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Abstract
Biomedical research has long relied on small-animal studies to elucidate disease process and develop new medical treatments. The introduction of in vivo functional imaging technology, such as PET, has allowed investigators to peer inside their subjects and follow disease progression longitudinally as well as improve understanding of normal biological processes. Recent developments in CRISPR, immuno-PET, and high-resolution in vivo imaging have only increased the importance of small-animal, or preclinical, PET imaging. Other drivers of preclinical PET innovation include new combinations of imaging technologies, such as PET/MR imaging, which require changes to PET hardware.
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Affiliation(s)
- Adrienne L Lehnert
- Department of Radiology, University of Washington, 1959 Northeast Pacific Street, UW Box 356043, Seattle, WA, USA.
| | - Robert S Miyaoka
- Department of Radiology, University of Washington, 1959 Northeast Pacific Street, UW Box 356043, Seattle, WA, USA
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Desmonts C, Lasnon C, Jaudet C, Aide N. PET imaging and quantification of small animals using a clinical SiPM-based camera. EJNMMI Phys 2023; 10:61. [PMID: 37804338 PMCID: PMC10560240 DOI: 10.1186/s40658-023-00583-2] [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: 04/07/2023] [Accepted: 09/29/2023] [Indexed: 10/09/2023] Open
Abstract
BACKGROUND Small-animal PET imaging is an important tool in preclinical oncology. This study evaluated the ability of a clinical SiPM-PET camera to image several rats simultaneously and to perform quantification data analysis. METHODS Intrinsic spatial resolution was measured using 18F line sources, and image quality was assessed using a NEMA NU 4-2018 phantom. Quantification was evaluated using a fillable micro-hollow sphere phantom containing 4 spheres of different sizes (ranging from 3.95 to 7.86 mm). Recovery coefficients were computed for the maximum (Amax) and the mean (A50) pixel values measured on a 50% isocontour drawn on each sphere. Measurements were performed first with the phantom placed in the centre of the field of view and then in the off-centre position with the presence of three scattering sources to simulate the acquisition of four animals simultaneously. Quantification accuracy was finally validated using four 3D-printed phantoms mimicking rats with four subcutaneous tumours each. All experiments were performed for both 18F and 68Ga radionuclides. RESULTS Radial spatial resolutions measured using the PSF reconstruction algorithm were 1.80 mm and 1.78 mm for centred and off-centred acquisitions, respectively. Spill-overs in air and water and uniformity computed with the NEMA phantom centred in the FOV were 0.05, 0.1 and 5.55% for 18F and 0.08, 0.12 and 2.81% for 68Ga, respectively. Recovery coefficients calculated with the 18F-filled micro-hollow sphere phantom for each sphere varied from 0.51 to 1.43 for Amax and from 0.40 to 1.01 for A50. These values decreased from 0.28 to 0.92 for Amax and from 0.22 to 0.66 for A50 for 68 Ga acquisition. The results were not significantly different when imaging phantoms in the off-centre position with 3 scattering sources. Measurements performed with the four 3D-printed phantoms showed a good correlation between theoretical and measured activity in simulated tumours, with r2 values of 0.99 and 0.97 obtained for 18F and 68Ga, respectively. CONCLUSION We found that the clinical SiPM-based PET system was close to that obtained with a dedicated small-animal PET device. This study showed the ability of such a system to image four rats simultaneously and to perform quantification analysis for radionuclides commonly used in oncology.
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Affiliation(s)
- Cédric Desmonts
- Nuclear Medicine Department, University Hospital of Caen, Avenue de La Côte de Nacre, 14033, Caen Cedex 9, France.
