PubMed Health⌕ Search

Biomedical subjects

Kengo Ito

Publications and source records attributed to Kengo Ito.

At least 19 recordsLinked to original sources
PubMed2006

An abnormal accumulation of fluorine-18-FDG PET in cytomegalovirus enteritis--a case report.

The source of a fever of unknown origin (FUO) and watery diarrhea in a 63-yr-old female with a history of disturbance of consciousness due to moyamoya disease was examined. Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), colonoscopy, blood analysis, and determination of cytomegalovirus (CMV) antigenemia were performed. FDG was found to be accumulated in the wall of a dilated colon, and extended from the transverse to sigmoid colon. Colonoscopy revealed edematous, inflammatory, and punched out lesions in accordance with the areas of abnormal FDG uptake. A biopsy specimen showed the antibody of CMV in the colonic mucosa, and CMV antigenemia was detected by an immunohistochemical assay using a monoclonal antibody for CMV pp65 antigen. From these findings, we strongly suspected CMV enteritis.

Cytomegalovirus↗
PubMed2006

Cerebral glucose metabolism change in patients with complex regional pain syndrome: a PET study.

PURPOSE: The aim of this study was to examine abnormalities of the central nervous system in patients with chronic pain who were diagnosed with complex regional pain syndrome (CRPS). MATERIALS AND METHODS: Brain activity was assessed using (18)F-fluorodeoxyglucose positron emission tomography. The data collected from 18 patients were compared with data obtained from 13 normal age-matched controls. RESULTS: Our results showed that glucose metabolism was bilaterally increased in the secondary somatosensory cortex, mid-anterior cingulated cortex (ACC) or posterior cingulated cortex (PCC) (or both), parietal cortex, posterior parietal cortex (PPC), and cerebellum as well as in the right posterior insula and right thalamus in our patients. In contrast, glucose metabolism was reduced contralaterally in the dorsal prefrontal cortex and primary motor cortex. Glucose metabolism was bilaterally elevated in the mid-ACC/PCC and the PPC, which correlated with pain duration. CONCLUSION: These data suggested that glucose metabolism in the brains of patients with CRPS changes dramatically at each location. In particular, glucose metabolism was increased in the areas concerned with somatosensory perception, possibly due to continuous painful stimulation.

Adult↗
PubMed2006

Application of 18F-FDG PET for monitoring the therapeutic effect of antiinflammatory drugs on stabilization of vulnerable atherosclerotic plaques.

UNLABELLED: The rupture of atherosclerotic vulnerable plaques and subsequent formation of thrombi are the main factors responsible for myocardial and cerebral infarctions. Because macrophage infiltration plays an essential role in plaque rupturing, pharmacologic therapy that reduces macrophage infiltration is required to stabilize the vulnerable plaques. The monitoring of therapeutic effect is important in assessing the therapeutic effects of drugs for individual patients. We previously reported that (18)F-FDG accumulates in macrophage-rich plaques. The present study was undertaken to investigate the usefulness of (18)F-FDG PET for monitoring therapies that target vascular inflammation. METHODS: Myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits were used in this study. The antioxidant probucol was included in the diet fed to 4 rabbits starting at 10 mo of age (probucol group). In a control study, 4 rabbits received standard rabbit chow (control group). (18)F-FDG PET experiments were performed on both groups before the study and at 1, 3, and 6 mo after treatment. After the last imaging session, the rabbits were sacrificed at 3 h after injection of (18)F-FDG, and the aortas were removed. The accumulated radioactivity was then measured, and the number of macrophages was determined by examination of stained sections. RESULTS: At the age of 10 mo, before the treatment, the aorta could be imaged by (18)F-FDG PET in all rabbits. The aorta could not be imaged after 6 mo of probucol treatment, whereas intense radioactivity was observed in the control rabbits throughout the investigation. The standardized uptake values (SUVs) of the aorta were decreased significantly in the probucol group after 3 mo of intervention as compared with the pretreatment period. The SUVs of the control group were increased gradually at 6 mo. Radioactivity in the aorta was significantly lower in the probucol group than that in the control group. Macrophages were already present at the beginning of the study, and probucol treatment for 6 mo resulted in a significant reduction of macrophage infiltration. CONCLUSION: (18)F-FDG PET was able to image the reduction of inflammation by probucol. (18)F-FDG PET should be useful for evaluating the therapeutic effect of drugs clinically and for the development of new drugs that can stabilize vulnerable plaques. (18)F-FDG PET should be useful for evaluating the therapeutic effect of drugs clinically and for the development of new drugs that can reduce inflammation of vulnerable plaques.

