The eagle-wing finding in FP-CIT SPECT, as a characteristic finding in patients with DESH- type iNPH.

Purpose: Although dopamine transporter (DAT) imaging has been reported to be useful for differentiating idiopathic Normal Pressure Hydrocephalus (iNPH) from its mimics, the radiological findings of DAT imaging in iNPH have not been established. We investigated [I] N-ω-fluoropropyl-2β-carboxymethoxy-3β-(4-iodophenyl) nortropane (FP-CIT) single photon emission computed tomography (SPECT) images from patients with disproportionately enlarged subarachnoid-space hydrocephalus (DESH)-type iNPH to understand the characteristics of DAT images of iNPH.

Methods: We retrospectively collected 11 DESH-type iNPH patients without comorbidities who underwent FP-CIT SPECT imaging.

Regional differences in glucose metabolic decline and tau deposition in the Alzheimer's continuum brain.

Background: Alzheimer's disease (AD) is characterized by the accumulation of amyloid-β and tau proteins, leading to neurofibrillary tangles. A biomarker-based diagnostic method called the ATN system categorizes AD pathology into amyloid-β (A), tau (T), and neurodegeneration (N). The relationship between regional tau deposition and reduced glucose metabolism in the preclinical AD stage is not well understood.

Crossover evaluation of time-of-flight-based attenuation correction in brain F-FDG and F-flutemetamol PET.

Background: Brain-dedicated positron emission tomography (PET) systems offer high spatial resolution and sensitivity for accurate clinical assessments. Attenuation correction (AC) is important in PET imaging, particularly in brain studies. This study assessed the reproducibility of attenuation maps (µ-maps) generated by a specialized time-of-flight (TOF) brain-dedicated PET system for imaging using different PET tracers.

Prediction of 1 cm dose-equivalent rate on the day after administration of Lu-DOTATATE from In-somatostatine receptor scintigraphy prior to treatment.

Objective: When patients administered Lu-DOTATATE are released or discharged from rooms where radiopharmaceuticals are used, the time required for release or discharge varies across patients. This study investigated whether the amount of radioactivity accumulated on In-somatostatine receptor scintigraphy (In-SRS) performed prior to treatment can predict the 1 cm dose-equivalent rate at a distance of 1 m from the patient on the day after Lu-DOTATATE administration.

Methods: Whole-body planar In-SRS images were acquired for 21 patients.

Generating PET Attenuation Maps via Sim2Real Deep Learning-Based Tissue Composition Estimation Combined with MLACF.

Deep learning (DL) has recently attracted attention for data processing in positron emission tomography (PET). Attenuation correction (AC) without computed tomography (CT) data is one of the interests. Here, we present, to our knowledge, the first attempt to generate an attenuation map of the human head via Sim2Real DL-based tissue composition estimation from model training using only the simulated PET dataset.

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.

Organ-Specific Positron Emission Tomography Scanners for Breast Imaging: Comparison between the Performances of Prior and Novel Models.

The performances of photomultiplier tube (PMT)-based dedicated breast positron emission tomography (PET) and silicon photomultiplier tube (SiPM)-based time-of-flight (TOF) PET, which is applicable not only to breast imaging but also to head imaging, were compared using a phantom study. A cylindrical phantom containing four spheres (3-10 mm in diameter) filled with F-FDG at two signal-to-background ratios (SBRs), 4:1 and 8:1, was scanned. The phantom images, which were reconstructed using three-dimensional list-mode dynamic row-action maximum likelihood algorithm with various β-values and post-smoothing filters, were visually and quantitatively compared.

Impact of respiratory gating and ECG gating on F-FDG PET/CT for cardiac sarcoidosis.

Background: The aim of this study was to estimate the impact of respiratory and electrocardiogram (ECG)-gated FDG positron emission tomography (PET)/computed tomography (CT) on the diagnosis of cardiac sarcoidosis (CS).

