scholarly journals In Vitro Hypoxia Responsiveness Of Fdg And Faza Retention: Influence Of Shaking Versus Stagnant Conditions, Glass Versus Polystyrene Substrata And Cell Number Down-Scaling

2020 ◽  
Author(s):  
Morten Busk ◽  
Michael R Horsman ◽  
Jens Overgaard ◽  
Steen Jakobsen
Keyword(s):  
Single Photon ◽  
Photon Emission ◽  
Cell Number ◽  
Medium Composition ◽  
Emission Computed Tomography ◽  
Experimental Conditions ◽  
Positron Emission ◽  
Orbital Shaking ◽  
Petri Dishes

Abstract Background. In vitro experiments using radiolabeled molecules is fundamental for Positron emission tomography (PET) or single photon emission computed tomography (SPECT) tracer development and various metabolic assays, but no consensus on appropriate incubation conditions exists. Specifically, the use of shaking versus non-shaking conditions, cell number to medium volume and the choice of cell plating material may unintentionally influence cellular oxygenation and medium composition. This is problematic when testing the oxygen-dependence of tracers including 18F-fluoro-2-deoxyglucose (FDG) and hypoxia-selective 2-nitroimidazoles (e.g., 18F-fluoroazomycin-arabinoside, FAZA) or when doing prolonged experiments. The purpose of this study was to assess the influence of various experimental conditions on tracer retention. Methods. Tumor cells were seeded in a) Glass or standard Polystyrene Petri dishes or as b) discrete droplets in polystyrene Petri dishes or on 9 mm glass coverslips positioned in glass Petri dishes. When confluent, cells were pre-equilibrated for 2h to 21%, 0.5% or 0% O2 and FDG or FAZA was added, followed by cell harvest and analysis of radioactivity 1h (FDG) or 3h (FAZA) after. Experiments were conducted with/without orbital shaking. Results. The influence of hypoxia on tracer retention varied widely among cell lines, but shaking-induced convection did not influence uptake. In contrast, hypoxia-driven FAZA, and to some extent FDG, retention was much lower in cells grown on polyethylene than glass. Scaling-down the number of cells did not compromise accuracy. Conclusions. Most experiments can be performed appropriately in the absence of shaking and with downscaling of cell number but the use of conventional plasticware is highly problematic for studies on tracers and drugs that are metabolized and retained or activated at low O2 levels.

scholarly journals In Vitro Hypoxia Responsiveness Of Fdg And Faza Retention: Influence Of Shaking Versus Stagnant Conditions, Glass Versus Polystyrene Substrata And Cell Number Down-Scaling

2020 ◽  
Author(s):  
Morten Busk ◽  
Michael R Horsman ◽  
Jens Overgaard ◽  
Steen Jakobsen
Keyword(s):  
Single Photon ◽  
Photon Emission ◽  
Cell Number ◽  
Medium Composition ◽  
Emission Computed Tomography ◽  
Experimental Conditions ◽  
Positron Emission ◽  
Orbital Shaking ◽  
Petri Dishes

Abstract Background. In vitro experiments using radiolabeled molecules is fundamental for Positron emission tomography (PET) or single photon emission computed tomography (SPECT) tracer development and various metabolic assays, but no consensus on appropriate incubation conditions exists. Specifically, the use of shaking versus non-shaking conditions, cell number to medium volume and the choice of cell plating material may unintentionally influence cellular oxygenation and medium composition. This is problematic when testing the oxygen-dependence of tracers including 18F-fluoro-2-deoxyglucose (FDG) and hypoxia-selective 2-nitroimidazoles (e.g., 18F-fluoroazomycin-arabinoside, FAZA) or when doing prolonged experiments. The purpose of this study was to assess the influence of various experimental conditions on tracer retention. Methods. Tumor cells were seeded in a) Glass or standard Polystyrene Petri dishes or as b) discrete droplets in polystyrene Petri dishes or on 9 mm glass coverslips positioned in glass Petri dishes. When confluent, cells were pre-equilibrated for 2h to 21%, 0.5% or 0% O2 and FDG or FAZA was added, followed by cell harvest and analysis of radioactivity 1h (FDG) or 3h (FAZA) after. Experiments were conducted with/without orbital shaking. Results. The influence of hypoxia on tracer retention varied widely among cell lines, but shaking-induced convection did not influence uptake. In contrast, hypoxia-driven FAZA, and to some extent FDG, retention was much lower in cells grown on polyethylene than glass. Scaling-down the number of cells did not compromise accuracy. Conclusions. Most experiments can be performed appropriately in the absence of shaking and with downscaling of cell number but the use of conventional plasticware is highly problematic for studies on tracers and drugs that are metabolized and retained or activated at low O2 levels.

scholarly journals In Vitro Hypoxia Responsiveness of [18F]FDG and [18F]FAZA Retention: Influence of Shaking Versus Stagnant Conditions, Glass Versus Polystyrene Substrata and Cell Number Down-Scaling