Animals↗
PubMed2005

Development of a practical image-based scatter correction method for brain perfusion SPECT: comparison with the TEW method.

PURPOSE: An image-based scatter correction (IBSC) method was developed to convert scatter-uncorrected into scatter-corrected SPECT images. The purpose of this study was to validate this method by means of phantom simulations and human studies with 99mTc-labeled tracers, based on comparison with the conventional triple energy window (TEW) method. METHODS: The IBSC method corrects scatter on the reconstructed image I(mub)AC with Chang's attenuation correction factor. The scatter component image is estimated by convolving I(mub)AC with a scatter function followed by multiplication with an image-based scatter fraction function. The IBSC method was evaluated with Monte Carlo simulations and 99mTc-ethyl cysteinate dimer SPECT human brain perfusion studies obtained from five volunteers. The image counts and contrast of the scatter-corrected images obtained by the IBSC and TEW methods were compared. RESULTS: Using data obtained from the simulations, the image counts and contrast of the scatter-corrected images obtained by the IBSC and TEW methods were found to be nearly identical for both gray and white matter. In human brain images, no significant differences in image contrast were observed between the IBSC and TEW methods. CONCLUSION: The IBSC method is a simple scatter correction technique feasible for use in clinical routine.

Algorithms↗
PubMed2005

18F-FDG uptake by primary tumor as a predictor of intratumoral lymphatic vessel invasion and lymph node involvement in non-small cell lung cancer: analysis of a multicenter study.

UNLABELLED: Intratumoral lymphatic vessel invasion and lymph node involvement are important factors in the planning of therapeutic strategies, particularly limited surgical resection in patients with non-small cell lung cancer. (18)F-FDG uptake within the primary lesion correlates with aggressiveness on PET studies. The more metabolically active the tumor, the more aggressive are the findings. The aim of this multicenter study was to determine whether (18)F-FDG uptake of the primary tumor is a predictor of intratumoral lymphatic vessel invasion and lymph node metastasis in patients with non-small cell lung cancer. METHODS: One hundred thirty-two patients with lung cancer were studied. All patients underwent a thoracotomy within 4 wk of the (18)F-FDG PET study. A 3-point visual scoring system (low, moderate, or high grade in comparison with mediastinal activity) was used to interpret (18)F-FDG uptake within the primary lesions. The degree of (18)F-FDG uptake in the primary tumor was correlated with the incidence of intratumoral lymphatic vessel invasion and lymph node involvement. Multivariate analysis was performed with logistic multivariate analysis to assess the joint effects and interactions of the variables (age, sex, tumor size, histology, and (18)F-FDG uptake) on intratumoral lymphatic vessel invasion and lymph node involvement. RESULTS: Intratumoral lymphatic vessel invasion and lymph node involvement were found in 7.1% and 5.9%, respectively, of the patients classified in the low-grade group, and in 14.3% and 10.0%, respectively, of the patients classified in the moderate-grade group. In contrast, of the patients classified in the group with high (18)F-FDG uptake, intratumoral lymphatic vessel invasion and lymph node involvement were found in 39.7% and 38.9%, respectively. Multivariate analysis showed that only (18)F-FDG uptake was a significant factor for intratumoral lymphatic vessel invasion and that tumor size and (18)F-FDG uptake were significant factors for lymph node involvement. Of the patients in the high-grade group whose tumors were classified as > or =3 cm in size, lymph node involvement was found in 51.5%. In contrast, of the patients in the low- to moderate-grade group whose tumors were classified as <3 cm in size, lymph node involvement was found in only 9.1% (P < 0.0001). CONCLUSION: Patients with a low to moderate (18)F-FDG uptake in the primary lesion had a significantly lower risk of concurrent intratumoral lymphatic vessel invasion and nodal involvement than did patients with a high (18)F-FDG uptake. In patients with non-small cell lung cancer, (18)F-FDG uptake by the primary tumor is a strong predictor of intratumoral lymphatic vessel invasion and lymph node metastasis.

