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Biomedical subjects

J Hatazawa

Publications and source records attributed to J Hatazawa.

At least 55 records · Page 3Linked to original sources
PubMed1998

Noninvasive quantitation of cerebral blood flow using oxygen-15-water and a dual-PET system.

UNLABELLED: Measurement of the arterial input function is essential for quantitative assessment of physiological function in vivo using PET. However, frequent arterial blood sampling is invasive and labor intensive. Recently, a PET system has been developed that consists of two independent PET tomographs for simultaneously scanning the brain and heart, which should avoid the need for arterial blood sampling. The aim of this study was to validate noninvasive quantitation with this system for 15O-labeled compounds. METHODS: Twelve healthy volunteers underwent a series of PET studies after C15O inhalation and intravenous H2(15)O administration using a Headtome-V-Dual tomograph (Shimadzu Corp., Kyoto, Japan). The C15O study provided gated blood-pool images of the heart simultaneously with quantitative static blood-volume images of both the brain and heart. Weighted-integrated H2(15)O sinograms were acquired for estimating rate constant (K1) and distribution-volume (Vd) images in the brain, in addition to single-frame sinograms for estimating autoradiographic cerebral blood flow images. Noninvasive arterial input functions were determined from the heart scanner (left ventricular chamber) according to a previously developed model and compared directly to invasive input functions measured with an on-line beta probe in six subjects. RESULTS: The noninvasive input functions derived from this PET system were in good agreement with those obtained by continuous arterial blood sampling in all six subjects. There was good agreement between quantitative values obtained noninvasively and those using the invasive input function: average autoradiographic regional cerebral blood flow was 0.412 +/- 0.058 and 0.426 +/- 0.062 ml/min/g, K1 of H2(15)O was 0.416 +/- 0.073 and 0.420 +/- 0.067 ml/min/ml and Vd of H2(15)O was 0.800 +/- 0.080 and 0.830 +/- 0.070 ml/ml for the noninvasive and invasive input functions, respectively. In addition to the brain functional parameters, the system also simultaneously provided cardiac function such as regional myocardial blood flow (0.84 +/- 0.19 ml/min/g), left ventricular volume (132 +/- 22 mm at end diastole and 45 +/- 14 ml at end systole) and ejection fraction (66% +/- 5%). CONCLUSION: This PET system allows noninvasive quantitation in both the brain and heart simultaneously without arterial cannulation, and may prove useful in clinical research.

Adult↗
PubMed1998

Imaging neurochemistry of cerebrovascular disease with PET and SPECT.

Pathophysiology of cerebrovascular disease has been studied by measuring cerebral blood flow and energy metabolism using single photon emission computed tomography (SPECT) and positron emission tomography (PET). These parameters are measures for brain tissue consisting of heterogeneous components such as neurons, glial cells, and blood vessels. It is still difficult to evaluate brain damages specifically involving either neurons or other components. Several trials were recently conducted to visualize neuron-specific injury in cerebrovascular disease by means of 11C flumazenil for PET and 123I-iomazenil for SPECT. These tracers selectively bind to central benzodiazepine receptor which is purely neuronal. A reduced accumulation of these ligands was found in the area surrounding the complete infarction and in the cortex remote from putaminal hemorrhage, indicating the existence of neuron specific injury not visualized by CT and MR. Neurological deficits were well correlated with the loss of cortical accumulation of these ligands. These preliminary studies indicated a potential of neurochemical imaging in cerebrovascular disease. Vulnerability to ischemia which may differ among brain tissue components, among subpopulations of neurons, and among pre-synaptic and post-synaptic functions can be more precisely examined. Neurochemical imaging can be also applied to reveal releases and re-organization of each neurotransmitter-acceptor system after stroke.

Brain↗
PubMed1998

[Long-term follow-up study with PET in a case of superficial siderosis].

