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Knyzeliene A, Shaw R, Balogh V, Tavares AAS. Kinetic Modeling Methods in Preclinical Positron Emission Tomography Imaging. Methods Mol Biol 2024; 2729:441-455. [PMID: 38006511 DOI: 10.1007/978-1-0716-3499-8_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
There is an expanding number of applications for preclinical positron emission tomography (PET) imaging. Kinetic modeling of PET data provides rich multiparameter information on radiotracer uptake and binding in tissue from a single experiment. In this chapter, we provide a practical step-by-step protocol to assist with collection of PET data for kinetic modeling studies in rats and mice.
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Affiliation(s)
| | - Robert Shaw
- Queen's Medical Research Institute, Edinburgh, UK
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2
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Kumar M, Salem K, Jeffery JJ, Fowler AM. PET Imaging of Estrogen Receptors Using 18F-Based Radioligands. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2022; 2418:129-151. [PMID: 35119664 DOI: 10.1007/978-1-0716-1920-9_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In vivo molecular imaging of estrogen receptor alpha (ER) can be performed via positron emission tomography (PET) using ER-specific radioligands, such as 16α-[18F]fluoro-17β-estradiol (18F-FES). 18F-FES is a radiopharmaceutical recently approved by the United States Food and Drug Administration for use with PET imaging to detect ER+ lesions in patients with recurrent or metastatic breast cancer as an adjunct to biopsy. 18F-FES PET imaging has been used in clinical studies and preclinical research to assess whole-body ER protein expression and ligand binding function across multiple metastatic sites, to demonstrate inter-tumoral and temporal heterogeneity of ER expression, to quantify the pharmacodynamic effects of ER antagonist treatment, and to predict endocrine therapy response. 18F-FES PET has also been studied for imaging ER in endometrial and ovarian cancer. This chapter details the experimental protocol for 18F-FES PET imaging of ER in preclinical tumor xenograft models. Consistent adherence to key methodologic details will facilitate obtaining meaningful and reproducible 18F-FES PET preclinical imaging results, which could yield additional insight for clinical trials regarding imaging biomarkers and oncologic therapy.
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Affiliation(s)
- Manoj Kumar
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Department of Radiology, Canary Center at Stanford for Cancer Early Detection, Stanford School of Medicine, Palo Alto, CA, USA
| | - Kelley Salem
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | | | - Amy M Fowler
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
- University of Wisconsin Carbone Cancer Center, Madison, WI, USA.
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
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3
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Convert L, Sarrhini O, Paillé M, Salem N, Charette PG, Lecomte R. The ultra high sensitivity blood counter: a compact, MRI-compatible, radioactivity counter for pharmacokinetic studies in µL volumes. Biomed Phys Eng Express 2022; 8. [PMID: 35038694 DOI: 10.1088/2057-1976/ac4c29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Accepted: 01/17/2022] [Indexed: 11/11/2022]
Abstract
Quantification of physiological parameters in preclinical pharmacokinetic studies based on nuclear imaging requires the monitoring of arterial radioactivity over time, known as the arterial input function (AIF). Continuous derivation of the AIF in rodent models is very challenging because of the limited blood volume available for sampling. To address this challenge, an Ultra High Sensitivity Blood Counter (UHS-BC) was developed. The device detects beta particles in real-time using silicon photodiodes, custom low-noise electronics, and 3D-printed plastic cartridges to hold standard catheters. Two prototypes were built and characterized in two facilities. Sensitivities up to 39% for18F and 58% for11C-based positron emission tomography (PET) tracers were demonstrated.99mTc and125I based Single Photon Emission Computed Tomography (SPECT) tracers were detected with greater than 3% and 10% sensitivity, respectively, opening new applications in nuclear imaging and fundamental biology research. Measured energy spectra show all relevant peaks down to a minimum detectable energy of 20 keV. The UHS-BC was shown to be highly reliable, robust towards parasitic background radiation and electromagnetic interference in the PET or MRI environment. The UHS-BC provides reproducible results under various experimental conditions and was demonstrated to be stable over days of continuous operation. Animal experiments showed that the UHS-BC performs accurate AIF measurements using low detection volumes suitable for small animal models in PET, SPECT and PET/MRI investigations. This tool will help to reduce the time and number of animals required for pharmacokinetic studies, thus increasing the throughput of new drug development.
