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European Journal of Nuclear Medicine... Jul 2023Monoclonal antibody (mAb)-based PET (immunoPET) imaging can characterise tumour lesions non-invasively. It may be a valuable tool to determine which patients may benefit...
PURPOSE
Monoclonal antibody (mAb)-based PET (immunoPET) imaging can characterise tumour lesions non-invasively. It may be a valuable tool to determine which patients may benefit from treatment with a specific monoclonal antibody (mAb) and evaluate treatment response. For Zr immunoPET imaging, higher sensitivity of state-of-the art PET/CT systems equipped with silicon photomultiplier (SiPM)-based detector elements may be beneficial as the low positron abundance of Zr causes a low signal-to-noise level. Moreover, the long physical half-life limits the amount of activity that can be administered to the patients leading to poor image quality even when using long scan durations. Here, we investigated the difference in semiquantitative performance between the PMT-based Biograph mCT, our clinical reference system, and the SiPM-based Biograph Vision PET/CT in Zr immunoPET imaging. Furthermore, the effects of scan duration reduction using the Vision on semiquantitative imaging parameters and its influence on image quality assessment were evaluated.
METHODS
Data were acquired on day 4 post 37 MBq Zr-labelled mAb injection. Five patients underwent a double scan protocol on both systems. Ten patients were scanned only on the Vision. For PET image reconstruction, three protocols were used, i.e. one camera-dependent protocol and European Association of Nuclear Medicine Research Limited (EARL) standards 1 and 2 compliant protocols. Vision data were acquired in listmode and were reprocessed to obtain images at shorter scan durations. Semiquantitative PET image parameters were derived from tumour lesions and healthy tissues to assess differences between systems and scan durations. Differently reconstructed images obtained using the Vision were visually scored regarding image quality by two nuclear medicine physicians.
RESULTS
When images were reconstructed using 100% acquisition time on both systems following EARL standard 1 compliant reconstruction protocols, results regarding semiquantification were comparable. For Vision data, reconstructed images that conform to EARL1 standards still resulted in comparable semiquantification at shorter scan durations (75% and 50%) regarding 100% acquisition time.
CONCLUSION
Scan duration of Zr immunoPET imaging using the Vision can be decreased up to 50% compared with using the mCT while maintaining image quality using the EARL1 compliant reconstruction protocol.
Topics: Humans; Positron Emission Tomography Computed Tomography; Neoplasms; Reference Standards; Antibodies, Monoclonal; Positron-Emission Tomography; Image Processing, Computer-Assisted
PubMed: 36947185
DOI: 10.1007/s00259-023-06194-4 -
Molecular Imaging and Biology Aug 2023NMDA receptors (NMDARs) dysfunction plays a central role in the physiopathology of psychiatric and neurodegenerative disorders whose mechanisms are still poorly...
PURPOSE
NMDA receptors (NMDARs) dysfunction plays a central role in the physiopathology of psychiatric and neurodegenerative disorders whose mechanisms are still poorly understood. The development of a PET (positron emission tomography) tracer able to selectively bind to the NMDARs intra-channel PCP site may make it possible to visualize NMDARs in an open and active state. We describe the in vitro pharmacological characterization of [F]-fluoroethylnormemantine ([F]-FNM) and evaluate its ability to localize activated NMDA receptors in a rat preclinical model of excitotoxicity.
PROCEDURES
The affinity of the non-radioactive analog for the intra-channel PCP site was determined in a radioligand competition assay using [H]TCP ([H]N-(1-[thienyl]cyclohexyl)piperidine) on rat brain homogenates. Selectivity was also investigated by the displacement of specific radioligands targeting various cerebral receptors. In vivo brain lesions were performed using stereotaxic quinolinic acid (QA) injections in the left motor area (M1) of seven Sprague Dawley rats. Each rat was imaged with a microPET/CT camera, 40 min after receiving a dose of 30 MBq + / - 20 of [F]-FNM, 24 and 72 h after injury. Nine non-injured rats were also imaged using the same protocol.
RESULTS
FNM displayed IC value of 13.0 ± 8.9 µM in rat forebrain homogenates but also showed significant bindings on opioid receptors. In the frontal and left somatosensory areas, [F]FNM PET detected a mean of 37% and 41% increase in [F]FNM uptake (p < 0,0001) 24 and 72 h after QA stereotaxic injection, respectively, compared to the control group.
