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J Nakagawara

Publications and source records attributed to J Nakagawara.

At least 19 recordsLinked to original sources
PubMed2001

Putaminal hyperperfusion in dystonic posturing on subtracted SPECT: a case report.

Dystonic posturing (DP) is one of the most reliable lateralizing symptoms for mesial temporal lobe epilepsy, although the mechanism remains unclear. We demonstrated a hyperperfusion area in the right putamen on subtracted postictal SPECT by using the automatic registration technique in one patient with ictal DP of the left hand. The putamen may play a key role in DP, similar to other diseases with dystonia.

Adult↗
PubMed2000

[Quantitative evaluation for scatter and attenuation correction in 99mTc SPECT--multicenter cooperation phantom study].

A multicenter cooperation phantom study was conducted to evaluate the accuracy of a triple energy window scatter correction technique in combination with various attenuation correction methods for 99mTc single photon emission computed tomography (SPECT) imaging. Six centers participated in this research and the data obtained with seven SPECT instruments were analyzed. The phantom used in the experiment was a 20 x 10 cm cylinder filled with homogeneous 99mTc solution, containing two kinds of cold spots (cold rod phantoms). One had a water-filled cylinder 5.5 cm in diameter positioned 2.5 cm from the center. The other contained 6 water-filled cylinders of various sizes. Contrasts of cold regions were in the range from 74% to 120% (true 100%). Another phantom had the shape of a pie-chart divided into six chambers symmetrically positioned in a cylinder 20 cm in diameter and 10 cm in height. Each chamber had volume of 480 ml and contained homogeneous 99mTc solution of different concentrations. This phantom was used to test for linearity between the radio activity concentration and reconstructed count density (linearity phantom). The intercept of the regression line obtained from the linearity phantom was 8.4 kBq ml-1 without scatter correction and -6.8 kBq ml-1 with scatter correction. Contrast was in the range from 78% to 132% (true 100%). The mean relative error for the measured activity concentration was 4.9% +/- 3.5% (mean +/- sd).

Phantoms, Imaging↗
PubMed1998

[A case of clear cell meningioma originating from the cerebellar tentorium].

We report herein on a case of clear cell meningioma originating from the cerebellar tentorium, surgically treated by occipital transtentorial approach (OTT). A 67-year-old woman was admitted to our hospital in September, 1996, complaining of gait disturbance. MRI revealed an isointense mass on T1 and T2 WI, clearly enhanced with gadolinium in the right upper cerebellum originating from the tentorium. A left vertebral angiogram showed tumor stain from the right superior cerebellar artery. The tumor was subtotally removed by OTT on September 24, 1996. Gamma knife radiosurgery was performed for regrowing tumor 6 months after surgery. Histological examination revealed that the tumors were composed of sheets of clear, glycogen-rich cells and lobulated by thin connective tissues. There were no malignant findings, but some tumor cells had infiltrated into the cerebellar cortex. Immunohistochemistry showed that tumor cells were positive for EMA and vimentin, but negative for keratin. MIB-1 staining index was 7.02%. From these findings, this case was diagnosed as a typical clear cell meningioma originating from the cerebellar tentorium. From a review of the literature including our case, clear cell meningioma may be clinicopathologically malignant, so careful follow-up will be necessary.

Aged↗
PubMed1997

Quantification of regional cerebral blood flow and vascular reserve in childhood moyamoya disease using [123I]IMP-ARG method.

Both regional cerebral blood flow (rCBF) and regional vascular reserve (rVR) in ten childhood Moyamoya disease were quantified pre- and post-operatively by autoradiographic processing using single photon emission computed tomography (SPECT) and N-isopropyl-rho-iodoamphetamine (IMP) (IMP-ARG method) to estimate hemodynamic effectiveness of surgical revascularization. Before surgery, in two patients, rCBF was reduced in the whole territories and loss of rVR in the anterior circulation was observed; +4.3% in the anterior cerebral artery (ACA), -3.0% in the middle cerebral artery (MCA) and +17.5% in posterior cerebral artery (PCA) territories. After surgery, in eight patients without transient ischemic attack (TIA) episodes, rCBF at rest was maintained around subnormal level in the whole territories, and mean rVR was up to +11.9, +17.3 and +28.3% in ACA, MCA and PCA territories, respectively. However, rVR in the anterior circulation was significantly reduced in comparison with rVR in the posterior circulation. Quantification of both resting rCBF and rVR using IMP-ARG method could provide reliable information concerning on surgical indication and its effectiveness in childhood Moyamoya disease.

