Optimization of penalization function in Bayesian penalized likelihood reconstruction algorithm for [F]flutemetamol amyloid PET images.

Point-spread-function (PSF) correction is not recommended for amyloid PET images due to Gibbs artifacts. Q.Clear™, a Bayesian Penalized Likelihood (BPL) reconstruction method without incorporating PSF correction reduces these artifacts but degrades image contrast by our previous findings.

Development of a novel phantom for tau PET imaging.

Purpose: The cortical uptake of tau positron emission tomography (PET) tracers corresponds to the Braak stage and reflects the distribution and progression of tau neurofibrillary tangles. The present study aimed to develop and validate the basic performance of a novel tau PET phantom, as well as to establish standard test procedures and analytical methods.

Methods: The tau PET phantom consisted of a brain simulation section simulated medial temporal lobe region and resolution and uniformity sections.

Assessment of Gray Matter Microstructural Alterations in Alzheimer's Disease by Free Water Imaging.

Background: Cortical neurodegenerative processes may precede the emergence of disease symptoms in patients with Alzheimer's disease (AD) by many years. No study has evaluated the free water of patients with AD using gray matter-based spatial statistics.

Objective: The aim of this study was to explore cortical microstructural changes within the gray matter in AD by using free water imaging with gray matter-based spatial statistics.

Deep Learning-Driven Estimation of Centiloid Scales from Amyloid PET Images with C-PiB and F-Labeled Tracers in Alzheimer's Disease.

Background: Standard methods for deriving Centiloid scales from amyloid PET images are time-consuming and require considerable expert knowledge. We aimed to develop a deep learning method of automating Centiloid scale calculations from amyloid PET images with C-Pittsburgh Compound-B (PiB) tracer and assess its applicability to F-labeled tracers without retraining.

Methods: We trained models on 231 C-PiB amyloid PET images using a 50-layer 3D ResNet architecture.

Phantom and clinical evaluation of the Bayesian penalised likelihood reconstruction algorithm Q.Clear without PSF correction in amyloid PET images.

Purpose: Bayesian penalised likelihood (BPL) reconstruction, which incorporates point-spread-function (PSF) correction, provides higher signal-to-noise ratios and more accurate quantitation than conventional ordered subset expectation maximization (OSEM) reconstruction. However, applying PSF correction to brain PET imaging is controversial due to Gibbs artefacts that manifest as unpredicted cortical uptake enhancement. The present study aimed to validate whether BPL without PSF would be useful for amyloid PET imaging.

Improving image quality using the pause function combination to PROPELLER sequence in brain MRI: a phantom study.

While some MRI systems offer a "pause" function, combining it with the PROPELLER method for image quality improvement remains underexplored. This study investigated whether repositioning the head after pausing during PROPELLER imaging enhances image quality. All brain phantom images in this study were obtained using a 3.

Performance Characteristics of a New-Generation Digital Bismuth Germanium Oxide PET/CT System, Omni Legend 32, According to NEMA NU 2-2018 Standards.

The Omni Legend 32 PET/CT system features silicon photomultiplier (SiPM)-based detectors with bismuth germanium oxide crystals and a 32-cm axial field of view (FOV). The present study aimed to determine the performance characteristics of the Omni Legend 32 PET/CT system according to National Electrical Manufacturers Association (NEMA) NU 2-2018 standards. The PET component of this system comprises 22 detector modules; each module contains 24 detector blocks with 72 bismuth germanium oxide crystals with a volume of 4.

Impact of irregular waveforms on data-driven respiratory gated PET/CT images processed using MotionFree algorithm.

Objectives: MotionFree® (AMF) is a data-driven respiratory gating (DDG) algorithm for image processing that has recently been introduced into clinical practice. The present study aimed to verify the accuracy of respiratory waveform and the effects of normal and irregular respiratory motions using AMF with the DDG algorithm.

Methods: We used a NEMA IEC body phantom comprising six spheres (37-, 28-, 22-, 17-, 13-, and 10 mm diameter) containing F.

Tau positron emission tomography in patients with cognitive impairment and suspected Alzheimer's disease.

Alzheimer's disease (AD) is diagnosed by the presence of both amyloid β and tau proteins. Recent advances in molecular PET imaging have made it possible to assess the accumulation of these proteins in the living brain. PET ligands have been developed that bind to 3R/4R tau in AD, but not to 3R tau or 4R tau alone.

Toward standardization of tau PET imaging corresponding to various tau PET tracers: a multicenter phantom study.

Objective: Tau positron emission tomography (PET) imaging is a recently developed non-invasive tool that can detect the density and extension of tau neurofibrillary tangles. Tau PET tracers have been validated to harmonize and accelerate their development and implementation in clinical practice. Whereas standard protocols including injected dose, uptake time, and duration have been determined for tau PET tracers, reconstruction parameters have not been standardized.