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Affiliation(s)
- Laurence Convert
- Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke, 3000 boul. de l'Université, Parc Innovation, Pavillon P2, Sherbrooke, Sherbrooke, Quebec, J1K0A5, CANADA
| | - Otman Sarrhini
- Sherbrooke Molecular Imaging Centre of CRCHUS and Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, 3001 12 ave Nord, Sherbrooke, Quebec, J1H 5N4, CANADA
| | - Maxime Paillé
- Sherbrooke Molecular Imaging Centre of CRCHUS and Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, 3001 12 Ave Nord, Sherbrooke, Quebec, J1H 5N4, CANADA
| | - Nicolas Salem
- Biogen Idec Inc, 225 Binney St, Cambridge, Massachusetts, 02142, UNITED STATES
| | - Paul Gilles Charette
- Laboratoire Nanotechnologies Nanosystèmes (LN2) - CNRS UMI-3463, Université de Sherbrooke, 3000 boul. de l'Université, Parc Innovation, Pavillon P2, Sherbrooke, Quebec, J1K 0A5, CANADA
| | - Roger Lecomte
- Sherbrooke Molecular Imaging Centre of CRCHUS and Department of Nuclear Medicine and Radiobiology, Universite de Sherbrooke, 3001 12 Ave Nord, Sherbrooke, Quebec, J1K 2R1, CANADA
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Bini J, Lattin CR, Toyonaga T, Finnema SJ, Carson R. Optimized Methodology for Reference Region and Image-Derived Input Function Kinetic Modeling in Preclinical PET. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2022; 6:454-462. [PMID: 36185820 PMCID: PMC9524424 DOI: 10.1109/trpms.2021.3088606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
PET imaging of small animals is often used for assessing biodistribution of a novel radioligand and pharmacology in small animal models of disease. PET acquisition and processing settings may affect reference region or image-derived input function (IDIF) kinetic modeling estimates. We examined four different factors in comparing quantitative results: 1) effect of reconstruction algorithm, 2) number of MAP iterations, 3) strength of the MAP prior, and 4) Attenuation and scatter. The effect of these parameters has not been explored for small-animal reference region and IDIF kinetic modeling approaches. Dynamic PET/CT scans were performed in 3 species with 3 different tracers: house sparrows with [11C]raclopride, rats with [18F]AS2471907 (11βHSD1) and mice with [11C]UCB-J (SV2A). FBP yielded lower kinetic modeling estimates compared to 3D-OSEM-MAP reconstructions, in sparrow and rat studies. Target resolutions (MAP prior strength) of 1.5 and 3.0mm demonstrated reduced VT in rats but only 3.0mm reduced BP ND in sparrows. Therefore, use of the highest target resolution (0.8mm) is warranted. We demonstrated using kinetic modeling that forgoing CT-based attenuation and scatter correction may be appropriate to improve animal throughput when using short-lived radioisotopes in sparrows and mice. This work provides recommendations and a framework for future optimization of kinetic modeling for preclinical PET methodology with novel radioligands.
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Affiliation(s)
- Jason Bini
- Yale School of Medicine, New Haven, CT, USA
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GABA A Receptors in the Mongolian Gerbil: a PET Study Using [ 18F]Flumazenil to Determine Receptor Binding in Young and Old Animals. Mol Imaging Biol 2021; 22:335-347. [PMID: 31102039 DOI: 10.1007/s11307-019-01371-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE Plastic changes in the central auditory system involving the GABAergic system accompany age-related hearing loss. Such processes can be investigated with positron emission tomography (PET) imaging using [18F]flumazenil ([18F]FMZ). Here, [18F]FMZ PET-based modeling approaches allow a simple and reliable quantification of GABAA receptor binding capacity revealing regional differences and age-related changes. PROCEDURES Sixty-minute list-mode PET acquisitions were performed in 9 young (range 5-6 months) and 11 old (range 39-42 months) gerbils, starting simultaneously with the injection of [18F]FMZ via femoral vein. Non-displaceable binding potentials (BPnd) with pons as reference region were calculated for auditory cortex (AC), inferior colliculus (IC), medial geniculate body (MGB), somatosensory cortex (SC), and cerebellum (CB) using (i) a two-tissue compartment model (2TCM), (ii) the Logan plot with image-derived blood-input (Logan (BI)), (iii) a simplified reference tissue model (SRTM), and (iv) the Logan reference model (Logan (RT)). Statistical parametric mapping analysis (SPM) comparing young and old gerbils was performed using 3D parametric images for BPnd based on SRTM. Results were verified with in vitro autoradiography from five additional young gerbils. Model assessment included the Akaike information criterion (AIC). Hearing was evaluated using auditory brainstem responses. RESULTS BPnd differed significantly between models (p < 0.0005), showing the smallest mean difference between 2TCM as reference and SRTM as simplified procedure. SRTM revealed the lowest AIC values. Both volume of distribution (r2 = 0.8793, p = 0.018) and BPnd (r2 = 0.8216, p = 0.034) correlated with in vitro autoradiography data. A significant age-related decrease of receptor binding was observed in auditory (AC, IC, MGB) and other brain regions (SC and CB) (p < 0.0001, unpaired t test) being confirmed by SPM using pons as reference (p < 0.0001, uncorrected). CONCLUSION Imaging of GABAA receptor binding capacity in gerbils using [18F]FMZ PET revealed SRTM as a simple and robust quantification method of GABAA receptors. Comparison of BPnd in young and old gerbils demonstrated an age-related decrease of GABAA receptor binding.
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Abstract
Positron emission tomography (PET) is a non-invasive imaging technology employed to describe metabolic, physiological, and biochemical processes in vivo. These include receptor availability, metabolic changes, neurotransmitter release, and alterations of gene expression in the brain. Since the introduction of dedicated small-animal PET systems along with the development of many novel PET imaging probes, the number of PET studies using rats and mice in basic biomedical research tremendously increased over the last decade. This article reviews challenges and advances of quantitative rodent brain imaging to make the readers aware of its physical limitations, as well as to inspire them for its potential applications in preclinical research. In the first section, we briefly discuss the limitations of small-animal PET systems in terms of spatial resolution and sensitivity and point to possible improvements in detector development. In addition, different acquisition and post-processing methods used in rodent PET studies are summarized. We further discuss factors influencing the test-retest variability in small-animal PET studies, e.g., different receptor quantification methodologies which have been mainly translated from human to rodent receptor studies to determine the binding potential and changes of receptor availability and radioligand affinity. We further review different kinetic modeling approaches to obtain quantitative binding data in rodents and PET studies focusing on the quantification of endogenous neurotransmitter release using pharmacological interventions. While several studies have focused on the dopamine system due to the availability of several PET tracers which are sensitive to dopamine release, other neurotransmitter systems have become more and more into focus and are described in this review, as well. We further provide an overview of latest genome engineering technologies, including the CRISPR/Cas9 and DREADD systems that may advance our understanding of brain disorders and function and how imaging has been successfully applied to animal models of human brain disorders. Finally, we review the strengths and opportunities of simultaneous PET/magnetic resonance imaging systems to study drug-receptor interactions and challenges for the translation of PET results from bench to bedside.