Adolescent↗
PubMed1997

Incomplete brain infarction of reperfused cortex may be quantitated with iomazenil.

BACKGROUND AND PURPOSE: [123I]Iomazenil is a specific radioligand for the central benzodiazepine receptor that may be useful as an indicator of the intactness of cortical neurons after focal cerebral ischemia. We evaluated the binding of this receptor in reperfused cortex among patients with ischemic stroke to detect viable neurons in cortex that appeared structurally intact on conventional neuroimaging studies. METHODS: Fourteen patients were selected by (1) angiography within 24 hours of onset showing embolic occlusion of an intracranial artery, (2) cerebral blood flow showing ischemia of moderate severity in 12 cases and spontaneous reflow in 2 cases, and (3) thrombolysis with reperfusion within 24 hours in most cases. Thirty reperfused cortical areas that remained structurally intact, 7 infarcted cortical areas, and 6 contralateral cerebellar areas with reduced blood flow were selected as regions of interest to estimate receptor binding 5 days to 23 months after the stroke. A two-compartment model was used to compute the distribution volume (Vd) of iomazenil in relative units, with Vd proportional to benzodiazepine receptor concentration. The side-to-side asymmetry ratio of Vd was calculated. RESULTS: The mean asymmetry ratio was 0.89 +/- 0.11 (range, 0.64 to 1.05), 0.50 +/- 0.15 (range, 0.23 to 0.67), and 0.97 +/- 0.05 (range, 0.90 to 1.04) in reperfused cortex, infarcted cortex, and contralateral cerebellum, respectively. Compared with unity, both reperfused cortex and infarcted cortex showed significant decrease of Vd (P < .001). Contralateral cerebellum showing diaschisis had no reduction of Vd. On MRI, obtained 3 or 6 months after the stroke, mild cortical atrophy was observed in two reperfused areas where the asymmetry ratio was moderately reduced (0.64 and 0.80). CONCLUSIONS: The reduction of benzodiazepine receptor concentration in reperfused cortex that remained structurally intact is likely to be the result of injury involving only a limited number of neurons (ie, incomplete infarction). Our data suggest that the degree of viability of ischemic cortex apparently salvaged by early reperfusion can be quantified by iomazenil.

Aged↗
PubMed1997

Early effects of gamma knife radiosurgery on brain metastases: assessment by 201TlCl SPECT and 99mTc-DTPA-human serum albumin SPECT.

Thallium-201 chloride (201TlCl) single photon emission computed tomography (SPECT) was used to determine tumor viability, and the early and delayed images of technetium-99m-diethylenetriaminepenta-acetic acid-human serum albumin (99mTc-HSA-D) SPECT were used to assess tumor vascularity and permeability, respectively, in 17 patients with 18 brain metastases. SPECT was performed before, 1 week after, and 1 month after radiosurgery. The ratios of 201Tl and 99mTc-HSA-D uptake in a tumor were expressed as a ratio to uptake in the corresponding normal contralateral areas (uptake index). Magnetic resonance imaging with gadolinium was used to determine tumor volume. 201Tl index decreased significantly 1 week (p < 0.05) and 1 month (p < 0.005) after radiosurgery. In contrast, 99mTc-HSA-D indices of early and delayed images obtained at 1 week after radiosurgery were not significantly different from the pretreatment values. However, both were significantly low (p < 0.05) 1 month after radiosurgery. No change in tumor volume was detected 1 week following radiosurgery, but there was a significant decrease (p < 0.005) after 1 month. The reduction in tumor viability that occurs before the appearance of evidence of tumor shrinkage represents the early effect of radiosurgery on brain metastases. Reduction in tumor size, vascularity, and permeability occur subsequently.

Adult↗
PubMed1996

Multiple segmental agenesis of the cerebral arteries: case report.

A case of multiple segmental agenesis of the cerebral arteries is presented. Cerebral angiography demonstrated bilateral so-called carotid rete mirabile, a similar "rete" of the right vertebral artery and intradural duplication of the left vertebral artery. These abnormalities are thought to be caused by multiple segmental agenesis of the cerebral arteries as they penetrate the dura mater. The embryological and anatomical significance of these findings is discussed.