CONCLUSIONS
In spite of FNM's poor affinity for NMDAR PCP site, this study supports the ability of this tracer to track massive activation of NMDARs in neurological diseases.
Topics: Rats; Animals; Receptors, N-Methyl-D-Aspartate; Rats, Sprague-Dawley; Phencyclidine; Brain Injuries; Positron-Emission Tomography; Brain
PubMed: 36944798
DOI: 10.1007/s11307-023-01811-y -
Saudi Pharmaceutical Journal : SPJ :... Feb 2023The paper begins by identifying the key historical elements in the development of nuclear medicine imaging, focusing on the Anger camera and single photon emission... (Review)
Review
The paper begins by identifying the key historical elements in the development of nuclear medicine imaging, focusing on the Anger camera and single photon emission computed tomography (SPECT) technologies. In this context, key reference is made to the physics of detection in Anger camera systems, especially key components such as the sodium iodide crystal, the function and performance of photomultiplier tubes, and the collimator design. It is discovered that within each component of technology, there are fundamental physical relationships that govern the performance of each component, and that overall image quality is the result of the complex interaction of all such elements. The increasing use of SPECT/CT imaging is described and illustrated with a range of typical clinical applications, which include brain, spinal, cardiac, and cancer studies. The use of CT imaging functionality allows for SPECT image correction based on compensation for absorption within tissue. Reference is also made to the basics of positron emission tomography (PET) imaging and, in particular, to the integration of PET/CT systems where the anatomy profile of the CT image is used to provide correction for photon absorption. A summary is provided of the radionuclides and radiopharmaceuticals commonly used in PET/CT imaging and a range of image studies referenced includes those of nasopharyngeal carcinoma, lung cancer investigation, brain investigation (cancer detection and dementia) and cardiac function. Reference is made to the development of "time of flight" (TOF) technology for improving of image resolution in PET/CT systems. Furthermore, SPECT/CT and PET/CT imaging systems are compared, where a key factor identified is the significantly higher number of photons detected with PET/CT technology and improved image resolution.
PubMed: 36942267
DOI: 10.1016/j.jsps.2022.12.013 -
Micromachines Jan 2023In this paper, a blue fluorescent organic light-emitting diode (OLED) with a 1 cm emitting area was fabricated by a solution process. The ITO/spin MADN:13%...
In this paper, a blue fluorescent organic light-emitting diode (OLED) with a 1 cm emitting area was fabricated by a solution process. The ITO/spin MADN:13% UBD-07/TPBi/Al was used as the basic structure in which to add a hole-injection layer PEDOT:PSS and an electron-injection layer LiF, respectively. The device structure was optimized to obtain a longer lifetime. Firstly, the TPBi, which is an electron transport layer and a hole-blocking layer, was added to the structure to increase the electron transport rate. When the TPBi thickness was increased to 20 nm, the luminance was 221 cd/m, and the efficiency was 0.52 cd/A at a voltage of 8 V. Since the addition of the hole-injection layer (HIL) increased the hole current but did not increase the electron current, the electron transport layer (ETL) Alq with the lowest unoccupied molecular orbital (LUMO) was added as stepped ETL to help the TPBi transport more electron current into the emitting layer. When the thickness of the TPBi/Alq was 10 nm/15 nm, the luminance reached 862 cd/m, the efficiency was 1.29 cd/A, and the lifetime increased to 252 min. Subsequently, a hole-injection layer PEDOT:PSS with a thickness of 55 nm was added to make the ITO surface flatter and to reduce the probability of a short circuit caused by the spike effect. At this time, the luminance of 311 cd/m, the efficiency of 0.64 cd/A, and the lifetime of 121 min were obtained. Following this, the thickness of the emitting layer was doubled to increase the recombination probability of the electrons and the holes. When the thickness of the emitting layer was 90 nm, and the thermal evaporation method was used, the efficiency was 3.23 cd/A at a voltage of 8V, and the lifetime was improved to 482 min. Furthermore, when the thickness of the hole-injection layer PEDOT:PSS was increased to 220 nm, the efficiency increased to 3.86 cd/A, and the lifetime was increased to 529 min. An infrared thermal image camera was employed to detect the temperature variation of the blue OLEDs. After the current was gradually increased, it was found that the heat accumulation of the device became more and more significant. When the driving current reached 50 mA, the device burnt out. It was found that the maximum temperature that the OLED device could withstand was approximately 58.83 degrees C at a current of 36.36 mA.
