Each year since 1996, the Dana Alliance for Brain Initiatives promotes Brain Awareness Week. The initiative brings together people from academia, government, and professional and advocacy groups to celebrate the brain and promote brain research that supports prevention, treatment, and cures for brain disorders.
Imaging the Brain—CT and MRI
Two of the commonly used technologies for brain imaging are computed tomography (CT) and magnetic resonance imaging (MRI). The doctor who orders the imaging exam will select one over the other based on a number of considerations, including the type of imaging needed, the individual needs of the patient, and the relative risks associated with each alternative. We’ll look at some of the features of each technology and how they can help identify a number of different brain disorders.
MRI is capable of producing clearer and more detailed images than other techniques, making it an invaluable tool for evaluating brain tumors. It is also particularly beneficial for detecting strokes in their early stages. Other conditions that MRI of the brain is used to investigate include
- Multiple sclerosis
- Pituitary disorders
- Developmental abnormalities
MRI offers a couple of general benefits over CT. Instead of ionizing radiation, which is associated with increased cancer risk, MRI uses a powerful magnet to produce images of the body. Additionally, in the event contrast material is needed for the exam, the type of contrast used is less likely to cause an allergic reaction than that used with CT exams.
On the other hand, MRI is not for everyone. Because it operates using a powerful magnet, some implanted devices, embedded shrapnel, and other metallic objects or materials can make MRI unsafe for some patients. Any such objects must be evaluated prior to the exam to determine whether they pose a risk to the patient. Additionally, some people suffer from severe anxiety or claustrophobia that makes completing the exam difficult or impossible without sedation.
CT scans are able to image bone, blood vessels, and soft tissues all at once and can be completed quickly, making them especially valuable in emergency situations. As a result, CT is often used to assess conditions of the brain that can be immediately life threatening, such as those caused by severe head injury, aneurysm, or bleeding or clotting in the brain. It’s also used to allow doctors to visualize the area to be sampled during brain biopsy as well as plan for radiation therapy to treat brain cancer.
CT scanning offers some distinct benefits over MRI. In addition to being able to produce images much more quickly than MRI, a CT scan is much less sensitive to movement, making it easier for many patients to successfully complete the exam. It can also be performed on patients who may not be candidates for MRI because of embedded metal in their bodies.
A CT scan uses X-rays, which means that the patient receives a small amount of ionizing radiation during the exam. The effective radiation dose for a CT scan of the head, however, is relatively low—just one fifth of the dose delivered during an abdominal scan and one third of that delivered in a spinal scan.
If you have a condition that may necessitate brain imaging, it’s important to thoroughly discuss your symptoms and health history with your doctor so they can order the most appropriate type of exam for your needs. If you would like more information about CT and MRI exams, click the links below to access our free resources.
“Magnetic Resonance Imaging (MRI)—Head.” Radiologyinfo.org. Accessed 15 Feb 2019.
“Computed Tomography (CT)—Head.” Radiologyinfo.org. Accessed 15 Feb 2019.