
It usually takes 1 to 2 weeks for the results of an MRI scan to come through, unless they’re needed urgently.
How does an MRI scan work?
Most of the human body is made up of water molecules. These consist of hydrogen and oxygen atoms.
At the centre of each hydrogen atom is an even smaller particle called a proton. Protons are like tiny magnets and are very sensitive to magnetic fields.
The MRI scanner has powerful magnets. This means that when you lie inside it, the protons in your body line up in the same direction. This is similar to when a magnet pulls the needle of a compass. You will not be able to feel this happening.
Short bursts of radio waves are then sent into the body, knocking the protons out of alignment. When the radio waves are turned off, the protons realign. This sends out radio signals, which are picked up by receivers.
These signals provide information about the exact location of the protons in the body. They also help to show the difference between types of tissue in the body. This is because the protons in different types of tissue realign at different speeds and produce distinct signals.
Who can have an MRI scan?
Magnetic resonance imaging (MRI) is very safe and most people are able to have the procedure.
However, there are some instances where an MRI scan may not be recommended.
Before having an MRI scan, you should tell medical staff if:
- you think you have any metal in or on your body
- you’re pregnant or breastfeeding
- you have had a previous allergic reaction to a contrast agent
- you have known problems with your kidneys
You should tell the person who is referring you for an MRI scan if you have any metal in your body. You must also tell them if you’re pregnant. This will allow the Radiology department to check whether it’s safe for you to have your MRI scan before you arrive for your appointment.
There’s no evidence to suggest MRI scans pose a risk during pregnancy. However your specific case will be reviewed by the clinical team looking after you to decide whether an MRI scan is right for you.
The Radiographers will change the settings on the scanner to make it as safe as possible for you and your baby.
Contrast agents, which are sometimes given as part of the scan, will only be given if a Radiologist decides this is right for you.
Metal implants or fragments
Having something metallic in your body doesn’t necessarily mean you can’t have an MRI scan. However, it’s important that the medical staff carrying out the scan are aware of it.
They can decide on a case-by-case basis if there are any risks. They’ll also decide if further measures need to be taken to ensure the scan is as safe as possible. For example, it may be possible to make it safe for a pacemaker or defibrillator to be scanned when certain conditions are met.
You may need to have an X-ray if you’re unsure about any metal fragments in your body.
Examples of metal implants or fragments that you should make your Radiographer aware of before being scanned include:
- a pacemaker – a small electrical device used to control an irregular heartbeat
- an implantable cardioverter-defibrillator (ICD) – a similar device to a pacemaker that uses electrical shocks to regulate heartbeats
- metal plates, wires, screws or rods – used during surgery for bone fractures
- a nerve stimulator – an electrical implant used to treat long-term nerve pain
- a cochlear implant – a device similar to a hearing aid that’s surgically implanted inside the ear
- a drug pump implant – used to treat long-term pain by delivering painkilling medication directly to an area of the body, such as the lower back
- brain aneurysm clips – small metal clips used to seal blood vessels in the brain that would otherwise be at risk of rupturing (bursting)
- metallic fragments in or near your eyes or blood vessels (people who do welding or metalwork for a living have a higher risk of this)
- prosthetic (artificial) metal heart valves
- penile implants – used to treat erectile dysfunction (impotence)
- eye implants – like small metal clips used to hold the retina in place
- an intrauterine device (IUD) – a contraceptive device made of plastic or copper that fits inside the womb
- artificial joints – like those used for a hip replacement or knee replacement
- dental fillings and bridges
- tubal ligation clips – used in female sterilisation
- surgical clips or staples – used to close wounds after an operation
- tattoos and permanent make-up
- foreign bodies like bullets or shrapnel
- breast expanders
- insulin pumps
- glucose monitoring devices
Most implants can be scanned safely using MRI. However, it’s important that the Radiology department are aware of them. This means they can check whether any adjustments need to be made to ensure the scan is safe for you.
MRI for Children
Axial MRI image of the brain (left) and sagittal MRI image of the knee (right). An MRI is a diagnostic imaging procedure that uses a powerful magnet, radiofrequencies and a computer to produce images of a child’s organs and structures. MRI stands for magnetic resonance imaging.
The MRI machine looks like a small tunnel. The exam table moves through the opening of the tunnel. The machine makes cross-sectional images of the body, most often referred to as slices. Just imagine looking at a piece of bread from the middle of the loaf — that’s what an MRI machine can do. It’s useful to see tissues anywhere in the body that otherwise may only be seen through surgery.
MRI with contrast
During an MRI exam, your child may be given a gadolinium-based contrast agent (GBCA) through an intravenous line (IV). A contrast agent (also called a dye) can enhance the visibility of internal body structures seen in the MRI pictures. Not all MRI studies need to use a contrast agent. If IV contrast has been ordered by your child’s doctor, it is because it can sometimes help us provide the earliest and most accurate diagnosis of certain diagnoses.