Long-term follow-up study with positron emission tomography (PET) has been conducted in a patient with superficial siderosis for ten years. A 63-year-old right-handed woman began to exhibit a cerebellar ataxia when she was 52 years old. Thereafter she has been exhibiting a slowly progressive course of pyramidal signs, hearing loss, anosmia, bilateral sciatica and memory disturbance in addition to the cerebellar ataxia. Series of x-ray CT and MRI disclosed a progressive atrophy of the cerebellum, specifically in the superior vermis, and a mild diffuse atrophy in the cerebral hemispheres, whereas no significant atrophy was seen in the brainstem. A marked hypointensity was seen along the rim of the brain structures including brainstem, cerebellum, sylvian fissures and the medial temporal lobes on MR T 2-weighted images. This hypointensity was also found at the edges of the third and fourth ventricles. These findings were regarded as haemosiderin deposit. By using oxygen-15, PET was carried out repeatedly with ten-year interval. In the initial PET study, both cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were mildly decreased in the cerebellar hemispheres and the occipital cortices. The follow-up PET study revealed a progressive reduction of CMRO2 in the brainstem, cerebellar hemispheres and temporal cortices including the hippocampus in which the haemosiderin deposition was marked on MRI, whereas the reduction of CBF was not advanced as compared with CMRO2. It was suggested that the progressive reduction of CMRO2 in the brain sites where the haemosiderin deposition was observed on MRI reflected the clinical course of neurological deterioration.

Brain↗
PubMed1997

Misery perfusion with preserved vascular reactivity in Alzheimer's disease.

To elucidate the hemodynamic pathophysiology underlying Alzheimer's disease (AD), cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2) and oxygen extraction fraction (OEF) were measured with positron emission tomography in 10 patients with probable AD and in 20 age-matched normal volunteers. By the 15O intravenous bolus injection method, CBF was measured during resting state, CO2 inhalation (hypercapnia) and hyperventilation (hypocapnia), and the vascular reactivity (VR) was estimated by comparing the CBF changes (delta CBF%/PaCO2 mmHg) in the hyper- or hypocapnic to the resting state. By the 15O2 single-breath method or 15O steady-state method, CMRO2 and OEF were measured during resting state. Based on 26 regions of interest, local CBF, CMRO2 and OEF were compared statistically between the two groups. As compared with the control group, the mean CBF and CMRO2 decreased to as low as 77.0% and 88.4% of the normal values, respectively, while the mean OEF increased by 12.1% (p < 0.05) in AD patients. These changes were most pronounced in the supramarginal and superior temporal gyri. There was no focal change in VR in the AD group, and no significant difference was seen in VR to either hyper- or hypocapnia between AD and control groups. The results may suggest a vascular involvement, possibly at the capillary level, that might cause a relative misery perfusion syndrome accompanied by preserved vascular reactivity in AD.

Adult↗
PubMed1997

MRI of acute cerebral infarction: a comparison of FLAIR and T2-weighted fast spin-echo imaging.

Fluid-attenuated inversion-recovery (FLAIR) sequences have been reported to provide high sensitivity to a wide range of central nervous system diseases. To our knowledge, however, FLAIR sequences have not been used to study patients with acute cerebral infarcts. We evaluated the usefulness of FLAIR sequences in this context. FLAIR sequences were acquired on a 0.5 T superconducting unit within 8 h of the onset in 19 patients (aged 26-80 years) with a total of 23 ischaemic lesions. The images were reviewed retrospectively by three neuroradiologists, and the FLAIR images were compared with T2-weighted fast spin-echo images. All but one of the ischaemic lesions involving grey matter was clearly demonstrated on FLAIR images as increased signal intensity in cortical or central grey matter. FLAIR images were particularly useful for detecting the hyperacute cortical infarcts within 3 h of onset, which were not readily detected on the spin-echo images. In 9 of 11 patients with complete proximal occlusion, the distal portion of the cerebral artery was visible as an area of high signal intensity on FLAIR images.

Acute Disease↗
PubMed1997

Regional correlations between the EEG and oxygen metabolism in dementia of Alzheimer's type.