Adult↗
PubMed1996

Effect of Gamma Knife radiosurgery on acoustic neurinomas. Assessment by 99mTc-DTPA-human serum albumin- and 201TlCl-single photon emission computed tomography.

Single photon emission computed tomography (SPECT) was performed on 16 patients with acoustic neurinoma before and 1 and 2 years after Gamma Knife surgery. 201TICI-SPECT was used to determine tumor viability. Early and delayed images of 99mTc-DTPA-human serum albumin (99mTc-HSA-D)-SPECT were used to assess tumor vascularity and permeability, respectively. There was a statistically significant decrease in the 99mTc-HSA-D index of the early image at 1 year (p = 0.013) and at 2 years (p = 0.018) after Gamma Knife surgery. On the other hand, the 201Tl index and the 99mTc-HSA-D index of the delayed image were not significantly different from their pretreatment values. These observations demonstrate that a reduction in tumor vascularity without a decrease in tumor viability may be one of the effects of Gamma Knife surgery on acoustic neurinomas.

Adult↗
PubMed1996

Ischemic stroke and incomplete infarction.

BACKGROUND: The concept of selective vulnerability or selective loss o f individual neurons, with survival of glial and vascular elements as one of the consequences of a systemic ischemic-hypoxic insult (eg, transient cardiac arrest or severe hypotension), has been recognized for decades. In contrast, selective neuronal death as one of the lesions that may develop in the brain after occluding an intracranial artery is an idea not readily acknowledged in the current medical literature dealing with human stroke. SUMMARY OF REVIEW: A review of pertinent publications reveals that selective neuronal injury after middle cerebral artery occlusion was observed in autopsy specimens over 40 years ago, although its pathogenesis remains unclear. Recent observations in both humans and animals suggest that selective neuronal necrosis (rather than infarct) is the consequence of either a short-term arterial occlusion or permanent occlusion accompanied by ischemia of moderate severity. During the acute and subacute states of an ischemic stroke, the loss of a limited number of neurons (ie, incomplete infarction) does not result in structural changes discernible by either CT or conventional MRI. However, the loss of a selected number of neurons may be demonstrable in vivo by calculating the corresponding loss of benzodiazepine receptors. The use of specific radiotracers in combination with single-photon emission CT or positron emission tomography allows demonstration of a decrease in gamma-aminobutyric acid-ergic receptor sites at places where many neurons have been lethally injured. CONCLUSIONS: We aim to alert physicians to the potential development of incomplete brain infarctions in patients with intracranial arterial occlusions. Recognizing incomplete infarcts is particularly important in the context of stroke therapy with thrombolytic and neuroprotective agents. This brain lesion is likely to be the consequence of an arterial occlusion with a resultant ischemia of moderate severity (eg, regional blood flows in the range of 15 to 20 mL x 100 g-1 x min-1).

Animals↗
PubMed1996

[A phase 3 clinical trial of 123I-iomazenil, a new central-type benzodiazepine receptor imaging agent (Part 1)--report on clinical usefulness in diagnosis of various brain diseases].

Iomazenil (IMZ) is a partial inverse agonist of central-type benzodiazepine receptors (BZR) which binds specifically to BZR with high affinity. The safety and clinical effectiveness of 123I-IMZ SPECT in the diagnosis of brain diseases were evaluated in 655 patients with various brain diseases, such as epilepsy, cerebrovascular diseases, degenerative diseases and mental disorders relating to BZR. This was a Phase 3 study conducted as a multicenter trial at 52 collaborating institutions. There was no significant adverse reactions in the clinical symptoms or abnormal laboratory test values. The investigators judged 123I-IMZ SPECT to be effective in 95% of 638 analyzed cases. The injected dose did not correlate with the image quality or the clinical effectiveness of 123I-IMZ SPECT, suggesting that these items depend largely on the characteristics of the apparatus used, the disease or pathology of the patients, rather than the dose. We conclude that 123I-IMZ imaging is safe and provides effective information based on BZR binding which is useful in the diagnosis of various brain diseases.

Adolescent↗
PubMed1996

[A phase 3 clinical trial of 123I-iomazenil, a new central-type benzodiazepine receptor imaging agent (Part 2)--Report on clinical usefulness in diagnosis of degenerative neurological diseases and mental disorders].

