Validation of the design of a high-sensitivity and high-resolution PET system for a preclinical PET/EPR hybrid scanner.

We report the development of a high-sensitivity and high-resolution PET subsystem for a next-generation preclinical PET/EPR hybrid scanner for investigating and improving hypoxia imaging with PET. The PET subsystem consists of 14 detector modules (DM) installed within a cylindrical supporting frame whose outer and inner diameters are 115mm and 60mm, respectively. Each DM contains eight detector units (DU) in a row and each DU is made of a 12×12 array of 1×1×10mm LYSO crystals (with a 1.

DOI- and TOF-capable PET array detector using double-ended light readout and stripline-based row and column electronic readout.

We investigate a highly multiplexing readout for depth-of-interaction (DOI) and time-of-flight PET detector consisting of an N×N crystals whose light outputs at the front and back ends are detected by using silicon photomultipliers (SiPM). The front N×N SiPM array is read by using a stripline (SL) configured to support discrimination of the row position of the signal-producing crystal. The back N×N SiPM array is similarly read by an SL for column discrimination.

Simultaneous Activity and Attenuation Estimation in TOF-PET With TV-Constrained Nonconvex Optimization.

An alternating direction method of multipliers (ADMM) framework is developed for nonsmooth biconvex optimization for inverse problems in imaging. In particular, the simultaneous estimation of activity and attenuation (SAA) problem in time-of-flight positron emission tomography (TOF-PET) has such a structure when maximum likelihood estimation (MLE) is employed. The ADMM framework is applied to MLE for SAA in TOF-PET, resulting in the ADMM-SAA algorithm.

A Preclinical Positron Emission Tomography (PET) and Electron-Paramagnetic-Resonance-Imaging (EPRI) Hybrid System: PET Detector Module.

We report the design and experimental validation of a compact positron emission tomography (PET) detector module (DM) intended for building a preclinical PET and electron-paramagnetic-resonance-imaging hybrid system that supports sub-millimeter image resolution and high-sensitivity, whole-body animal imaging. The DM is eight detector units (DU) in a row. Each DU contains 12×12 lutetium-yttrium oxyorthosilicate (LYSO) crystals having a 1.

Evaluation of an Image-Derived Input Function for Kinetic Modeling of Nicotinic Acetylcholine Receptor-Binding PET Ligands in Mice.

Positron emission tomography (PET) radioligands that bind with high-affinity to α4β2-type nicotinic receptors (α4β2Rs) allow for in vivo investigations of the mechanisms underlying nicotine addiction and smoking cessation. Here, we investigate the use of an image-derived arterial input function and the cerebellum for kinetic analysis of radioligand binding in mice. Two radioligands were explored: 2-[F]FA85380 (2-FA), displaying similar pKa and binding affinity to the smoking cessation drug varenicline (Chantix), and [F]Nifene, displaying similar pKa and binding affinity to nicotine.

Accelerator-Based Production of Scandium Radioisotopes for Applications in Prostate Cancer: Toward Building a Pipeline for Rapid Development of Novel Theranostics.

In the field of nuclear medicine, the β -emitting Sc and β -emitting Sc are promising candidates in cancer diagnosis and targeted radionuclide therapy (TRT) due to their favorable decay schema and shared pharmacokinetics as a true theranostic pair. Additionally, scandium is a group-3 transition metal (like Lu) and exhibits affinity for DOTA-based chelators, which have been studied in depth, making the barrier to implementation lower for Sc than for other proposed true theranostics. Before Sc can see widespread pre-clinical evaluation, however, an accessible production methodology must be established and each isotope's radiolabeling and animal imaging capabilities studied with a widely utilized tracer.

The value of using heterogeneous detector groups for the development of time-of-flight (TOF) positron emission tomography (PET) systems.

. Much recent attention on positron emission tomography (PET) is the development of time-of-flight (TOF) systems with ever-improving coincidence time resolution (CTR). This is because, when all other factors remain the same, a better CTR leads to images of better statistics and effectively increases the sensitivity of the system.

