In order to take a picture of a person's brain and obtain certain information about it, the medical community uses a magnetic resonance imaging system (called an MRI). An MRI produces pictures of the brain by using magnetic fields as well as energy from radio waves. These MRI images can show the existence of brain tumours and their growth being experienced, blood vessel blockage in the brain (and the severity), as well as other signs of disease. But in order to determine what an abnormal brain MRI looks like, a medical professional must first know what a normal one looks like.
An MRI is a medical test that is non-invasive and relatively pain-free, although you may be bothered by some of the clicking noises that the machine automatically makes as it takes images of the brain. The test, performed as a patient lays on a flat surface that adjoins a large circular machine with its centre removed, entails that the person remain quiet and still for a period of time (between 30 and 90 minutes) as the machine's energy radio waves pass over the head and a magnetic field of the machine in order to capture two- and three-dimensional images of the brain.
As early as 1946, nuclear magnetic resonance imaging experiments were being undertaken in the United States, by two individual scientists: Felix Bloch of Stanford University and Edward Purcell of Harvard (see Resources for a link). In 1952, these two men were awarded the Nobel Prize for Physics due to their discovery of NMR Spectroscopy. In July of 1977, the first MRI exam was actually completed in the United States and that machine now sits in the Smithsonian Institute as a testament to the history of MRI use in America.
An MRI alters the magnetic field of the body part being viewed. Normal tissue and abnormal tissues don't produce the same images when this process of magnetic radio waves crosses the magnetic field of the body part being viewed, aiding medical personnel in detecting abnormalities.
Normal MRI Brain Images
Normal brain images produced by an MRI will have some basic properties--they will appear equal in proportion on both the left and the right sides of the image on the page, as well as equal in size and colouration dimension for each section of the brain imaged. For example, the brain axial image (a view from above the head) is similar in appearance to a walnut when it has been perfectly halved with no damage resulting to the nut contained on the inside of the shell. This brain image in an MRI would reflect a normal functioning brain.
Abnormal MRI Brain Images
Abnormal brain images will vary depending upon the medical illness or disease that is present in the patient. This is due to the fact that illnesses affect different parts of the brain and will only be represented in that particular portion of the brain during the imaging process. One noticeable difference that will be present in every situation, however, is the obvious inequality between the two sides or portions of the brain being viewed. If the image shows a larger-sized portion of the brain on the left side in comparison to the right, then there is evidence of an abnormality. Another abnormal brain image could be reflected in colour variation. For example, generally an MRI produces an image with muted grey colouring. If the MRI image has a portion of the brain that appears as white, then this can represent an abnormal brain MRI image. Additionally, abnormal brain MRI images can look much darker in certain areas instead of the general muted shade of grey.