2020 ◽  
Author(s):  
Morten Busk ◽  
Michael R Horsman ◽  
Jens Overgaard ◽  
Steen Jakobsen
Keyword(s):  
Single Photon ◽  
Photon Emission ◽  
Cell Number ◽  
Medium Composition ◽  
Emission Computed Tomography ◽  
Experimental Conditions ◽  
Positron Emission ◽  
Orbital Shaking ◽  
Petri Dishes

Abstract Background. In vitro experiments using radiolabeled molecules is fundamental for Positron emission tomography (PET) or single photon emission computed tomography (SPECT) tracer development and various metabolic assays, but no consensus on appropriate incubation conditions exists. Specifically, the use of shaking versus non-shaking conditions, cell number to medium volume and the choice of cell plating material may unintentionally influence cellular oxygenation and medium composition. This is problematic when testing the oxygen-dependence of tracers including 18F-fluoro-2-deoxyglucose ([18F]FDG) and hypoxia-selective 2-nitroimidazoles (e.g., 18F-fluoroazomycin-arabinoside, [18F]FAZA) or when doing prolonged experiments. The purpose of this study was to assess the influence of various experimental conditions on tracer retention. Methods. Tumor cells were seeded in a) Glass or standard Polystyrene Petri dishes or as b) discrete droplets in polystyrene Petri dishes or on 9 mm glass coverslips positioned in glass Petri dishes. When confluent, cells were pre-equilibrated for 2h to 21%, 0.5% or 0% O2 and [18F]FDG or [18F]FAZA was added, followed by cell harvest and analysis of radioactivity 1h ([18F]FDG) or 3h ([18F]FAZA) after. Experiments were conducted with/without orbital shaking. Results. The influence of hypoxia on tracer retention varied widely among cell lines, but shaking-induced convection did not influence uptake. In contrast, hypoxia-driven [18F]FAZA, and to some extent [18F]FDG, retention was much lower in cells grown on polyethylene than glass. Scaling-down the number of cells did not compromise accuracy. Conclusions. Tracer retention was similar under stagnant and forced convection conditions suggesting that the former approach may be appropriate even when accurate control of oxygen and tracer availability is required. In contrast, conventional plasticware should be used with caution when studying tracers and drugs that are metabolized and retained or activated at low O2 levels. Downscaling of cell number, by reducing the effective growth area, was feasible, without compromising accuracy.

High non-specific binding of the β1-selective radioligand 2-125I-ICI-H

2003 ◽  
Vol 42 (04) ◽  
pp. 173-180 ◽  
Author(s):  
M. P. Law ◽  
K. Kopka ◽  
St. Wagner ◽  
S. Luthra ◽  
V. W. Pike ◽  
...  
Keyword(s):  
Specific Activity ◽  
Single Photon ◽  
Specific Binding ◽  
Photon Emission ◽  
Radiochemical Yield ◽  
Emission Computed Tomography ◽  
Biodistribution Studies ◽  
Positron Emission

Summary: Aim: As results of cardiac biopsies suggest, myocardial β1-adrenoceptor density is reduced in patients with chronic heart failure. However, changes in cardiac β2-adrenoceptors vary. With suitable radiopharmaceuticals single photon emission computed tomography (SPECT) and positron emission tomography (PET) offer the opportunity to assess β-adrenoceptors non-invasively. Among the novel racemic analogues of the established β1-selective adrenoceptor antagonist ICI 89.406 the iodinated 2-I-ICI-H showed high affinity and selectivity to β1-adrenoceptors in murine ventricular membranes. The aim of this study was its evaluation as a putative sub-type selective β1-adrenergic radioligand in cardiac imaging. Methods: Competition studies in vitro and in vivo were used to investigate the kinetics of 2-I-ICI-H binding to cardiac β-adrenoceptors in mice and rats. In addition, the radiosynthesis of 2-125I-ICI-H from the silylated precursor 2-SiMe3-ICI-H was established. The specific activity was 80 GBq/µmol, the radiochemical yield ranged from 70 to 80%. Results: The unlabelled compound 2-I-ICI-H showed high β1-selectivity and -affinity in the in vitro competition studies. In vivo biodistribution studies apparently showed low affinity to cardiac β-adrenoceptors. The radiolabelled counterpart 2-125I-ICI-H showed a high degree of non-specific binding in vitro and no specific binding to cardiac β1-adrenoceptors in vivo. Conclusion: Because of its high non-specific binding 2-125I-ICI-H is no suitable radiotracer for imaging in vivo.