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Bahri S, Horowitz M, Malbert CH. Inward Glucose Transfer Accounts for Insulin-Dependent Increase in Brain Glucose Metabolism Associated with Diet-Induced Obesity. Obesity (Silver Spring) 2018; 26:1322-1331. [PMID: 29956494 DOI: 10.1002/oby.22243] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 05/21/2018] [Indexed: 02/05/2023]
Abstract
OBJECTIVE There is a general agreement that there are changes in brain metabolism in insulin-resistant individuals during conditions of hyperinsulinemia. However, the impact on obesity is unclear, and the metabolic constants underlying these modifications are unknown. The aim of this study was to evaluate these changes in a large animal model of diet-induced obesity. METHODS Twenty adult miniature pigs were fed with either an obesogenic diet or a regular diet for 5 months. At that time, fat deposition was evaluated using computed tomography scanning, and 18 fluorodeoxyglucose positron emission tomography images were acquired dynamically both in the fasted state and during a euglycemic-hyperinsulinemic clamp. Glucose uptake rates and pixel-wise modeled brain volumes were calculated together with brain connectivity. RESULTS Whole-body insulin sensitivity was reduced by more than 50% in the obesity group. During insulin stimulation, whole-brain insulin-induced increased glucose uptake was unaltered in lean animals but increased markedly in the animals with obesity. The increased glucose uptake reflected an increase in the inward transfer without changes in phosphorylation or outward brain transport. Connectivity was increased in the animals with obesity CONCLUSIONS: Diet-induced obesity is associated with an increase in insulin-stimulated brain glucose uptake as a consequence of a larger inward transfer. These changes occurred together with an increased connectivity in reference to regions associated with memory recollection.
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Affiliation(s)
- Senda Bahri
- Aniscan Unit, Department of Human Nutrition, Institut National de la Recherche Agronomique, Saint-Gilles, France
- Research Unit UR/11ES09, University of Tunis El Manar, Tunis, Tunisia
| | - Michael Horowitz
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Charles-Henri Malbert
- Aniscan Unit, Department of Human Nutrition, Institut National de la Recherche Agronomique, Saint-Gilles, France
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Dai Y, Chen X, Yin J, Wang G, Wang B, Zhan Y, Nie Y, Wu K, Liang J. Investigation of the influence of sampling schemes on quantitative dynamic fluorescence imaging. BIOMEDICAL OPTICS EXPRESS 2018; 9:1859-1870. [PMID: 29675325 PMCID: PMC5905930 DOI: 10.1364/boe.9.001859] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 02/22/2018] [Accepted: 03/18/2018] [Indexed: 05/08/2023]
Abstract
Dynamic optical data from a series of sampling intervals can be used for quantitative analysis to obtain meaningful kinetic parameters of probe in vivo. The sampling schemes may affect the quantification results of dynamic fluorescence imaging. Here, we investigate the influence of different sampling schemes on the quantification of binding potential (BP) with theoretically simulated and experimentally measured data. Three groups of sampling schemes are investigated including the sampling starting point, sampling sparsity, and sampling uniformity. In the investigation of the influence of the sampling starting point, we further summarize two cases by considering the missing timing sequence between the probe injection and sampling starting time. Results show that the mean value of BP exhibits an obvious growth trend with an increase in the delay of the sampling starting point, and has a strong correlation with the sampling sparsity. The growth trend is much more obvious if throwing the missing timing sequence. The standard deviation of BP is inversely related to the sampling sparsity, and independent of the sampling uniformity and the delay of sampling starting time. Moreover, the mean value of BP obtained by uniform sampling is significantly higher than that by using the non-uniform sampling. Our results collectively suggest that a suitable sampling scheme can help compartmental modeling of dynamic fluorescence imaging provide more accurate results and simpler operations.
