Masashi Kameyama

Tokyo Metropolitan Institute for Geriatrics and Gerontology

Background The method of obtaining pseudo‐cerebral blood flow images from the initial minutes of amyloid PET scans has been proposed. This technique proves to be highly valuable as it not only indicates the presence of amyloid accumulation but also reveals sites of neurodegeneration. However, the obtained early images represent the K1 image rather...

Background The method of obtaining pseudo‐cerebral blood flow images from the initial minutes of amyloid PET scans has been proposed. This technique proves to be highly valuable as it not only indicates the presence of amyloid accumulation but also reveals sites of neurodegeneration. However, the obtained early images represent the K1 image rather...

We present a patient with type 2 diabetes mellitus and a variant hemoglobin whose HbA1c levels were falsely elevated regardless of the measurement method [high-performance liquid chromatography (HPLC), enzymatic, and immuno-assay] used. The causes of the falsely high HbA1c levels in this patient were investigated. The patient was a 73-year-old man...

Although α-synuclein seed amplification assays (α-syn SAA) are promising, its sensitivity may be affected by heterogeneity among patients with Lewy body disease (LBD). We evaluated whether α-syn SAA sensitivity is affected by patient heterogeneity, using ¹²³ I-meta-iodobenzylguanidine (MIBG) cardiac scintigraphy in early drug-naïve patients. Thirty...

Currently, monoamine oxidase B is recognized as the primary target of ¹⁸ F-THK5351, although ¹⁸ F-THK5351 was initially developed to target neurofibrillary tangles (NFTs) in Alzheimer disease. When clinically applying ¹⁸ F-THK5351 PET to visualize ongoing astrogliosis via estimating monoamine oxidase B levels, a crucial concern is how much degree ¹...

Argyrophilic grain disease (AGD) is one of the major pathological backgrounds of senile dementia. Dementia with grains refers to cases of dementia for which AGD is the sole background pathology responsible for dementia. Recent studies have suggested an association between dementia with grains and parkinsonism. In this study, we aimed to present two...

Background. Although patients can present with progressive pseudobulbar palsy due to neurodegenerative diseases, detection of the precise location of radiological abnormalities can be difficult. 18F-THK5351 was initially developed as a tau positron emission tomography (PET) tracer. Later, it was found to sensitively detect astrogliosis associated w...

Background Patients tend to lose the ability to smile during the clinical course of dementia. However, details of such impairment remain obscure presumably due to difficulty of quantifying facial expression. Feature extraction is now automated as a result of recent developments in artificial intelligence (AI). The authors applied a model to quantif...

The recent evolution of artificial intelligence (AI) can be considered life‐changing. In particular, there is great interest in emerging hot topics in AI such as image classification and natural language processing. Our world has been revolutionized by convolutional neural networks and transformer for image classification and natural language proce...

Background Hemoglobin A1c (HbA1c) levels are low in patients with hemolytic anemia, as HbA1c reflects mean erythrocyte age (MRBC). Erythrocyte creatine (EC) is a hemolytic indicator that also reflects MRBC. We previously reported an equation for estimating MRBC using EC (EC‐MRBC). Aims In this study, EC‐MRBC was compared to the HbA1c level express...

Corticobasal syndrome (CBS) is characterized by symptoms related to the asymmetric involvement of the cerebral cortex and basal ganglia. However, early detection of asymmetric imaging abnormalities can be challenging. Previous studies reported asymmetric ¹⁸F-THK5351 PET abnormalities in CBS patients, but the sensitivity for detecting such abnormali...

Background Centiloid Scale (CL) was developed to standardize the quantitative results of amyloid beta (Aβ) positron emission tomography (PET). CL can allow not only categorization of the binary results of amyloid PET as positive or negative, but also parametric weighting within each category. To date, several neuropathological studies evaluated the...

Both cerebrospinal fluid (CSF) homovanillic acid (HVA) and striatal dopamine transporter (DAT) binding on single-photon emission computed tomography (SPECT) reflect nigrostriatal dopaminergic function, but studies on the relationship between the two have been limited. It is also unknown whether the reported variance in striatal DAT binding among di...

We have demonstrated that Cognitive function has a stronger correlation with perceived age than with chronological age (Umeda‐Kameyama et al. 2020). Based on this study, we hypothesized that cognitive decline appears in one's face, and have demonstrated the possibility of artificial intelligence to detect cognitive decline using a facial photograph...

