scholarly journals Dual-[11C]Tracer Single-Acquisition Positron Emission Tomography Studies

2001 ◽  
Vol 21 (12) ◽  
pp. 1480-1492 ◽  
Author(s):  
Robert A. Koeppe ◽  
David M. Raffel ◽  
Scott E. Snyder ◽  
Edward P. Ficaro ◽  
Michael R. Kilbourn ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Computer Simulations ◽  
Emission Tomography ◽  
Parameter Estimates ◽  
Model Parameters ◽  
Tracer Injection ◽  
Positron Emission ◽  
Dynamic Scan ◽  
Dual Tracer

The ability to study multiple physiologic processes of the brain simultaneously within the same subject would provide a new means to explore the interactions between neurotransmitter systems in vivo. Currently, examination of two distinct neuropharmacologic measures with positron emission tomography (PET) necessitates performing two separate scans spaced in time to allow for radionuclide decay. The authors present results from a dual-tracer PET study protocol using a single dynamic-scan acquisition where the injections of two tracers are offset by several minutes. Kinetic analysis is used to estimate neuropharmacologic parameters for both tracers simultaneously using a combined compartmental model configuration. This approach results in a large reduction in total study time of nearly 2 hours for carbon-11–labeled tracers. As multiple neuropharmacologic measures are obtained at nearly the same time, interventional protocols involving a pair of dual-tracer scans become feasible in a single PET session. Both computer simulations and actual human PET studies were performed using combinations of three different tracers: [11C]flumazenil, N-[11C]methylpiperidinyl propionate, and [11C]dihydrotetrabenazine. Computer simulations of tracer-injection separations of 10 to 30 minutes showed the feasibility of the approach for separations down to 15 to 20 minutes or less. Dual-tracer PET studies were performed in 32 healthy volunteers using injection separations of 10, 15, or 20 minutes. Model parameter estimates for each tracer were similar to those obtained from previously performed single-injection studies. Voxel-by-voxel parametric images were of good quality for injections spaced by 20 minutes and were nearly as good for 15-minute separations, but were degraded noticeably for some model parameters when injections were spaced by only 10 minutes. The authors conclude that dual-tracer single-scan PET is feasible, yields accurate estimates of multiple neuropharmacologic measures, and can be implemented with a number of different radiotracer pairs.

scholarly journals Muscarinic Cholinergic Receptor Measurements with [18F]FP-TZTP: Control and Competition Studies

1998 ◽  
Vol 18 (10) ◽  
pp. 1130-1142 ◽  
Author(s):  
Richard E. Carson ◽  
Dale O. Kiesewetter ◽  
Elaine Jagoda ◽  
Margaret G. Der ◽  
Peter Herscovitch ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Basal Ganglia ◽  
Specific Binding ◽  
Emission Tomography ◽  
Ache Inhibitor ◽  
Parameter Estimates ◽  
Tracer Injection ◽  
Positron Emission ◽  
Muscarinic Cholinergic

[18F]Fluoropropyl-TZTP (FP-TZTP) is a subtype-selective muscarinic cholinergic ligand with potential suitability for studying Alzheimer's disease. Positron emission tomography studies in isofluorane-anesthetized rhesus monkeys were performed to assess the in vivo behavior of this radiotracer. First, control studies (n = 11) were performed to characterize the tracer kinetics and to choose an appropriate model using a metabolite-corrected arterial input function. Second, preblocking studies (n = 4) with unlabeled FP-TZTP were used to measure nonspecific binding. Third, the sensitivity of [18F]FP-TZTP binding to changes in brain acetylcholine (ACh) was assessed by administering physostigmine, an acetylcholinesterase (AChE) inhibitor, by intravenous infusion (100 to 200 μg·kg−1·h−1) beginning 30 minutes before tracer injection (n = 7). Tracer uptake in the brain was rapid with K1 values of 0.4 to 0.6 mL·min−1·mL−1 in gray matter. A model with one tissue compartment was chosen because reliable parameter estimates could not be obtained with a more complex model. Volume of distribution ( V) values, determined from functional images created by pixel-by-pixel fitting, were very similar in cortical regions, basal ganglia, and thalamus, but significantly lower ( P < 0.01) in the cerebellum, consistent with the distribution of M2 cholinergic receptors. Preblocking studies with unlabeled FP-TZTP reduced V by 60% to 70% in cortical and subcortical regions. Physostigmine produced a 35% reduction in cortical specific binding ( P < 0.05), consistent with increased ACh competition. The reduction in basal ganglia (12%) was significantly smaller ( P < 0.05), consistent with its markedly higher AChE activity. These studies indicate that [18F]FP-TZTP should be useful for the in vivo measurement of muscarinic receptors with positron emission tomography.