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Affiliation(s)
- Yunpeng Dai
- Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education & School of Life Science and Technology, Xidian University, Xi'an, Shaanxi 710071, China
- These authors contributed equally to this work
| | - Xueli Chen
- Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education & School of Life Science and Technology, Xidian University, Xi'an, Shaanxi 710071, China
- These authors contributed equally to this work
| | - Jipeng Yin
- State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
- These authors contributed equally to this work
| | - Guodong Wang
- State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Bo Wang
- Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education & School of Life Science and Technology, Xidian University, Xi'an, Shaanxi 710071, China
| | - Yonghua Zhan
- Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education & School of Life Science and Technology, Xidian University, Xi'an, Shaanxi 710071, China
| | - Yongzhan Nie
- State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Kaichun Wu
- State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Jimin Liang
- Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education & School of Life Science and Technology, Xidian University, Xi'an, Shaanxi 710071, China
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Wong YC, Ilkova T, van Wijk RC, Hartman R, de Lange ECM. Development of a population pharmacokinetic model to predict brain distribution and dopamine D2 receptor occupancy of raclopride in non-anesthetized rat. Eur J Pharm Sci 2017; 111:514-525. [PMID: 29106979 DOI: 10.1016/j.ejps.2017.10.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 09/13/2017] [Accepted: 10/22/2017] [Indexed: 12/11/2022]
Abstract
BACKGROUND Raclopride is a selective antagonist of the dopamine D2 receptor. It is one of the most frequently used in vivo D2 tracers (at low doses) for assessing drug-induced receptor occupancy (RO) in animals and humans. It is also commonly used as a pharmacological blocker (at high doses) to occupy the available D2 receptors and antagonize the action of dopamine or drugs on D2 in preclinical studies. The aims of this study were to comprehensively evaluate its pharmacokinetic (PK) profiles in different brain compartments and to establish a PK-RO model that could predict the brain distribution and RO of raclopride in the freely moving rat using a LC-MS based approach. METHODS Rats (n=24) received a 10-min IV infusion of non-radiolabeled raclopride (1.61μmol/kg, i.e. 0.56mg/kg). Plasma and the brain tissues of striatum (with high density of D2 receptors) and cerebellum (with negligible amount of D2 receptors) were collected. Additional microdialysis experiments were performed in some rats (n=7) to measure the free drug concentration in the extracellular fluid of the striatum and cerebellum. Raclopride concentrations in all samples were analyzed by LC-MS. A population PK-RO model was constructed in NONMEM to describe the concentration-time profiles in the unbound plasma, brain extracellular fluid and brain tissue compartments and to estimate the RO based on raclopride-D2 receptor binding kinetics. RESULTS In plasma raclopride showed a rapid distribution phase followed by a slower elimination phase. The striatum tissue concentrations were consistently higher than that of cerebellum tissue throughout the whole experimental period (10-h) due to higher non-specific tissue binding and D2 receptor binding in the striatum. Model-based simulations accurately predicted the literature data on rat plasma PK, brain tissue PK and D2 RO at different time points after intravenous or subcutaneous administration of raclopride at tracer dose (RO <10%), sub-pharmacological dose (RO 10%-30%) and pharmacological dose (RO >30%). CONCLUSION For the first time a predictive model that could describe the quantitative in vivo relationship between dose, PK and D2 RO of raclopride in non-anesthetized rat was established. The PK-RO model could facilitate the selection of optimal dose and dosing time when raclopride is used as tracer or as pharmacological blocker in various rat studies. The LC-MS based approach, which doses and quantifies a non-radiolabeled tracer, could be useful in evaluating the systemic disposition and brain kinetics of tracers.
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Affiliation(s)
- Yin Cheong Wong
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Trayana Ilkova
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Rob C van Wijk
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Robin Hartman
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Elizabeth C M de Lange
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.
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Dai Y, Chen X, Yin J, Kang X, Wang G, Zhang X, Nie Y, Wu K, Liang J. Investigation of injection dose and camera integration time on quantifying pharmacokinetics of a Cy5.5-GX1 probe with dynamic fluorescence imaging in vivo. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:86001. [PMID: 27488591 DOI: 10.1117/1.jbo.21.8.086001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 07/14/2016] [Indexed: 05/24/2023]
Abstract
The aim of this article is to investigate the influence of a tracer injection dose (ID) and camera integration time (IT) on quantifying pharmacokinetics of Cy5.5-GX1 in gastric cancer BGC-823 cell xenografted mice. Based on three factors, including whether or not to inject free GX1, the ID of Cy5.5-GX1, and the camera IT, 32 mice were randomly divided into eight groups and received 60-min dynamic fluorescence imaging. Gurfinkel exponential model (GEXPM) and Lammertsma simplified reference tissue model (SRTM) combined with a singular value decomposition analysis were used to quantitatively analyze the acquired dynamic fluorescent images. The binding potential (Bp) and the sum of the pharmacokinetic rate constants (SKRC) of Cy5.5-GX1 were determined by the SRTM and EXPM, respectively. In the tumor region, the SKRC value exhibited an obvious trend with change in the tracer ID, but the Bp value was not sensitive to it. Both the Bp and SKRC values were independent of the camera IT. In addition, the ratio of the tumor-to-muscle region was correlated with the camera IT but was independent of the tracer ID. Dynamic fluorescence imaging in conjunction with a kinetic analysis may provide more quantitative information than static fluorescence imaging, especially for a priori information on the optimal ID of targeted probes for individual therapy.