Iomazenil (IMZ) is a partial inverse agonist of central-type benzodiazepine receptors (BZR) which binds specifically to BZR with high affinity. A multi-center Phase 3 clinical study was performed to evaluate the clinical usefulness of 123I-IMZ-SPECT in the diagnosis of brain disorders in 169 patients with degenerative neurological diseases and 37 patients with mental disorders such as neurotic, stress-related and somatoform disorders. In dementia, the decrease in activity in late images, obtained three hours after administration of 123I-IMZ, correlated negatively with the dementia score. In Parkinson's disease and spinocerebellar degeneration. 123I-IMZ showed a more profound decrease in uptake in late images than seen in the cerebral blood flow (CBF) images, and this decrease was in proportion to the duration and severity of the illness. In mental disorders, the ratio of the late to early image counts showed a negative correlation with Hamilton's anxiety scale in all regions in the brain cortices. In panic disorders, the ratio of the cerebral count to the cerebellar count in the late images correlated negatively with the severity of the attack in the frontal, temporal and parietal cortices. These results suggest that 123I-IMZ-SPECT enables us to evaluate the neuronal damage in degenerative diseases and the decrease in the BZR binding potential in mental disorders.

Adult↗
PubMed1996

[A phase 3 clinical trial of 123I-iomazenil, a new central-type benzodiazepine receptor imaging agent (Part 3)--Report on clinical usefulness in epilepsy].

A Phase 3 clinical trial of 123I-Iomazenil (IMZ), a tracer which binds specifically to central-type benzodiazepine receptors (BZR), was performed, and the clinical usefulness of IMZ was evaluated in 121 patients with epilepsy (106 cases with partial epilepsy and 15 cases with generalized epilepsy). A regional abnormality in the BZR distribution was detected in late IMZ images in 20 of 24 cases without abnormal MRI and/or X-ray CT findings. Moreover, only 16 of these 20 cases showed abnormal findings in the cerebral blood flow (CBF) images. In partial epilepsy, abnormal regions in late IMZ images agreed or partially agreed with epileptic foci estimated from the clinical symptoms of epileptic seizures, interictal EEG, and MRI and/or X-ray CT findings in 76%, 70% and 96% of the cases detected. These regions also agreed or partially agreed with the estimated epileptic foci in 92% of the cases with foci estimated by combination of those three methods and in 72% of those estimated by ictal EEG. The agreement or partial agreement rates of late IMZ images with each of the other methods were higher than those of CBF images, although the differences were not significant. For surgically-proven epileptic foci without any abnormality in the CBF image, abnormal regions were detected in late IMZ images. These findings suggest that IMZ SPECT is a useful new tool for detecting epileptic foci based on the distribution of BZR in the brain.

Adult↗
PubMed1996

[A phase 3 clinical trial of 123I-iomazenil, a new central-type benzodiazepine receptor imaging agent (Part 4)--Report on clinical usefulness in diagnosis of cerebrovascular diseases].

Single photon emission computed tomography (SPECT) using 123I-Iomanzenil (IMZ), a tracer which binds specifically to central-type benzodiazepine receptors, was performed in patients with cerebrovascular diseases (CVD) to determine the clinical signicigance of IMZ SPECT studies in evaluating the pathophysiology of CVD. IMZ SPECT images obtained three hours after administration of the tracer were compared with the images of cerebral blood flow (CBF) studies in 206 cases. In regions with decreased CBF, the uptake of IMZ was relatively preserved in patients with cerebral thrombosis in comparison with cerebral embolism, and in those with perforator branch infarction in comparison with cortical infarction. The uptake of IMZ decreased as a function of both the severity of the decrease in the CBF and the duration of illness in regions with a significantly decreased perfusion reserve. These results suggest that decreased IMZ binding in ischemic stroke reflects the neuronal damage caused by the cerebral ischemia. On the other hand, in patients with intracerebral hemorrhage, the cortical uptake of IMZ was relatively well-preserved in regions with decreased CBF, and the decrease in the uptake of IMZ was more profound as a function of the decrease in the CBF, especially in cases of putaminal hemorrhage. These results also suggest that the decreased cortical CBF is a remote effect caused by a neuronal disconnection, and neuronal damage may occur in regions with severely impaired CBF.

