Although hypercholesterolemia has been recognized as a risk factor for coronary heart disease (CHD) for decades, only in recent years have clinical trials definitively shown the efficacy of lowering serum cholesterol to prevent the occurrence or worsening of CHD. In 1985, an NIH consensus conference published guidelines for the diagnosis and treatment of hypercholesterolemia. Prior to 1985, physicians and lay people alike were not yet convinced of the necessity to know one's cholesterol level, nor did they know what levels should be treated. In a community-based survey of cardiovascular risk factors, known as the San Antonio Heart Study, in which 1,932 Mexican-Americans (MAs) and 1,133 non-Hispanic whites (NHWs) were examined between 1979 and 1985, the authors found that only 36/501 MAs (7%) and 54/312 NHWs (17%) in the moderate- or high-risk categories were aware that their cholesterols were high. Of the total number aware, including those whose cholesterol levels were in the low-risk range, only 23/97 MAs (24%) and 29/108 NHWs (27%) were receiving dietary or drug treatment. Of those being treated, only 9/23 MAs (39%) and 12/29 NHWs (41%) were effectively controlled. Mexican-Americans were less likely to be aware of their hypercholesterolemia than non-Hispanic whites, but both ethnic groups had low levels of treatment.

Adult↗

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Longitudinal changes in cognitive function and regional cerebral function in Alzheimer's disease: a SPECT blood flow study.

In Alzheimer's disease (AD), SPECT imagining of regional cerebral blood flow (rCBF) has emphasized deficits in the posterior association cortex. Previous studies have shown an association between these deficits and cognitive performance, both on overall cognitive tests and more specific tests such as praxis and language. Frontal deficits have been reported in more severe patients. This has led to the conclusion that the deficit in AD, at least with functional neuroimaging, starts in the posterior association cortex, and later in the disease process "spreads" to involve the frontal cortex. This study set out to measure, in a group of AD patients, the change over time of cognitive performance and the pattern of functional deficit measured by neuroimaging. Change in function was measured using 99TCm-HMPAO and SPECT and change in cognitive function using the CAMCOG. Two time points were used, 0 and 2 years. Twenty-four patients satisfying the DSM-III R criteria for probable AD were studied, nine of whom were subsequently diagnosed as having AD at post-mortem. The most striking finding was the effect that decreases in frontal lobe function had on cognitive function. A similar study by the same group, using the same techniques and many of the same patients but at only one time point, showed a correlation between cognitive function and rCBF in the parietal and posterior temporal lobes. This suggests that as AD patients deteriorate from unaffected to mild or moderately affected, the posterior association cortex exerts the greatest effect on cognitive deficit. In this longitudinal study, we found, using a MANOVA, that there were significant decreases over time for all the cortical regions studied, but that no region decreased significantly more than any other. In addition we found a correlation between change in frontal rCBF and change in cognitive function (both overall cognitive function and the CAMCOG sub tests of language and praxis). These data suggest, in contrast to the previous study, that as the disease progresses from mild or moderate to moderate or severe, the frontal cortex exerts the greatest effect on cognitive decline. These data support the concept of the deficit in functional imaging spreading from posterior to anterior as the disease progresses. However, both the initial pattern of deficit and the change over time were very heterogeneous when examined qualitatively. A posterior to anterior spread is the predominant pattern for the group as a whole, but individual patients, and possibly groups of patients, may well show alternative patterns.

Aged↗

PubMedDate not supplied

Digital mapping of multi-parameter contrast functions in magnetic resonance (MR) imaging using a standard MR computer system and digital display.

A technique is described which utilises the full analysis and display capabilities of a commercial MRI system to produce digital maps of multi-parameter functions produced by MR contrast theory. The technique is utilised to determine the effects of nominating specific overall scan times on the optimum solutions as produced by the theory and it is shown that different solutions are obtained when the theory is applied using typical clinical constraints. The digital mapping approach is potentially of great value in prospectively determining pulse timing parameters to produce optimum contrast images, in producing contrast maps to aid retrospective image interpretation, and as a training aid for clinicians inexperienced in the interpretation MR images.

Computer Graphics↗

PubMedDate not supplied

The use of in vitro magnetic resonance tissue studies to optimise pulse sequences in the imaging of intracranial haemorrhage.

The choice of appropriate MR pulse sequences to highlight a particular pathology to best advantage is not always straightforward. In this study of intracranial haemorrhage, tissue relaxation times measured in vitro were entered into a computer program which calculated the signal intensity of each tissue (brain, blood, CSF, and bloody CSF) for all possible echo (TE) and repeat (TR) times. Analysis of graph plots of the results enabled the selection of pulse sequences which gave optimal separation of the signal intensities of intracranial haemorrhage from those of normal intracranial contents. The sequences thus chosen were used successfully in the imaging of patients with intracranial haemorrhage.

Cerebral Hemorrhage↗