A voxel-based morphometric study of ageing in 465 normal adult human brains.

http://lib.ajaums.ac.ir/booklist/archives%20of%20neurology_24%20Jan-2_17.pdf

The cardiovascular health study: Design and rationale

We propose that cerebrovascular disease may predispose, precipitate, or perpetuate some geriatric depressive syndromes. The "vascular depression" hypothesis is supported by the comorbidity of depression, vascular disease, and vascular risk factors and the association of ischemic lesions to distinctive behavioral symptoms. Disruption of prefrontal systems or their modulating pathways by single lesions or by an accumulation of lesions exceeding a threshold are hypothesized to be central mechanisms in vascular depression. The vascular depression concept can generate studies of clinical and heuristic value. Drugs used for the prevention and treatment of cerebrovascular disease may be shown to reduce the risk for vascular depression or improve its outcomes. The choice of antidepressants in vascular depression may depend on their effect on neurologic recovery from ischemic lesions. Research can clarify the pathways to vascular depression by focusing on the site of the lesion, the resultant brain dysfunction, the presentation of depression and time of onset, and the contribution of nonbiological factors.

'Vascular depression' hypothesis.

Voxel-based-morphometry (VBM) is a whole-brain, unbiased technique for characterizing regional cerebral volume and tissue concentration differences in structural magnetic resonance images. We describe an optimized method of VBM to examine the effects of age on grey and white matter and CSF in 465 normal adults. Global grey matter volume decreased linearly with age, with a significantly steeper decline in males. Local areas of accelerated loss were observed bilaterally in the insula, superior parietal gyri, central sulci, and cingulate sulci. Areas exhibiting little or no age effect (relative preservation) were noted in the amygdala, hippocampi, and entorhinal cortex. Global white matter did not decline with age, but local areas of relative accelerated loss and preservation were seen. There was no interaction of age with sex for regionally specific effects. These results corroborate previous reports and indicate that VBM is a useful technique for studying structural brain correlates of ageing through life in humans.

/pdf/a-voxel-based-morphometric-study-of-ageing-in-465-normal-37kumjm2kg.pdf

A voxel-based morphometric study of ageing in 465 normal adult human brains

The aim of this study was to assess the feasibility of a differentiation of iodine from other materials and of different body tissues using dual energy CT. Ten patients were scanned on a SOMATOM Definition Dual Source CT (DSCT; Siemens, Forchheim, Germany) system in dual energy mode at tube voltages of 140 and 80 kVp and a ratio of 1:3 between tube currents. Weighted CT Dose Index ranged between 7 and 8 mGy, remaining markedly below reference dose values for the respective body regions. Image post-processing with three-material decomposition was applied to differentiate iodine or collagen from other tissue. The results showed that a differentiation and depiction of contrast material distribution is possible in the brain, the lung, the liver and the kidneys with or without the underlying tissue of the organ. In angiographies, bone structures can be removed from the dataset to ease the evaluation of the vessels. The differentiation of collagen makes it possible to depict tendons and ligaments. Dual energy CT offers a more specific tissue characterization in CT and can improve the assessment of vascular disease. Further studies are required to draw conclusions on the diagnostic value of the individual applications.

Material differentiation by dual energy CT: initial experience

The relationship between size of cerebral ventricles in chronic schizophrenics and performance on a comprehensive neuropsychological battery, the Standardized Luria-Nebraska Neuropsychological Battery, was investigated. Ventricular size was determined by using a planimeter to measure the size of the lateral ventricles and the ventricular body, if present, on the computerized tomographic (CT) scan image that showed the largest lateral ventricles. This number was divided by the size of the brain as a whole on the same image of the CT scan to yield a ventricular brain ratio. This ratio was then correlated with the scores on the Luria-Nebraska Neuropsychological Battery. Eight of the 14 scales of the Luria-Nebraska Neuropsychological Battery correlated significantly at the .05 level with the ventricular brain ratio in a sample of 42 chronic schizophrenics with an average age of 32.3 years. Overall, there was a multiple correlation of .72 between the ventricular brain ratio and Luria scores. The overall ventricular brain ratio for the schizophrenics was significantly above that found in normal populations. Changes in the size of the ventricles in schizophrenics appear to have significant correlates with measures of neuropsychological performance.

Cerebral Ventricular Size and Neuropsychological Impairment in Young Chronic Schizophrenics: Measurement by the Standardized Luria-Nebraska Neuropsychological Battery

A semiautomated computer analysis was developed to estimate fluid volumes in each hemicranium from computed tomography scans. The method was used to estimate total ventricular and sulcal fluid in 123 normal subjects aged 23-88 years. A wide range of normal values was found. The trend was for the estimated ventricular and sulcal fluid volumes to remain relatively constant until age 60 and then to increase at an increasing rate thereafter. Ventricular enlargement occurred in the absence of sulcal enlargement and vice versa. The estimate of the volume of the ventricles was related to skull size. When this was taken into account, the size of the ventricles showed no sex difference. The cranial cavity was larger in men than in women, and, in both genders, the left hemicranium and the left ventricle were larger on the average than their right counterparts. The limitations of computed cranial tomography as a quantitative tool are discussed in detail.

http://www.ajnr.org/content/ajnr/3/1/1.full.pdf

Changes on computed cranial tomography with aging: intracranial fluid volume.

Energy dependent reconstruction in X-ray computerized tomography.

• Recent findings of enlarged ventricles and sulcal widening in the computed tomographic (CT) scans of schizophrenic subjects have raised questions about the etiology and treatment of this disorder. Measures obtained from computerized analyses of CT scans of 30 schizophrenic and 33 normal subjects showed no significant difference between the groups in ventricular or sulcal fluid volumes. The discrepancy between our findings and those of other investigators may have been due to different measurement techniques or to differences in the samples. A second study was undertaken to examine the first possibility. Its results suggest that our findings and those based on measurements of planimetric ventricle-brain ratios (VBRs) are highly correlated, but that VBRs from one study may not be compared with those in another to establish population differences. Differences in patient samples appear to constitute an important source of discrepancy in CT findings.

Computed tomography in schizophrenics and normal volunteers. I. Fluid volume.

• Quantification of ventricular and sulcal volumes from the computed tomographic (CT) scans of 45 schizophrenic patients and 57 normal controls was carried out using a semiautomated computerized approach. The sizes of all cerebrospinal fluid spaces measured were significantly related to age in the control population. An age regression model was used to compare patients and controls. Schizophrenics had slightly larger ventricles and considerably larger sulci than controls. Enlargement of the ventricles and sulci was not correlated with measures of negative symptoms or neuropsychological Impairment. The CT scans of eight very ill chronically institutionalized schizophrenics were also analyzed. Their CT findings did not differ significantly from the larger group of schizophrenics studied. Our results show that the cerebral atrophy found in schizophrenia is diffuse in nature and does not relate clearly to measures of disease severity or chronicity.

/pdf/computed-tomographic-evidence-for-generalized-sulcal-and-idq8wru4xk.pdf

Leslie M. Zatz

Papers

Cerebral Ventricular Size and Neuropsychological Impairment in Young Chronic Schizophrenics: Measurement by the Standardized Luria-Nebraska Neuropsychological Battery

Changes on computed cranial tomography with aging: intracranial fluid volume.

Energy dependent reconstruction in X-ray computerized tomography.

Computed tomography in schizophrenics and normal volunteers. I. Fluid volume.

Computed Tomographic Evidence for Generalized Sulcal and Ventricular Enlargement in Schizophrenia