There are several different types and brands of GBCA that may be used. If your child’s study needs to use one of the gadolinium agents, your child’s medical team will provide additional detail about the specific contrast agent being used, including a copy of this letter.
Children’s Hospital of Philadelphia currently uses contrast agents from three manufacturers of gadolinium. Fact sheets from these manufacturers are available on the Food and Drug Administration (FDA) website.
GBCA has been approved for clinical use in the United States for more than 30 years, and hundreds of millions of doses have been given safely to patients throughout the world. If you have any questions, do not hesitate to ask to speak with a Radiology staff member.
A video introduction to MRI
This child-friendly video cartoon can help prepare your child for getting an MRI. See what an MRI machine looks like, hear the MRI noise, and learn how the MRI scan works.
What should you do prior to the exam?
There are different preparations to follow according to exactly what type of MRI scan your child is having. If your child:
- Will not be sedated, there are no special preparations to follow.
- Will be sedated for the exam, please follow the sedation preparation guidelines provided to you by your medical team. Sedation is required for all children up to 8 years old.
- Will be having an MRI Cholangiogram, then your child may have nothing to eat or drink four hours prior to the exam time. If your child is also being sedated for this exam, please follow the sedation guidelines.
If your child has a noted allergy to radiographic contrast, additional preparations may be necessary.
Dress your child comfortably, in clothes that are easily removed (sweat clothes, t-shirts). Your child may be given a gown to change into for the MRI, if required.
If you have copies of your child’s previous imaging studies from another institution, please bring them for comparison.
MRI safety precautions
MRI does not pose any risks unless your child has any kind of implanted metal objects or devices in her body. For this reason, your child will screened to ensure both of you are safe to enter the magnetic field.
All implants or devices must be approved by the MRI technologists and radiologists before entering the magnetic field. For efficiency, please bring the following information about your child’s device with you:
- Name of manufacturer
- Date of placement
- Name of device and composition (composition may not be listed but we can research it if needed)
The following are not allowed into the CHOP MRI:
- Defibrillators (IAED)
- Greenfield filters
- Women who are pregnant (1st trimester)
- Transdermal medication patches
The following must be evaluated:
- Cochlear Implants
The following require special care before and after entering the MRI field:
- IV fluids
- PCA pumps
- Programmable VP shunts
- Vagal nerve stimulators
All jewelry and metal (zippers, snaps) must be removed prior to entering the scanner room.
Note: Only one parent or guardian will be allowed to accompany the child into the scanner room; other arrangements should be made for siblings. The parent or guardian accompanying the child to their MRI must be safety screened before entering the scanner room.
Parents or guardians who are pregnant or may be pregnant will not be permitted to accompany their child during the MRI scan. Please make sure that there is someone else available to be with the child during the scan, if needed.
What should you and your child expect during the exam?
- If your child is receiving contrast or sedation, we will bring you to a room for the pre-MRI work-up. We will place an IV in your child’s hand, arm or foot. Your child may feel a little pinch.
- Once in the MRI control room, the technologist will ask why the MRI is being performed, will explain the scan to both you and your child, and will repeat the safety screening process.
- You and your child will then enter the MRI scanning room with the technologist. The room may feel cold, so it’s a good idea to dress in layers.
- You will be asked to sit near the scanner. You may bring something to read.
- The technologist will help to position your child on the MRI table according to the type of scan she is having. While many children are positioned on their backs, some scans require children to lie on their stomach or side, head first or feet first.
- The scan can be quite loud, so you and your child will be given ear plugs to help block out some of the noise.
- Once your child is comfortable on the table, a red light will come on to help align her body to the correct position for the scan. Your child will then be moved into the tunnel of the MRI scanner. Depending on her position, your child may not be able to see you or talk with you.
- After the technologist leaves the scanning room, the MRI will begin. The MRI scanner makes many sequences of loud noises, each of which may sound somewhat different. Listen to some of these sounds.
There will be a brief pause after each sequence. The technologist may give your child directions or prompts through a speaker. Your child will be able to speak to the technologist through the speaker.
The technologist will ask your child to hold very still during the scan. Any type of movement during the MRI will make the images appear blurry, so the scan may have to be repeated. This will make the test take longer.
Your child will not feel the magnetic field from the MRI scan, but may become uncomfortable from holding still. The MRI scan can take from 30 minutes to one hour for each body part being examined. While some patients do not require sedation for their MRI, others may benefit from emotional and/or medicinal support. Remember, sedation is required for all children under 8. Regardless of your child’s needs, the MRI team is there to help her get through the experience in the best way possible.