scholarly journals The Quantitative Analysis of D2-Dopamine Receptors in Baboon Striatum in vivo with 3-N-[2'-18F]Fluoroethylspiperone Using Positron Emission Tomography

1990 ◽  
Vol 10 (5) ◽  
pp. 720-726 ◽  
Author(s):  
S. Jovkar ◽  
K. Wienhard ◽  
G. Pawlik ◽  
H. H. Coenen
Keyword(s):  
Positron Emission Tomography ◽  
Kinetic Model ◽  
Dopamine Receptors ◽  
Specific Activity ◽  
Emission Tomography ◽  
Parameter Estimates ◽  
Model Parameters ◽  
Positron Emission ◽  
Model Configuration

We used the ligand 3- N-[2'-18F]fluoroethylspiperone (FESP), which binds to D2-dopamine receptors in the striatum, and positron emission tomography (PET) to quantify striatal D2-dopamine densities ( Bmax) and binding kinetics in baboon brain in vivo. Sequential PET scans were obtained for 4 h post injection. Various similar models based on a nonlinear kinetic four-compartment model that takes into account the effect of ligand specific activity were used. We investigated the effect of exact model configuration on the reliability of Bmax and other kinetic transfer coefficients. We found that with the ligand FESP and dynamic PET studies, the estimated values of Bmax and other model parameters are sensitive to the choice of model configuration, ligand specific activity, and data analysis technique. The limitations of the reliability of parameter estimates in a complex kinetic model for receptor ligands were studied in simulation calculations. Results showed that the accuracy of estimated values of Bmax is affected by both the ligand binding properties and the injected dose of ligand. The estimated average value of kinetic model parameters was as follows: ligand-receptor dissociation constant k4 = 0.0080 min−1; the product of ligand-receptor association constant and fraction of ligand available to bind to specific receptors f2 ka = 0.0052 (min n M)−1; and D2-dopamine receptor density Bmax = 37.5 pmol g−1.

scholarly journals Dual-Tracer Positron-Emission Tomography for Identification of Culprit Carotid Plaques and Pathophysiology In Vivo

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Nicholas R. Evans ◽  
Jason M. Tarkin ◽  
Mohammed M. Chowdhury ◽  
Elizabeth P.V. Le ◽  
Patrick A. Coughlin ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Emission Tomography ◽  
Carotid Plaques ◽  
Positron Emission ◽  
Dual Tracer

scholarly journals Positron Emission Tomography Compartmental Models: A Basis Pursuit Strategy for Kinetic Modeling

2002 ◽  
Vol 22 (12) ◽  
pp. 1425-1439 ◽  
Author(s):  
Roger N. Gunn ◽  
Steve R. Gunn ◽  
Federico E. Turkheimer ◽  
John A. D. Aston ◽  
Vincent J. Cunningham
Keyword(s):  
Positron Emission Tomography ◽  
Kinetic Modeling ◽  
Impulse Response Function ◽  
Emission Tomography ◽  
Basis Pursuit ◽  
Parameter Estimates ◽  
Binding Studies ◽  
General Applicability ◽  
Positron Emission

A kinetic modeling approach for the quantification of in vivo tracer studies with dynamic positron emission tomography (PET) is presented. The approach is based on a general compartmental description of the tracer's fate in vivo and determines a parsimonious model consistent with the measured data. The technique involves the determination of a sparse selection of kinetic basis functions from an overcomplete dictionary using the method of basis pursuit denoising. This enables the characterization of the systems impulse response function from which values of the systems macro parameters can be estimated. These parameter estimates can be obtained from a region of interest analysis or as parametric images from a voxel-based analysis. In addition, model order estimates are returned that correspond to the number of compartments in the estimated compartmental model. Validation studies evaluate the methods performance against two preexisting data led techniques, namely, graphical analysis and spectral analysis. Application of this technique to measured PET data is demonstrated using [11C]diprenorphine (opiate receptor) and [11C]WAY-100635 (5-HT1A receptor). Although the method is presented in the context of PET neuroreceptor binding studies, it has general applicability to the quantification of PET/SPECT radiotracer studies in neurology, oncology, and cardiology.

scholarly journals Measurement of Radiotracer Concentration in Brain Gray Matter Using Positron Emission Tomography: MRI-Based Correction for Partial Volume Effects

