Quantitative assessment of kidney split function and mean transit time in healthy patients using dynamic F-FDG PET/MRI studies with denoising and deconvolution methods making use of Legendre polynomials.

Purpose: Our objective was to assess a deconvolution and denoising technique based on Legendre polynomials compared to matrix deconvolution on dynamic F-FDG renography of healthy patients.

Method: The study was carried out and compared to the data of 24 healthy patients from a published study who underwent examinations with Tc-MAG3 planar scintigraphy and F-FDG PET/MRI. Due to corruption issues in some data used in the published article, post-publication measurements were provided.

Characterization of Pt-coated twin paraboloidal laboratory capillary high energy X-ray optics.

Novel focusing optics composed of twin paraboloidal capillaries coated with Pt, for laboratory X-ray sources are presented and characterized. The optics are designed to focus the X-rays, resulting in an achromatic focused beam with photon energies up to 40 keV. The performance of the optics under different operational conditions is studied by comparing the energy-photon count spectra of the direct and focused beams.

Indexing of superimposed Laue diffraction patterns using a dictionary-branch-bound approach.

X-ray Laue diffraction is an important method for characterizing the local crystallographic orientation and elastic strain in polycrystalline materials. Existing analysis methods are designed mainly to index a single or a few Laue diffraction pattern(s) recorded in a detector image. In this work, a novel method called dictionary-branch-bound (DBB) is presented to determine the crystallographic orientations of multiple crystals simultaneously illuminated by a parallel X-ray incident beam, using only the spot positions in a detector image.

Deconvolution of Tc-99m-Mercaptoacetyltriglycine Renograms with the Concomitant Use of a Sparse Legendre Polynomial Representation and the Moore-Penrose Pseudo-inverse.

Objectives: This study aimed to introduce an improved deconvolution technique for Tc-99m-mercaptoacetyltriglycine renograms based on the combination of a sparse Legendre polynomial representation and the Moore-Penrose inversion matrix (LG). This method reduces the effect of noise on the measurement of renal retention function transit time (TT).

Methods: The stability and accuracy of the proposed method were tested using a renal database containing Monte Carlo-simulated studies and real adult patient data.

In vivo exploration of synaptic projections in frontotemporal dementia.

The purpose of this exploratory research is to provide data on synaptopathy in the behavioral variant of frontotemporal dementia (bvFTD). Twelve patients with probable bvFTD were compared to 12 control participants and 12 patients with Alzheimer's disease (AD). Loss of synaptic projections was assessed with [F]UCBH-PET.

A parametric study of occupational radiation dose in interventional radiology by Monte-Carlo simulations.

This paper presents the results of a parametric study on the occupational exposure in interventional radiology to explore the influence of various variables on the staff doses. These variables include the angiography beam settings: x-ray peak voltage (kVp), added copper filtration, field diameter, beam projection and source to detector distance. The study was performed using Monte-Carlo simulations with MCNPX for more than 5600 combinations of parameters that account for different clinical situations.

Legendre Polynomials: A Fully Automatic Method for Noise Reduction in Tc-Mercaptoacetyltriglycine Renogram Analysis.

Our purpose was to develop a fully automatic method to deal with the presence of high levels of noise interfering with quantitative analysis of fast, dynamic mercaptoacetyltriglycine renogram images. A method based on Legendre polynomials to fit and filter time-activity curves was proposed. The method was applied to a renal database that contains Monte Carlo (MC)-simulated studies and real adult patient data.

Exploring with [F]UCB-H the in vivo Variations in SV2A Expression through the Kainic Acid Rat Model of Temporal Lobe Epilepsy.

Purpose: The main purpose of this study was to understand how the positron emission tomography (PET) measure of the synaptic vesicle 2A (SV2A) protein varies in vivo during the development of temporal lobe epilepsy (TLE) in the kainic acid rat model.

Procedures: Twenty Sprague Dawley male rats were administered with multiple systemic doses of saline (control group, n = 5) or kainic acid (5 mg/kg/injection, epileptic group, n = 15). Both groups were scanned at the four phases of TLE (early, latent, transition, and chronic phase) with the [F]UCB-H PET radiotracer and T2-structural magnetic resonance imaging.

In vivo imaging of synaptic loss in Alzheimer's disease with [18F]UCB-H positron emission tomography.

Purpose: Loss of brain synapses is an early pathological feature of Alzheimer's disease. The current study assessed synaptic loss in vivo with positron emission tomography and an 18F-labelled radiotracer of the synaptic vesicle protein 2A, [18F]UCB-H.

Methods: Twenty-four patients with mild cognitive impairment or Alzheimer's disease and positive [18F]Flutemetamol amyloid-PET were compared to 19 healthy controls.