PubMed: 36837978
DOI: 10.3390/mi14020278 -
Diagnostic and Interventional Imaging 2023Myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) assessment with non-invasive techniques represent an important tool to evaluate both coronary artery... (Review)
Review
Myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) assessment with non-invasive techniques represent an important tool to evaluate both coronary artery disease severity and extent. Currently, cardiac positron emission tomography-computed tomography (PET-CT) is the "gold standard" for the assessment of coronary function and provides accurate estimations of baseline and hyperemic MBF and MFR. Nevertheless, due to the high cost and complexity, PET-CT is not widely used in clinical practice. The introduction of cardiac-dedicated cadmium-zinc-telluride (CZT) cameras has renewed researchers' interest on MBF quantitation by single-photon emission computed tomography (SPECT). Indeed, many studies evaluated MPR and MBF measurements by dynamic CZT-SPECT in different cohorts of patients with suspected or overt coronary artery disease. As well, many others have compared the values obtained by CZT-SPECT to the ones by PET-CT, showing good correlations in detecting significant stenosis, although with different and non-standardized cut-off values. Nevertheless, the lack of standardized protocol for acquisition, reconstruction and elaboration makes more difficult to compare different studies and to further assess the real advantages of MBF quantitation by dynamic CZT-SPECT in clinical routine. Many are the issues involved in the bright and dark sides of dynamic CZT-SPECT. They include different type of CZT cameras, different execution protocols, different tracers with different myocardial extraction fraction and distribution, different software packages with different tools and algorithms, often requiring manual post-processing elaboration. This review article provides a clear summary of the state of the art on MBF and MPR evaluation by dynamic CZT-SPECT and outlines the major issues to solve to optimize this technique.
Topics: Humans; Coronary Artery Disease; Positron Emission Tomography Computed Tomography; Tomography, Emission-Computed, Single-Photon; Cadmium; Myocardial Perfusion Imaging
PubMed: 36797156
DOI: 10.1016/j.diii.2023.02.001 -
Scientific Reports Jan 2023A novel laboratory platform has been designed and built for the irradiation of a plasma crystal (PC) with an electron beam (e-beam) having an energy around 10 keV and a...
A novel laboratory platform has been designed and built for the irradiation of a plasma crystal (PC) with an electron beam (e-beam) having an energy around 10 keV and a current of tens of milliamperes. The pulsed e-beam collimated to a few millimeter-size spot is aimed at a crystal made of dust particles levitated in a radio-frequency (RF) plasma. The platform consists of three vacuum chambers connected in-line, each with different utility: one for generating free electrons in a pulsed hollow-anode Penning discharge, another for the extraction and acceleration of electrons at [Formula: see text] kV and for focusing the e-beam in the magnetic field of a pair of circular coils, and the last one for producing PCs above a RF-driven electrode. The main challenge is to obtain both a stable e-beam and PC by insuring appropriate gas pressures, given that the e-beam is formed in high vacuum ([Formula: see text] Torr), while the PC is produced at much higher pressures ([Formula: see text] Torr). The main diagnostics include a high speed camera, a Faraday cup and a Langmuir probe. Two applications concerned with the creation of a pair of dust flow vortices and the rotation of a PC by the drag force of the e-beam acting on the strongly coupled dust particles are presented. The dust flow can become turbulent as demonstrated by the energy spectrum, featuring vortices at different space scales.
PubMed: 36653432
DOI: 10.1038/s41598-023-28152-8 -
Journal of Structural Biology: X 2023Advances in electron detection have been essential to the success of high-resolution cryo-EM structure determination. A new generation of direct electron detector called...