Simultaneous activity and attenuation estimation in TOF-PET with TV-constrained nonconvex optimization.

An alternating direction method of multipliers (ADMM) framework is developed for nonsmooth biconvex optimization for inverse problems in imaging. In particular, the simultaneous estimation of activity and attenuation (SAA) problem in time-of-flight positron emission tomography (TOF-PET) has such a structure when maximum likelihood estimation (MLE) is employed. The ADMM framework is applied to MLE for SAA in TOF-PET, resulting in the ADMM-SAA algorithm.

Trapping of Nicotinic Acetylcholine Receptor Ligands Assayed by Cellular Studies and PET Imaging.

A question relevant to nicotine addiction is how nicotine and other nicotinic receptor membrane-permeant ligands, such as the anti-smoking drug varenicline (Chantix), distribute in brain. Ligands, like varenicline, with high pK and high affinity for α4β2-type nicotinic receptors (α4β2Rs) are trapped in intracellular acidic vesicles containing α4β2Rs Nicotine, with lower pK and α4β2R affinity, is not trapped. Here, we extend our results by imaging nicotinic PET ligands in male and female mouse brain and identifying the trapping brain organelle as Golgi satellites (GSats).

The optimal F-fluoromisonidazole PET threshold to define tumor hypoxia in preclinical squamous cell carcinomas using pO electron paramagnetic resonance imaging as reference truth.

Purpose: To identify the optimal threshold in F-fluoromisonidazole (FMISO) PET images to accurately locate tumor hypoxia by using electron paramagnetic resonance imaging (pO EPRI) as ground truth for hypoxia, defined by pO [Formula: see text] 10 mmHg.

Methods: Tumor hypoxia images in mouse models of SCCVII squamous cell carcinoma (n = 16) were acquired in a hybrid PET/EPRI imaging system 2 h post-injection of FMISO. T2-weighted MRI was used to delineate tumor and muscle tissue.

Multiplexing Readout for Time-of-Flight (TOF) PET Detectors Using Striplines.

A recent trend in PET instrumentation is the use of silicon photomultipliers (SiPMs) for high-resolution and time-of-flight (TOF) detection. Due to its small size, a PET system can use a large number of SiPMs and hence effective and scalable multiplexing readout methods become important. Unfortunately, multiplexing readout generally degrades the fast timing properties necessary for TOF, especially at high channel reduction.

Improving Tumor Hypoxia Location in F-Misonidazole PET with Dynamic Contrast-enhanced MRI Using Quantitative Electron Paramagnetic Resonance Partial Oxygen Pressure Images.

Purpose: To enhance the spatial accuracy of fluorine 18 (F) misonidazole (MISO) PET imaging of hypoxia by using dynamic contrast-enhanced (DCE) MR images as a basis for modifying PET images and by using electron paramagnetic resonance (EPR) partial oxygen pressure (pO) as the reference standard.

Materials And Methods: Mice ( = 10) with leg-borne MCa4 mammary carcinomas underwent EPR imaging, T2-weighted and DCE MRI, and F-MISO PET/CT. Images were registered to the same space for analysis.

Rational design of silicon structures for optically controlled multiscale biointerfaces.

Silicon-based materials have been widely used. However, remotely controlled and interconnect-free silicon configurations have been rarely explored, because of limited fundamental understanding of the complex physicochemical processes that occur at interfaces between silicon and biological materials. Here, we describe rational design principles, guided by biology, for establishing intracellular, intercellular and extracellular silicon-based interfaces, where the silicon and the biological targets have matched properties.

Optimization-Based Image Reconstruction From Low-Count, List-Mode TOF-PET Data.

Objective: We investigate an optimization-based approach to image reconstruction from list-mode data in digital time-of-flight (TOF) positron emission tomography (PET) imaging.

Method: In the study, the image to be reconstructed is designed as a solution to a convex, non-smooth optimization program, and a primal-dual algorithm is developed for image reconstruction by solving the optimization program. The algorithm is first applied to list-mode TOF-PET data of a typical count level from physical phantoms and a human subject.