Evaluating the In Vivo Specificity of [F]UCB-H for the SV2A Protein, Compared with SV2B and SV2C in Rats Using microPET.

The synaptic vesicle protein 2 (SV2) is involved in synaptic vesicle trafficking. The SV2A isoform is the most studied and its implication in epilepsy therapy led to the development of the first SV2A PET radiotracer [F]UCB-H. The objective of this study was to evaluate in vivo, using microPET in rats, the specificity of [F]UCB-H for SV2 isoform A in comparison with the other two isoforms (B and C) through a blocking assay.

Discrimination of dynamically and post-dynamically recrystallized grains based on EBSD data: application to Inconel 718.

The importance of angular resolution in EBSD analyses is discussed based on an Inconel 718 sample containing several populations of recrystallized grains, with subtle differences in dislocation contents. Classical EBSD analyses (with angular resolution in the range of 0.5-1°) do not allow for distinguishing recrystallized grains grown dynamically or post-dynamically.

Quantification of [F]UCB-H Binding in the Rat Brain: From Kinetic Modelling to Standardised Uptake Value.

Purpose: [F]UCB-H is a specific positron emission tomography (PET) biomarker for the Synaptic Vesicle protein 2A (SV2A), the binding site of the antiepileptic drug levetiracetam. With a view to optimising acquisition time and simplifying data analysis with this radiotracer, we compared two parameters: the distribution volume (Vt) obtained from Logan graphical analysis using a Population-Based Input Function, and the Standardised Uptake Value (SUV).

Procedures: Twelve Sprague Dawley male rats, pre-treated with three different doses of levetiracetam were employed to develop the methodology.

Measuring brain synaptic vesicle protein 2A with positron emission tomography and [F]UCB-H.

Introduction: Brain distribution of synaptic vesicle protein 2A was measured with fluorine-18 UCB-H ([F]UCB-H) and positron emission tomography (PET).

Methods: Images of synaptic density were acquired in healthy volunteers (two young participants and two seniors). Input function was measured by arterial blood sampling (arterial input function) and derived from PET images using carotid activity (image-derived input function).

Monte Carlo simulations of the dose from imaging with GE eXplore 120 micro-CT using GATE.

Purpose: Small animals are increasingly used as translational models in preclinical imaging studies involving microCT, during which the subjects can be exposed to large amounts of radiation. While the radiation levels are generally sublethal, studies have shown that low-level radiation can change physiological parameters in mice. In order to rule out any influence of radiation on the outcome of such experiments, or resulting deterministic effects in the subjects, the levels of radiation involved need to be addressed.

Biodistribution and Radiation Dosimetry for the Novel SV2A Radiotracer [(18)F]UCB-H: First-in-Human Study.

Purpose: [(18)F]UCB-H is a novel radiotracer with a high affinity for synaptic vesicle glycoprotein 2A (SV2A), a protein expressed in synaptic vesicles. SV2A is the binding site of levetiracetam, a "first-in-class" antiepileptic drug with a distinct but still poorly understood mechanism of action. The objective of this study was to determine the biodistribution and radiation dosimetry of [(18)F]UCB-H in a human clinical trial and to establish injection limits according to biomedical research guidelines.

Evaluation of 18F-UCB-H as a novel PET tracer for synaptic vesicle protein 2A in the brain.

Unlabelled: Synaptic vesicle protein 2 isoforms are critical for proper nervous system function and are involved in vesicle trafficking. The synaptic vesicle protein 2A (SV2A) isoform has been identified as the binding site of the antiepileptic levetiracetam (LEV), making it an interesting therapeutic target for epilepsy. (18)F-UCB-H is a novel PET imaging agent with a nanomolar affinity for human SV2A.

Hybrid microPET imaging for dosimetric applications in mice: improvement of activity quantification in dynamic microPET imaging for accelerated dosimetry applied to 6-[18 F]fluoro-L-DOPA and 2-[18 F]fluoro-L-tyrosine.

Purpose: Dynamic microPET imaging has advantages over traditional organ harvesting, but is prone to quantification errors in small volumes. Hybrid imaging, where microPET activities are cross-calibrated using post scan harvested organs, can improve quantification. Organ harvesting, dynamic imaging and hybrid imaging were applied to determine the human and mouse radiation dosimetry of 6-[18 F]fluoro-L-DOPA and 2-[18 F]fluoro-L-tyrosine and compared.

In vivo PET/CT in a human glioblastoma chicken chorioallantoic membrane model: a new tool for oncology and radiotracer development.

