Benzodiazepine receptor imaging with iomazenil SPECT in aphasic patients with cerebral infarction.

To investigate the relationship between prognosis of aphasia and neuronal damage in the cerebral cortex, we evaluated the distribution of central-type benzodiazepine receptor (BZR) binding in post-stroke aphasics with [123I]iomazenil and SPECT. We performed iomazenil SPECT in six aphasic patients (aged from 45 to 75 years; all right-handed) with unilateral left cerebral infarction. Three patients showed signs of Broca's aphasia and the other three Wernicke's aphasia. Cerebral blood flow (CBF) imaging was performed with [123I]iodoamphetamine (IMP). The regions of interest (ROIs) on both images were set in the cerebral cortex, cerebellar cortex and language-relevant area in both hemispheres. Three patients were classified in the mild prognosis group and the other three in the moderate prognosis group. The left language-relevant area was more closely concerned with the difference in aphasic symptoms than the right one in both BZR and CBF distribution, but the ipsilateral to the contralateral ratio (I/C ratio) in the language-relevant areas in the BZR distribution was significantly lower in the moderate prognosis group than in the mild prognosis group, although no difference was seen for these values between the two groups in the CBF distribution. These results suggest that BZR imaging, which makes possible an increase in neuronal cell viability in the cerebral cortex, is useful not only for clarifying the aphasic symptoms but also for evaluating the prognosis of aphasia in patients with cerebral infarction.

[A quantitative study of regional cerebral blood flow in patients with dementia of Alzheimer type using single photon emission computed tomography--clinical application of the IMP autoradiographic method (IMP ARG method)].

We quantitatively measured regional cerebral blood flow (rCBF) in 37 patients with dementia of Alzheimer type (DAT) to investigate the clinical utilities of the N-isopropyl-p-[123I]iodoamphetamine autoradiographic method (IMP ARG method) that is a quantitative method more simplified and less invasive for IMP-SPECT developed by Iida et al. A given standard input function and a given value of distribution volume (Vd) used for the rCBF measurement of this method were calculated from the dynamic study by six normal volunteers. Mean values [SD] of rCBF (ml/ 100 g/min) in the Cerebral Cortex were 49.0 [6.0] in the controls (n = 20), 42.6 [5.9] in mild DAT group (n = 14), 36.7 [5.5] in moderate DAT group (n = 12), and 26.4 [7.5] in severe DAT group (n = 11), respectively. These values were significantly different between each neighboring group. Moreover, the correlations between the score by the Hasegawa dementia scale (HDS-R) and each rCBF were significant in the temporal, parietal, and frontal cortex. These findings suggest that the rCBF measurement in IMP-SPECT using this method is useful for the diagnosis of the clinical severity in patients with DAT.

[Regional cerebral blood flow and periventricular hyperintensity in silent cerebral infarction--comparison with multi-infarct dementia].

In order to investigate relationship between regional cerebral blood flow (rCBF) and the white matter lesions on MRI in silent cerebral infarction, we quantitatively measured rCBF by 123I-IMP autoradiography method (IMP ARG method) and single photon emission tomography (SPECT) in 36 patients with silent cerebral infarction (SCI group), 22 patients with multi-infarct dementia (MID group), and 16 control subjects without periventricular hyperintensity (PVH) and lacunar infarction on MRI (CL group). Regions of interest (ROIs) on rCBF images were set in the frontal (F), temporal (T), parietal (P), occipital (O) cortex, and the cerebral white matter (W). The severity of PVH on MRI T2-weighted image was divided into four grades (grade 0-3). Our results: 1) Though the frequency of hypertension was significantly higher in SCI group and MID group compared with CL group, no significant difference was seen in the mean age among these three groups. 2) rCBF in the white matter and cerebral cortices except the occipital cortex in SCI group was significantly low compared with CL group (gamma CBFSCI/gamma CBFCL: W 0.87, F 0.87, P 0.88, O 0.92). 3) rCBF in the white matter and cerebral cortices, especially in the white matter and frontal cortex, in MID group was significantly low compared with SCI group (gamma CBFMID/gamma CBFCL: W 0.69, F 0.71, T 0.74, P 0.75, O 0.81). 4) The mean grade of PVH in MID group was significantly higher that that in SCI group (SCI 1.1 vs MID 2.5). 5) The severity of PVH was significantly correlated with each rCBF in the white matter and cerebral cortices, especially in the white matter and frontal cortex. Our findings suggest that the quantitative measurement of rCBF by IMP ARG method is useful for the follow-up study in the patients with silent cerebral infarction as well as the evaluation of the severity of PVH on MRI.

