The effect of COVID-19 on nuclear medicine and radiopharmacy activities: A global survey.

Globally, COVID-19 affected radiopharmaceutical laboratories. This study sought to determine the economic, service, and research impacts of COVID-19 on radiopharmacy. This online survey was conducted with the participation of employees from nuclear medicine and radiopharmaceutical companies.

Imaging Pulmonary Blood Vessels and Ventilation-Perfusion Mismatch in COVID-19.

COVID-19 hypoxemic patients although sharing a same etiology (SARS-CoV-2 infection) present themselves quite differently from one another. Patients also respond differently to prescribed medicine and to prone Vs supine bed positions. A severe pulmonary ventilation-perfusion mismatch usually triggers moderate to severe COVID-19 cases.

3D Attention M-net for Short-axis Left Ventricular Myocardium Segmentation in Mice MR cardiac Images.

Small rodent cardiac magnetic resonance imaging (MRI) plays an important role in preclinical models of cardiac disease. Accurate myocardial boundaries delineation is crucial to most morphological and functional analysis in rodent cardiac MRIs. However, rodent cardiac MRIs, due to animal's small cardiac volume and high heart rate, are usually acquired with sub-optimal resolution and low signal-to-noise ratio (SNR).

Diffeomorphic Upsampling of Serially Acquired Sparse 2D Cross-Sections in Cardiac MRI.

In this paper, we propose a new technique for interpolating shapes in order to upsample a sparsely acquired serial-section image stack. The method is based on a maximum a posteriori estimation strategy which models neighboring sections as observations of random deformations of an image to be estimated. We show the computation of diffeomorphic trajectories between observed sections and define estimated upsampled image sections as a Jacobian-weighted sum of flowing images at corresponding distances along those trajectories.

Assessment of diabetic neuropathy with emission tomography and magnetic resonance spectroscopy.

Diabetic neuropathies (DNs) are nerve-damaging disorders associated with diabetes. They are commonly attributed to peripheral nerves and primarily affect the limbs of the patient. They cause altered sensitivity to external stimuli along with loss in balance and reflexes of the affected patient.

Metabotropic glutamate receptor 5 - a promising target in drug development and neuroimaging.

This review summarizes the contributions by various teams of scientists in assessing the metabotropic glutamate receptor 5 (mGluR5) as a biomarker in neuropsychiatric disorders and diseases. Development of positive and negative allosteric modulators of mGluR5 is reviewed, as is the development of PET radioligands that have the potential to measure mGluR5 receptor density in neurological disorders and during therapeutic interventions. PET imaging provides an effective tool to assess the specificity of new drugs, select dose regimens in clinical trials, and study drug mechanisms of action.

In vivo PET imaging of cardiac presynaptic sympathoneuronal mechanisms in the rat.

Unlabelled: The sympathetic nervous system of the heart plays a key role in the pathophysiology of various cardiac diseases. Small-animal models are valuable for obtaining further insight into mechanisms of cardiac disease and therapy. To determine the translational potential of cardiac neuronal imaging from rodents to humans, we characterized the rat sympathetic nervous system using 3 radiotracers that reflect different subcellular mechanisms: (11)C-meta-hydroxyephedrine (HED), a tracer of neuronal transport showing stable uptake and no washout in healthy humans; (11)C-phenylephrine (PHEN), a tracer of vesicular leakage and intraneuronal metabolic degradation with initial uptake and subsequent washout in humans; and (11)C-epinephrine (EPI), a tracer of vesicular storage with stable uptake and no washout in humans.

Disulfiram inhibits defluorination of (18)F-FCWAY, reduces bone radioactivity, and enhances visualization of radioligand binding to serotonin 5-HT1A receptors in human brain.

Unlabelled: (18)F-trans-4-Fluoro-N-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide ((18)F-FCWAY) is a PET radioligand for imaging serotonin 5-hydroxytryptamine-1A receptors in brain. (18)F-FCWAY undergoes significant defluorination, with high uptake of radioactivity in the skull and resulting spillover contamination in the underlying neocortex. The cytochrome P450 enzyme CYP2E1 defluorinates many drugs.

Cardiac sympathetic neuronal imaging using PET.

Introduction: Balance of the autonomic nervous system is essential for adequate cardiac performance, and alterations seem to play a key role in the development and progression of various cardiac diseases.

Pet As An Imaging Tool: PET imaging of the cardiac autonomic nervous system has advanced extensively in recent years, and multiple pre- and postsynaptic tracers have been introduced. The high spatial and temporal resolution of PET enables noninvasive quantification of neurophysiologic processes at the tissue level.

PET imaging of brain 5-HT1A receptors in rat in vivo with 18F-FCWAY and improvement by successful inhibition of radioligand defluorination with miconazole.

Unlabelled: 18F-FCWAY (18F-trans-4-fluoro-N-(2-[4-(2-methoxyphenyl) piperazin-1-yl)ethyl]-N-(2-pyridyl)cyclohexanecarboxamide) is useful in clinical research with PET for measuring serotonin 1A (5-HT1A) receptor densities in brain regions of human subjects but has significant bone uptake of radioactivity due to defluorination. The uptake of radioactivity in skull compromises the accuracy of measurements of 5-HT1A receptor densities in adjacent areas of brain because of spillover of radioactivity through the partial-volume effect. Our aim was to demonstrate with a rat model that defluorination of 18F-FCWAY may be inhibited in vivo to improve its applicability to measuring brain regional 5-HT1A receptor densities.

Cardiac and extracardiac sympathetic denervation in Parkinson's disease with orthostatic hypotension and in pure autonomic failure.