Purpose In Lewy body diseases (LBD), various symptoms occur depending on the distribution of Lewy body in the brain, and the findings of brain perfusion and dopamine transporter single-photon emission computed tomography (DAT-SPECT) also change accordingly. We aimed to evaluate the correlation between brain perfusion SPECT and quantitative indices...

Objectives Whereas HbA1c values are known to be low relative to glycemia in patients with hemolytic anemia, including compensatory anemia, low HbA1c levels along with negative results for conventional hemolysis indicators have been reported in patients with latent hemolysis. Conversely, glycated albumin (GA) is a glycemic control indicator unaffect...

Background and Objectives ¹²³ I-meta-iodobenzyl-guanidine ( ¹²³ I-MIBG) myocardial scintigraphy is employed as a diagnostic imaging test to differentiate Lewy body diseases (LBDs), including Parkinson’s disease and dementia with Lewy bodies, from other similar diseases. However, its diagnostic accuracy lacks validation compared with that of the gol...

Shortening the amount of time required to acquire amyloid positron emission tomography (PET) brain images while maintaining the accuracy of quantitative evaluation would help to overcome motion artifacts associated with Alzheimer's disease patients. The present study aimed to validate the quantitative accuracy of [18F]florbetapir ([18F]FBP) imaging...

Objective The γ-Ray Evaluation with iodoamphetamine for Cerebral Blood Flow Assessment (REICA) is a new method for quantifying cerebral blood flow (CBF) using single-photon emission computed tomography (SPECT) and [ ¹²³ I] N -isopropyl- p -iodoamphetamine ( ¹²³ I-IMP). The present study aimed to validate the REICA method using data including acetaz...

Cerebral blood flow (CBF) / cerebral blood volume (CBV) ratio derived by [¹⁵O] H2O/ CO2 and CO positron emission tomography (PET) examination has been used as an index for cerebral perfusion pressure (CPP). CBF/CBV was demonstrated to be related mean arterial pressure (MAP) in baboons. However, this formula has not been confirmed to be proportionat...

Introduction: With an aging population, valvular heart disease (VHD) of a degenerative etiology has been increasing. Although calcification of valves and mitral annulus (MAC) increase in the elderly, these calcification lesions are considered as one of the causes of embolic stroke of undetermined source (ESUS). On the other hand, it is difficult to...

Cerebral blood flow (CBF) / cerebral blood volume (CBV) ratio derived by [ ¹⁵ O] H 2 O/ CO 2 and CO positron emission tomography (PET) examination has been used empirically as an index for cerebral perfusion pressure (CPP). However, this equation lacks a theoretical basis and furthermore, has not been confirmed to be proportionate to CPP, as direct...

Purpose We aimed to evaluate the diagnostic performances of quantitative indices obtained from dopamine transporter (DAT) single-photon emission computed tomography (SPECT) and ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy for Parkinsonian syndromes (PS) using the classification and regression tree (CART) analysis. Methods We retrospectively en...

Background and Purpose Little evidence exists on the role of type 1 metabotropic glutamate receptor (mGluR1) in the pathophysiology of Alzheimer's disease (AD), although mGluR1 may be involved in the regulation of neuronal excitability and synaptic plasticity. We have recently reported that mGluR1 availability in the early stage of AD is equivalent...

Despite the increasing incidence and high morbidity associated with dementia, a simple, non-invasive, and inexpensive method of screening for dementia is yet to be discovered. This study aimed to examine whether artificial intelligence (AI) could distinguish between the faces of people with cognitive impairment and those without dementia.121 patien...

Background: In clinical practice, equivocal findings are inevitable in visual interpretation of whether amyloid positron emission tomography (PET) is positive or negative. It is therefore necessary to establish a more objective quantitative evaluation method for determining the indication for disease-modifying drugs currently under development. Aim...

In a previous study, a method of obtaining mean erythrocyte age ( $$M_{RBC}$$ M RBC ) from HbA1c and average plasma glucose (AG) was proposed. However, the true value of the hemoglobin glycation constant ( $$k_g$$ k g dL/mg/day), required for this model has yet to be well characterized. Another study also proposed a method of deriving $$M_{RBC}$$ M...

