The few side effects of an MRI with contrast include the possible allergic reaction to the contrast agent, movement or disruption of metal in the body, and nephrogenic systemic fibrosis in patients with severe kidney failure. A magnetic resonance imaging (MRI) scan uses radio waves and a magnetic field to capture detailed images of a patient’s organs and tissues. The effect of MRI scans on fetuses is not well understood, and therefore pregnant women may want to consider alternative exams. Some patients may experience other side effects that result from anxiety about the scan or from having to remain enclosed in a large, tube-shaped machine for an indefinite amount of time.
An MRI is a noninvasive medical test that allows a medical professional to examine a patient’s organs, skeletal system, and tissues. A magnetic field is created around a patient and directs radio waves at the body to make high-resolution images. This field can affect any metal in a patient’s body, posing both a safety risk as well as a risk to the integrity of the images.
Patients with metallic joint prostheses, artificial heart valves, or a pacemaker should let their technologists know prior to being scanned. Other potential safety hazards in this category include metal clips that prevent aneurysms from leaking, cochlear implants, and a bullet or shrapnel. An implantable heart defibrillator can also be a problem.
Some potential side effects of an MRI with contrast involve the contrast agent or dye itself. A contrast agent is injected into the patient through a vein and can enhance an MRI scan, but not all MRI scans require this step. In most cases, the contrast agent is gadolinium-based.
Approximately 1 in 1,000 patients will experience a mild non-allergic reaction to the contrast agent. Signs of this include nausea, headache, and a metallic taste in the mouth. Mild allergic reactions occur in about 1 in 10,000 patients, and severe reactions in around 1 in 100,000. An allergic reaction usually occurs within an hour of injection and may cause a rash or swelling at the injection site to difficulty breathing and facial swelling.
One of the most serious side effects of an MRI with contrast is the increased risk of developing nephrogenic systemic fibrosis in patients with severe kidney failure. This is a rare but debilitating disease that causes thickening of organs, tissues, and skin, and there is no cure or effective treatment. Patients with severe kidney problems may be given the lowest possible dose of contrast agent or an alternative imaging test to mitigate this risk.
The majority of MRI machines are large, tube-shaped magnets open at both ends. A patient lies flat on a movable table and is moved slowly into the tube. How far a patient is inserted into a machine depends on what parts of the body are to be scanned. Once inside, there is not much space between the patient and the tube wall.
A typical MRI scan lasts approximately an hour but can be longer. During the scan, the patient must remain extremely still to avoid blurring the images. The procedure itself is painless, but the machine makes repetitive noises like tapping and thumping. As a result, many patients will wear ear plugs or listen to music.
Some side effects of an MRI may actually result from anxiety about the exam rather than from the test itself. It is common for patients to be anxious. Not only are many worried about the results, but they are also concerned about the procedure itself and having to lie still in a narrow tube for so long.
Anxious patients can exhibit many symptoms, including dizziness, headaches, and stomach pain. These feelings of anxiety may be heightened if the patient is also claustrophobic. Claustrophobic patients may request to be sedated before the scan or be placed on an open MRI machine that is not completely enclosed. Experienced technologists are typically understanding and will work to ensure that patients are as comfortable as possible in order to avoid any side effects triggered by anxiety.