Unlabelled: For many years the laboratory mouse has been used as the standard model for in vivo oncology research, particularly in the development of novel PET tracers, but the growth of tumors on chicken chorioallantoic membrane (CAM) provides a more rapid, low cost, and ethically sustainable alternative. For the first time, to our knowledge, we demonstrate the feasibility of in vivo PET and CT imaging in a U87 glioblastoma tumor model on chicken CAM, with the aim of applying this model for screening of novel PET tracers.

Methods: U87 glioblastoma cells were implanted on the CAM at day 11 after fertilization and imaged at day 18.

Preclinical radiation dosimetry for the novel SV2A radiotracer [18F]UCB-H.

Background: [18F]UCB-H was developed as a novel radiotracer with a high affinity for synaptic vesicle protein 2A, the binding site for the antiepileptic levetiracetam. The objectives of this study were to evaluate the radiation dosimetry of [18F]UCB-H in a preclinical trial and to determine the maximum injectable dose according to guidelines for human biomedical research. The radiation dosimetry was derived by organ harvesting and dynamic micro positron emission tomography (PET) imaging in mice, and the results of both methods were compared.

Quantitative capabilities of four state-of-the-art SPECT-CT cameras.

Background: Four state-of-the-art single-photon emission computed tomography-computed tomography (SPECT-CT) systems, namely Philips Brightview, General Electric Discovery NM/CT 670 and Infinia Hawkeye 4, and Siemens Symbia T6, were investigated in terms of accuracy of attenuation and scatter correction, contrast recovery for small hot and cold structures, and quantitative capabilities when using their dedicated three-dimensional iterative reconstruction with attenuation and scatter corrections and resolution recovery.

Methods: The National Electrical Manufacturers Association (NEMA) NU-2 1994 phantom with cold air, water, and Teflon inserts, and a homemade contrast phantom with hot and cold rods were filled with 99mTc and scanned. The acquisition parameters were chosen to provide adequate linear and angular sampling and high count statistics.

Use of a beta microprobe system to measure arterial input function in PET via an arteriovenous shunt in rats.

Background: Kinetic modeling of physiological function using imaging techniques requires the accurate measurement of the time-activity curve of the tracer in plasma, known as the arterial input function (IF). The measurement of IF can be achieved through manual blood sampling, the use of small counting systems such as beta microprobes, or by derivation from PET images. Previous studies using beta microprobe systems to continuously measure IF have suffered from high background counts.

NEMA NU4-2008 image quality performance report for the microPET focus 120 and for various transmission and reconstruction methods.

Unlabelled: This work aimed to evaluate the image quality and accuracy of attenuation and scatter corrections provided with the microPET Focus 120 scanner using the National Electrical Manufacturers Association NU4-2008 image quality phantom.

Methods: Attenuation correction was obtained from transmission measurements using either a (68)Ge or a (57)Co point source. Fully corrected emission images were reconstructed using Fourier rebinning (FORE) and filtered backprojection (FBP).

Comparison of different types of commercial filtered backprojection and ordered-subset expectation maximization SPECT reconstruction software.

Unlabelled: The aim of this study was to compare the performance of filtered backprojection (FBP) and ordered-subset expectation maximization (OSEM) reconstruction algorithms available in several types of commercial SPECT software.

Methods: Numeric simulations of SPECT acquisitions of 2 phantoms were used: the National Electrical Manufacturers Association line phantom used for the assessment of SPECT resolution and a phantom with uniform, hot-rod, and cold-rod compartments. For FBP, no filtering and filtering of the projections with either a Butterworth filter (order 3 or 6) or a Hanning filter at various cutoff frequencies were considered.

Hot and cold contrasts in high-resolution Tc-99m planar scintigraphy: a survey of fifty-two camera heads using the PICKER thyroid phantom.

This study was aimed at comparing the sensitivity and hot and cold contrasts obtained when imaging the PICKER thyroid phantom using gamma cameras fitted with either their ultra-high or high-resolution low-energy parallel hole collimator. Seventeen camera models from Elscint, General Electric, Siemens and Sopha Medical Vision were involved in the study for a total of 30 cameras and 52 camera heads. A single operator conducted the study in order to minimize the impact of human factors.

Resolution improvement and noise reduction in human pinhole SPECT using a multi-ray approach and the SHINE method.

Purpose: This work aimed at quantifying the gains in spatial resolution and noise that could be achieved when using resolution modelling based on a multi-ray approach and additionally the Statistical and Heuristic Noise Extraction (SHINE) method in human pinhole single photon emission tomography (PH-SPECT).

Methods: PH-SPECT of two line phantoms and one homogeneous cylinder were recorded using parameters suited for studies of the human neck area. They were reconstructed using pinhole dedicated ordered subsets expectation maximisation algorithm including a resolution recovery technique based on 7 or 21 rays.