MRI Frequently Asked Questions
What Should I Do To Prepare For My MRI scan?
Properly preparing for your study ahead of time will save you both time and frustration. Due to the fact that the MRI unit contains a very strong magnet you will want to come with the least amount of removable metal as possible. This includes bobby pins, jewelry, belts, pocket change, etc. Mr. T is not allowed in the MRI suite! When you arrive the technologist will have you lock up your remaining objects such as your wallet or purse, keys, cell phone, and any other valuables you may have.
It's a good idea to wear loose fitting clothing without any metal for your study. Many centers will have you change into a gown before the study either way. They may also have you walk through a metal detector or use a hand held metal detector as an extra precaution.
Specific studies may require additional preparation. For example, an abdominal MRI may require you to not eat or drink for 4-12 hours before your exam. Your imaging center should convey these things to you before you arrive for your exam. It's not a bad idea to ask about prep when you schedule just to make sure you have your ducks in a row.
A contrast enhanced MRI may require blood work beforehand. This is typically for patients above 65 years old, with diabetes, recent onset of hypertension, or with prior or current kidney disease. If you are ordered for a study with contrast it's helpful to confirm that you do or do not need blood work before your study. This may save you a trip and a headache.
If you happen to have any implantable devices such as stents, pain or insulin pumps, heart valves, stimulators, or any other surgically implanted metal or objects it's extremely important to bring an information card or have the make and model of the object before you arrive. Many centers will not perform the exam without identifying information about the implant.
Will My Head Be In The Tube?
Many patients ask if their head will be in the magnet but it really depends on what exam they are having done. The center of the body part that needs to be examined has to be in the center of the magnet. If you're having a brain MRI your head will need to be in the middle of the magnet. Conversely if you are having a foot MRI your head will be way out of the center and most likely out of the tube. Sometimes people may liken being in an MRI machine to being in a coffin or buried alive. This is not the case. While you are in the MRI scanner you will have a steady supply of airflow, light from within the scanner, music and the voice of your friendly technologist. We are not undermining claustrophobia, however with the right attitude and mindset going into the test we are confident in you to complete your exam.
If you are feeling a little anxious about having your MRI that's normal, but have confidence that you can do it! Here are a few things to keep in mind that will help:
Realize you can not get stuck in the MRI, the table can be pulled out by the Technologist by hand in case of a power outage.
Keep your eyes closed or ask for a mask. Most facillities will have eye masks on hand.
Use earplugs and headphones with music. Pick music that will nicely accompany the MRI, something with an up beat tempo.
Bring a friend or family member to come in the room and hold your hand.
Lastly, if all else fails you can ask your doctor for a prescription to take a sedative before your MRI scan.
Remember, if you do have an issue with claustrophobia don't feel bad or down about it. It is very common for people to get claustrophic during an MRI. If this does happen to you, take a deep breath have confidence in your self and your Technologist to get you through your exam. Also, don't forget to apply the tips above to make your next MRI an enjoyable one.
Can I Have An MRI With A Pacemaker or a Defibrillator?
Although 99 % of medical professionals will tell you no that's not actually true anymore. A few hospitals around the country have gotten together teams of electrophysiologists, cardiologists, and cardiac nurses to provide this vital service to patient who desperately need MRI's. Johns Hopkins is the most notably and experienced in this field. Check out the following link to get an extremely detailed article of how all this actually works technically: http://circep.ahajournals.org/content/6/2/419.long. You can even call the following number to schedule an MRI at Johns Hopkins Hospital for a patient who has an implanted cardiac device. 410-464- 6713. Another good link to check out in from University of Wisconsin who also has quite a bit of experience https://www.radiology.wisc.edu/fileShelf/forReferring/MRI_Safety_Subcomittee_on_Pacemakers_Memo.pdf?buster=1457722960.
Can I Have An MRI With Extensive Dental Work?
99% of dental work is 100% safe for an MRI. Braces, fillings, crowns, dental implants, all of them will cause no harm to you during your study. The only thing to watch out for is an implant that utilizes a dental magnet. Unfortunately it can cause damage to the implant itself and cause the patient pain. If an MRI is absolutely necessary a risk benefit analysis should be determined between the ordering doctor and the radiologist.
