Biomedical subjects

Ryoi Goto

Publications and source records attributed to Ryoi Goto.

10 recordsLinked to original sources

PubMed2006

Database of normal human cerebral blood flow measured by SPECT: I. Comparison between I-123-IMP, Tc-99m-HMPAO, and Tc-99m-ECD as referred with O-15 labeled water PET and voxel-based morphometry.

OBJECTIVES: Three accumulative tracers, iodine-123-labeled N-isopropyl-p-iodoamphetamine (I-123-IMP), technetium-99m-labeled hexamethylpropyleneamineoxime (Tc-99m-HMPAO), and technetium-99m-labeled ethyl cysteinate dimer (Tc-99m-ECD) are widely used to measure cerebral blood flow (CBF) in single-photon emission computed tomography (SPECT). In the present study, normal regional distribution of CBF measured with three different SPECT tracers was entered into a database and compared with regional distribution of CBF measured by positron emission tomography (PET) with H2(15)O. The regional distribution of tissue fractions of gray matter determined by voxel-based morphometry was also compared with SPECT and PET CBF distributions. METHODS: SPECT studies with I-123-IMP, Tc-99m-HMPAO, and Tc-99m-ECD were performed on 11, 20, and 17 healthy subjects, respectively. PET studies were performed on 11 healthy subjects. Magnetic resonance (MR) imaging studies for voxel-based morphometry were performed on 43 of the 48 subjects who underwent SPECT study. All SPECT, PET, and MR images were transformed into the standard brain format with the SPM2 system. The voxel values of each SPECT and PET image were globally normalized to 50 ml/100 ml/min. Gray matter, white matter, and cerebrospinal fluid images were segmented and extracted from all transformed MR images by applying voxel-based morphometry methods with the SPM2 system. RESULTS: Regional distribution of all three SPECT tracers differed from that of H2150 in the pons, midbrain, thalamus, putamen, parahippocampal gyrus, posterior cingulate gyrus, temporal cortex, and occipital cortex. No significant correlations were observed between the tissue fraction of gray matter and CBF with any tracer. CONCLUSION: Differences in regional distribution of SPECT tracers were considered to be caused mainly by differences in the mechanism of retention of tracers in the brain. Regional distribution of CBF was independent of regional distribution of gray matter fractions, and consequently the blood flow per gray matter volume differed for each brain region.

Brain↗

PubMed2006

Database of normal human cerebral blood flow measured by SPECT: II. Quantification of I-123-IMP studies with ARG method and effects of partial volume correction.

UNLABELLED: The limited spatial resolution of SPECT causes a partial volume effect (PVE) and can lead to the significant underestimation of regional tracer concentration in the small structures surrounded by a low tracer concentration, such as the cortical gray matter of an atrophied brain. The aim of the present study was to determine, using 123I-IMP and SPECT, normal CBF of elderly subjects with and without PVE correction (PVC), and to determine regional differences in the effect of PVC and their association with the regional tissue fraction of the brain. METHODS: Quantitative CBF SPECT using 123I-IMP was performed in 33 healthy elderly subjects (18 males, 15 females, 54-74 years old) using the autoradiographic method. We corrected CBF for PVE using segmented MR images, and analyzed quantitative CBF and regional differences in the effect of PVC using tissue fractions of gray matter (GM) and white matter (WM) in regions of interest (ROIs) placed on the cortical and subcortical GM regions and deep WM regions. RESULTS: The mean CBF in GM-ROIs were 31.7 +/- 6.6 and 41.0 +/- 8.1 ml/100 g/min for males and females, and in WM-ROIs, 18.2 +/- 0.7 and 22.9 +/- 0.8 ml/100 g/min for males and females, respectively. The mean CBF in GM-ROIs after PVC were 50.9 +/- 12.8 and 65.8 +/- 16.1 ml/100 g/min for males and females, respectively. There were statistically significant differences in the effect of PVC among ROIs, but not between genders. The effect of PVC was small in the cerebellum and parahippocampal gyrus, and it was large in the superior frontal gyrus, superior parietal lobule and precentral gyrus. CONCLUSION: Quantitative CBF in GM recovered significantly, but did not reach values as high as those obtained by invasive methods or in the H2(15)O PET study that used PVC. There were significant regional differences in the effect of PVC, which were considered to result from regional differences in GM tissue fraction, which is more reduced in the frontoparietal regions in the atrophied brain of the elderly.

Aged↗

PubMed2006

Both global gray matter volume and regional gray matter volume negatively correlate with lifetime alcohol intake in non-alcohol-dependent Japanese men: a volumetric analysis and a voxel-based morphometry.