- Normandy University, UNICAEN, INSERM 1086 ANTICIPE, Caen, France.
| | - Charline Lasnon
- Normandy University, UNICAEN, INSERM 1086 ANTICIPE, Caen, France
- Nuclear Medicine Department, UNICANCER, Comprehensive Cancer Centre F. Baclesse, Caen, France
| | - Cyril Jaudet
- Radiophysics Department, UNICANCER, Comprehensive Cancer Centre F. Baclesse, Caen, France
| | - Nicolas Aide
- Normandy University, UNICAEN, INSERM 1086 ANTICIPE, Caen, France
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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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Development of a new advanced animal cradle for small animal multiple imaging modalities: acquisition and evaluation of high-throughput multiple-mouse imaging. Phys Eng Sci Med 2021; 44:1367-1376. [PMID: 34724162 DOI: 10.1007/s13246-021-01065-4] [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: 07/02/2020] [Accepted: 10/12/2021] [Indexed: 10/20/2022]
Abstract
The physiological conditions of small animals are an essential component to be considered when acquiring images for pre-clinical studies, and they play a vital role in the overall results of a study. However, several previous studies did not consider these conditions. In this study, a new animal cradle that can be modified and adjusted to suit multiple imaging modalities such as positron emission tomography (PET)/computed tomography (CT) and magnetic resonance imaging (MRI) was developed. Unlike previous cradles where only one mouse can be imaged at a time, a total of four mice can be imaged simultaneously using this new cradle. Additionally, fusion images with high-throughput multiple-mouse imaging (MMI) of PET/MRI and PET/CT images can be acquired using this newly developed cradle. The dynamic brain images were also acquired simultaneously by applying PET dynamic imaging technology to high-throughput MMI methods. The results of this study suggest that the newly developed small animal cradle can be widely used in pre-clinical studies.
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Houghton V, Du Preez A, Lefèvre-Arbogast S, de Lucia C, Low DY, Urpi-Sarda M, Ruigrok SR, Altendorfer B, González-Domínguez R, Andres-Lacueva C, Aigner L, Lucassen PJ, Korosi A, Samieri C, Manach C, Thuret S. Caffeine Compromises Proliferation of Human Hippocampal Progenitor Cells. Front Cell Dev Biol 2020; 8:806. [PMID: 33015033 PMCID: PMC7505931 DOI: 10.3389/fcell.2020.00806] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 07/31/2020] [Indexed: 12/15/2022] Open
Abstract
The age-associated reduction in the proliferation of neural stem cells (NSCs) has been associated with cognitive decline. Numerous factors have been shown to modulate this process, including dietary components. Frequent consumption of caffeine has been correlated with an increased risk of cognitive decline, but further evidence of a negative effect on hippocampal progenitor proliferation is limited to animal models. Here, we used a human hippocampal progenitor cell line to investigate the effects of caffeine on hippocampal progenitor integrity and proliferation specifically. The effects of five caffeine concentrations (0 mM = control, 0.1 mM ∼ 150 mg, 0.25 mM ∼ 400 mg, 0.5 mM ∼ 750 mg, and 1.0 mM ∼ 1500 mg) were measured following acute (1 day) and repeated (3 days) exposure. Immunocytochemistry was used to quantify hippocampal progenitor integrity (i.e., SOX2- and Nestin-positive cells), proliferation (i.e., Ki67-positive cells), cell count (i.e., DAPI-positive cells), and apoptosis (i.e., CC3-positive cells). We found that progenitor integrity was significantly reduced in supraphysiological caffeine conditions (i.e., 1.0 mM ∼ 1500 mg), but relative to the lowest caffeine condition (i.e., 0.1 mM ∼ 150 mg) only. Moreover, repeated exposure to supraphysiological caffeine concentrations (i.e., 1.0 mM ∼ 1500 mg) was found to affect proliferation, significantly reducing % Ki67-positive cells relative to control and lower caffeine dose conditions (i.e., 0.1 mM ∼ 150 mg and 0.25 mM ∼ 400 mg). Caffeine treatment did not influence apoptosis and there were no significant differences in any measure between lower doses of caffeine (i.e., 0.1 mM, 0.25 mM, 0.5 mM) – representative of daily human caffeine intake – and control conditions. Our study demonstrates that dietary components such as caffeine can influence NSC integrity and proliferation and may be indicative of a mechanism by which diet affects cognitive outcomes.