Background The perceived age of older adults, as measured by their facial appearances, has been demonstrated to be a robust biomarker of aging predictive of survival, telomere length, and DNA methylation and reportedly correlates with carotid atherosclerosis and bone status. This study aims to determine whether metrics of dementia, including genera...

Objective: The aim of this multicenter prospective study was to compare the sensitivity of 18F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) with that of 67Ga single photon emission computed tomography (SPECT) for the identification of the site of greatest importance for the final diagnosis of the cause of feve...

Voxel-based morphometry (VBM) analysis of nuclear Magnetic Resonance Imaging (MRI) data allows the identification of medial temporal lobe (MTL) atrophy and is widely used to assist the diagnosis of Alzheimer's disease (AD). However, its reliability in the clinical environment has not yet been confirmed. To determine the credibility of VBM, amyloid...

Background Visual snow syndrome (VSS) is a neurological condition characterized by persistent flickering dots in the visual fields, palinopsia, enhanced entoptic phenomenon, photophobia, and nyctalopia. Neuroimaging evidence supports the role of the visual association cortex in visual snow syndrome. Case series: We provided clinical care to three p...

Objective The \(\gamma\)-Ray Evaluation with Iodoamphetamine for Cerebral blood flow Assessment (REICA) method is a new method for cerebral blood flow (CBF) quantification with SPECT and [123I] IMP, which does not require invasive arterial blood sampling, or the use of a regression formula. Moreover, it takes into consideration tracer retention, wh...

Three patients with neurological disorders (cerebral infarction, progressive multifocal leukoencephalopathy, and multiple sclerosis) underwent F-THK5351 and C-L-deprenyl PET on the same day to visualize lesions undergoing astrogliosis by measuring MAO-B activity. BPND map and SUV image with F-THK5351 as well as Ki map, Ki/K1 map and SUV image with...

Aim The perceived age of older adults, as measured by their facial appearance, has been shown to be a robust biomarker of aging predictive of survival, telomere length and DNA methylation, and reportedly correlates with carotid atherosclerosis and bone status. This study aimed to determine whether metrics of dementia, including general cognition, v...

Background To differentiate dementia with Lewy bodies (DLB) from Alzheimer disease (AD) using a single imaging modality is challenging, because of their common hypometabolic findings. Scaled subprofile modeling/principal component analysis (SSM/PCA), an unsupervised artificial intelligence, has the potential to offer an alternative to image analysi...

Estimating the lifespan of erythrocytes is useful for the differential diagnosis of anemia. However, measuring the lifespan of erythrocytes was very difficult; therefore, it was seldom measured. Erythrocyte creatine (EC) decreases reflecting erythrocyte age. We developed a method to obtain mean erythrocyte age (MRBC) from EC.We reanalyzed the previ...

Abstract Background A cerebrospinal fluid (CSF)-mask algorithm has been developed to reduce the adverse influence of CSF-low-counts on the diagnostic utility of the specific binding ratio (SBR) index calculated with Southampton method. We assessed the effect of the CSF-mask algorithm on the diagnostic performance of the SBR index for parkinsonian s...

Objective Many studies have demonstrated the superiority of white matter (WM) reference regions (RR) in amyloid PET studies in comparison to cerebellar RR. However, the principle behind its improved measurement stability is yet to be elucidated. Our study aimed to determine the origin of WM stability; stability over cerebral blood flow and input fu...

The differentiation of dementia with Lewy bodies (DLB) from Alzheimer’s disease (AD) using brain perfusion single photon emission tomography is important but is challenging because these conditions exhibit typical features. The cingulate island sign (CIS) is the most recently identified specific feature of DLB for a differential diagnosis. The curr...

Aim: In a previous study, a method of obtaining mean erythrocyte age (MRBC) from HbA1c and average plasma glucose (AG) was proposed. However, the true value of the hemoglobin glycation constant (kg dL/mg/day), required for this model has yet to be well characterized. Another study also proposed a method of deriving MRBC from erythrocyte creatine (E...

Backgrounds: Erythrocyte creatine (EC) decreases reflecting erythrocyte age. Methods: We developed an EC model, which showed a bi- or mono-exponential relationship between mean erythrocyte age (MRBC) and EC. We reanalyzed the previously published data of 21 patients with hemolytic anemia which included EC and 51Cr half-life. Results: MRBC and loge...