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Affiliation(s)
- Yunpeng Dai
- Xidian University, Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education and School of Life Science and Technology, 266 Xinglong Section of Xifeng Road, Xi'an 710071, China
| | - Xueli Chen
- Xidian University, Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education and School of Life Science and Technology, 266 Xinglong Section of Xifeng Road, Xi'an 710071, China
| | - Jipeng Yin
- Fourth Military Medical University, State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, 127 Changle Road, Xi'an 710032, China
| | - Xiaoyu Kang
- Fourth Military Medical University, State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, 127 Changle Road, Xi'an 710032, China
| | - Guodong Wang
- Fourth Military Medical University, State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, 127 Changle Road, Xi'an 710032, China
| | - Xianghan Zhang
- Xidian University, Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education and School of Life Science and Technology, 266 Xinglong Section of Xifeng Road, Xi'an 710071, China
| | - Yongzhan Nie
- Fourth Military Medical University, State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, 127 Changle Road, Xi'an 710032, China
| | - Kaichun Wu
- Fourth Military Medical University, State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Xijing Hospital, 127 Changle Road, Xi'an 710032, China
| | - Jimin Liang
- Xidian University, Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education and School of Life Science and Technology, 266 Xinglong Section of Xifeng Road, Xi'an 710071, China
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Convert L, Lebel R, Gascon S, Fontaine R, Pratte JF, Charette P, Aimez V, Lecomte R. Real-Time Microfluidic Blood-Counting System for PET and SPECT Preclinical Pharmacokinetic Studies. J Nucl Med 2016; 57:1460-6. [DOI: 10.2967/jnumed.115.162768] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 03/29/2016] [Indexed: 02/03/2023] Open
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Evans E, Buonincontri G, Izquierdo D, Methner C, Hawkes RC, Ansorge RE, Krieg T, Carpenter TA, Sawiak SJ. Combining MRI with PET for partial volume correction improves image-derived input functions in mice. IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2015; 62:628-633. [PMID: 26213413 PMCID: PMC4510926 DOI: 10.1109/tns.2015.2433897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Accurate kinetic modelling using dynamic PET requires knowledge of the tracer concentration in plasma, known as the arterial input function (AIF). AIFs are usually determined by invasive blood sampling, but this is prohibitive in murine studies due to low total blood volumes. As a result of the low spatial resolution of PET, image-derived input functions (IDIFs) must be extracted from left ventricular blood pool (LVBP) ROIs of the mouse heart. This is challenging because of partial volume and spillover effects between the LVBP and myocardium, contaminating IDIFs with tissue signal. We have applied the geometric transfer matrix (GTM) method of partial volume correction (PVC) to 12 mice injected with 18F-FDG affected by a Myocardial Infarction (MI), of which 6 were treated with a drug which reduced infarction size [1]. We utilised high resolution MRI to assist in segmenting mouse hearts into 5 classes: LVBP, infarcted myocardium, healthy myocardium, lungs/body and background. The signal contribution from these 5 classes was convolved with the point spread function (PSF) of the Cambridge split magnet PET scanner and a non-linear fit was performed on the 5 measured signal components. The corrected IDIF was taken as the fitted LVBP component. It was found that the GTM PVC method could recover an IDIF with less contamination from spillover than an IDIF extracted from PET data alone. More realistic values of Ki were achieved using GTM IDIFs, which were shown to be significantly different (p<0.05) between the treated and untreated groups.
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Affiliation(s)
- Eleanor Evans
- Wolfson Brain Imaging Centre, University of Cambridge, Cambridge, UK, CB2 0QQ ( )
| | - Guido Buonincontri
- Wolfson Brain Imaging Centre and the Department of Medicine, University of Cambridge, Cambridge, UK, CB2 0QQ ( )
| | - David Izquierdo
- Athinoula A. Martinos Center for Biomedical Imaging, 149 Thirteenth Street, Suite 2301, Charlestown, MA, 02129 ( )
| | - Carmen Methner
- Department of Medicine, University of Cambridge and is now at Oregon Health and Science University, Portland, OR, 97239 ( )
| | - Rob C Hawkes
- Wolfson Brain Imaging Centre, University of Cambridge, Cambridge, UK, CB2 0QQ ( )
| | - Richard E Ansorge
- Department of Physics, University of Cambridge, Cambridge, UK, CB3 0HE ( )
| | - Thomas Krieg
- Member of the Department of Medicine, University of Cambridge, Cambridge, UK, CB2 0QQ ( )
| | - T Adrian Carpenter
- Wolfson Brain Imaging Centre, University of Cambridge, Cambridge, UK, CB2 0QQ ( )
| | - Stephen J Sawiak
- Member of both the Wolfson Brain Imaging Centre, and the Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge, UK, CB2 3EB ( )
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Roehrbacher F, Bankstahl JP, Bankstahl M, Wanek T, Stanek J, Sauberer M, Muellauer J, Schroettner T, Langer O, Kuntner C. Development and performance test of an online blood sampling system for determination of the arterial input function in rats. EJNMMI Phys 2015; 2:1. [PMID: 26501803 PMCID: PMC4545758 DOI: 10.1186/s40658-014-0106-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 08/27/2014] [Indexed: 11/25/2022] Open
Abstract
Background For positron emission tomography (PET) kinetic modelling, an accurate determination of the arterial input function is required. In this study, a blood sampling system was developed and tested using different radiotracers in rats. Methods The detector consists of pairs of lutetium yttrium oxyorthosilicate (LYSO) detectors, photomultiplier tubes and lead shield assembled within a steel casing working in coincidence mode. Rats were cannulated with microtubes in the femoral artery and vein for arterial blood sampling as well as administration of the PET tracers. Connected PTFE microtubes were centred between the LYSO crystals using a special holder. To enhance sensitivity, three layers with two coils were used. A flexible tube pump was used to ensure a constant blood flow. Performance of the detector was assessed with [18F]fludeoxyglucose (FDG), [18F]ciprofloxacin, (R)-[11C]verapamil, [11C]tariquidar, [11C]mephobarbital and [11C]MC113. Obtained input function curves were compared with manual samples drawn every 5 s during the first 3 min and further on at 5, 10, 20, 30, 40, 50 and 60 min after radiotracer injection. After manual sampling, an arterio/venous shunt was established. Shape and area-under-the-curve (AUC; Bq/μl*h) of the input functions were evaluated. Results The developed detector system provided an absolute sensitivity of 6.5%. Maximum peak values agreed well between manual samples and the detector with a mean difference of −0.4% ± 7.0% (max 12.0%, min −9.9%). AUC values also exhibited an excellent correlation (R = 0.996) between manual sampling and detector measurements with a mean difference of 9.3% ± 9.7% (max 24.1%, min −3.2%). The system was able to measure peak blood activity concentration levels of 110 to 2,000 Bq/μl which corresponds to injected activities from 5.5 to 100 MBq depending on the used radiotracer, applied volume and weight of the animal. Conclusions This study demonstrates that the developed blood sampling system can be used for in vivo small animal PET studies in rats in a reliable way. The usage of the systems enhances the accuracy of the input curve as handling of small blood samples especially with low activity (as for C-11) is prone to measurement errors. Additionally, the radiation dose of the experimenters can be reduced, as it is not required anymore to continuously draw samples where the personal is in close contact to the radioactive animals and blood.