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Affiliation(s)
- Vikki Houghton
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom
| | - Andrea Du Preez
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom
| | | | - Chiara de Lucia
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom
| | - Dorrain Y Low
- INRA, UMR 1019, Human Nutrition Unit, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Mireia Urpi-Sarda
- Nutrition, Food Science and Gastronomy Department, Faculty of Pharmacy and Food Science, CIBER Fragilidad y Envejecimiento Saludable, Instituto de Salud Carlos III, University of Barcelona, Barcelona, Spain
| | - Silvie R Ruigrok
- Brain Plasticity Group, Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, Netherlands
| | - Barbara Altendorfer
- Institute of Molecular Regenerative Medicine, Spinal Cord Injury and Tissue Regeneration Center Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Raúl González-Domínguez
- Nutrition, Food Science and Gastronomy Department, Faculty of Pharmacy and Food Science, CIBER Fragilidad y Envejecimiento Saludable, Instituto de Salud Carlos III, University of Barcelona, Barcelona, Spain
| | - Cristina Andres-Lacueva
- Nutrition, Food Science and Gastronomy Department, Faculty of Pharmacy and Food Science, CIBER Fragilidad y Envejecimiento Saludable, Instituto de Salud Carlos III, University of Barcelona, Barcelona, Spain
| | - Ludwig Aigner
- Institute of Molecular Regenerative Medicine, Spinal Cord Injury and Tissue Regeneration Center Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Paul J Lucassen
- Brain Plasticity Group, Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, Netherlands
| | - Aniko Korosi
- Brain Plasticity Group, Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, Netherlands
| | - Cécilia Samieri
- University of Bordeaux, INSERM, BPH, U1219, Bordeaux, France
| | - Claudine Manach
- INRA, UMR 1019, Human Nutrition Unit, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Sandrine Thuret
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.,Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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de Lange C, Solberg R, Holtedahl JE, Tulipan A, Barlinn J, Trigg W, Wickstrøm T, Saugstad OD, Malinen E, Revheim ME. Dynamic TSPO-PET for assessing early effects of cerebral hypoxia and resuscitation in new born pigs. Nucl Med Biol 2018; 66:49-57. [PMID: 30257223 DOI: 10.1016/j.nucmedbio.2018.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 07/27/2018] [Accepted: 08/19/2018] [Indexed: 01/07/2023]
Abstract
INTRODUCTION Inflammation associated with microglial activation may be an early prognostic indicator of perinatal hypoxic ischemic injury, where translocator protein (TSPO) is a known inflammatory biomarker. This piglet study used dynamic TSPO-PET with [18F]GE180 to evaluate if microglial activation after global perinatal hypoxic injury could be detected. METHODS New born anesthetized pigs (n = 14) underwent hypoxia with fraction of inspired oxygen (FiO2)0.08 until base excess -20 mmol/L and/or a mean arterial blood pressure decrease to 20 mm Hg, followed by resuscitation with FiO2 0.21 or 1.0. Three piglets served as controls and one had intracranial injection of lipopolysaccharide (LPS). Whole body [18F]GE180 Positron emission tomography-computed tomography (PET-CT) was performed repeatedly up to 32 h after hypoxia and resuscitation. Volumes of interest were traced in the basal ganglia, cerebellum and liver using MRI as anatomic correlation. Standardized uptake values (SUVs) were measured at baseline and four time-points, quantifying microglial activity over time. Statistical analysis used Mann Whitney- and Wilcoxon rank test with significance value set to p < 0.05. RESULTS At baseline (n = 5), mean SUVs ±1 standard deviation were 0.43 ± 0.10 and 1.71 ± 0.62 in brain and liver respectively without significant increase after hypoxia at the four time-points (n = 5-13/time point). Succeeding LPS injection, SUV increased 80% from baseline values. CONCLUSIONS Cerebral inflammatory response caused by severe asphyxia was not possible to detect with [18F]GE180 PET CT the first 32 h after hypoxia and only sparse hepatic uptake was revealed. ADVANCES IN KNOWLEDGE Early microglial activation as indicator of perinatal hypoxic ischemic injury was not detectable by TSPO-PET with [18F]GE180. IMPLICATIONS FOR PATIENT CARE TSPO-PET with [18F]GE180 might not be suitable for early detection of perinatal hypoxic ischemic brain injury.