To determine the relationship between EEG slowing and cerebral hypometabolism in dementia, 10 patients with dementia of Alzheimer's type (DAT) were evaluated with quantitative topographic EEG and positron emission tomography (PET). Power in each 1-Hz frequency band from 2-20 Hz, power ratio index, and normalised PET data from corresponding cortical sites were compared to data obtained from 20 normal volunteers. PET revealed significant parieto-temporal hypometabolism, and topographic EEG mapping and power spectrum analysis revealed a slowing of the background EEG that was most pronounced in the parietal-temporal areas. Correlation analysis between EEG power spectrum data and CMRO2 revealed significant negative correlations for frequencies below 8 Hz and significant positive correlations above 8 Hz in the parieto-temporal regions, which have previously been identified as the areas most severely affected by pathological changes associated with DAT. Correlation coefficients plotted as functions of frequency illustrated the relationships between EEG changes and reduced CMRO2, supporting previous views that EEG slowing in DAT may be related to hypometabolism in cortical regions most affected by the disease.

Aged↗
PubMed1997

Distribution of heat shock proteins in eutopic and ectopic endometrium in endometriosis and adenomyosis.

OBJECTIVE: To evaluate the pathophysiologic role of heat shock proteins and to examine the effect of danazol on these proteins in patients with endometriosis and adenomyosis. DESIGN: Immunohistochemical identification of human heat shock proteins 27, 60, and 70 in endometrial glandular cells identified using monoclonal antibodies. SETTING: Department of obstetrics and gynecology in a university hospital. PATIENT(S): Subjects were 119 women with documented endometriosis or adenomyosis. The subjects were divided into three groups: fertile control (n = 38), with 14 in the proliferative phase and 24 in the secretory phase; endometriosis (n = 38); and adenomyosis (n = 43), including 33 who underwent hysterectomy and 10 treated with danazol. MAIN OUTCOME MEASURE(S): Staining of glandular cells by semiquantitative immunostaining (evaluation nomogram) score. RESULT(S): Significantly increased expression of heat shock protein 27 was noted in eutopic endometrium from patients with endometriosis and adenomyosis as compared with controls, regardless of the menstrual phase. The scores for heat shock protein 27 and heat shock protein 70 in the ectopic endometrium of patients with endometriosis were low compared with those in eutopic endometrium, whereas in adenomyosis, the scores were similar to those of eutopic endometrium. After treatment with danazol, the expression of heat shock proteins returned to control levels. CONCLUSION(S): We suggest that abnormally increased expression of heat shock proteins plays a role in the pathophysiology of endometriosis and adenomyosis.

Adult↗
PubMed1997

Intracarotid recombinant human tumor necrosis factor-alpha reduces cerebral blood flow and methionine uptake in rat brain tumors.

The aim of the present study is to understand the therapeutic effects of recombinant human tumor necrosis factor-alpha (rH-TNF) on hemocirculation and metabolism of brain tumors. Using double-label autoradiographic technique, we have monitored changes in regional cerebral blood flow (rCBF) and protein-bound fraction of (3H-methyl)-L-methionine, expressed as acid-insoluble fraction (AIF), in rat brain tumors following treatment with intracarotid rH-TNF. The central portion of tumors showed a significant decrease in rCBF and AIF at 4 hours after the injection (p < 0.01, p < 0.05, respectively, as compared with non-treated control rats), turned microscopically necrotic at 24 hours, and became more extensively necrotic at 72 hours. Tumor cells remained viable only in the peripheral portion of the tumors after the treatment. The peripheral portion also showed a moderate decrease in rCBF, but less change in AIF to 4 to 72 hours after the treatment. Neither ipsilateral nor contralateral non-involved cortex demonstrated appreciable changes in rCBF and AIF during the observed period. Intracarotid rH-TNF selectively reduces tumor rCBF and AIF, resulting in histological modification.

Animals↗
PubMed1997

Subependymoma of the septum pellucidum: characterization by PET.

We report the evaluation of a subependymoma of the septum pellucidum by positron emission tomography (PET) with analysis of 18F-fluorodeoxyglucose (FDG) kinetics. The tumor showed exceedingly low rates of glucose metabolism (rCMRG1) and kinetic constants (K1, K2, and K3). This hypometabolism indicates low cellular density and slow growth.

Adult↗
PubMed1997

Indications for differential diagnosis of nontumor central nervous system diseases from tumors. A positron emission tomography study.