BACKGROUND: Non-alcohol-dependent heavy drinkers, as well as alcohol-dependent individuals, show brain atrophy. The purpose of this study was to evaluate whether there are correlations between global and regional gray matter volumes and the lifetime alcohol intake using volumetric analysis and voxel-based morphometry (VBM) among Japanese non-alcohol-dependent male individuals. METHODS: High-resolution three-dimensional magnetic resonance images were acquired from 405 Japanese non-alcohol-dependent male individuals. The collected images were normalized, segmented for volumetric analysis, and additionally smoothed for VBM. For volumetric analysis, the partial correlation coefficient was estimated between the gray matter ratio, which represents the percentage of gray matter volume in the intracranial volume, and the lifetime alcohol intake adjusted for the age of each subject. Multiple regression analysis was performed among regional gray matter volume, lifetime alcohol intake, and age using VBM. RESULTS: Volumetric analysis revealed that gray matter ratio showed a negative correlation with the lifetime alcohol intake adjusted for age (p=0.059, partial correlation coefficient=-0.091). The VBM revealed that the gray matter volumes of the bilateral middle frontal gyri showed a significant negative correlation with the lifetime alcohol intake adjusted for age and systolic blood pressure (left side, p=0.006, Z=4.77; right side, p=0.023, Z=4.45, and p=0.046, Z=4.27). CONCLUSIONS: Our study suggests that non-alcohol-dependent Japanese male individuals show that both global gray matter volume and regional gray matter volume have negative correlations with the lifetime alcohol intake. Our study may contribute to clarifying the mechanism underlying the brain structural changes because of alcohol influence in healthy non-alcohol-dependent individuals.

Adolescent↗

PubMed2005

Male elderly subthreshold depression patients have smaller volume of medial part of prefrontal cortex and precentral gyrus compared with age-matched normal subjects: a voxel-based morphometry.

BACKGROUND: The brain morphological changes in subthreshold depression (sD) have not been clarified. We examined the structural difference in regional gray matter volume between community-dwelling elderly subjects with sD and age-matched nondepressed normal subjects by voxel-based morphometry (VBM) based on magnetic resonance imaging (MRI). METHODS: Thirty-four community-dwelling elderly subjects with sD and 109 age-matched nondepressed normal subjects were studied by MRI. We defined subjects with sD as those who showed a Geriatric Depression Scale score of 15 or higher and a Mini Mental State Examination score of 22 or higher, and do not fulfill the criteria of major depressive disorder (MDD) in the Diagnostic and Statistical Manual for Mental Disorders IV. We collected brain magnetic resonance images of 34 subjects with sD and 109 age-matched normal subjects, and analyzed the difference in regional gray matter volume between these two groups by VBM. RESULTS: Male subjects with sD had significantly smaller volumes of the medial part of the bilateral frontal lobes and the right precentral gyrus than normal male subjects. LIMITATIONS: We have not clarified the discrepancy in the results of gender difference. CONCLUSIONS: Our study revealed that even community-dwelling elderly male subjects with sD show bilateral prefrontal gray matter volume reduction, which was reported to be observed in elderly patients with MDD, although there is no significant volume reduction in the hippocampus, which was also reported to be observed in MDD. Our study may contribute to clarifying the mechanism underlying brain pathological changes in sD.

Age of Onset↗

PubMed2005

Effects of tissue heterogeneity on cerebral vascular response to acetazolamide stress measured by an I-123-IMP autoradiographic method with single-photon emission computed tomography.

