Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging technique that uses powerful magnets and radio waves to create detailed pictures of organs and tissues inside the body. For people scheduled for this procedure, a common question is whether they can eat beforehand. Preparation rules regarding food and drink depend entirely on the specific type of scan being performed, as requirements for image clarity and patient safety change based on the area of the body being examined.
When Eating is Permitted
The majority of routine MRI scans do not require any dietary restrictions, allowing patients to eat and drink as they normally would. Scans focused on structures outside of the digestive tract are unaffected by the presence of food in the stomach or intestines. Examples include imaging of the brain, spine, joints, and extremities like the knee or shoulder, as well as standard head and neck scans.
For these scans, food intake does not interfere with the magnetic field or the clarity of the resulting images. Although fasting is not mandated, it is suggested to eat a light meal before the appointment to maintain comfort, especially since the procedure can last between 30 and 90 minutes. Heavy or greasy meals are best avoided, as they can lead to discomfort or indigestion when lying still. Patients should ensure they arrive with a comfortable bladder, as they cannot leave the scanner once imaging begins.
Scans That Require Fasting
Strict fasting is mandatory for specific MRI procedures, primarily those focusing on the abdominal and pelvic regions. These restrictions ensure both the quality of the diagnostic images and patient safety. Abdominal scans, particularly those involving the liver, pancreas, bile ducts (MRCP), or small bowel (MRE), require an empty stomach.
The primary reason for fasting is to minimize internal movement caused by the digestive process, known as peristalsis. Food and fluid in the gastrointestinal tract stimulate these involuntary muscle contractions, which can cause blurring or artifacts in the images of adjacent organs. Fasting also helps the gallbladder distend, or fill with bile, making it easier to visualize anomalies.
Fasting is also required when an intravenous (IV) contrast agent, such as Gadolinium, is administered during the scan. The contrast injection can occasionally cause side effects like nausea or vomiting. Having an empty stomach significantly reduces the risk of aspiration, the dangerous inhalation of stomach contents into the lungs if vomiting occurs while the patient is lying flat. The typical fasting window for these procedures ranges from four to six hours before the scheduled appointment time.
Guidelines for Hydration and Medications
Guidelines for liquid intake often differ from those for solid food, even when fasting is required. Clear liquids, most often plain water, are permitted up to a few hours before the scan, even for procedures requiring food fasting. Staying hydrated is beneficial, especially before a contrast-enhanced MRI, as it helps the body process and eliminate the contrast agent afterward.
For patients who must take prescription drugs, such as those for high blood pressure or heart problems, it is recommended to take these medications as usual with only a small sip of water. Patients who manage diabetes with insulin or other medications must consult their ordering physician or the imaging facility beforehand. Fasting can affect blood sugar levels, and medication dosages may need temporary adjustment to prevent hypoglycemia. All patients should follow the specific instructions provided by their care team, as protocols vary between facilities and scan types.
After the MRI: Next Steps
Following the completion of the MRI, the immediate next steps depend on whether contrast or sedation was used during the procedure. For patients who received an IV contrast agent, the most important action is promoting the elimination of Gadolinium from the body. Patients are encouraged to drink plenty of fluids, such as two to three liters of water or non-caffeinated beverages, over the next 24 hours to help flush the agent through the kidneys.
If the patient received any form of sedation, a mandatory safety protocol is put into effect. Sedation impairs judgment and coordination, requiring a responsible adult to drive the patient home and remain with them for the first 24 hours. During this period, the patient must not drive, operate heavy machinery, make legal decisions, or consume alcohol. Once home and fully awake, patients can gradually resume eating, starting with sips of fluid and soft foods before progressing to a regular diet. The final images are sent to a radiologist for interpretation, and the results are typically forwarded to the referring physician within a few days.