1992 ◽  
Vol 12 (4) ◽  
pp. 571-583 ◽  
Author(s):  
Hans W. Müller-Gärtner ◽  
Jonathan M. Links ◽  
Jerry L. Prince ◽  
R. Nick Bryan ◽  
Elliot McVeigh ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Computer Simulations ◽  
Gray Matter ◽  
Emission Tomography ◽  
Tracer Concentration ◽  
Partial Volume ◽  
Partial Volume Effects ◽  
Positron Emission ◽  
Volume Effects

Accuracy in in vivo quantitation of brain function with positron emission tomography (PET) has often been limited by partial volume effects. This limitation becomes prominent in studies of aging and degenerative brain diseases where partial volume effects vary with different degrees of atrophy. The present study describes how the actual gray matter (GM) tracer concentration can be estimated using an algorithm that relates the regional fraction of GM to partial volume effects. The regional fraction of GM was determined by magnetic resonance imaging (MRI). The procedure is designated as GM PET. In computer simulations and phantom studies, the GM PET algorithm permitted a 100% recovery of the actual tracer concentration in neocortical GM and hippocampus, irrespective of the GM volume. GM PET was applied in a test case of temporal lobe epilepsy revealing an increase in radiotracer activity in GM that was undetected in the PET image before correction for partial volume effects. In computer simulations, errors in the segmentation of GM and errors in registration of PET and MRI images resulted in less than 15% inaccuracy in the GM PET image. In conclusion, GM PET permits accurate determination of the actual radiotracer concentration in human brain GM in vivo. The method differentiates whether a change in the apparent radiotracer concentration reflects solely an alteration in GM volume or rather a change in radiotracer concentration per unit volume of GM.

scholarly journals Development of a blood sample detector for multi-tracer positron emission tomography using gamma spectroscopy

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Carlos Velasco ◽  
Adriana Mota-Cobián ◽  
Jesús Mateo ◽  
Samuel España
Keyword(s):  
Positron Emission Tomography ◽  
Blood Sample ◽  
Pet Imaging ◽  
Spectroscopic Analysis ◽  
Gamma Spectroscopy ◽  
Emission Tomography ◽  
Blood Samples ◽  
Positron Emission

Abstract Background Multi-tracer positron emission tomography (PET) imaging can be accomplished by applying multi-tracer compartment modeling. Recently, a method has been proposed in which the arterial input functions (AIFs) of the multi-tracer PET scan are explicitly derived. For that purpose, a gamma spectroscopic analysis is performed on blood samples manually withdrawn from the patient when at least one of the co-injected tracers is based on a non-pure positron emitter. Alternatively, these blood samples required for the spectroscopic analysis may be obtained and analyzed on site by an automated detection device, thus minimizing analysis time and radiation exposure of the operating personnel. In this work, a new automated blood sample detector based on silicon photomultipliers (SiPMs) for single- and multi-tracer PET imaging is presented, characterized, and tested in vitro and in vivo. Results The detector presented in this work stores and analyzes on-the-fly single and coincidence detected events. A sensitivity of 22.6 cps/(kBq/mL) and 1.7 cps/(kBq/mL) was obtained for single and coincidence events respectively. An energy resolution of 35% full-width-half-maximum (FWHM) at 511 keV and a minimum detectable activity of 0.30 ± 0.08 kBq/mL in single mode were obtained. The in vivo AIFs obtained with the detector show an excellent Pearson’s correlation (r = 0.996, p < 0.0001) with the ones obtained from well counter analysis of discrete blood samples. Moreover, in vitro experiments demonstrate the capability of the detector to apply the gamma spectroscopic analysis on a mixture of 68Ga and 18F and separate the individual signal emitted from each one. Conclusions Characterization and in vivo evaluation under realistic experimental conditions showed that the detector proposed in this work offers excellent sensibility and stability. The device also showed to successfully separate individual signals emitted from a mixture of radioisotopes. Therefore, the blood sample detector presented in this study allows fully automatic AIFs measurements during single- and multi-tracer PET studies.

scholarly journals Correction to: In vivo imaging of early stages of rheumatoid arthritis by α5β1-integrin-targeted positron emission tomography

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Johannes Notni ◽  
Florian T. Gassert ◽  
Katja Steiger ◽  
Peter Sommer ◽  
Wilko Weichert ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Positron Emission Tomography ◽  
In Vivo Imaging ◽  
Emission Tomography ◽  
Early Stages ◽  
Positron Emission ◽  
Α5β1 Integrin

Following publication of the original article [1], the authors have reported an error in the ‘Histopathology’ (under ‘Materials and methods’) section of the article that compromises the reproducibility of the paper.

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