Adult↗
PubMed2004

Rat-PET study without anesthesia: anesthetics modify the dopamine D1 receptor binding in rat brain.

Positron emission tomography (PET) measurements in 6-month-old F344/N rats were performed in the conscious state and the influence of chloral hydrate, ketamine, and pentobarbital anesthesia on dopamine D(1) (DA-D(1)) receptor binding was evaluated using [(11)C]SCH23390, a selective DA-D(1) receptor ligand. To perform the PET study in conscious rats, an original fixation apparatus was developed and the animals were trained to acclimate to the scanning atmosphere for 3 h. This training was carried out twice a day for 2 weeks. PET measurements in conscious rats were successful, since the trained rats scarcely moved during the scanning (as monitored by video camera) and since highly reproducible measurements of binding potential (BP) were derived from their scanning. Chloral hydrate and ketamine anesthesia significantly increased the striatal BP of DA-D(1) receptors by 36% and 46%, respectively, compared to that observed in the conscious state. In contrast, pentobarbital markedly decreased the BP by 41%. These BP values of DA-D(1) receptors were calculated using a curve-fitting method. Our results indicate that PET studies in rats should be performed in the conscious state since the anesthetics dramatically modified ligand-receptor bindings, such as DA-D(1) receptor binding, in rat brain.

Anesthesia↗
PubMed2004

Visual hallucination in Parkinson's disease with FDG PET.

To determine the characteristics of cerebral glucose metabolism in Parkinson's disease patients with visual hallucinations, group comparison studies using [18F]fluorodeoxyglucose positron emission tomography were performed. Nondemented Parkinson's disease patients in advanced stages were classified into two groups: (1) patients without visual hallucinations; (2) patients with visual hallucinations. Compared to patients without hallucinations, the relative regional cerebral glucose metabolic rate was greater in the frontal areas in patients with visual hallucinations, and the increase reached a significant level in the left superior frontal gyrus. Relative frontal hypermetabolism may be a feature of Parkinson's disease patients with visual hallucinations.

Aged↗
PubMed2004

Cognitive- and motor-related regions in Parkinson's disease: FDOPA and FDG PET studies.

OBJECTIVE: Using 6-[(18)F]fluoro-L-dopa (FDOPA) and [(18)F]fluorodeoxyglucoce (FDG) positron emission tomography (PET), multiple regression analyses were performed to determine the specific brain regions that are related to cognitive and motor symptoms in nondemented patients with Parkinson's disease. METHODS: Spatially normalized images of FDOPA influx rate constant (Ki) values and relative regional cerebral metabolic rates for glucose (rrCMRglc) were created. Raven's Coloured Progressive Matrices (RCPM) scores and the Unified Parkinson's Disease Rating Scale (UPDRS) motor scores were used to determine the patients' cognitive and motor functions, respectively. Multiple correlation analyses between the FDOPA and FDG images and the cognitive and motor scores were performed for each voxel. RESULTS: RCPM score was significantly positively correlated with the FDOPA Ki in the left hippocampus and with the rrCMRglc in the left middle frontal gyrus and right retrosplenial cortex. Motor function was significantly positively correlated with the FDOPA Ki in the bilateral striatum and with the rrCMRglc in association areas and primary visual cortex. The level of motor function was significantly inversely correlated with the FDOPA Ki in the anterior cingulate gyrus and with the rrCMRglc in bilateral primary motor cortex and right putamen. CONCLUSIONS: Changes of striatal FDOPA uptake and rrCMRglc in the primary motor cortex likely represent dysfunction in the motor system involving the corticobasal ganglia-thalamocortical loop. Change of FDOPA uptake in the anterior cingulate gyrus may be related to up-regulation of dopamine synthesis in surviving dopamine neurons. The regions where correlation with cognitive function was observed belong to a cognitive frontoparietal-hippocampal network.

