Publications by authors named "Yasuhiko Ikari"

The Alzheimer disease (AD) continuum is a neurodegenerative disorder with cognitive decline and pathologic changes. Tau PET imaging can detect tau pathology, and F-flortaucipir PET imaging is expected to visualize progression through the stages of AD, for which quantitative assessment is essential. Two measurement methods, statistically defined multiblock barycentric discriminant analysis (MUBADA)/parametric estimation of reference signal intensity (PERSI) and anatomically defined tau meta-volume of interest (VOI)/cerebellar gray matter (CGM) for SUV ratio (SUVR), were compared in this study to assess their relationship to AD clinical stage using 2 open multicenter PET databases.

View Article and Find Full Text PDF

Purpose: This study aimed to identify disposable items with low amyloid positron emission tomography (PET) agent radioactivity adsorption for accurate injections using a radiopharmaceutical activity supplier.

Methods: First, we investigated disposable items currently used for amyloid PET agent injection. Next, we measured the residual radioactivity rates of amyloid PET agents on three-way stopcocks, extension tubes, butterfly needles, and indwelling needles to identify disposable items with low radioactivity adsorption.

View Article and Find Full Text PDF

Objective: A new tau PET tracer [F]MK-6240 has been developed; however, its dosimetry and pharmacokinetics have been published only for a European population. This study investigated the safety, radiation dosimetry, pharmacokinetics and biodistribution of [F]MK-6240 in Japanese elderly subjects. Also, the pattern and extent of brain retention of [F]MK-6240 in Japanese healthy elderly subjects and patients with Alzheimer's disease (AD) were investigated.

View Article and Find Full Text PDF

The pharmacokinetics of telmisartan are nonlinear within the clinical dose range. To identify the underlying mechanism of this nonlinearity, we conducted a PET study in healthy subjects using [C]telmisartan. Eight healthy male subjects were enrolled in a 2-way crossover study.

View Article and Find Full Text PDF

Background: Amyloid PET plays a vital role in detecting the accumulation of in vivo amyloid-β (Aβ). The quantification of Aβ accumulation has been widely performed using the region of interest (ROI)-based mean cortical standardized uptake value ratio (mcSUVR). However, voxel-based statistical analysis has not been well studied.

View Article and Find Full Text PDF

Dynamic C-PiB PET imaging with kinetic analysis has been performed for accurate quantification of amyloid binding in patients with Alzheimer's disease (AD). In this study, we measured the whole-body biodistribution of C-PiB in nine subjects. We then evaluated the effect of body activity on quantitative accuracy of brain C-PiB three-dimensional (3D) dynamic PET.

View Article and Find Full Text PDF

Brain imaging techniques, such as computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET), can provide essential and objective information for the early and differential diagnosis of dementia. Amyloid PET is especially useful to evaluate the amyloid-β pathological process as a biomarker of Alzheimer's disease. This article reviews critical points about technical considerations on the scanning and image analysis methods for amyloid PET.

View Article and Find Full Text PDF

Purpose: The aim of this study was to assess the inter-rater variability of the visual interpretation of C-PiB PET images regarding the positivity/negativity of amyloid deposition that were obtained in a multicenter clinical research project, Japanese Alzheimer's Disease Neuroimaging Initiative (J-ADNI). The results of visual interpretation were also compared with a semi-automatic quantitative analysis using mean cortical standardized uptake value ratio to the cerebellar cortex (mcSUVR).

Methods: A total of 162 C-PiB PET scans, including 45 mild Alzheimer's disease, 60 mild cognitive impairment, and 57 normal cognitive control cases that had been acquired as J-ADNI baseline scans were analyzed.

View Article and Find Full Text PDF

Objective: With the advent of regenerative/cell therapy for Parkinson's disease (PD), F-FDOPA has drawn new attention as a biomarker of the therapeutic that cannot be evaluated with radiopharmaceuticals for dopamine transporter. Since most previous F-FDOPA PET studies were carried out many years ago with a PET scanner of lower resolution and with F-FDOPA of low specific activity synthesized from F-F, we used a newer PET/CT scanner with a high-resolution condition and F-FDOPA synthesized from F-F to re-evaluate this technique on normal subjects and patients with PD, together with D receptor imaging with C-raclopride (RAC).