To accurately differentiate nontumor central nervous system (CNS) diseases from brain tumors, we retrospectively evaluated the cerebral circulation and metabolism in patients with nontumor CNS diseases using positron emission tomography (PET). Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), the metabolic rates of oxygen (rCMRO2), and of glucose (rCMRGI), and the uptake of 11C-methyl-L-methionine (11C-Met) were visually evaluated in lesions and compared with values for the contralateral white matter regions. PET findings were correlated with those of x-ray computed tomography (CT) and magnetic resonance imaging (MRI), and were analyzed for nontumor CNS diseases and cerebral gliomas. rCBF and rCBV were changeable from disease to disease or from stage to stage of disease progression. rOEF and rCMRO2 remained low in 5 and 6, respectively, of 9 nontumor CNS diseases examined, whereas these parameters were increased in CNS infections such as brain abscess. Overall, noteworthy was the locally increased rOEF and rCMRO2 in the patients with a brain abscess in contrast to the values for patients with gliomas. rCMRGI reflected biological characteristics of each disease, and correlated with cell density, whether reactive glial cells or inflammatory cells. 11C-Met was accumulated at a certain stage of nontumor CNS diseases, which implied uptake of the tracer as a result of disruption of the blood-brain barrier as well as metabolic incorporation.

Adolescent↗
PubMed1997

Subacute and chronic subarachnoid hemorrhage: diagnosis with fluid-attenuated inversion-recovery MR imaging.

PURPOSE: To evaluate fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) imaging in the detection of subacute and chronic subarachnoid hemorrhage. MATERIALS AND METHODS: The authors performed 19 FLAIR MR imaging examinations at 0.5 T in 14 adult patients with subarachnoid hemorrhage 3-45 days after the ictus and 22 FLAIR examinations in 22 adult control subjects. The detection of subacute and chronic subarachnoid hemorrhage on FLAIR images was compared with the detection on conventional spin-echo MR and computed tomographic (CT) images. RESULTS: In the detection of subacute subarachnoid hemorrhage, FLAIR (100% detection) was significantly superior to T1-weighted imaging (36% detection, P < .01), T2-weighted imaging (0% detection, P < .02), and CT (45% detection, P < .02 [Fisher exact test]). Although FLAIR imaging (63% detection) was superior in chronic subarachnoid hemorrhage detection, there were no statistically significant differences between modalities. FLAIR imaging demonstrated all subarachnoid hemorrhage areas as high-signal-intensity areas within 18 days and up to a maximum of 45 days after the ictus. In a blind comparison, no FLAIR images acquired in control subjects were confused with those acquired in patients. CONCLUSION: FLAIR diagnostic images are superior to conventional MR or CT images in patients with subacute subarachnoid hemorrhage.

Acute Disease↗
PubMed1997

Subcortical hypoperfusion associated with asymptomatic white matter lesions on magnetic resonance imaging.

BACKGROUND AND PURPOSE: We examined whether hemodynamic and metabolic abnormalities in the cerebral white matter, basal ganglia, and thalamus are associated with asymptomatic white matter lesions (WML) depicted on MR images. METHODS: A positron emission tomographic study with H2(15)O, C15O, and 15O2 was performed in eight normal control subjects without any WML (mean +/- 1 SD age, 68.5 +/- 10.2 years) and in 15 asymptomatic subjects with WML (71.3 +/- 8.5 years) to measure regional cerebral blood flow (CBF), cerebral blood volume, oxygen extraction fraction (OEF), and oxygen metabolic rate. RESULTS: In the cerebral white matter in the asymptomatic subjects with WML, significantly lower CBF (20.3 +/- 3.9 mL/100 mL per minute; P < .05) and significantly higher OEF (0.43 +/- 0.08; P < .05) were found compared with those for control subjects (23.5 +/- 2.6 mL/100 mL per minute and 0.37 +/- 0.06, respectively). The severity of WML was not related to the magnitude of hypoperfusion. In the basal ganglia, significantly lower CBF (44.9 +/- 6.9 mL/100 mL per minute; P < .01) and significantly higher OEF (0.54 +/- 0.08; P < .01) were found in the WML group than in control subjects (70.1 +/- 12.0 mL/100 mL/min and 0.39 +/- 0.03, respectively). In the thalamus, there was no significant difference in CBF and OEF between the control and WML groups. CONCLUSIONS: Hypoperfusion of the cerebral white matter and basal ganglia in asymptomatic WML subjects may be induced by the arteriosclerosis of long penetrating medullary arteries and lenticulostriate arteries but may not be directly related to the production of WML. The role of hypoperfusion in the production of WML and acceleration of its development remains to be elucidated.