Correlation between in vitro and in vivo Data of Radiolabeled Peptide for Tumor Targeting

2019 ◽  
Vol 19 (12) ◽  
pp. 950-960
Author(s):  
Soghra Farzipour ◽  
Seyed Jalal Hosseinimehr
Keyword(s):  
Tumor Targeting ◽  
Single Photon ◽  
Specific Binding ◽  
Specific Interaction ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Mixed Effect ◽  
Radiolabeled Peptides

Tumor-targeting peptides have been generally developed for the overexpression of tumor specific receptors in cancer cells. The use of specific radiolabeled peptide allows tumor visualization by single photon emission computed tomography (SPECT) and positron emission tomography (PET) tools. The high affinity and specific binding of radiolabeled peptide are focusing on tumoral receptors. The character of the peptide itself, in particular, its complex molecular structure and behaviors influence on its specific interaction with receptors which are overexpressed in tumor. This review summarizes various strategies which are applied for the expansion of radiolabeled peptides for tumor targeting based on in vitro and in vivo specific tumor data and then their data were compared to find any correlation between these experiments. With a careful look at previous studies, it can be found that in vitro unblock-block ratio was unable to correlate the tumor to muscle ratio and the success of radiolabeled peptide for in vivo tumor targeting. The introduction of modifiers’ approaches, nature of peptides, and type of chelators and co-ligands have mixed effect on the in vitro and in vivo specificity of radiolabeled peptides.

scholarly journals A Nordic survey of CT doses in hybrid PET/CT and SPECT/CT examinations

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Natalie A. Bebbington ◽  
Bryan T. Haddock ◽  
Henrik Bertilsson ◽  
Eero Hippeläinen ◽  
Ellen M. Husby ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Single Photon ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Single Photon Emission ◽  
Positron Emission ◽  
Pet Ct ◽  
Clinical Purpose ◽  
Single Photon Emission Computed ◽  
Photon Emission Computed Tomography

Abstract Background Computed tomography (CT) scans are routinely performed in positron emission tomography (PET) and single photon emission computed tomography (SPECT) examinations globally, yet few surveys have been conducted to gather national diagnostic reference level (NDRL) data for CT radiation doses in positron emission tomography/computed tomography (PET/CT) and single photon emission computed tomography/computed tomography (SPECT/CT). In this first Nordic-wide study of CT doses in hybrid imaging, Nordic NDRL CT doses are suggested for PET/CT and SPECT/CT examinations specific to the clinical purpose of CT, and the scope for optimisation is evaluated. Data on hybrid imaging CT exposures and clinical purpose of CT were gathered for 5 PET/CT and 8 SPECT/CT examinations via designed booklet. For each included dataset for a given facility and scanner type, the computed tomography dose index by volume (CTDIvol) and dose length product (DLP) was interpolated for a 75-kg person (referred to as CTDIvol,75kg and DLP75kg). Suggested NDRL (75th percentile) and achievable doses (50th percentile) were determined for CTDIvol,75kg and DLP75kg according to clinical purpose of CT. Differences in maximum and minimum doses (derived for a 75-kg patient) between facilities were also calculated for each examination and clinical purpose. Results Data were processed from 83 scanners from 43 facilities. Data were sufficient to suggest Nordic NDRL CT doses for the following: PET/CT oncology (localisation/characterisation, 15 systems); infection/inflammation (localisation/characterisation, 13 systems); brain (attenuation correction (AC) only, 11 systems); cardiac PET/CT and SPECT/CT (AC only, 30 systems); SPECT/CT lung (localisation/characterisation, 12 systems); bone (localisation/characterisation, 30 systems); and parathyroid (localisation/characterisation, 13 systems). Great variations in dose were seen for all aforementioned examinations. Greatest differences in DLP75kg for each examination, specific to clinical purpose, were as follows: SPECT/CT lung AC only (27.4); PET/CT and SPECT/CT cardiac AC only (19.6); infection/inflammation AC only (18.1); PET/CT brain localisation/characterisation (16.8); SPECT/CT bone localisation/characterisation (10.0); PET/CT oncology AC only (9.0); and SPECT/CT parathyroid localisation/characterisation (7.8). Conclusions Suggested Nordic NDRL CT doses are presented according to clinical purpose of CT for PET/CT oncology, infection/inflammation, brain, PET/CT and SPECT/CT cardiac, and SPECT/CT lung, bone, and parathyroid. The large variation in doses suggests great scope for optimisation in all 8 examinations.

Neuroimaging and the Origin of Psychiatric Symptoms in Dementia

1997 ◽  
Vol 8 (S3) ◽  
pp. 239-243 ◽  
Author(s):  
David L. Sultzer
Keyword(s):  
Computed Tomography ◽  
Density Functional ◽  
Psychiatric Symptoms ◽  
Functional Neuroimaging ◽  
Single Photon ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Positron Emission ◽  
Single Photon Emission Computed ◽  
Photon Emission Computed Tomography

Neuroimaging studies have contributed greatly to our understanding of Alzheimer's disease and other dementias. Computed tomography and magnetic resonance imaging reveal brain structure and aid in the diagnostic evaluation of patients with cognitive impairment. Functional neuroimaging studies use positron emission tomography, single-photon emission computed tomography, and other methods to measure regional cerebral activity, including metabolic rate, blood flow, and neuroreceptor density. Functional neuroimaging results can be useful clinically and have also been used in a variety of research applications to examine physiologic variables in neuropsychiatric illnesses.

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