Although dental work is safe for MRI it can take a toll on the image quality. The scanner cannot "tune" correctly with a large amount of metal and it could affect the diagnostic efficacy of the scan. A good example is actually braces. If there is a question about something near the base of the brain the artifact (image distortion and blind spots) can render the image useless. Although rare there have been times when the MRI information is pertinent enough to warrant the patient having the braces removed for the scan.
Can I eat or drink anything before an MRI?
The answer to this question depends on both the institutional preference and the MRI study you are having performed. Generally you can eat or drink whatever you like before your study. With this being said there are certain studies in which you should abstain from food or drink before your exam. Abdominal and pelvic MRI studies are most diagnostic when the patient has been fasting for 4 hours or more. If you are having a contrast injection some centers recommend not eating anything beforehand as well. When contrast is rapidly injected blood rushes in and out of the stomach quickly. Some patients don't notice it but this sensation causes others to vomit. Better safe than.... messy.
How Long Will My MRI Take?
Although it depends on the exam most single MRI exams take about 20- 30 minutes. If your doctor is requesting a contrast enhanced MRI plan on adding another 15 minutes or so.
Some specialty studies like cardiac MRI or MRI nerve imaging can take 60- 120 minutes but they are not typical.
Is It Safe To Have The MRI Contrast?
Overall gadolinium, which is the standard MRI contrast, is extremely safe. Sever allergic reactions occur in about 1: 50,000 patients. To give you some perspective the chances of being struck by lighting at some point in your life are about 1:12,000. Gadolinium is a drug and, just like any drug you've ever taken, there is a possibility that you could be allergic to it; but the odds are in your favor by a landslide.
There is a group of patients that need to take caution before having an injection of contrast: those who have compromised renal function. If your kidneys aren't working well gadolinium can cause some serious damage. All institutions should have a screening policy for patients potentially receiving contrast. Those who are over 60 years of age, who have diabetes, who've had a recent spike in blood pressure or uncontrolled hypertension, who have or have had a history of kidney disease, or those on dialysis are potentially at risk. All of these things send up red flags that will require blood work before the study to check kidney function.
Are MRI Scans Safe?
MRI's are considered extremely safe. The safety of MRI exams has been studied since it's inception and no adverse effects have been reported or documented. Unlike other radiology modalities like XRay and CAT Scan there is no ionizing radiation involved in an MRI study.
With this being said there is one area in which damage can occur during an MRI: your hearing. MRIs are extremely loud and adequate hearing protection should be utilized. TO give you some perspective consider that permanent hearing loss can occur at about 85 decibels. MRI exams can exceed 110 decibels. To reduce your risk of damage it's important you properly use ear plugs. They should be given to you at any MRI facility. I would recommend using headphones in combination with the earplugs if they are available.
On an odd note recent studies have suggested that exposure to a strong magnetic field can alter one's moral judgement calls. Check out this MIT study http://news.mit.edu/2010/moral-control-0330.
You can always say the MRI made you do it....
What is the difference between an Open and Closed MRI?
Open MRI and Closed MRI work the same way technically but there are a few differences between them. In any MRI unit there is an invisible magnetic field around the scanner generated by the scanner magnet itself. In a standard closed magnet the field is congruent and unbroken therefore the magnet is able to achieve it's highest capable field strength which is usually 1 Tesla- 3 Tesla in strength. Due to the strength of the unbroken magnetic field closed magnets are capable of producing higher resolution images. An example of a closed magnet is pictured below.
Open magnets have a break in the magnetic field (hence "open") and therefore the magnetic field strength cannot be as high. The typical field strength for open magnets is between 0.2 Tesla and 0.7 Tesla. The open aspect of the magnet is appealing to claustrophobic patients for obvious reasons. Patients with a larger body type may also find an open magnet more tolerable than a closed one. Due to the fact that they are not closed on the sides.
The choice between open or closed really comes down to 2 things: 1) Can you tolerate the closed magnet? If not then consider asking your doctor for sedation before your study or opt for an open magnet. 2) Is your study one that can even be performed on an open magnet. Some studies like cardiac MRI, nerve imaging, and high resolution musculoskeletal and body imaging cannot be performed on an open magnet. Consider talking with your doctor or even a radiologist at the desired imaging center if you have any questions about the diagnostic quality of your specific study on an open magnet.