Full-body MRI scans are becoming more popular for preventive health and disease diagnosis due to being non-invasive and radiation-free. However, many people haven't had an MRI scan before and are not entirely sure how to prepare for one. This article will look into one of the most common questions from people preparing for an MRI scan: can I eat before an MRI?
In most circumstances, you can eat and drink as normal before an MRI scan. However, in some circumstances, you will be required to fast. It is essential to follow the preparation guidelines provided by your healthcare professional as these will advise you on what to do in your specific circumstances.
This article will explain what types of MRI scans require fasting and why these MRI scans require fasting. It will also detail other dos and don’ts in preparing for an MRI scan.
Eating before an MRI is usually allowed for standard MRI scans, which don’t use contrast or are not focussed on areas surrounding the gastrointestinal tract. Although the majority of MRI scans do not require fasting before a scan, advice may differ depending on the procedures at a particular hospital or imaging center. As a result, it is always essential to confirm specific pre-scan instructions with the doctor or another healthcare professional, as they will be able to advise you specifically on what you should do.
Approximately 25% of MRI scans are performed using contrast agents. Contrast agents are used in MRIs to increase the visual differences between tissues and fluids in the body. The increase in contrast enhances the quality of the images, thus allowing more accurate diagnoses. Contrast agents are commonly used with areas such as soft tissue, abnormal tissue, blood vessels, and specific organs. For example, gadolinium-based contrast agents are commonly used in cardiac imaging as they allow the imaging of a myocardial infarction. Contrast agents are administered by injecting into a vein in the hand or arm through an intravenous (IV) line. The injection of contrast agents can cause nausea and vomiting, which can be particularly dangerous when lying down (as in an MRI scanner) due to the risk of airway blockage. Fasting is therefore recommended before an MRI with contrast agents to reduce the risk of vomiting and ensure clear imaging.
Eating or drinking triggers processes in the body to digest what has just been ingested. This involves peristalsis - involuntary muscle contractions throughout the digestive tract to move the food through the digestive system. These muscle movements can cause smearing or anomalies in the MRI image (known as artifacts). Artifacts may decrease the quality of the MRI image and could obscure any disease-associated anomalies or tumors in surrounding tissues. To prevent this from happening, people undergoing abdominal or pelvic MRIs must fast prior to the scan as this will decrease the muscle movements of peristalsis, giving a clearer image. MRI scans focusing on areas such as the liver or pancreas will require fasting as these organs are located adjacent to the digestive tract and, therefore, experience peristalsis-related artifacts, decreasing image quality.
Magnetic resonance cholangiopancreatography (MRCP) is a specialized form of MRI imaging that is used to visualize the bile ducts and the pancreas. Patients must fast before this procedure to:
MRIs can be used to investigate digestive symptoms, such as identifying and locating gastrointestinal bleeding or locating suspected obstructions. Fasting before these MRI scans is essential as an empty GI tract and minimized peristalsis is key for good visualization of bleeding or blockages.
MRI is a non-invasive procedure used for imaging; however, it can be combined with invasive procedures to provide real-time imaging and guidance. For example, MRI can be used to guide surgeons when fitting a heart catheter, and MRI-guided biopsies can be carried out to precisely locate abnormal tissue for sampling. These procedures may require a general anesthetic. Patients must fast before undergoing general anesthetic to reduce the risk of vomiting - vomiting can be dangerous when under anesthetic as the stomach contents can be inhaled into the lungs.
MRI scans are radiation-free, non-invasive procedures and, as such, are nothing to worry about. However, there are certain ways that you can prepare for an MRI and certain things to avoid. Medical professionals will advise you on these before you undergo your scan.
Dos:
Don’ts:
Medical professionals will inform you whether it is necessary for you to fast prior to your MRI scan. If fasting is necessary, then you will be required to fast for up to 4 hours before the scan (this may change depending on what is being scanned and differing procedures at different hospitals). If you struggle with managing hunger, it may be wise to schedule an early appointment, if possible, to limit how long you will have to go without food once awake. MRI staff can provide personalized advice and will address any concerns that you may have.
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Summary: Can You Eat Before an MRI?
Although many MRI scans will be able to proceed without any prior fasting, a sub-selection of scans will require fasting before undergoing the scan. Scans requiring fasting may include those using a contrast agent, abdominal and pelvic scans, magnetic resonance cholangiopancreatography, gastrointestinal scans, and any scans requiring general anesthesia. These scans require fasting for a variety of reasons, including reducing the risk of vomiting and preventing digestive movements (peristalsis) from interfering with images and reducing their quality. In addition to fasting (if required), there are other ways to prepare for an MRI scan, such as removing all metal items from your person, staying hydrated, and ensuring that you aren’t wearing any personal care products that could interfere with the image quality.
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