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Affiliation(s)
- Friedrich Roehrbacher
- Radiation Safety and Applications, Seibersdorf Laboratories GmbH, Seibersdorf, 2444, Austria.
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Hannover, 30625, Germany.
| | - Marion Bankstahl
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine, Hannover, 30559, Germany. .,Centre for Systems Neuroscience, Hannover, 30559, Germany.
| | - Thomas Wanek
- Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, 2444, Austria.
| | - Johann Stanek
- Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, 2444, Austria.
| | - Michael Sauberer
- Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, 2444, Austria.
| | - Julia Muellauer
- Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, 2444, Austria.
| | - Thales Schroettner
- Radiation Safety and Applications, Seibersdorf Laboratories GmbH, Seibersdorf, 2444, Austria.
| | - Oliver Langer
- Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, 2444, Austria. .,Department of Clinical Pharmacology, Medical University of Vienna, Vienna, 1090, Austria.
| | - Claudia Kuntner
- Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, 2444, Austria.
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Prasad R, Zaidi H. Scatter characterization and correction for simultaneous multiple small-animal PET imaging. Mol Imaging Biol 2014; 16:199-209. [PMID: 23990147 DOI: 10.1007/s11307-013-0683-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
PURPOSE The rapid growth and usage of small-animal positron emission tomography (PET) in molecular imaging research has led to increased demand on PET scanner's time. One potential solution to increase throughput is to scan multiple rodents simultaneously. However, this is achieved at the expense of deterioration of image quality and loss of quantitative accuracy owing to enhanced effects of photon attenuation and Compton scattering. The purpose of this work is, first, to characterize the magnitude and spatial distribution of the scatter component in small-animal PET imaging when scanning single and multiple rodents simultaneously and, second, to assess the relevance and evaluate the performance of scatter correction under similar conditions. METHODS The LabPET™-8 scanner was modelled as realistically as possible using Geant4 Application for Tomographic Emission Monte Carlo simulation platform. Monte Carlo simulations allow the separation of unscattered and scattered coincidences and as such enable detailed assessment of the scatter component and its origin. Simple shape-based and more realistic voxel-based phantoms were used to simulate single and multiple PET imaging studies. The modelled scatter component using the single-scatter simulation technique was compared to Monte Carlo simulation results. PET images were also corrected for attenuation and the combined effect of attenuation and scatter on single and multiple small-animal PET imaging evaluated in terms of image quality and quantitative accuracy. RESULTS A good agreement was observed between calculated and Monte Carlo simulated scatter profiles for single- and multiple-subject imaging. In the LabPET™-8 scanner, the detector covering material (kovar) contributed the maximum amount of scatter events while the scatter contribution due to lead shielding is negligible. The out-of field-of-view (FOV) scatter fraction (SF) is 1.70, 0.76, and 0.11% for lower energy thresholds of 250, 350, and 400 keV, respectively. The increase in SF ranged between 25 and 64% when imaging multiple subjects (three to five) of different size simultaneously in comparison to imaging a single subject. The spill-over ratio (SOR) increases with increasing the number of subjects in the FOV. Scatter correction improved the SOR for both water and air cold compartments of single and multiple imaging studies. The recovery coefficients for different body parts of the mouse whole-body and rat whole-body anatomical models were improved for multiple imaging studies following scatter correction. CONCLUSIONS The magnitude and spatial distribution of the scatter component in small-animal PET imaging of single and multiple subjects simultaneously were characterized, and its impact was evaluated in different situations. Scatter correction improves PET image quality and quantitative accuracy for single rat and simultaneous multiple mice and rat imaging studies, whereas its impact is insignificant in single mouse imaging.
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Affiliation(s)
- Rameshwar Prasad
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, 1211, Geneva, Switzerland
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Grafström J, Stone-Elander S. Comparison of methods for evaluating radiolabelled Annexin A5 uptake in pre-clinical PET oncological studies. Nucl Med Biol 2014; 41:793-800. [PMID: 25156038 DOI: 10.1016/j.nucmedbio.2014.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 07/15/2014] [Accepted: 07/21/2014] [Indexed: 12/16/2022]
Abstract
PURPOSE The uptakes of radiolabel led AnnexinA5 (AnxA5) and a size-matched control protein in experimental tumours were evaluated by kinetic analyses and compared with standard uptake values (SUVs) to investigate whether the method of analysis may impact on the conclusions that can be drawn. PROCEDURES PET scans of the (11)C-labelled proteins performed in untreated and doxorubicin-treated mice with head and neck carcinoma xenografts were retrospectively analysed. The appropriateness of using the Logan graphical analyses for reversibly binding radiotracers in these models was evaluated and confirmed. Distribution volume ratios (DVRs) of the regions of interest to reference muscle tissue were compared to those based on the image-derived input function from arterial blood. SUVs were calculated in the same individuals. RESULTS DVRs based on reference muscle tissue gave results similar to those based on the arterial blood and may be preferred since they are simpler to calculate. In the inter-group comparisons of baseline versus chemotherapy treatment or AnxA5 versus control protein, differences in DVR quantifications had a 20- to 40-fold higher statistical significance than differences in SUVs. As quantified using the control protein, the amount of free ligand in the vascular space of tumours may be large due to enhanced permeability and retention (EPR) contributions at baseline and affected during treatment, which has implications for quantifications of the specifically bound radioligand. CONCLUSIONS These results demonstrate that the quantification method as well as the controls used can be important for interpreting the uptake in tumours of the medium-sized protein ligand AnxA5 and its use in monitoring the effects of therapy on cell death in the tumours. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE These results provide additional support for the recognition that more detailed investigations on the effects of the tumour microenvironment on the targeting capability of imaging radiopharmaceuticals are needed.