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Affiliation(s)
- Charlotte de Lange
- Div. of Radiology and Nuclear Medicine, Oslo University Hospital, PO box 4950, Nydalen, N-0424 Oslo, Norway.
| | - Rønnaug Solberg
- Dept. of Paediatric Research, Oslo University Hospital, PO box 4950, Nydalen, N-0424 Oslo, Norway; Dept. of Pediatrics, Vestfold Hospital Trust, Tønsberg, Norway
| | - Jon Erik Holtedahl
- Dept. of Medical Physics, Oslo University Hospital, PO box 4950, Nydalen, N-0424 Oslo, Norway
| | - Andreas Tulipan
- Div. of Radiology and Nuclear Medicine, Oslo University Hospital, PO box 4950, Nydalen, N-0424 Oslo, Norway
| | - Jon Barlinn
- Dept. of Pediatrics, Oslo University Hospital, PO box 4950, Nydalen, N-0424 Oslo, Norway
| | | | | | - Ola Didrik Saugstad
- Dept. of Paediatric Research, Oslo University Hospital, PO box 4950, Nydalen, N-0424 Oslo, Norway; Faculty of Medicine, University of Oslo, PO Box1078, Blindern, N-0316 Oslo, Norway
| | - Eirik Malinen
- Dept. of Medical Physics, Oslo University Hospital, PO box 4950, Nydalen, N-0424 Oslo, Norway; Dept. of Physics, University of Oslo, P.O Box 1048, Blindern, N-0316 Oslo, Norway
| | - Mona Elisabeth Revheim
- Div. of Radiology and Nuclear Medicine, Oslo University Hospital, PO box 4950, Nydalen, N-0424 Oslo, Norway; Faculty of Medicine, University of Oslo, PO Box1078, Blindern, N-0316 Oslo, Norway
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Vanhove C, Bankstahl JP, Krämer SD, Visser E, Belcari N, Vandenberghe S. Accurate molecular imaging of small animals taking into account animal models, handling, anaesthesia, quality control and imaging system performance. EJNMMI Phys 2015; 2:31. [PMID: 26560138 PMCID: PMC4642455 DOI: 10.1186/s40658-015-0135-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/05/2015] [Indexed: 11/22/2022] Open
Abstract
Small-animal imaging has become an important technique for the development of new radiotracers, drugs and therapies. Many laboratories have now a combination of different small-animal imaging systems, which are being used by biologists, pharmacists, medical doctors and physicists. The aim of this paper is to give an overview of the important factors in the design of a small animal, nuclear medicine and imaging experiment. Different experts summarize one specific aspect important for a good design of a small-animal experiment.
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Affiliation(s)
- Christian Vanhove
- Department of Electronics and Information Systems, MEDISIP, Ghent University-iMinds Medical IT-IBiTech, De Pintelaan 185 block B, B-9000, Ghent, Belgium.