Age and Sex-Related Effects on Single-Subject Gray Matter Networks in Healthy Participants.

Recent developments in image analysis have enabled an individual's brain network to be evaluated and brain age to be predicted from gray matter images. Our study aimed to investigate the effects of age and sex on single-subject gray matter networks using a large sample of healthy participants. We recruited 812 healthy individuals (59.

Generation of liver metastases in a mouse model using ultrasound-guided intravenous injection.

Here, we present a protocol to generate a murine model of liver metastasis by directly injecting tumor cells into the portal vein under ultrasound guidance. We describe steps for animal and cell preparation and two techniques for injecting tumor cells. One technique is freehand, while the other technique is device-assisted using a 3D-printed prototype device.

Impact of γ factor in the penalty function of Bayesian penalized likelihood reconstruction (Q.Clear) to achieve high-resolution PET images.

Background: The Bayesian penalized likelihood PET reconstruction (BPL) algorithm, Q.Clear (GE Healthcare), has recently been clinically applied to clinical image reconstruction. The BPL includes a relative difference penalty (RDP) as a penalty function.

Free water derived by multi-shell diffusion MRI reflects tau/neuroinflammatory pathology in Alzheimer's disease.

Introduction: Free-water (FW) imaging, a new analysis method for diffusion magnetic resonance imaging (MRI), can indicate neuroinflammation and degeneration. We evaluated FW in Alzheimer's disease (AD) using tau/inflammatory and amyloid positron emission tomography (PET).

Methods: Seventy-one participants underwent multi-shell diffusion MRI, F-THK5351 PET, C-Pittsburgh compound B PET, and neuropsychological assessments.

Effect of the Gant-Miwa-Thiersch Procedure for Rectal Prolapse on the Mesorectum.

Rectal prolapse (RP) most commonly occurs among elderly women and is caused by vulnerable suspensory tissue in the pelvis. In Japan, the Gant-Miwa-Thiersch procedure (GMT) is recommended for elderly people with poor general health. We retrospectively analyzed clinical data from 12 patients who underwent GMT at our hospital from September 2005 to July 2021 and investigated the effect of GMT on the mesorectum using abdominal-pelvic computed tomography (CT) performed for other diseases.

Evaluation of quantitative accuracy among different scatter corrections for quantitative bone SPECT/CT imaging.

Although scatter correction improves SPECT image contrast and thus image quality, the effects of quantitation accuracy under various conditions remain unclear. The present study aimed to empirically define the conditions for the optimal scatter correction of quantitative bone SPECT/CT images. Scatter correction was performed by applying dual and triple energy windows (DEW and TEW) with different sub-energy window widths, and effective scatter source estimation (ESSE) to CT-based scatter correction.

Determination of optimal regularization factor in Bayesian penalized likelihood reconstruction of brain PET images using [ F]FDG and [ C]PiB.

Purpose: The Bayesian penalized likelihood (BPL) reconstruction algorithm, Q.Clear, can achieve a higher signal-to-noise ratio on images and more accurate quantitation than ordered subset-expectation maximization (OSEM). The reconstruction parameter (β) in BPL requires optimization according to the radiopharmaceutical tracer.

Software development for quantitative analysis of brain amyloid PET.

Introduction: Centiloid (CL) scaling has become a standard quantitative measure in amyloid PET because it allows the direct comparison of results across sites, even when different analytical methods or PET tracers are used.

Methods: In the present study, we developed new standalone software to easily handle a pipeline for accurate calculation of the CL scale for the five currently available amyloid PET tracers- C-PiB, F-florbetapir, F-flutemetamol, F-florbetaben, and F-NAV4694. This pipeline requires reorientation and coregistration of PET and MRI, anatomic standardization of coregistered PET to a standardized space using a warping parameter for coregistered MRI, application of standard volumes of interest (VOIs) to the warped PET, calculation of the standardized uptake value ratio (SUVR) for the target VOIs, and finally conversion of the SUVR to the CL scale.

Efficacy of a newly developed bioabsorbable pancreatic clip for distal pancreatectomy in swine.

Purpose: At present, ≥ 20% of patients experience clinically relevant postoperative pancreatic fistula (POPF) after distal pancreatectomy (DP).

Methods: We developed a new bioabsorbable pancreatic clip (BioPaC) made of polycaprolactone that does not crush the pancreatic parenchyma during occlusion of the pancreatic stump. We confirmed the efficacy of this BioPac in a porcine DP model and compared it to a linear stapling device (Reinforce®).