Aged↗
PubMed1997

Technetium-99m-ECD brain SPECT in misery perfusion.

UNLABELLED: Discordant findings of 99mTc-methyl cysteinate dimer (99mTc-ECD) brain distribution have been reported when brain tissue is supplied by excess blood flow. We evaluated changes in 99mTc-ECD brain activity in the opposing pathological state, in which cerebral blood flow (CBF) is more profoundly impaired than metabolism, and analyzed the relationship of 99mTc-ECD activity with CBF and metabolism to investigate the dominant regulating factor on 99mTc-ECD distribution. METHODS: Twelve patients with unilateral intracranial steno-occlusive diseases were evaluated using dynamic and static 99mTc-ECD SPECT. Relative 99mTc-ECD activities and the retention ratio of the affected and unaffected cortices were compared with CBF and oxygen metabolism obtained by PET. Change in the relationships until 1 hr after tracer injection were also analyzed. RESULTS: Relative 99mTc-ECD activity was significantly correlated with CBF, and the highest correlation was obtained for the first minute of imaging (r = 0.674, p < 0.0010. Fifteen minutes after injection, the correlation coefficient with CBF decreased, whereas higher correlation was observed with the parameter of oxygen metabolism (r = 0.758-0.815, p < 0.001). Changes in the retention ratio were dependent on changes in oxygen metabolism, and the retention ratio for the high oxygen extraction fraction (OEF) area was the same as that for the normal OEF area. CONCLUSION: In addition to CBF, brain distribution on 99mTc-ECD SPECT images is affected by brain metabolism, especially on delayed images after injection. The degree of discrepancy between CBF and metabolism should be considered when interpreting images of the misery perfusion state.

Blood-Brain Barrier↗
PubMed1997

Regional cerebral blood flow measurement with iodine-123-IMP autoradiography: normal values, reproducibility and sensitivity to hypoperfusion.

UNLABELLED: We recently proposed a simplified technique for measuring regional cerebral blood flow (rCBF) using the [123I]N-isopropyl-p-iodoamphetamine (IMP) autoradiographic (ARG) method with SPECT (the IMP-ARG method). We examined normal values of rCBF and the reproducibility and sensitivity to hypoperfusion in stroke patients using this method. METHODS: By using a standard arterial input, a single static scan, a fixed distribution volume (Vd) and one-point arterial blood sampling, we measured rCBF in 39 normal volunteers (19 men and 20 women; mean ages 61 +/- 11 yr for the men and 60 +/- 12 yr for the women). Eighteen neurologically stable patients with prior stroke (mean age = 65 +/- 11 yr) were studied twice at a mean interval of 97 days. In 16 patients (7 men and 9 women, mean age = 63 +/- 5 yr) with subarachnoid hemorrhage, rCBF was measured 1-2 wk after onset. Cerebral vasospasm was evaluated by repeated angiography. The mean rCBF in the vasospastic area was compared with that in a nonvasospastic area. RESULTS: The mean rCBFs of the cerebral cortex and centrum semiovale in the volunteers were 33.0 +/- 5.1 ml/100 g/min and 25.0 +/- 4.5 ml/100 g/min, respectively. There was no age-dependent change in rCBF, but the women showed significantly higher cortical rCBF than the men (p < 0.05). In the stroke patients, the whole-brain CBF values showed high reproducibility, with high correlations between those obtained at the first and second studies (y = -3.5 + 1.03x; r = 0.90; p < 0.001). In the subarachnoid hemorrhage patients, the vasospastic area showed significantly lower rCBF than the normal cortical rCBF (p < 0.01) and the nonvasospastic area (p < 0.01). Brain regions with rCBF levels below 20 ml/100 g/min showed infarction on the follow-up CT scan. CONCLUSION: The IMP-ARG method is reproducible, sensitive to hypoperfusion and feasible for the quantitative evaluation of rCBF in routine clinical practice.

Aged↗