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Preclinical Molecular Imaging, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Stefanie D Krämer
- Radiopharmaceutical Sciences/Biopharmacy, ETH Zurich, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 4, CH-8093, Zurich, Switzerland
| | - Eric Visser
- Department of Radiology and Nuclear Medicine, Radboudumc, 6525 GA Nijmegen, the Netherlands
| | - Nicola Belcari
- Department of Physics, University of Pisa and INFN sezione di Pisa, 56127 Pisa, Italy
| | - Stefaan Vandenberghe
- Department of Electronics and Information Systems, MEDISIP, Ghent University-iMinds Medical IT-IBiTech, De Pintelaan 185 block B, B-9000, Ghent, Belgium
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NEMA NU 4-Optimized Reconstructions for Therapy Assessment in Cancer Research with the Inveon Small Animal PET/CT System. Mol Imaging Biol 2014; 17:403-12. [DOI: 10.1007/s11307-014-0805-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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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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Lajtos I, Czernin J, Dahlbom M, Daver F, Emri M, Farshchi-Heydari S, Forgacs A, Hoh CK, Joszai I, Krizsan AK, Lantos J, Major P, Molnar J, Opposits G, Tron L, Vera DR, Balkay L. Cold wall effect eliminating method to determine the contrast recovery coefficient for small animal PET scanners using the NEMA NU-4 image quality phantom. Phys Med Biol 2014; 59:2727-46. [PMID: 24800813 DOI: 10.1088/0031-9155/59/11/2727] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The contrast recovery coefficients (CRC) were evaluated for five different small animal PET scanners: GE Explore Vista, Genisys4, MiniPET-2, nanoScan PC and Siemens Inveon. The NEMA NU-4 2008 performance test with the suggested image quality phantom (NU4IQ) does not allow the determination of the CRC values for the hot regions in the phantom. This drawback of NU4IQ phantom motivated us to develop a new method for this purpose. The method includes special acquisition and reconstruction protocols using the original phantom, and results in an artificially merged image enabling the evaluation of CRC values. An advantageous feature of this method is that it stops the cold wall effect from distorting the CRC calculation. Our suggested protocol results in a set of CRC values contributing to the characterization of small animal PET scanners. GATE simulations were also performed to validate the new method and verify the evaluated CRC values. We also demonstrated that the numerical values of this parameter depend on the actual object contrast of the hot region(s) and this mainly comes from the spillover effect. This effect was also studied while analysing the background activity level around the hot rods. We revealed that the calculated background mean values depended on the target contrast in a scanner specific manner. Performing the artificially merged imaging procedure and additional simulations using the micro hollow sphere (MHS) phantom geometry, we also proved that the inactive wall around the hot spheres can have a remarkable impact on the calculated CRC. In conclusion, we have shown that the proposed artificial merging procedure and the commonly used NU4IQ phantom prescribed by the NEMA NU-4 can easily deliver reliable CRC data otherwise unavailable for the NU4IQ phantom in the conventional protocol or the MHS phantom.
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Affiliation(s)
- Imre Lajtos
- Department of Nuclear Medicine, Medical Center, University of Debrecen, 4032 Debrecen, Nagyerdei krt. 98, Hungary
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Habte F, Ren G, Doyle TC, Liu H, Cheng Z, Paik DS. Impact of a multiple mice holder on quantitation of high-throughput MicroPET imaging with and without Ct attenuation correction. Mol Imaging Biol 2014; 15:569-75. [PMID: 23479323 DOI: 10.1007/s11307-012-0602-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
PURPOSE The aim of this study is to evaluate the impact of scanning multiple mice simultaneously on image quantitation, relative to single mouse scans on both a micro-positron emission tomography/computed tomography (microPET/CT) scanner (which utilizes CT-based attenuation correction to the PET reconstruction) and a dedicated microPET scanner using an inexpensive mouse holder "hotel." METHODS We developed a simple mouse holder made from common laboratory items that allows scanning multiple mice simultaneously. It is also compatible with different imaging modalities to allow multiple mice and multi-modality imaging. For this study, we used a radiotracer ((64)Cu-GB170) with a relatively long half-life (12.7 h), selected to allow scanning at times after tracer uptake reaches steady state. This also reduces the effect of decay between sequential imaging studies, although the standard decay corrections were performed. The imaging was also performed using a common tracer, 2-deoxy-2-[(18) F]fluoro-D-glucose (FDG), although the faster decay and faster pharmacokinetics of FDG may introduce greater biological variations due to differences in injection-to-scan timing. We first scanned cylindrical mouse phantoms (50 ml tubes) both in a groups of four at a time (multiple mice mode) and then individually (single mouse mode), using microPET/CT and microPET scanners to validate the process. Then, we imaged a first set of four mice with subcutaneous tumors (C2C12Ras) in both single- and multiple-mice imaging modes. Later, a second set of four normal mice were injected with FDG and scanned 1 h post-injection. Immediately after completion of the scans, ex vivo biodistribution studies were performed on all animals to provide a "gold-standard" to compare quantitative values obtained from PET. A semi-automatic threshold-based region of interest tool was used to minimize operator variability during image analysis. RESULTS Phantom studies showed less than 4.5 % relative error difference between the single- and multiple-mice imaging modes of PET imaging with CT-based attenuation correction and 18.4 % without CT-based attenuation correction. In vivo animal studies (n = 4) showed <5 % (for (64)Cu, p > 0.686) and <15 % (for FDG, p > 0.4 except for brain image data p = 0.029) relative mean difference with respect to percent injected dose per gram (%ID/gram) between the single- and multiple-mice microPET imaging mode when CT-based attenuation correction is performed. Without CT-based attenuation correction, we observed relative mean differences of about 11 % for (64)Cu and 15 % for FDG. CONCLUSION Our results confirmed the potential use of a microPET/CT scanner for multiple mice simultaneous imaging without significant sacrifice in quantitative accuracy as well as in image quality. Thus, the use of the mouse "hotel" is an aid to increasing instrument throughput on small animal scanners with minimal loss of quantitative accuracy.
