Brain MRI Scan (Magnetic Resonance Imaging)

What Is It?

A Brain MRI (alternately called a brain scan, MRI scan, or magnetic resonance imaging) is a neurological test which produces a high-resolution image of the contents of the head. It is a commonly used study to evaluate patients with neurological complaints to investigate for diseases of the brain. MRI scans can be performed for other parts of the body as well, including the spine, extremities and chest.

Magnetic resonance imaging, the scientific term behind a brain MRI, is a relatively new technique which uses the quantum mechanical characteristics of protons in your body tissues to create an image. The specific details of the science behind an MRI is quite complex. In general, the patient is placed in a large magnet which aligns all their protons into the same spin. A radiofrequency pulse stimulates these protons, most abundant in water, and an electrical coil around the head detects the signals that result. In the end, the computer uses complex mathematics to convert these signals into an image which the physicians read and interpret.

The appearance of an MRI scanner is similar to a CT Scan in that it is a large donut-shaped tube. The patient's lays on a table while their head is inside the "donut". Unlike a CT scan, no x-rays are used to produce a brain MRI so there is no exposure to radiation. The patient does not feel anything during the performance of the study although some patients complain of claustrophobia while in the scanner.

Sometimes a brain MRI is performed with injection of a contract agent. This is basically a dye that is injected into the blood which shows up brightly on the MRI scan. It can help to make some diagnoses more clearly visible, such as many brain tumors.

What Is It Used For?

As mentioned above, an MRI produces a high-resolution image of the internal parts of the body. There are several different types of MRI imaging which focus on different characteristics of the tissues. By interpreting these various images that are produced, a radiologist or other physicians can help to make diagnoses of medical conditions.

Not all medical conditions have specific findings on MRI. For example, a patient in coma due to uncontrolled diabetes would typically show nothing abnormal in their brain. Rather, brain MRI is good at showing structural changes in or around the brain. For example, MRI is excellent at detecting tumors of the nervous system. They can also show changes in the tissue of the brain consistent with stroke and hemorrhage, or bleeding into the brain.

MRI is more expensive and slower to perform than CT scan, so they are not used for every patient. Pathologies which can be easily diagnosed quickly on a CAT scan, such as acute head trauma and bone pathology, will use that type of brain scan. MRI however is more versatile and shows better resolution of subtle details than a CT scan so it is used frequently for stroke, tumors, spinal disease and other pathology.

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Important Note: This site is not intended to offer medical advice. Every patient is different, and only your personal physician can help to counsel you about what is best for your situation. What we offer is general reference information about various disorders and treatments for your education.

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