In the 1980s Magnetic Resonance Imaging or MRI scans astounded the medical society by not just taking an image of the brain itself, but by concentrating on water molecules, as an alternative to imaging the degree to which the various parts of the head absorb x-rays. MRIs represent the speed at which rotating hydrogen atoms of water molecules inside various parts of the brain either line up or fall out of arrangement with a powerful magnetic field. These different values of de-magnetisation or magnetisation are inputted into a computer. Slice like images are formed in a sequence and put on view on the screen or x-ray type film in hues of grey. Irregular compositions, like brain tumors or the signs of multiple sclerosis, are shown in their own hues of grey and are also identifiable by their contours and positions.
The patient lies flat on a plane table that moves into and out of a hole in the scanner that looks a lot like an oversize doughnut hole. The hole is narrow, so patients suffering from claustrophobia have to notify their doctors if this might be a hitch. A loud noise is produced every time the radio frequency coils are turned off and on. A technologist may need to inject a needle in the patientâ€™s vein to dispense a distinct substance.
A situation in which MRIs are basically not done is when the patient has a heart pacemaker. The machineâ€™s magnet may disturb the pacemaker and stop the heart. An MRI is also avoided when the patient is gravely ill.