Methods And Results: Imaging from thirty-one patients was acquired on a PET/CT scanner equipped with a respiratory- and ECG-gating system. Non-gated PET images and three kinds of gated PET/CT images were created from identical list-mode clinical PET data: respiratory-gated PET during expiration (EX), ECG-gated PET at end diastole (ED), and ECG-gated PET at end systole (ES).

Visualization of tumor hypoxia and re-oxygenation after stereotactic body radiation therapy in early peripheral lung cancer: A prospective study.

Background And Purpose: In this study, fluoromisonidazole positron emission tomography (F-MISO PET/CT) was used to evaluate tumor hypoxia and re-oxygenation in patients with lung tumors treated with stereotactic body radiation therapy (SBRT).

Materials And Methods: Patients with T1-2 N0 lung cancer were included in this study. The prescribed dose was 48-52 Gy in four fractions.

[The Questionnaire Survey of Japanese Practice and Environment for Targeted Radionuclide Therapy in 2021].

Purpose: Recently, the targeted radionuclide therapy (TRT) was urgently required to adapt the practice and environment because of the implementation of novel therapeutic radiopharmaceuticals such as alpha- and beta- radionuclides therapy. The present study aimed to clarify the questionnaire survey with the current situation (safety controls for workers and patients) at Japanese TRT facilities.

Methods: The massive questionnaire survey, 2 months from October to November 2021, was conducted among nationwide 251 facilities that have performed TRT in the past two years.

Regional cerebral THK5351 accumulations correlate with neuropsychological test scores in Alzheimer continuum.

Objectives: We evaluated the relationship between regional accumulations of the tau positron emission tomography (PET) tracer THK5351 and cognitive dysfunction in the Alzheimer's disease (AD) continuum.

Methods: The cases of 18 patients with AD or mild cognitive impairment (MCI) due to AD who underwent three-dimensional MRI, fluoro-2-deoxyglucose (FDG)-(PET), Pittsburgh compound B (PiB)-amyloid PET, and THK5351-tau PET were analyzed. Their mean age was 70.

Evaluation of the performance of a high-resolution time-of-flight PET system dedicated to the head and breast according to NEMA NU 2-2012 standard.

Background: This study evaluated the physical performance of a positron emission tomography (PET) system dedicated to the head and breast according to the National Electrical Manufacturers Association (NEMA) NU2-2012 standard.

Methods: The spatial resolution, sensitivity, scatter fraction, count rate characteristics, corrections for count losses and randoms, and image quality of the system were determined. All measurements were performed according to the NEMA NU2-2012 acquisition protocols, but image quality was assessed using a brain-sized phantom.

The usefulness of the total metabolic tumor volume for predicting the postoperative recurrence of thoracic esophageal squamous cell carcinoma.

Background: Induction or adjuvant therapies are not always beneficial for thoracic esophageal squamous cell carcinoma (ESCC) patients, and it is thus important to identify patients at high risk for postoperative ESCC recurrence. We investigated the usefulness of the total metabolic tumor volume (TMTV) for predicting the postoperative recurrence of thoracic ESCC.

Methods: We retrospectively analyzed the cases of 163 thoracic ESCC patients (135 men, 28 women; median age of 66 [range 34-82] years) treated at our hospital in 2007-2012.

Attenuation correction for phantom tests: an alternative to maximum-likelihood attenuation correction factor-based correction for clinical studies in time-of-flight PET.

Objectives: This study evaluates the phantom attenuation correction (PAC) method as an alternative to maximum-likelihood attenuation correction factor (ML-ACF) correction in time-of-flight (TOF) brain positron emission tomography (PET) studies.

Methods: In the PAC algorithm, a template emission image [Formula: see text] and a template attenuation coefficient image [Formula: see text] are prepared as a data set based on phantom geometry. Position-aligned attenuation coefficient image [Formula: see text] is derived by aligning [Formula: see text] using parameters that match the template emission image [Formula: see text] to measured emission image [Formula: see text].

