MRI is an important imaging tool for diagnosing and assessing a wide range of medical conditions. If an MRI may be in your future, here are six basic facts you should know.
MRI stands for magnetic resonance imaging. The magnet used in MRI causes the protons in the hydrogen atoms in the body to align in a way that the scanner can pick up as a radio signal, which the computer is then able to translate into a three-dimensional image that a radiologist can read. In this way, MRI creates exceptionally detailed images that can differentiate among soft tissues better than other medical imaging technologies.[1]
While MRI generally produces more detailed images than CT, it is also a slower procedure that is much more sensitive to movement than CT. For this reason, CT is often preferred over MRI in emergency situations and for patients who are unable to remain still for prolonged periods.
High-risk breast MRI is well established as a method for enhanced breast cancer screening for women with at least a 20% lifetime risk of breast cancer. Abbreviated breast MRI is a cutting-edge technology that makes the sensitivity of MRI cancer detection available to more women—particularly those who have dense breast tissue, which makes it more difficult to spot developing cancer on a mammogram. Abbreviated breast MRI is a supplemental screening exam used in conjunction with an annual mammogram.
Unlike CT exams, mammograms, and other methods that use X-rays to produce images, MRI provides a look inside the body without using radiation.
Headphones to play relaxing music, extra pillows or blankets, or just someone to hold your hand can make a world of difference if you’re anxious about an MRI. A wide-bore machine can also help alleviate the feeling of claustrophobia during the exam. If however, your anxiety is more severe, your doctor may prescribe a sedative to help you relax.
There are important cautions and contraindications to observe when deciding whether MRI is appropriate for an individual. The powerful magnet used in MRI creates some risks, and the contrast dye used in many MRI exams poses others.
The presence of a strong magnet means that ferromagnetic materials can pose specific dangers in an MRI room. Clinics and hospitals must observe strict protocols to keep metallic objects such as tools and oxygen tanks separate from MRI machines, and patients are advised to avoid bringing metal items into the room with them. Certain implanted medical devices or embedded shrapnel can make MRI inadvisable for this reason. Others, however, can be safely accommodated. Be sure to give your MRI technologist detailed information about any medical devices or other metallic materials in your body before an MRI exam.
The gadolinium-based contrast dyes that are often used in MRI is less likely than the iodine-based contrasts used in CT scans to produce allergic reactions. However, patients with decreased kidney function face a risk of a serious complication known as nephrogenic systemic fibrosis (NSF), which causes thickening of the skin, organs, and other tissues. It’s important to be thorough when answering questions about your medical history in preparation for any procedure. If you have risk factors such as a history of kidney disease, a kidney function test will be ordered to determine whether gadolinium contrast is appropriate for your exam.
Additionally, recent studies have found evidence of gadolinium retention in the brain for months or years following MRI examination. Specific risks have not be associated with this retention; however, the FDA has advised increased caution in the use of gadolinium-based contrast agents in light of these findings.
Iowa Radiology provides a wide range of state-of-the-art medical imaging services to serve our patients. These include traditional MRI exams in addition to abbreviated breast MRI. For more information about MRI and gadolinium-based contrast, download our free ebook.
Sources
[1] "MRI—Benefits and Risks." FDA.gov. 9 Dec 2017. Accessed 15 July 2019.