Unlabelled: The uptake of 6-(18)F-fluorodopamine by cardiac noradrenergic nerves enables visualization of the sympathetic innervation of the left ventricular myocardium by PET. Patients with Parkinson's disease (PD) and orthostatic hypotension (OH) (PD+OH) or with pure autonomic failure (PAF) have markedly decreased myocardial 6-(18)F-fluorodopamine-derived radioactivity, consistent with cardiac sympathetic denervation, a phenomenon that neurochemical, neuropharmacologic, and, most recently, postmortem neuropathologic studies have confirmed. In this study, we examined whether 6-(18)F-fluorodopamine can visualize sympathetic innervation in extracardiac organs and, if so, whether patients with PD+OH or PAF have neuroimaging evidence of extracardiac noradrenergic denervation.

Quantification of brain phosphodiesterase 4 in rat with (R)-[11C]Rolipram-PET.

Objective: Phosphodiesterase 4 (PDE4) catabolizes the second messenger 3', 5'-cyclic adenosine monophosphate and may play a critical role in brain diseases. Our aim was to quantify PDE4 in rats with positron emission tomography (PET).

Methods: High (n = 6) and low specific activity (SA) (n = 2) higher affinity ((R)-[(11)C]rolipram) and high SA lower affinity ((S)-[(11)C]rolipram) (n = 2) enantiomers were intravenously administered to Sprague-Dawley rats.

PET imaging of brain with the beta-amyloid probe, [11C]6-OH-BTA-1, in a transgenic mouse model of Alzheimer's disease.

Purpose: The purpose of this study was to evaluate the capacity of [11C]6-OH-BTA-1 and positron emission tomography (PET) to quantify beta-amyloid (Abeta) plaques in the Tg2576 mouse model of Alzheimer's disease (AD).

Methods: PET imaging was performed with the NIH ATLAS small animal scanner in six elderly transgenic mice (Tg2576; age 22.0+/-1.

Whole-body biodistribution and radiation dosimetry estimates for the PET dopamine transporter probe 18F-FECNT in non-human primates.

Background And Aim: 2 beta-Carbomethoxy-3-(4-chlorophenyl)-8-(2-[18F]fluoroethyl)nortropane (18F-FECNT) is a selective radioligand for the in vivo quantification of dopamine transporters by using positron emission tomography. The aim of the current study was to quantify the distribution of radioactivity in three rhesus monkeys after the injection of approximately 185 MBq (5 mCi) of 18F-FECNT.

Method: Whole-body images were acquired at 23-30 time points for a total of 220 min following injection of the radioligand.

Synthesis and evaluation of two 18F-labeled 6-iodo-2-(4'-N,N-dimethylamino)phenylimidazo[1,2-a]pyridine derivatives as prospective radioligands for beta-amyloid in Alzheimer's disease.

This study evaluated (18)F-labeled IMPY [6-iodo-2-(4'-N,N-dimethylamino)phenylimidazo[1,2-a]pyridine] derivatives as agents for imaging beta-amyloid plaque with positron emission tomography (PET). The precursor for radiolabeling and reference compounds was synthesized in up to five steps from commercially accessible starting materials. One of the two N-methyl groups of IMPY was substituted with either a 3-fluoropropyl (FPM-IMPY) or a 2-fluoroethyl (FEM-IMPY) group.

Effect of scatter correction on the compartmental measurement of striatal and extrastriatal dopamine D2 receptors using [123I]epidepride SPET.

Prior studies with anthropomorphic phantoms and single, static in vivo brain images have demonstrated that scatter correction significantly improves the accuracy of regional quantitation of single-photon emission tomography (SPET) brain images. Since the regional distribution of activity changes following a bolus injection of a typical neuroreceptor ligand, we examined the effect of scatter correction on the compartmental modeling of serial dynamic images of striatal and extrastriatal dopamine D(2) receptors using [(123)I]epidepride. Eight healthy human subjects [age 30+/-8 (range 22-46) years] participated in a study with a bolus injection of 373+/-12 (354-389) MBq [(123)I]epidepride and data acquisition over a period of 14 h.

Quantification of nicotinic acetylcholine receptors in human brain using [123I]5-I-A-85380 SPET.

The purpose of this study was to assess the utility of a new single-photon emission tomography ligand, [123I]5-iodo-3-[2(S)-2-azetidinylmethoxy]pyridine (5-I-A-85380), to measure regional nAChR binding in human brain. Six healthy nonsmoker subjects (two men and four women, age 33 +/- 15 years) participated in both a bolus (dose: 317 +/- 42 MBq) and a bolus plus constant infusion (dose of bolus: 98 +/- 32 MBq, B/I=6.7 +/- 2.

Acrylate-based transdermal therapeutic system of nitrendipine.

The objective of the present research investigation was to fabricate an acrylate-based transdermal therapeutic system (TTS) of nitrendipine, which could deliver drug at maximum input rate so as to deliver drug in minimum patch size. Transdermal patches were fabricated using synthesized acrylate pressure-sensitive adhesives (PSAs): PSA1, PSA2, and commercially available PSA3 and PSA4 using d-limonene as permeation enhancer. Effect of concentration of d-limonene on permeation kinetics of nitrendipine in PSAs was studied.

Formulation optimization and stability study of transdermal therapeutic system of nicorandil.

The aim of this research investigation was to fabricate acrylate-based stable transdermal therapeutic system (TTS) of nicorandil, which could deliver drug through transdermal route. Monolithic TTS was fabricated in pressure sensitive adhesives (PSAs)--(a) terpolymer (PSA1) of 2-ethylhexyl acrylate, methyl methacrylate, and acrylic acid, (b) copolymer (PSA2) of 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid, and vinyl acetate, and (c) Eudragit E100 pressure sensitive adhesive (PSA3). To enhance the flux of nicorandil, skin permeation enhancer N-methyl-2-pyrrolidone (NMP) was investigated at different concentrations (0.