Automatic detection of primary and metastatic lesions on cervicothoracic region and whole-body bone using a uniform machine-learnable approach for [18F]-FDG-PET/CT image analysis.

We propose a method to detect primary and metastatic lesions with Fluorine-18 fluorodeoxyglucose (FDG) accumulation in the lung field, neck, mediastinum, and bony regions on the FDG-PET/CT images. To search for systemic lesions, various anatomical structures must be considered. The proposed method is addressed by using an extraction process for anatomical regions and a uniform lesion detection approach.

High-Resolution Silicon Photomultiplier Time-of-Flight Dedicated Head PET System for Clinical Brain Studies.

We acquired brain F-FDG and F-flutemetamol PET images using a time-of-flight system dedicated to the head (dhPET) and a conventional whole-body PET/CT (wbPET) system and evaluated the clinical superiority of dhPET over wbPET. There were 18 subjects for the F-FDG PET study and 17 subjects for the F-flutemetamol PET study. F-FDG PET images were first obtained using wbPET, followed by dhPET.

High 11 C-Methionine Uptake in a Parasellar Inflammatory Pseudotumor.

A 20-year-old man had left visual impairment and homonymous hemianopsia. MRI findings suggested enlargement of an optic glioma, because optic glioma was indicated by MRI 14 years earlier without a definite pathological diagnosis. 11 C-methionine (MET) PET showed high uptake in the tumor in the parasellar region.

Initial evaluation of a new maximum-likelihood attenuation correction factor-based attenuation correction for time-of-flight brain PET.

Aim: The aim of this study was to evaluate an image reconstruction algorithm, including a new maximum-likelihood attenuation correction factor (ML-ACF) for time of flight (TOF) brain positron emission tomography (PET).

Methods: The implemented algorithm combines an ML-ACF method that simultaneously estimates both the emission image and attenuation sinogram from TOF emission data, and a scaling method based on anatomical features. To evaluate the algorithm's quantitative accuracy, three-dimensional brain phantom images were acquired and soft-tissue attenuation coefficients and emission values were analyzed.

Application of correlated component analysis to dynamic PET time-activity curves denoising.

Positron emission tomography (PET) is a physiological, non-invasive imaging technique, which forms an essential part of nuclear medicine. The data obtained in a PET scan represent the concentration of an administered radiotracer in tissues over time. Quantitative analysis of PET data makes possible the assessments of in-vivo physiological processes.

Usefulness of respiratory-gated PET acquisition during delayed F-FDG PET/CT scanning for patients with liver metastases.

Objectives: To assess respiratory-gated (RG) positron emission tomography (PET) acquisition for patients with liver metastases during delayed PET/computed tomography (CT) scanning with fluorine-18-fluorodeoxyglucose (F-FDG).

Methods: Nineteen patients with liver metastases who had undergone early whole-body F-FDG PET/CT scans without the RG technique and delayed scans with the RG technique were retrospectively selected. The maximum standardized uptake value (SUV) of 41 liver lesions and the tumor-to-liver uptake ratios (TLRs) for these same lesions were compared among three data sets: early non-respiratory-gated (early non-RG) images, delayed non-respiratory-gated (delayed non-RG) images, and delayed respiratory-gated (delayed RG) images.

Improving contrast between gray and white matter of Logan graphical analysis' parametric images in positron emission tomography through least-squares cubic regression and principal component analysis.

Logan graphical analysis (LGA) is a method forquantification of tracer kinetics in positron emission tomography (PET). The shortcoming of LGA is the presence of a negative bias in the estimated parameters for noisy data. Various approaches have been proposed to address this issue.

Quantitative Evaluation of F-Flutemetamol PET in Patients With Cognitive Impairment and Suspected Alzheimer's Disease: A Multicenter Study.

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. We aimed to determine cutoffs for positivity in quantitative analysis of F-flutemetamol PET in patients with cognitive impairment and suspected Alzheimer's disease (AD).