Alzheimer disease: measuring loss of cerebral gray matter with MR imaging

Article Abstract:

It is thought that a relationship exists between Alzheimer's disease (AD) and loss of gray matter in the brain. The major problem in establishing such a relationship is the difficulty in measuring gray matter volume noninvasively, that is, without entering the skull. Present methods in use are not sensitive enough to detect clinically significant variations in amounts or to localize losses to specific areas of the brain. A new technique, dual-sequence magnetic resonance (MR) imaging was developed as a more sensitive technique for measuring gray matter, white matter and cerebrospinal fluid levels (CSF) in the intact brain, both as a whole and by regions. Fourteen outpatients thought to be suffering from AD and 14 healthy subjects were examined using this technique. Gray matter and CSF levels were calculated in both the brain as a whole and in six regions (frontal, temporal, parietal, occipital, central, posterior fossa). The results showed that the subjects suspected to have AD had significantly lower gray matter levels in their brains as a whole compared with the healthy subjects. The areas of the brain shown to be most affected by such losses were the temporal lobes (13.8 percent average reduction) and central regions (12.8 percent). The results indicate that this MR technique is sensitive enough for clinical studies and confirm a relationship between AD and gray matter loss. This latter finding is consistent with pathological studies of brains from deceased AD sufferers. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Alzheimer's disease, Brain, Magnetic resonance imaging

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Carpal tunnel: MR imaging

Article Abstract:

Carpal tunnel syndrome (CTS) is characterized by muscle soreness, tenderness and weakness of the muscles of the thumb caused by pressure on the median nerve that goes through the carpal tunnel of the wrist. Magnetic resonance (MR) imaging was used to examine the appearance of the carpal tunnel to evaluate soft-tissue abnormalities associated with carpal tunnel syndrome. MR images demonstrated swelling within the carpal tunnel, especially at the point were the median nerve (combines both sensory and motor functions to the hand) enters the carpal tunnel. It was found that the nerve flattens within the carpal tunnel at the point of the pisiform bone, the smallest carpal bone at the base of the wrist. Researchers concluded that axial plane imaging (images running along a line through the middle digit) provided the most information in cases of carpal tunnel syndrome. Axial images identified all ligaments, tendons, nerves, and blood vessels at the wrist. The ability of MR imaging to show the median and ulnar nerves, as they are entrapped in carpal tunnel syndrome, is useful in evaluating this disorder.

Causes of, Physiological aspects, Hand, Carpal tunnel syndrome, Median nerve, Entrapment neuropathies, Carpal bones, Nerve compression syndromes

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