[Benzodiazepine receptor and cerebral blood flow in early Alzheimer's disease--SPECT study using 123I-iomazenil and 123I-IMP].

This study was designed to investigate benzodiazepine receptors (BZR) and cerebral blood flow (CBF) in patients with early Alzheimer's disease. Imaging of BZR and measurement of CBF were performed by SPECT using 123I-Iomazenil (IMZ) and 123I-IMP respectively, in seven patients with early Alzheimer's disease and five patients with unilateral left cerebral infarction as controls. The values for the normal cerebral hemisphere (ratio to the contralateral cerebellum) in patients with cerebral infarction were adopted as control values. In patients with Alzheimer's disease, the CBF (ratio to cerebellum) decreased significantly in the frontal cortex and the parietal cortex compared with the control values. There was no significant difference in late IMZ SPECT counts (ratio to cerebellum) and washout (the ratio of late-to-early IMZ SPECT counts) between patients with Alzheimer's disease and the controls. However, the late IMZ SPECT counts and washout decreased in one patient with moderate dementia. There was a significant correlation between the severity of dementia and the late IMZ SPECT counts in the temporal cortex and the parietal cortex. These results suggest that benzodiazepine binding sites are relatively well preserved in patients with early Alzheimer's disease, and reduction of the CBF is caused by neuronal dysfunction rather than by neuronal loss. IMZ SPECT study is useful and necessary for clarifying the pathophysiological state in Alzheimer's disease.

[Cerebello-cerebral functional relationship in spinocerebellar degeneration using positron emission tomography].

In order to investigate the laterality of cerebellar ataxia and its influence for the cerebral cortex in spinocerebellar degeneration (SCD), regional cerebral blood flow (r CBF) was measured using positron emission tomography (PET) in 10 patients with sporadic olivopontocerebellar atrophy (sOPCA), 7 patients with hereditary SCD (h SCD), and 10 age matched control subjects. The laterality of cerebellar ataxia was evaluated by the total score of the difference between left and right limbs of three limb-coordination tests. The lateralities of rCBF were calculated by asymmetry indices (AIs) of each region of interest in the cerebellum, thalamus, caudate, putamen, cerebral cortices. The laterality of cerebellar ataxia was significantly correlated with AI in the cerebellum in patients with sOPCA. Furthermore, significant negative correlations were observed between AI in the cerebellum and each AI in the thalamus, frontal cortex in patients with sOPCA. However, no correlations were observed between AI in the cerebellum and the other AIs in controls and patients with h SCD. Duration of illness in patients with sOPCA with laterality is shorter than that in patients without laterality. These results suggest that the existence of crossed cerebello-cerebral diaschisis (CCCD) resulting from transneuronal deactivation through cerebello-thalamo-cerebral pathway in patients with the early stage of sOPCA with laterality.

[Relationship between cognitive function and regional CBF in hereditary spinocerebellar degeneration--comparison between Joseph disease and OPCA of Menzel type].

Regional cerebral blood flow (rCBF) was measured using positron emission tomography (PET) in patients with Machado-Joseph disease (Joseph disease), hereditary OPCA of Menzel type (Menzel type), and in normal control subjects in order to investigate relationship between cognitive function and rCBF in 2 subgroups of hereditary spinocerebellar degeneration (SCD). Though absolute rCBF in the cerebellar hemisphere and pons was significantly low in each of 2 subgroups of SCD compared to the control group, no difference was seen between 2 subgroups of SCD in these regions. In addition, absolute rCBF in the cerebral cortices did not show significant difference among all groups. However, when the rCBF data was normalized to the occipital cortex for relative rCBF, in the patient group with Menzel type, relative rCBF in the thalamus was significantly low value compared to the control group and relative rCBF in the frontal, temporal, and parietal cortex, especially in the frontal, was significantly low value compared to the patient group with Joseph disease. Moreover, clinically cognitive impairments were seen in patients of Menzel type, but not in patients of Joseph disease. These findings suggest that the measurement of rCBF by PET is useful for the understanding of the pathophysiology of hereditary SCD subgroups as well as for the differential diagnosis of these diseases.