Modularized compact positron emission tomography detector for rapid system development.

We report the development of a modularized compact positron emission tomography (PET) detector that outputs serial streams of digital samples of PET event pulses via an Ethernet interface using the UDP/IP protocol to enable rapid configuration of a PET system by connecting multiple such detectors via a network switch to a computer. Presently, the detector is [Formula: see text] in extent (excluding I/O connectors) and contains an [Formula: see text] array of [Formula: see text] one-to-one coupled lutetium-yttrium oxyorthosilicate/silicon photomultiplier pixels. It employs cross-wire and stripline readouts to merge the outputs of the 216 detector pixels to 24 channels.

Investigation of optimization-based reconstruction with an image-total-variation constraint in PET.

Interest remains in reconstruction-algorithm research and development for possible improvement of image quality in current PET imaging and for enabling innovative PET systems to enhance existing, and facilitate new, preclinical and clinical applications. Optimization-based image reconstruction has been demonstrated in recent years of potential utility for CT imaging applications. In this work, we investigate tailoring the optimization-based techniques to image reconstruction for PET systems with standard and non-standard scan configurations.

Performance evaluation of the Trans-PET® BioCaliburn® LH system: a large FOV small-animal PET system.

Unlabelled: The Trans-PET(®) BioCaliburn(®) LH is a commercial positron emission tomography (PET) system for animal imaging. The system offers a large transaxial field-of-view (FOV) of 13.0 cm to allow imaging of multiple rodents or larger animals.

A PET system design by using mixed detectors: resolution properties.

We investigate a cylindrical positron emission tomography (PET) system design strategy that employs two groups of detectors with different resolutions. The reason for considering this strategy is the observation that in many tasks one would want a higher resolution in a targeted region, which contains lesions or organs of interest, than that in the rest of the subject. Although one can design a PET system to meet the highest resolution required by the imaging task, this is not cost efficient because the superior resolution outside the target region is not needed.

Activating the expression of human K-rasG12D stimulates oncogenic transformation in transgenic goat fetal fibroblast cells.

Humane use of preclinical large animal cancer models plays a critical role in understanding cancer biology and developing therapeutic treatments. Among the large animal candidates, goats have great potentials as sustainable sources for large animal cancer model development. Goats are easier to handle and cheaper to raise.

Accelerating image reconstruction in dual-head PET system by GPU and symmetry properties.

Positron emission tomography (PET) is an important imaging modality in both clinical usage and research studies. We have developed a compact high-sensitivity PET system that consisted of two large-area panel PET detector heads, which produce more than 224 million lines of response and thus request dramatic computational demands. In this work, we employed a state-of-the-art graphics processing unit (GPU), NVIDIA Tesla C2070, to yield an efficient reconstruction process.

Potentials of Digitally Sampling Scintillation Pulses in Timing Determination in PET.

We investigate the potentials of digitally sampling scintillation pulses techniques for positron emission tomography (PET) in this paper, focusing on the determination of the event time. We have built, and continue building, a digital library of PET event waveforms generated with various combinations of photo-detectors and scintillator materials, with various crystal sizes. Events in this digital library are obtained at a high sampling of 20 GSps (Giga-samples per second) so that their waveforms are recorded with high accuracy.

Windowed image reconstruction for time-of-flight positron emission tomography.

It has been well recognized that, in comparison with the conventional positron emission tomography (PET), the differential-time measurements made available in time-of-flight (TOF) PET imaging can reduce the propagation of data noise in reconstruction and lead to images having better statistical quality. This observation has been the motivation driving the interest in developing TOF-PET systems. In this paper, we make new observations that can extend the use of TOF-PET.

Spatial-resolution enhancement in computed tomography.

We propose an approach that combines an asymmetric fan-beam configuration and a new reconstruction algorithm to enhancing spatial resolution in computed tomography (CT). The asymmetric configuration can be achieved by changing the center of rotation (COR) from the conventional symmetric configuration. It does not, however, require new detectors and X-ray source nor alter the relative geometry between the detector and the X-ray source.