Advances in electron detection have been essential to the success of high-resolution cryo-EM structure determination. A new generation of direct electron detector called the Apollo, has been developed by Direct Electron. The Apollo uses a novel event-based MAPS detector custom designed for ultra-fast electron counting. We have evaluated this new camera, finding that it delivers high detective quantum efficiency (DQE) and low coincidence loss, enabling high-quality electron counting data acquisition at up to nearly 80 input electrons per pixel per second. We further characterized the performance of Apollo for single particle cryo-EM on real biological samples. Using mouse apoferritin, Apollo yielded better than 1.9 Å resolution reconstructions at all three tested dose rates from a half-day data collection session each. With longer collection time and improved specimen preparation, mouse apoferritin was reconstructed to 1.66 Å resolution. Applied to a more challenging small protein aldolase, we obtained a 2.24 Å resolution reconstruction. The high quality of the map indicates that the Apollo has sufficiently high DQE to reconstruct smaller proteins and complexes with high-fidelity. Our results demonstrate that the Apollo camera performs well across a broad range of dose rates and is capable of capturing high quality data that produce high-resolution reconstructions for large and small single particle samples.
PubMed: 36578473
DOI: 10.1016/j.yjsbx.2022.100080 -
Annals of Nuclear Cardiology 2022The International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial has had a great impact on the management of chronic... (Review)
Review
The International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial has had a great impact on the management of chronic coronary artery disease (CAD). One of the implications of this trial is the importance of close patient follow-up. To improve patient prognosis, evaluation of the residual extent of ischemia after treatment may be important because several studies have shown a close relationship between residual ischemia and cardiac events. For this assessment, myocardial perfusion single-photon emission computed tomography (MPS) has been utilized and is almost the only modality. Among the participants in the ISCHEMIA trial, more than 10% were excluded due to the absence of obstructive CAD. The pathophysiology of ischemia without non-obstructive coronary artery disease (INOCA) is gaining recognition; however, diagnosis is difficult, except for the assessment of myocardial flow reserve (MFR). Myocardial perfusion positron emission tomography (PET) is the most common modality for noninvasive evaluation of MFR; however, its availability in Japan is limited. For a breakthrough in this situation, a novel gamma camera with a cadmium zinc telluride (CZT) semiconductor might be one of the solutions that enables the evaluation of MFR with a commercially available perfusion tracer, similar to PET. Another solution is a novel PET tracer with a longer half-life. Clinical trials with F labeled perfusion agents have been initiated in Japan, and in a few years, delivery of this perfusion tracer will result in more frequent and easier assessment of MFR.
PubMed: 36540172
DOI: 10.17996/anc.22-00168 -
Cancer Imaging : the Official... Dec 2022With the rapid emergence of extended Field-of-View PET-cameras several new applications for radiopharmaceuticals become within reach. Main reason is the significant... (Review)
Review
With the rapid emergence of extended Field-of-View PET-cameras several new applications for radiopharmaceuticals become within reach. Main reason is the significant increase of the sensitivity of the PET-camera so that much less radioactivity can be administered. Issues that that hampered development or use of PET-radiopharmaceuticals become realistic again. Molar activity requirements can become less strict. New low-yielding radiochemistry methods may become applicable. Carbon-11 labelled compounds can revive and potentially be shipped to nearby PET-facilities. PET-radiopharmaceuticals with slow kinetics in comparison to their half life can still be used. As additional infrastructure and equipment will likely remain unchanged and keep the same sensitivity therefore there will be issues with kinetic modelling requiring analysis of plasma or metabolites samples with lower count rate. Besides the potential revival of failed radiopharmaceuticals, novel challenges are ahead to develop novel radiochemistry based on thus far unsuitable (low yielding or time consuming) reactions.
Topics: Humans; Radiopharmaceuticals; Positron Emission Tomography Computed Tomography; Cemeteries; Positron-Emission Tomography
PubMed: 36529738
DOI: 10.1186/s40644-022-00510-1 -
Optics Express Nov 2022A counter-propagating laser-beam platform using a spherical plasma mirror was developed for the kilojoule-class petawatt LFEX laser. The temporal and spatial overlaps of...
A counter-propagating laser-beam platform using a spherical plasma mirror was developed for the kilojoule-class petawatt LFEX laser. The temporal and spatial overlaps of the incoming and redirected beams were measured with an optical interferometer and an x-ray pinhole camera. The plasma mirror performance was evaluated by measuring fast electrons, ions, and neutrons generated in the counter-propagating laser interaction with a Cu-doped deuterated film on both sides. The reflectivity and peak intensity were estimated as ∼50% and ∼5 × 10 W/cm, respectively. The platform could enable studies of counter-streaming charged particles in high-energy-density plasmas for fundamental and inertial confinement fusion research.
PubMed: 36523045
DOI: 10.1364/OE.475945