Methods: PET scans were carried out with F-FDOPA for 120 min and with C-RAC for 60 min on 10 patients clinically diagnosed with PD and on 10 normal control subjects.

View Article and Find Full Text PDF

Background: While fluorodeoxyglucose (FDG) and amyloid PET is valuable for patient management, research, and clinical trial of therapeutics on Alzheimer's disease, the specific details of the PET scanning method including the PET camera model type influence the image quality, which may further affect the interpretation of images and quantitative capabilities. To make multicenter PET data reliable and to establish PET scanning as a universal diagnostic technique and a verified biomarker, we have proposed phantom test procedures and criteria for optimizing image quality across different PET cameras.

Results: As the method, four physical parameters (resolution, gray-white contrast, uniformity, and image noise) were selected as essential to image quality for brain FDG and amyloid PET and were measured with a Hoffman 3D brain phantom and a uniform cylindrical phantom on a total of 12 currently used PET models.

View Article and Find Full Text PDF

Introduction: Neuroinflammatory processes play an important role in the pathogenesis of Alzheimer's disease (AD). As a biomarker of neuroinflammatory processes, we designed (11)C-labeled ketoprofen methyl ester ([(11)C]KTP-Me) to increase the blood-brain barrier permeability of ketoprofen (KTP), a selective cyclooxygenase-1 (COX-1) inhibitor. Animal studies indicated that [(11)C]KTP-Me enters the brain and accumulates in activated microglia of inflammatory lesions.

View Article and Find Full Text PDF

Standardized uptake value (SUV) has been widely used as a semi-quantitative metric of uptake in FDGPET/ CT for diagnosis of malignant tumors and evaluation of tumor therapies. However, the SUV depends on various factors including PET/CT scanner specifications and reconstruction parameters. The purpose of this study is to harmonize the SUV among two PET/CT models of different generation: two units of Discovery ST Elite Performance(DSTEP) and Discovery 690 (D690) PET/CT scanners.

View Article and Find Full Text PDF

Objectives: The purpose of this study was to optimize image reconstruction conditions for brain (18)F-FDG, (11)C-PiB, (18)F-florbetapir and (18)F-flutemetamol PET imaging with Discovery-690 PET/CT for diagnosis and research on Alzheimer's disease (AD) based on the standard imaging protocols and phantom test procedures and criteria published by the Japanese society of nuclear medicine (JSNM).

Methods: A Hoffman 3D brain phantom and a cylindrical pool phantom were scanned according to the JSNM procedure, and the reconstruction conditions (iteration, subset, post-filter) were optimized so that the images satisfy the JSNM criteria regarding spatial resolution (FWHM ≤ 8 mm) and gray/white matter contrast (%contrast ≥ 55%) on the Hoffman phantom and uniformity (SD of small ROIs ≤ 0.0249) and image noise (coefficient of variation ≤ 15 %) on the pool phantom.

View Article and Find Full Text PDF

Unlabelled: Standardized uptake values (SUVs) have been widely used in the diagnosis of malignant tumors and in clinical trials of tumor therapies as semiquantitative metrics of tumor (18)F-FDG uptake. However, SUVs for small lesions are liable to errors due to partial-volume effect and statistical noise. The purpose of this study was to evaluate the reproducibility and accuracy of maximum and peak SUV (SUVmax and SUVpeak, respectively) of small lesions in phantom experiments.