OBJECTIVES: Single-photon emission computed tomography (SPECT) with iodine-123 (123I)-labeled N-isopropyl-p-iodoamphetamine (IMP) is widely used in measuring the cerebral blood flow (CBF) response to acetazolamide stress for assessment of cerebral vascular reserve. To quantitate CBF by means of SPECT with IMP, an autoradiographic (ARG) method has been developed and is widely used. Because the relation between the brain counts on the SPECT scan and CBF is not linear in the ARG method, a mixture of gray and white matter in a pixel causes errors in the calculation of CBF. In the present study, errors in the calculation of CBF and vascular response to acetazolamide stress by the ARG method due to tissue heterogeneity were estimated by simulation study. Correction for effects of tissue heterogeneity in SPECT data was also attempted. METHODS: Images of gray and white matter fraction were obtained by voxel-based morphometry analysis of magnetic resonance (MR) imaging data set. Ideal CBF images, which were generated from gray and white matter fraction images with assumed blood flow values for gray and white matter, were compared to CBF images generated by the ARG method. Correction for effects of tissue heterogeneity in SPECT data was performed with gray and white matter fraction data obtained from MR images. RESULTS: Systematic underestimation of CBF due to tissue heterogeneity was observed in all brain regions. In the neocortical regions, underestimation by -21% to -16%, -26% to -20%, -31% to -24%, and -35% to -27% was observed for gray and white matter blood flow of 80 and 20, 100 and 25, 120 and 30, and 140 and 35 ml/100 ml/min, respectively. Vascular response was also systematically underestimated in most brain regions. Vascular responses in the neocortical regions ranged from 17% to 20%, from 31% to 37%, and from 42% to 52% when ideal vascular responses were 25%, 50%, and 75%, respectively. After correction for the effects of tissue heterogeneity, values of vascular response to acetazolamide stress ranged from 64% to 116% in the neocortical regions, whereas values obtained by the ARG method ranged from 48% to 52%. CONCLUSION: Underestimation of the vascular response to acetazolamide stress due to tissue heterogeneity should be considered in the estimation of cerebral vascular reserve.

Acetazolamide↗

PubMed2005

Apparent CBF decrease with normal aging due to partial volume effects: MR-based partial volume correction on CBF SPECT.

Several studies using single photon emission tomography (SPECT) have shown changes in cerebral blood flow (CBF) with age, which were associated with partial volume effects by some authors. Some studies have also demonstrated gender-related differences in CBF. The present study aimed to examine age and gender effects on CBF SPECT images obtained using the 99mTc-ethyl cysteinate dimer and a SPECT scanner, before and after partial volume correction (PVC) using magnetic resonance (MR) imaging. Forty-four healthy subjects (29 males and 15 females; age range, 27-64 y; mean age, 50.0 +/- 9.8 y) participated. Each MR image was segmented to yield grey and white matter images and coregistered to a corresponding SPECT image, followed by convolution to approximate the SPECT spatial resolution. PVC-SPECT images were produced using the convoluted grey matter MR (GM-MR) and white matter MR images. The age and gender effects were assessed using SPM99. Decreases with age were detected in the anterolateral prefrontal cortex and in areas along the lateral sulcus and the lateral ventricle, bilaterally, in the GM-MR images and the SPECT images. In the PVC-SPECT images, decreases in CBF in the lateral prefrontal cortex lost their statistical significance. Decreases in CBF with age found along the lateral sulcus and the lateral ventricle, on the other hand, remained statistically significant, but observation of the spatially normalized MR images suggests that these findings are associated with the dilatation of the lateral sulcus and lateral ventricle, which was not completely compensated for by the spatial normalization procedure. Our present study demonstrated that age effects on CBF in healthy subjects could reflect morphological differences with age in grey matter.

Adult↗

PubMed2004

Error analysis of measured cerebral vascular response to acetazolamide stress by I-123-IMP autoradiographic method with single photon emission computed tomography: errors due to distribution volume of I-123-IMP.

OBJECTIVES: Iodine-123 (123I)-labeled N-isopropyl-p-iodoamphetamine (IMP) has been used as a cerebral blood flow (CBF) tracer for single-photon emission computed tomography (SPECT), and measurements of the CBF response to acetazolamide stress by SPECT with IMP are widely used to assess cerebral vascular reserve. To quantitate CBF by means of SPECT with IMP, an autoradiographic (ARG) method has been developed and is widely used. In the ARG method, CBF is calculated from the brain counts of the SPECT scan with an assumed distribution volume value of IMP (Vd). However, differences between true Vd and assumed Vd results in errors in calculated CBF. In the present study, errors in the CBF response to acetazolamide stress as calculated by the ARG method were investigated. METHODS: SPECT studies were performed on 12 patients with steno-occlusive lesions of the major cerebral artery. Two studies were performed on separate days. The first study was performed at rest (baseline), and the second during acetazolamide stress. SPECT scans were performed at 40 min (early scan) and 180 min (delayed scan) after intravenous injection of IMP. RESULTS: Although a simulation study showed that errors in calculated changes in CBF in response to acetazolamide stress, which result from differences between the true Vd and the assumed Vd, were larger when the baseline CBF and change in CBF were larger, values calculated by the ARG method with an assumed Vd were in good agreement with those calculated with true Vd obtained from early and delayed scan data. CONCLUSION: These data indicate that errors in the calculated CBF response to acetazolamide stress as calculated by the ARG method are negligible even at high CBF responses. The ARG method is therefore reliable for measurement of CBF response to acetazolamide stress.