Biological Transport↗
PubMed2003

Neuroradiologic and clinical abnormalities in dementia of diffuse neurofibrillary tangles with calcification (Kosaka-Shibayama disease).

We describe a characteristic dementia patient diagnosed as diffuse neurofibrillary tangles with calcification (DNTC). Neuropsychologically, dementia, including a decline in memory retention and intelligence, and anomic aphasia were recognized. Imaging revealed circumscribed temporal dominant atrophy and calcification of the basal ganglia and cerebellum. SPECT and FDG-PET revealed a remarkable reduction of blood flow and metabolism in the temporal lobes; however, there is no reduction in the basal ganglia and cerebellum, and FDOPA-PET also disclosed no abnormalities. This suggests that calcification and neuronal degeneration occur independently in DNTC.

Aged↗
PubMed2003

Asymmetrical enhancement of middle-latency auditory evoked fields with aging.

We studied the effects of aging on middle-latency auditory evoked fields (P50m), and analyzed their interhemispheric differences. Magnetic responses following tone-burst stimuli to the right ear were measured in groups of 11 younger and 15 elderly subjects. The elderly subjects showed marked asymmetry in the P50m amplitudes. In the elderly group, the mean amplitude of the contralateral P50m was significantly larger (P<0.0005) than that of the ipsilateral P50m, while no asymmetry was shown in the younger group. The amplitude enlargement in the contralateral P50m showed significant correlation with age (R=0.60, P<0.005), while the ipsilateral P50m showed no correlation with age. These results suggest that the contralateral and ipsilateral auditory pathways are affected differently by ageing.

Aged↗
PubMed2003

Synthesis and evaluation of 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-[11C]ethyl-1,3-dihydro-2H-benzimidazol-2-one as a brain ORL1 receptor imaging agent for positron emission tomography.

1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-[(11)C]ethyl-1,3-dihydro-2H-benzimidazol-2-one ([(11)C]CPEB) was synthesized by [(11)C]N-ethylation and evaluated as a potential brain ORL1 receptor imaging agent by positron emission tomography. The uptake of [(11)C]CPEB in the mouse brain was 1.9% dose/g, 2 min post-injection, and gradually decreased with time. Receptor-specific binding was observed, however, the contribution of other receptors was observed and the non-specific binding of [(11)C]CPEB was too high for imaging receptors in vivo. Therefore, [(11)C]CPEB is not a suitable tracer for in vivo ORL1 receptor imaging.

Animals↗
PubMed2003

Direct electrophilic radiofluorination of a cyclic RGD peptide for in vivo alpha(v)beta3 integrin related tumor imaging.

The association of the alpha(v)beta(3) integrin with tumor metastasis and tumor related angiogenesis has been suggested. Therefore, by imaging the alpha(v)beta(3) receptor with PET, information concerning the tumor status could be obtained. Cyclic peptides including the RGD sequence, were radiolabeled by direct electrophilic fluorination with [(18)F]AcOF. In tumor-bearing mice, the labeled peptides accumulated at the tumor with a high tumor to blood ratio. These findings suggest that an assessment of tumor characteristics may be obtained by using these (18)F-labeled peptides.

Acetates↗
PubMed2002

Direction of cross-modal information transfer affects human brain activation: a PET study.

The purpose of this study was to determine the functional organization of the human brain involved in cross-modal discrimination between tactile and visual information. Regional cerebral blood flow was measured by positron emission tomography in nine right-handed volunteers during four discrimination tasks; tactile-tactile (TT), tactile-visual (TV), visual-tactile (VT), and visual-visual (VV). The subjects were asked either to look at digital cylinders of different diameters or to grasp the digital cylinders with the thumb and index finger of the right hand using haptic interfaces. Compared with the motor control task in which the subjects looked at and grasped cylinders of the same diameter, the right lateral prefrontal cortex and the right inferior parietal lobule were activated in all the four discrimination tasks. In addition, the dorsal premotor cortex, the ventral premotor cortex, and the inferior temporal cortex of the right hemisphere were activated during VT but not during TV. Our results suggest that the human brain mechanisms underlying cross-modal discrimination have two different pathways depending on the temporal order in which stimuli are presented.