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Affiliation(s)
- Jonas Grafström
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Sharon Stone-Elander
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; PET Radiochemistry, Neuroradiology Department, R3:00, Karolinska University Hospital Solna, Stockholm, Sweden.
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16
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Kuntner C. Kinetic modeling in pre-clinical positron emission tomography. Z Med Phys 2014; 24:274-85. [PMID: 24629308 DOI: 10.1016/j.zemedi.2014.02.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 02/11/2014] [Accepted: 02/11/2014] [Indexed: 12/11/2022]
Abstract
Pre-clinical positron emission tomography (PET) has evolved in the last few years from pure visualization of radiotracer uptake and distribution towards quantification of the physiological parameters. For reliable and reproducible quantification the kinetic modeling methods used to obtain relevant parameters of radiotracer tissue interaction are important. Here we present different kinetic modeling techniques with a focus on compartmental models including plasma input models and reference tissue input models. The experimental challenges off deriving the plasma input function in rodents and the effect of anesthesia are discussed. Finally, in vivo application of kinetic modeling in various areas of pre-clinical research is presented and compared to human data.
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Affiliation(s)
- Claudia Kuntner
- Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, Austria.
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Miederer I, Maus S, Zwiener I, Podoprygorina G, Meshcheryakov D, Lutz B, Schreckenberger M. Evaluation of cannabinoid type 1 receptor expression in the rat brain using [18F]MK-9470 microPET. Eur J Nucl Med Mol Imaging 2013; 40:1739-47. [DOI: 10.1007/s00259-013-2483-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 06/04/2013] [Indexed: 02/02/2023]
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Hag AMF, Ripa RS, Pedersen SF, Bodholdt RP, Kjaer A. Small animal positron emission tomography imaging and in vivo studies of atherosclerosis. Clin Physiol Funct Imaging 2013; 33:173-85. [PMID: 23522010 DOI: 10.1111/cpf.12017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 11/30/2012] [Indexed: 12/31/2022]
Abstract
Atherosclerosis is a growing health challenge globally, and despite our knowledge of the disease has increased over the last couple of decades, many unanswered questions remain. As molecular imaging can be used to visualize, characterize and measure biological processes at the molecular and cellular levels in living systems, this technology represents an opportunity to investigate some of these questions in vivo. In addition, molecular imaging may be translated into clinical use and eventually pave the way for more personalized treatment regimes in patients. Here, we review the current knowledge obtained from in vivo positron emission tomography studies of atherosclerosis performed in small animals.
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Affiliation(s)
- Anne Mette Fisker Hag
- Cluster for Molecular Imaging, Faculty of Health and Medical Sciences, Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
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Convert L, Baril FG, Boisselle V, Pratte JF, Fontaine R, Lecomte R, Charette PG, Aimez V. Blood compatible microfluidic system for pharmacokinetic studies in small animals. LAB ON A CHIP 2012; 12:4683-4692. [PMID: 23000896 DOI: 10.1039/c2lc40550d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
New radiotracer developments for nuclear medicine imaging require the analysis of blood as a function of time in small animal models. A microfluidic device was developed to monitor the radioactivity concentration in the blood of rats and mice in real time. The microfluidic technology enables a large capture solid angle and a reduction in the separation distance between the sample and detector, thus increasing the detection efficiency. This in turn allows a reduction of the required detection volume without compromising sensitivity, an important advantage with rodent models having a small total blood volume (a few ml). A robust fabrication process was developed to manufacture the microchannels on top of unpackaged p-i-n photodiodes without altering detector performance. The microchannels were fabricated with KMPR, an epoxy-based photoresist similar to SU-8 but with improved resistance to stress-induced fissuring. Surface passivation of the KMPR enables non-diluted whole blood to flow through the channel for up to 20 min at low speed without clotting. The microfluidic device was embedded in a portable blood counter with dedicated electronics, pumping unit and computer control software for utilisation next to a small animal nuclear imaging scanner. Experimental measurements confirmed model predictions and showed a 4- to 19-fold improvement in detection efficiency over existing catheter-based devices, enabling a commensurate reduction in sampled blood volume. A linear dose-response relationship was demonstrated for radioactivity concentrations typical of experiments with rodents. The system was successfully used to measure the blood input function of rats in real time after radiotracer injection.