The differentiation of dementia with Lewy bodies (DLB) from Alzheimer’s disease (AD) using brain perfusion single photon emission tomography is important but has been a challenge because these conditions have common features. The cingulate island sign (CIS) is the most recently identified specific feature of DLB for a differential diagnosis. The pr...

Background: We sought to assess the machine learning-based combined diagnostic accuracy of three types of quantitative indices obtained using dopamine transporter single-photon emission computed tomography (DAT SPECT)-specific binding ratio (SBR), putamen-to-caudate ratio (PCR)/fractal dimension (FD), and asymmetry index (AI)-for parkinsonian synd...

Background Subjective cognitive decline (SCD) may herald the first symptoms of Alzheimer's disease (AD) whereas individuals with beta‐amyloid (Aβ) deposition are regarded as a high‐risk group for AD. Recently, amyloid positron emission tomography (PET) studies have demonstrated clinical and cognitive feature differences between Aβ‐positive and nega...

Mucin-producing urothelial-type adenocarcinoma of the prostate (MPUAP) is a rare, aggressive neoplasm thought to originate from the prostatic urethral urothelium. Our case is the first reported to show significantly increased serum levels of carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 in MPUAP. An autopsy revealed occult MPUAP...

Objective: [[Formula: see text]] N-isopropyl-p-iodoamphetamine ([Formula: see text]-IMP) is an ideal perfusion tracer for single photon emission computed tomography, which shows good linearity between cerebral blood flow (CBF) and accumulation. However, quantification of CBF using [Formula: see text]-IMP without arterial blood sampling has been ch...

PurposeQuantification of the tracer distribution would add objectivity to the visual assessments of dopamine transporter (DAT) single photon emission computed tomography (SPECT) data. Our study aimed to evaluate the diagnostic utility of fractal dimension (FD) as a quantitative indicator of tracer distribution and compared with the conventional qua...

HbA1c is used to estimate average glucose. Previous studies showed linear relationship between average glucose and HbA1c. We made a new theoretical relationship using recently proposed Γ-like function model of erythrocyte lifespan. We showed the relationship between average glucose and HbA1c; we approximated it into a simple hyperbolic function: Hb...

The cingulate island sign (CIS) that reflects sparing of the posterior cingulate cortex (PCC) relative to the precuneus plus cuneus on FDG-PET and brain perfusion SPECT, has been proposed as a feature of dementia with Lewy bodies (DLB). As the CIS is influenced by concomitant Alzheimer’s disease (AD)-type neurofibrillary tangle (NFT) pathology, we...

In Japan, 4.6 million people are living with dementia and the number is expected to rise to 7 million by 2025. Amyloid-β (Aβ) positron emission tomography (PET) is used for cognitively normal Japanese people with or without subjective cognitive decline (SCD) for the purpose of clinical trials or diagnosis. Nevertheless, no empirical studies have be...

A 41-year-old man underwent F-THK5351 PET 2 years after a right middle cerebral artery infarction. F-THK5351 PET imaging revealed intense radioligand uptake along the ipsilateral pyramidal tract from the corona radiata to the medulla; intense uptake changed from the right side to the left side with descending axial sections at the level of the pyra...

Purpose This study aimed to determine whether the SiPM-PET/CT, Discovery MI (DMI) performs better than the PMT-PET/CT system, Discovery 710 (D710). Methods The physical performance of both systems was evaluated using NEMA NU 2 standards. Contrast (%), uniformity and image noise (%) are criteria proposed by the Japanese Society of Nuclear Medicine...

The neural substrate of memory-deficit awareness has been studied in mild cognitive impairment and Alzheimer's disease (AD). However, little is known about that in dementia with Lewy bodies (DLB). To determine the neural substrates of memory-deficit awareness in DLB, we investigated the relationship between awareness of memory-deficit and glucose m...

Alzheimer’s disease (AD) patients exhibit olfactory dysfunction. However, the olfactory declineti precise nature is not fully understood. One hundred patients (60 AD, 28 amnestic mild cognitive impairment (aMCI), 12 Normal) were enrolled. All participants underwent olfactory function testing using an odour stick identification test for Japanese (OS...