View Article and Find Full Text PDF

This synopsis outlines the Japanese guideline Version 2.0 for the data acquisition protocol of oncology FDG-PET/CT scans that was created by a joint task force of the Japanese Society of Nuclear Medicine Technology, the Japanese Society of Nuclear Medicine and the Japanese Council of PET Imaging, and was published in Kakuigaku-Gijutsu 2013; 33:377-420 in Japanese. The guideline aims at standardizing the PET image quality among PET centers and different PET camera models by providing criteria for the IEC body phantom image quality as well as for the patient PET image quality based on the noise equivalent count (NEC), NEC density and liver signal-to-noise ratio, so that the appropriate scanning parameters can be determined for each PET camera.

View Article and Find Full Text PDF

Introduction: Neuroinflammatory processes play an important role in the pathogenesis of Alzheimer's disease and other brain disorders, and nonsteroidal anti-inflammatory drugs (NSAIDs) are considered therapeutic candidates. As a biomarker of neuroinflammatory processes, (11)C-labeled ketoprofen methyl ester ([(11)C]KTP-Me) was designed to allow cerebral penetration of ketoprofen (KTP), an active form of a selective cyclooxygenase-1 inhibitor that acts as an NSAID. Rat neuroinflammation models indicate that [(11)C]KTP-Me enters the brain and is retained in inflammatory lesions, accumulating in activated microglia.

View Article and Find Full Text PDF

Objective: To determine the optimal accumulation time for three-dimensional positron emission tomography (3D-PET) with (18)F-2-fluoro-2-deoxy-D-glucose ((18)F-FDG) to detect the brain uptake pattern typical of Alzheimer's disease (AD).

Methods: Patients with mild AD or amnestic mild cognitive impairment (MCI) and normal control subjects were recruited in the Japanese Alzheimer's disease neuroimaging initiative and examined with a PET scan during the 30-60 min after FDG injection. Three independent blinded experts interpreted the 30- to 60-min sum images, and images of patients with AD and MCI presenting AD patterns and normal subjects presenting normal patterns were used in the analysis.

View Article and Find Full Text PDF

Objective: Head motion during 30-min (six 5-min frames) brain PET scans starting 30 min post-injection of FDG was evaluated together with the effect of post hoc motion correction between frames in J-ADNI multicenter study carried out in 24 PET centers on a total of 172 subjects consisting of 81 normal subjects, 55 mild cognitive impairment (MCI) and 36 mild Alzheimer's disease (AD) patients.

Methods: Based on the magnitude of the between-frame co-registration parameters, the scans were classified into six levels (A-F) of motion degree. The effect of motion and its correction was evaluated using between-frame variation of the regional FDG uptake values on ROIs placed over cerebral cortical areas.

View Article and Find Full Text PDF

This synopsis outlines the Japanese guideline Version 1.0 for the data acquisition protocol of oncology FDG-PET/CT scans that was created by a joint task force of the Japanese Society of Nuclear Medicine Technology (JSNMT) and the Japanese Council of PET Imaging, and published in Kakuigaku-Gijutsu 29(2):195-235, 2009, in Japanese. The guideline aims at standardizing the PET image quality among facilities and different PET/CT scanner models by determining and/or evaluating the data acquisition condition in experiments using an IEC body phantom, as well as by proposing the criteria for human image quality evaluation using patient noise equivalent count (NEC), NEC density, and liver signal-to-noise ratio.

View Article and Find Full Text PDF

Unlabelled: Some antihistamine drugs that are used for rhinitis and pollinosis have a sedative effect as they enter the brain and block the H(1) receptor, potentially causing serious accidents. Receptor occupancy has been measured with PET under single-dose administration in humans to classify antihistamines as more sedating or as less sedating (or nonsedating). In this study, the effect of repeated administration of olopatadine, an antihistamine, on the cerebral H(1) receptor was measured with PET.

View Article and Find Full Text PDF

A PHP Error was encountered

Severity: Warning

Message: fopen(/var/lib/php/sessions/ci_sessionffl3cdjoumlpfisirvjgal3dod67tnct): Failed to open stream: No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 177

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: session_start(): Failed to read session data: user (path: /var/lib/php/sessions)

Filename: Session/Session.php

Line Number: 137

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once