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Affiliation(s)
- Laurence Convert
- Nanofabrication and Nanocharacterization Research Center, Department of Electrical and Computer Engineering, Université de Sherbrooke, 2500 Bd Université, Sherbrooke, QC, J1K 2R1, Canada
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Millet P, Moulin-Sallanon M, Tournier BB, Dumas N, Charnay Y, Ibáñez V, Ginovart N. Quantification of dopamine D(2/3) receptors in rat brain using factor analysis corrected [18F]Fallypride images. Neuroimage 2012; 62:1455-68. [PMID: 22659483 DOI: 10.1016/j.neuroimage.2012.05.075] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 04/20/2012] [Accepted: 05/26/2012] [Indexed: 11/15/2022] Open
Abstract
The goal of this work is to quantify the binding parameters of [(18)F]Fallypride in the striatal and extrastriatal regions of the rat brain using factor analysis (FA) to correct small animal PET kinetic imaging for spillover defluorination radioactivity. Eleven rats were employed for YAP-(S)PET acquisitions and metabolite studies. All kinetic parameters including B'(max) and K(d)V(R) were estimated with a three-tissue compartment seven-parameter model (3T-7k) on the basis of all the FA-corrected data from the multi-injection protocol. Binding potential (BP(ND)) was calculated with Logan's graphical analysis taking cerebellum as the reference region and using the first injection raw (BP(ND-RAW)) and FA-corrected (BP(ND-FA)) data. Three distinct factors corresponding to free+non-specific binding, specific binding and skull and gland accumulation were recovered from FA with their corresponding spatial distributions. The resulting reconstructed images without skull and gland accumulation were improved to provide a better contrast between specific and non-specific regions. Very bad fits were obtained when using time-activity curves (TACs) calculated from the raw [(18)F]Fallypride data, whereas all TACs were well fitted by the 3T-7k model after FA correction. FA-corrected data enables the cerebellar region to be used as reference for the Logan approach. The magnitude of the BP(ND-FA) values was increased from 21% to 108% across regions and the rank order of BP(ND-FA) values (Cx<Hip<MB≈Thal<VST<DST) matched those of B'(max) values. This [(18)F]Fallypride study in rats shows that all brain regions are contaminated by skull and gland radioactivity accumulation. We show that FA is a very effective method of correcting kinetic data for spillover activity. Moreover, the approach presented here with [(18)F]Fallypride data can be extended to other radioligands and also to human data which can be highly distorted by radiodefluorination as shown in the literature.
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Affiliation(s)
- Philippe Millet
- Clinical Neurophysiology and Neuroimaging Unit, Division of Neuropsychiatry, Department of Psychiatry, University Hospitals of Geneva, Switzerland.
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Herraiz JL, España S, Cabido R, Montemayor AS, Desco M, Vaquero JJ, Udias JM. GPU-Based Fast Iterative Reconstruction of Fully 3-D PET Sinograms. IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2011. [DOI: 10.1109/tns.2011.2158113] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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22
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Kudomi N, Sipilä H, Autio A, Oikonen V, Liljenbäck H, Tarkia M, Laivola J, Johansson J, Teräs M, Roivainen A. Cross-validation of Input Functions Obtained by H2 15O PET Imaging of Rat Heart and a Blood Flow-through Detector. Mol Imaging Biol 2011; 14:509-16. [DOI: 10.1007/s11307-011-0511-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Hu Z, Shi P. Sensitivity analysis for biomedical models. IEEE TRANSACTIONS ON MEDICAL IMAGING 2010; 29:1870-1881. [PMID: 20562035 DOI: 10.1109/tmi.2010.2053044] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
This article discusses the application of sensitivity analysis (SA) in biomedical models. Sensitivity analysis is widely applied in physics, chemistry, economics, social sciences and other areas where models are developed. By assigning a prior probability distribution to each model variable, the SA framework appeals to the posterior probabilities of the model to evaluate the relative importance of these variables on the output distribution based on the principle of general variance decomposition. Within this framework, the SA paradigm serves as an objective platform to quantify the contributions of each model factor relative to their empirical range. We present statistical derivations of variance-based SA in this context and discuss its detailed properties through some practical examples. Our emphasis is on the application of SA in the biomedical field. As we show, it may provide a useful tool for model quality assessment, model reduction and factor prioritization, and improve our understanding of the model structure and underlying mechanisms. When usual approaches for calculating sensitivity index involve the employment of Monte Carlo analysis, which is computationally expensive in the large-sampling paradigm, we develop two effective numerical approximate methods for quick SA evaluations based on the unscented transformation (UT) that utilize a deterministic sampling approach in place of random sampling to calculate posterior statistics. We show that these methods achieve an excellent compromise between computational burden and calculation precision. In addition, a clear guideline is absent to evaluate the importance of variable for model reduction, we also present an objective statistical criterion to quantitatively decide whether or not a descriptive parameter is nominal and may be discarded in ensuing model-based analysis without significant loss of information on model behavior.
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Affiliation(s)
- Zhenghui Hu
- State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China.
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Hooker JM. Modular strategies for PET imaging agents. Curr Opin Chem Biol 2009; 14:105-11. [PMID: 19880343 DOI: 10.1016/j.cbpa.2009.10.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 10/01/2009] [Accepted: 10/02/2009] [Indexed: 12/14/2022]
Abstract
In recent years, modular and simplified chemical and biological strategies have been developed for the synthesis and implementation of positron emission tomography (PET) radiotracers. New developments in bioconjugation and synthetic methodologies, in combination with advances in macromolecular delivery systems and gene-expression imaging, reflect a need to reduce radiosynthesis burden in order to accelerate imaging agent development. These new approaches, which are often mindful of existing infrastructure and available resources, are anticipated to provide a more approachable entry point for researchers interested in using PET to translate in vitro research to in vivo imaging.
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Affiliation(s)
- Jacob M Hooker
- Brookhaven National Laboratory, Medical Department, Building 555, Upton, NY 11973-5000, USA.
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Current and future aspects of molecular imaging. Methods 2009; 48:81-2. [DOI: 10.1016/j.ymeth.2009.05.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 05/22/2009] [Indexed: 11/20/2022] Open
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