[en] The activated cerebral regions and the timing of information processing in the hemispheres was investigated using event-related potentials (ERP) and regional cerebral blood flow (rCBF) as the neurophysiological indicators. Seven men and one woman (age 19-27 years) were asked to categorize two-syllable Japanese nouns (verbal condition) and to judge the difference between pairs of rectangles (spatial condition), both tests presented on a monochrome display. In the electroencephalogram (EEG) session, EEG were recorded from 16 electrode sites, with linked earlobe electrodes as reference. In the positron emission tomography (PET) session, rCBF were measured by the ¹⁵O-labeled H₂O bolus injection method. Regions of interest were the frontal, temporal, parietal, occipital and central lobes, and the entire cerebral hemispheres. When the subtracted voltages of the ERP in homologous scalp sites were compared for the verbal and spatial conditions, the significant differences were at F7·F8 and T5·T6 (the 10-20 system). The latencies of the differences at T5·T6 were around 200, 250 and 320 ms. A significant difference in rCBF between the verbal and spatial conditions was found only in the temporal region. It was concluded that early processing of information, that is, registration and simple recognition, may be performed mainly in the left temporal lobe for verbal information and in the right for spatial information. (author)

[en] We studied clinical significance of ^99mTc-L,L,-ethyl cysteine dimer (^99mTc-ECD) SPECT study in dementia and aphasia, and compared it with ^99mTc-HMPAO SPECT study. The subjects consisted of 13 patients, including 10 patients with dementia and 3 patients with aphasia. Hypoperfusion areas were detected in 5 out of 10 patients with dementia and 2 out of 3 patients with aphasia in ^99mTc-ECD SPECT, and in 4 out of 10 patients with dementia and all of 3 patients with aphasia in ^99mTc-HMPAO SPECT. The count rate ratios in ^99mTc-ECD and ^99mTc-HMPAO SPECT were correlated well with each other, and the contrast of the ^99mTc-ECD SPECT image was equivalent or slightly higher as compared with ^99mTc-HMPAO. Therefore, ^99mTc-ECD SPECT study was considered to be useful for the evaluation of cerebral perfusion in dementia and aphasia. (author)

[en] We studied the serial changes of CMRGlu in 6 patients with dementia of Alzheimer type. All patients demonstrated moderately severe dementia at the initial PET scan. Serial PET scans were performed at an interval of 12 to 24 months. Five of the 6 patients showed a deterioration of clinical symptoms at the second scan. The global CMRGlu serially decreased in all patients. An asymmetry of CMRGlu in both the frontal and parietal regions was observed at the initial PET scan, while the direction of asymmetry was preserved at the second PET scan. The ratios (frontal/parietal and parietal/striatum) of CMRGlu showed no interval change. Therefore, CMRGlu was considered to decrease progressively throughout the entire brain in patients with moderately severe dementia of Alzheimer type. (author)

[en] We compared I-123 IMP and 99m-Tc HMPAO SPECT studies with 0-15 H₂O and F-18 FDG PET studies, and evaluated the clinical significance of SPECT studies in dementia. Seventeen patients including 9 patients with Alzheimer's disease, 3 patients with Pick's disease and 5 patients with multi-infarct dementia were studied. IMP and HMPAO SPECT studies could not detect mildly affected areas when compared with FDG PET. However, they revealed decreased perfusion in the bilateral parietal regions in Alzheimer's disease and in the bilateral frontal regions in Pick's disease, while MRI and/or CT showed mild to moderate cerebral atrophy. IMP and HMPAO SPECT studies can be easily performed in clinical practice, and these findings were useful in the differential diagnosis of dementia. Our preliminary results suggested that SPECT studies with I-123 IMP and Tc-99m HMPAO, despite their limitations, are useful in the differential diagnosis of dementia. (author)

[en] Using positron emission computed tomography with F-18 fluoro-D-deoxyglucose, regional cerebral metabolic rate of glucose (rCMRglc) was measured in 8 patients with Alzheimer's disease and 3 healthy volunteers. A decreased rCMRglc was observed in the widespread cortex and basal ganglia of the cerebrum, but not observed in white matter, thalamus, and cerebellum. There was no bilateral difference. rCMRglc was the lowest in the parietal lobe, followed by the temporal lobe and the curvature of the frontal lobe. A decrease in rCMRglu was relatively mild in the inner part of the frontal lobe, primary sensory and motor area of the cerebral cortex, and cerebral basilar ganglia. Alzheimer's disease proved to be characterized by severe glucose metabolic disorder in the association area of the bilateral cerebral cortices. The degree of metabolic disorder was correlated with the degree of dementia in the outer part of the left frontal lobe and the curvature of the cerebral cortex. (Namekawa, K.)

