DEVELOPMENT OF DIAGNOSTIC TESTS OF ALZHEIMER’S DISEASE: BRAIN SCANNING
In recent years there have been many exciting developments in scanning techniques. It is now possible to have all sorts of brain scan and there have been great hopes that this new high-technology approach to studying diseases of the brain might lead to greater diagnostic accuracy. Some of these new techniques, for example the CT scan — also called a CAT scan — provide very detailed information about any structural changes within the brain, producing pictures that look like X-rays of different parts of the body.
The standard X-ray picture consists of a single X-ray plate on which are depicted all the structures that the X-rays have passed through, so that in a chest X-ray, the heart, the lungs, the ribs, the skin, and the other structures within the chest are all superimposed one upon the other. CT scanning allows the radiologist to examine pictures of an organ bit by bit, providing much greater detail. Another and newer type of scanning called MRI (magnetic resonance imaging) can do this even more effectively. These new scanning techniques have proved of great value in diagnosing many conditions such as strokes, tumours, and multiple sclerosis, but have failed to come up with any definite diagnostic evidence of Alzheimer’s disease, except by excluding other conditions that might mimic it.
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