Brain↗
PubMed1996

[Effects of compton scatter in quantitative brain SPECT].

Effects of Compton scatter has been investigated for quantitative single-photon emission computed tomography. Using a technique proposed by Ichihara and Ogawa (triple-energy window method) as a gold standard, effects of correcting the scatter has been evaluated for 5 different phantom configurations, as well as a clinical cerebral blood flow study with use of 123I-IMP. Without the scatter correction but with a correction for attenuation, a conventional reconstruction provided a non-uniform distribution for uniform phantom configurations, and the quantitative pixel counts being highly dependent on size and shape of the objects. On the other hand, a uniform distribution and quantitative pixel counts that were independent of size or shape of the object were obtained by applying the scatter correction using a conventional attenuation correction technique with use of a theoretical mu value of 0.146 cm-1, thus suggesting importance of the scatter correction. Similar results were observed without the scatter correction, if an empirical value of mu of 0.07 cm-1 was used in the attenuation correction. However, this procedure was found to decrease the image contrast between the high count and low count regions. Significant underestimation of 20-30% was caused in cortical gray matter regions, and overestimation of 20% in the white matter regions. In practical clinical studies, magnitude of the error is still unknown, and is probably dependent on shape, size and radioactivity distribution of the object. A further systematic study is required in order to investigate significance of the scatter correction in real clinical studies.

Adult↗
PubMed1996

[Phase 2 clinical study of 123I-iomazenil in various cerebral diseases: part 1--examination of injection dose and clinical indications].

A phase 2 study of 123I-Iomazenil (IMZ) was performed to evaluate its clinical usefulness in SPECT imaging of central-type benzodiazepine receptors (BZR). A total of 246 patients with various central nervous system disorders [82 with epilepsy, 94 with cerebrovascular disease (CVD), 47 with degenerative disorders, 14 with mental disorders relating to BZR and 9 with other diseases] were intravenously injected with 111-222 MBq of IMZ. Early and late images were obtained 15 min and 180 min after injection as the mid-scan time, respectively. In comparison with regional cerebral blood flow (rCBF) images, the uptake of IMZ in the late images, which reflect the regional distribution of BZR, was relatively preserved compared to the uptake of CBF tracers in most of the patients with CVD. In the area of hyperperfusion in the subacute phase of cerebral infarction, however, the defects of IMZ uptake were accompanied by increased uptake of the CBF tracers. On the other hand, late IMZ uptake in most of the patients with the other diseases was decreased more significantly than the uptake of the CBF tracers, suggesting that cortical neuronal damage is more prominent than rCBF in these diseases compared to the vascular perfusional state. No adverse reactions were recognized relating to the IMZ administration. These results suggest that IMZ may provide us with valuable information for assessing pathophysiological state in the brain, which are difficult to achieve with other imaging modalities.

Adult↗
PubMed1996

[Phase 2 clinical study of 123I-iomazenil in various cerebral diseases: part 2--clinical evaluation of central-type benzodiazepine receptor imaging with 123I-iomazenil SPECT].

A phase 2 clinical study of 123I-iomazenil (IMZ) was performed to evaluate its clinical usefulness as central-type benzodiazepine receptor imaging agent in 81 cases with epilepsy, 82 cases with cerebrovascular diseases (CVD), 35 cases with degenerative disorders and 14 cases with mental disorders. In epilepsy, IMZ SPECT images for detection of epileptic foci showed relatively high specificity compared with EEG recording in not only interictal but also ictal state, in spite of the fact that IMZ SPECT images was performed during interictally. It was surmised that IMZ SPECT provides valuable clinical information for detection of epileptic foci which are hard to be diagnosed by EEG. The frequency of abnormal findings by IMZ late images was higher than that by interictal blood flow images and comparable to that by ictal blood flow images. In patients with CVD, different observations were obtained between IMZ late images and blood flow images; for example, in regions of hemodynamic cerebral ischemia, postischemic reperfusion and other pathological perfusion, IMZ late images seemed to reflect the degree of cortical neuronal loss. In patients with degenerative disorders, the binding potential (calculated by a simple quantitative method for IMZ) and other parameters correlated with the dementia score. While the number of examined cases with mental disorders was limited, the frequency of abnormal findings with IMZ imaging was higher than that with morphological imaging.

Adult↗