Magnetization transfer measurements of the hippocampus in patients with Alzheimer's disease, vascular dementia, and other types of dementia.
ABSTRACT Although atrophy of structures in the medial temporal lobe has been considered an indication of Alzheimer's disease (AD), atrophic changes on MR images have also been associated with other dementing diseases and are not specific to AD. This study was undertaken to determine whether characteristic alterations in the hippocampus of patients with AD are detectable with magnetization transfer (MT) imaging.
Coronal MT imaging was performed in 35 patients with probable AD, in 14 patients with vascular dementia, in 13 patients with other types of dementia, and in 23 control subjects to measure MT ratios of the hippocampus. Medial temporal lobe atrophy was graded subjectively on a five-point scale.
Scores of medial temporal lobe atrophy in all dementia groups were significantly higher than those in control subjects, but no differences were found among the dementia groups. MT ratios in the hippocampus were significantly lower in patients with AD than in those with non-AD dementia and in the control subjects; however, no differences were found between the non-AD dementia patients and the control subjects. MT ratio measurements were better than visual analysis of atrophy for differentiating AD patients from those with non-AD dementia (an overall discrimination rate of 77% versus 65%). MT ratios significantly correlated with scores on the Mini-Mental State Examination and with medial temporal lobe atrophy in AD patients but not in patients with non-AD dementia.
MT measurements may be more specific than visual analysis in detecting structural damage of the hippocampus in AD patients and might be useful in discriminating AD from vascular dementia and other types of dementia.
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ABSTRACT: For better management of mild cognitive impairment in elderly patients, clinicians should be provided with instruments to detect early changes and predict their progression. To define this cognitive status between optimal and pathological aging, many concepts have been proposed, which actually describe various conditions and provide more or less precise criteria, leaving room for variable implementation. As a consequence, application of these criteria gave highly variable prevalence rates, Neuropathological studies indicate that the different criteria have variable power in detecting incipient Alzheimer's disease (AD) and suggest that the transition between mild cognitive impairment and ÀD is not merely quantitative. Follow-up studies have produced, according to the criteria used, a 2.5% to 16,6% annual rate for progression toward dementia, and have also shown that the criteria differ in their stability and predictive power. Baseline cognitive performances have some predictive value, but are difficult to apply in first-line medicine. Investigational techniques (structural and functional imaging, magnetic resonance spectroscopy, magnetization transfer imaging, cerebrospinal fluid neuro-chemistry, and apolipoprotein E genotype) are promising tools in the early diagnosis of AD, which remains the most frequent type of dementia in elderly people and probably the most frequent type developed by patients with mild cognitive deficit. The final goal is to offer early treatment to those patients who will evolve towards dementia, once they can be identified, in the case of AD, recent findings question the adequacy of cholinergic replacement therapies. In its current state, the criteria for mild cognitive deficit are hardly transferable to first-line medicine. However, disseminating the concept could help increase the sensitivity of general practitioners to the importance of cognitive complaints and signs in their elderly patients.Dialogues in clinical neuroscience 03/2003; 5(1):61-76.