[en] The CBF, CMRO₂ and CMRGlu were measured in patients with primary degenerative dementia including 5 patients with dementia of Alzheimer's type and 4 patients with Pick's disease, and then the correlation between the cerebral blood flow and energy metabolism was evaluated. The control subjects consisted of 5 age-matched normal volunteers. The CBF, CMRO₂ and CMRGlu decreased in the bilateral frontal, temporal and parietal regions in the patients with Alzheimer's dementia, while they decreased in the bilateral frontal and temporal regions in the patients with Pick's disease. Both the CBF and CMRO₂ were closely correlated with each other. However, the CMRGlu was more severely impaired than the CBF or CMRO₂ in both pathological conditions. These results suggested that CMRGlu began to decrease before the reduction of the aerobic metabolism and thus measuring the CMRGlu is considered to be the most sensitive method for detecting abnormal regions in primary degenerative dementia. (author)

[en] The time dependency of rCBF response to photic stimulation in the primary visual cortices was studied using H₂¹⁵O bolus-injection and PET. The subjects consisted of 5 normal volunteers aged from 25 to 40 years old. Their regional CBF was measured at 2 min and 7 min after the start of photic stimulation (frequency, 10 Hz). The percentage increases of rCBF were 19.6±7.9% (mean±SD, range: 8.9-27.6%) in the primary visual cortex on the left side and 23.2±13.6% (2.5-35.8%) on the right side at 2 min, respectively, while, in comparison, they were 25.3±20.0% (1.8-49.7%) on the left side and 25.3±16.4% (3.5-44.5%) on the right side at 7 min, respectively. No significant difference was found in the rCBF responses between at 2 min and 7 min. Therefore, the taming effect does not need to be considered when carrying out a photic stimulation study. (author)

[en] We studied the cerebral muscarinic acetylcholinergic receptor (mACh-R) by means of ¹¹C-N-methyl-4-piperidyl benzilate (¹¹C-NMPB) and positron emission tomography (PET) in Alzheimer''s disease (AD) cases, and the findings were compared with the cerebral blood flow (CBF) and the glucose metabolism (CMRGlc) to evaluate the relationship between the mACh-R and the CBF or the CMRGlc. The subjects consisted of 18 patients with AD and 18 age and sex matched normal volunteers. The patients were clinically diagnosed according to the criteria of the NINDS-ADRDA as having ''''probable AD'''' and were thus classified into two groups (mild and moderate AD) according to the severity of dementia determined by DSM-III-R. The CBF was measured by ^99mTc-HMPAO SPECT, and the CMRGlc was measured by ¹⁸FDG PET. The ¹¹C-NMPB uptake was evaluated by the graphical method and the ratio method (ROIs/Cerebellum). A significant mACh-R decrease and more severe CMRGlc decrease in the cortical region was seen in mild and moderate AD. The decrease in the CBF was not as obvious as that in the mACh-R and the CMRGlc. Our study thus suggested that the mACh-R decreased in patients with AD, and that the ¹⁸FDG PET was the most sensitive method for detecting the degenerative regions in patients with AD. (author)

[en] We evaluated the sex-related differences in the decline of the cerebral muscarinic acetylcholinergic receptor (mACh-R) due to aging by using ¹¹C-N-methyl-4-piperidyl benzilate (¹¹C-NMPB) and positron emission tomography (PET). The subjects consisted of 37 (20 males and 17 females) healthy volunteers. The ¹¹C-NMPB uptake was evaluated by the ratio method (regional ¹¹C-NMPB uptake/Cerebellar ¹¹C-NMPB uptake; rNMPB ratio). The correlation between sex, aging, and the rNMPB ratio in normal aging was evaluated by a multiple regression analysis. The rNMPB ratio was higher in females than in males throughout the entire cerebral region (p<0.01-p<0.0001) and the rNMPB ratio might thus possibly decline with age more rapidly in females. Our study therefore revealed the existence of sex-related differences in the cerebral mACh-R. (author)

[en] This study examined the influence of linearization correction (LC) on brain perfusion single-photon emission computed tomography (SPECT) for the diagnosis of Alzheimer's disease (AD). The early onset group (<65 years old) consisted of 10 patients with AD, and the late onset group (≥65 years old) of 13 patients with AD. Age-matched controls included seven younger and seven older normal volunteers. Tc-99m hexamethyl propyleneamine oxine (HMPAO) SPECT images were reconstructed with or without LC [LC (+) or LC (-)] and a statistical analysis was performed using a three-dimensional stereotactic surface projection (3D-SSP). In addition, a fully automatic diagnostic system was developed, which calculated the proportion of the number of abnormal pixels in the superior and inferior parietal lobule, as well as in the precuneus and posterior cingulate gyrus. The areas under the receiver-operating characteristic curve (AUCs) of the early onset group for conventional axial SPECT images, SPECT+3D-SSP images and the fully automatic diagnostic system were 0.71, 0.88, and 0.92 in LC (-) and 0.67, 0.85, and 0.91 in LC (+), respectively. The AUCs of the late onset group were 0.50, 0.61, and 0.79 in LC (-) and 0.49, 0.67, and 0.85 in LC (+), respectively. LC on Tc-99m HMPAO SPECT did not significantly influence the diagnostic performance for differentiating between AD and normal controls in either early or late onset AD. Further examination with individuals suffering from very mild dementia is, therefore, expected to elucidate the effect of LC on minimally hypoperfused areas. (author)