Acetazolamide↗

PubMed2004

Voxel-based morphometry of human brain with age and cerebrovascular risk factors.

The objectives of this study were to evaluate the correlations of the volumes of the gray matter and white matter with age, and the correlations of the tissue probabilities of the gray matter and white matter with age and several cerebrovascular risk factors. We obtained magnetic resonance (MR) images of the brain and clinical information from 769 normal Japanese subjects. We processed the MR images automatically by correcting for inter-individual differences in brain size and shape, and by segmenting the MR images into the gray matter and white matter. Volumetry of the brain revealed a significant negative correlation between the gray matter volume and age, which was not observed between white matter volume and age. Voxel-based morphometry showed that age, systolic blood pressure, and alcohol drinking correlated with the regional tissue probabilities of the gray matter and white matter.

Adolescent↗

PubMed2003

Regional differences between 99mTc-ECD and 99mTc-HMPAO SPET in perfusion changes with age and gender in healthy adults.

A number of studies using single-photon emission tomography (SPET) have shown perfusion changes with age in several cortical and subcortical areas, which might distort the results of perfusion imaging studies of neuropsychiatric disorders. Technetium-99m labelled ethyl cysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO) are both used as markers of cerebral perfusion, but have different pharmacokinetics and retention patterns. The aim of this study was to determine whether age and gender effects on perfusion SPET differ depending on whether (99m)Tc-HMPAO or (99m)Tc-ECD is used. Forty-five subjects (20 male and 25 female, mean age 52.8+/-6.6 years) were assigned to (99m)Tc-HMPAO SPET (HMPAO group), and 39 subjects (24 male and 15 female, mean age 52.6+/-6.7 years) to (99m)Tc-ECD SPET (ECD group). SPET images were obtained about 10 min after intravenous injection of approximately 800 MBq (99m)Tc-HMPAO or (99m)Tc-ECD using the same SPET scanner. Three-dimensional volumetric magnetic resonance imaging was performed to as7sess morphological changes in the grey matter. All image processing and statistical analyses were performed using SPM99 software. An area in the right anterior frontal lobe showed an increase in perfusion with age only in the HMPAO group, whereas areas in the bilateral retrosplenial cortex showed decreases in perfusion with age only in the ECD group; neither group showed corresponding changes in the grey matter. The present study shows that different effects of age on perfusion are observed depending on whether (99m)Tc-HMPAO and (99m)Tc-ECD is used. This suggests that the results of perfusion SPET are differently confounded depending on the tracer used, and that perfusion SPET with these tracers has limitations when used in research on subtle perfusion changes.

Age Factors↗

PubMed2002

Regional differences in distribution volume of I-123 IMP in the human brain: effect on CBF calculated by ARG method.

OBJECTIVE: Two methods of quantitating cerebral blood flow (CBF) with iodine-123-labeled N-isopropyl-p-iodoamphetamine (I-123 IMP) and a two-compartment model had been proposed; one is the table look-up (TLU) method and the other is the autoradiographic (ARG) method. The TLU method provides values of the cerebral blood flow (CBF) values and distribution volume of I-123 IMP (Vd) independently. In the ARG method, a fixed Vd is applied for the entire brain to calculate CBF. Our purpose was to evaluate regional differences in Vd in the human brain, or possible effects of regional differences in Vd on CBF calculated by the ARG method. METHODS: In the present study, two SPECT scans were acquired from each of eight normal subjects (aged 44.0 +/- 16.7) at 40 min and 180 min of mid-scan-time after intravenous 1 min infusion of 111 MBq IMP. A single arterial blood sampling was performed 10 min after the IMP infusion. All images were anatomically normalized and analyzed with SPM99 and Matlab. We generated CBF and Vd images for each subject by the TLU method and evaluated differences in Vd among brain structures. We subsequently generated another set of CBF images by the ARG method and examined differences between CBF calculated by the TLU method and that by the ARG method. RESULTS: Significant main effects of subject and brain structure in Vd were observed (two-way ANOVA). Vd values were higher in the deep gray matter than in the cerebral cortical regions. Among the cerebral cortical regions, no significant difference in Vd was observed. In spite of the significant differences in Vd among the brain structures, the voxel-by-voxel analyses as well as the ROI analyses revealed no statistically significant difference between CBF calculated by the TLU method and that by the ARG method. CONCLUSIONS: Although regional differences in Vd were observed, the present results support the assumption that a fixed Vd does not cause significant error in the calculation of CBF by the ARG method.

Adult↗