Adult↗
PubMed2002

Striatal and extrastriatal dysfunction in Parkinson's disease with dementia: a 6-[18F]fluoro-L-dopa PET study.

We investigated the relative differences in dopaminergic function through the whole brain in patients with Parkinson's disease without dementia (PD) and with dementia (PDD) using 6-[18F]fluoro-L-dopa (18F-dopa) PET and a voxel-by-voxel analysis. The 10 PD and 10 PDD patients were equivalently disabled, having mean scores of 3.2 +/- 0.6 and 3.2 +/- 0.7, respectively, on the Hoehn and Yahr rating scale. 18F-dopa influx constant (Ki) images of those patients and 15 normal age-matched subjects were transformed into standard stereotactic space. The significant differences between the groups (expressed in mean regional Ki values) were localized with statistical parametric mapping (SPM) on a voxel-by-voxel basis. Compared with the normal group, SPM localized declines of the 18F-dopa Ki bilaterally in the putamen, the right caudate nucleus and the left ventral midbrain for the PD group (P < 0.01, corrected). Compared with the normal group, the PDD group showed reduced 18F-dopa Ki bilaterally in the striatum, midbrain and anterior cingulate area (P < 0.01, corrected). A relative difference in 18F-dopa uptake between PD and PDD was the bilateral decline in the anterior cingulate area and ventral striatum and in the right caudate nucleus in the PDD group (P < 0.001, corrected). Accordingly, we conclude that dementia in PD is associated with impaired mesolimbic and caudate dopaminergic function.

Aged↗
PubMed2002

Changes of neural activity correlate with the severity of cortical ischemia in patients with unilateral major cerebral artery occlusion.

BACKGROUND AND PURPOSE: In major cerebral arterial steno-occlusive diseases, there can be remarkably decreased hemodynamic reserve without marked neurological impairments. In such settings, it is not known whether the neural activity is well maintained or disturbed according to the severity of cerebral ischemia. The present study was therefore undertaken to examine the neural activity under mild cerebral ischemia resulting from major cerebral arterial occlusion. METHODS: Seven patients with minor neurological impairment as well as either unilateral internal carotid artery or middle cerebral artery occlusion were studied. The severity of the cortical ischemia was assessed by measuring regional cerebral blood flow (rCBF) with positron emission tomography. The change in neural activity in the ischemic brain was then evaluated by means of somatosensory evoked magnetic field with magnetoencephalography. RESULTS: The rCBF in the primary sensory area and the strength of the initial component of somatosensory evoked magnetic field (N20 m) were significantly reduced (P<0.01) and the second component (P30 m) was significantly augmented (P<0.05) in the lesioned cerebral hemisphere as compared with the nonlesioned hemisphere. The asymmetry indexes for N20 m were positively correlated (r=0.78) and those for P30 m were inversely correlated (r=-0.92) with asymmetry indexes for rCBF. CONCLUSIONS: In patients with either unilateral internal carotid artery or middle cerebral artery occlusion and minor neural impairments, there was a reduction of afferent signal and an augmentation of the secondary response of the neurons in the primary sensory area. This showed correlation with the severity of cortical ischemia.

Adolescent↗
PubMed2002

[Current status of nuclear medicine. Clinical application of FDG-PET for cancer diagnosis. Colorectal cancer].

In Japan, colorectal cancer is the third most common cause of death from cancer. The recurrence rate after curative surgical treatment for colorectal cancer has been estimated at 30-40%, most frequently occurring within 3 years. Therefore, more accurate staging of recurrent colorectal cancer is required for more appropriate management decisions. This article focuses on the clinical value of PET with [18F]fluorodeoxyglucose (FDG) in the diagnosis of recurrent and primary colorectal cancers. The technical issues in clinical practice and the cost-effectiveness of FDG-PET in staging recurrent colorectal cancer will be covered.

Colorectal Neoplasms↗