If you’d like, our child life specialists will help you prepare and support your child during the procedure. We can also arrange to have a child life specialist at your child’s appointment to explain the procedure in developmentally appropriate ways and to help your child better cope with the stress of the hospital experience.
What should you do after the exam?
If your child received contrast, give your child plenty to drink during the day.
If your child received sedation, follow any instructions given by the sedation nurses.
The images from your child’s exam are interpreted on the same day and a report sent to your physician’s office.
Your physician may call us at 215-590-2584 with questions about the report.
What to expect before, during and after an MRI scan
If you’ve never experienced a magnetic resonance imaging (MRI) scan before, you might be anxious about what to expect.
But MRI scans are very safe and, unlike CT or X-ray scans, they don’t involve radiation because images are gathered using magnets. It’s typically a pleasant experience, and the imaging makes an enormous difference in helping doctors diagnose and treat certain medical conditions.
What is MRI?
MRI is what we call an “advanced imaging study.” It shows, in fine detail, what’s happening inside your soft tissues (parts of your body that aren’t bone).
Sometimes when undergoing an MRI scan, you’ll receive a contrast solution, which is a liquid given orally or through an IV. The solution can brighten certain areas of the body so that we can distinguish the structures and disease changes in your body more easily.
Why might I need an MRI scan?
There’s a long list of health conditions that MRI can help doctors monitor.
Among the conditions that we can diagnose and track from MRI are tumors, certain inflammatory and infectious diseases, spine abnormalities, joint problems, brain injuries and structural issues in your heart.
What do I need to prepare for an MRI scan?
Generally, you don’t have to do much to prepare before heading to the hospital or radiology lab. Once you arrive, a doctor or MRI technician will review medical conditions and history in a comprehensive safety screening and address any issues at that point.
However, for certain MRI examinations, you could be required to fast beforehand and will be notified by your doctor if that’s needed.
If you’ve had an MRI before and had an allergic reaction to any contrast solutions that were used, you could be asked take medication beforehand to reduce your risk of having another reaction.
If you’re claustrophobic and very nervous about undergoing an MRI scan, talk with your doctor about it beforehand. They may prescribe a sedative to help the experience go more smoothly for you.
What do I need to tell MRI technicians about medical conditions I have?
It’s important for the team to know about any implants or other “foreign bodies” you may have. This includes pacemakers, artificial heart valves, cochlear implants, joint implants and retained metal that remain in your body from previous injuries.
Remove metallic jewelry, including glasses. Tattoos usually are safe in MRI, but let technicians know about them so that they can make sure the size of tattoo and/or the type of ink used won’t be an issue.
If you have kidney disease, the team also will want to know so that they can gauge whether it’s appropriate to use a contrast solution.
If there’s a chance you might be pregnant, you’ll also be tested. MRI is generally safe during pregnancy, but if the team needs to use a contrast solution in your body to help make the images clearer, they may use alternative methods to make sure the fetus isn’t affected.
At The Ohio State University Wexner Medical Center, the pre-MRI screening process is extremely thorough, so your MRI team will know to ask you about these issues even if you forget to alert them.
What happens before I get into the MRI machine?
When you arrive at the MR suite, the technologist usually asks you to change into a hospital gown or loose-fitting clothing. You’ll lie on a firm table that eventually slides into the center of a donut-shaped cylindrical magnet.
You may be given earplugs. Some MRI suites will provide you with noise-canceling headphones, which soften the noise of the machine and give the technician an easy way to communicate instructions to you. Between instructions, you can relax and, if you wish, listen to music of your choice.
What will I feel or hear in the MRI machine?
Once you’re inside the machine, you’ll hear some buzzing, clunking and squeaking sounds as technicians switch the intensity of the magnet.
Some patients may feel some heat during an MRI scan, but this is rare.
Your job is simply to lie still while the machine takes images of your body. Some people even describe the experience as relaxing.
But if you’re ever uncomfortable, it’s easy to communicate with the technician, who’s there during the entire scan, to let them know that you need to change positions or come out of the machine.
What happens after an MRI scan?
If you were given a contrast solution, you’ll be monitored for a few minutes to ensure you haven’t had a rare, allergic reaction to it.
Afterward, you can go home while a radiologist (a doctor who is an expert in evaluating imaging scans) inspects your images and communicates with your healthcare team to discuss your diagnosis and questions they might have.
If you have any questions about the scan or the results, your radiologists are always available and happy to address your particular needs and any questions that you may have to make sure you have the best possible imaging care.
Mina S. Makary is chief resident in the Department of Radiology at The Ohio State University Wexner Medical Center.
In this video, our imaging technologist explains an MRI (magnetic resonance imaging), what it’s used for and what you can expect during this type of imaging exam.
Schedule your MRI at Ohio State. Learn more
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