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Affiliation(s)
- Frezghi Habte
- Molecular Imaging Program at Stanford (MIPS), Stanford, CA, USA,
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Cullinane C, Solomon B, Hicks RJ. Imaging of molecular target modulation in oncology: challenges of early clinical trials. Clin Transl Imaging 2014. [DOI: 10.1007/s40336-013-0047-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Nagy K, Tóth M, Major P, Patay G, Egri G, Häggkvist J, Varrone A, Farde L, Halldin C, Gulyás B. Performance evaluation of the small-animal nanoScan PET/MRI system. J Nucl Med 2013; 54:1825-32. [PMID: 23990683 DOI: 10.2967/jnumed.112.119065] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
UNLABELLED nanoScan is a high-resolution integrated system for consecutive PET and MR imaging of small laboratory animals. We evaluated the performance of the system, using the NEMA NU 4-2008 protocol for the PET component and the NEMA MS 1-2007, MS 2-2008, and MS 3-2007 standards for the MR imaging component. METHODS The imaging system uses magnetically shielded position-sensitive photomultiplier tubes and a compact 1-T permanent-magnet MR imaging platform. Spatial resolution, sensitivity, counting rate capabilities, and image quality parameters were evaluated in accordance with the aforementioned NEMA standards. Further in vivo evaluation experiments complement the physical validation results. RESULTS The spatial resolution of the PET system enabled the 0.8-mm rods of a Derenzo phantom to be resolved. With point source and 2-dimensional filtered backprojection reconstruction, the resolution varied from 1.50 to 2.01 mm in full width at half maximum in the radial direction and from 1.32 to 1.65 mm in the tangential direction within the radius of 25 mm. Peak absolute sensitivity was 8.41%. Scatter fraction was 17.3% and 34.0%, and maximum noise-equivalent counting rate was 406 and 119 kcps in the mouselike and ratlike phantom, respectively. The image quality test found a nonuniformity of 3.52% and a spillover ratio of 6.2% and 5.8% in water and air, respectively. In testing of the MR imaging component, artifact-free images with high signal-to-noise ratio were recorded. Geometric distortion was below 5%, and image uniformity was at least 94.5% and 96.6% for the 60- and 35-mm radiofrequency coils, respectively. CONCLUSION The nanoScan integrated small-animal PET/MR imaging system has excellent spatial resolution and sensitivity. The performance characteristics of the PET and the MR imaging components are not compromised as a result of their integration onto a single platform. Because of its combination of features and performance parameters, the system provides crucial advantages for preclinical imaging studies over existing PET/CT systems, especially in neurologic and oncologic research.
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Affiliation(s)
- Kálmán Nagy
- Psychiatry Section, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; and
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Lyons SK, Patrick PS, Brindle KM. Imaging mouse cancer models in vivo using reporter transgenes. Cold Spring Harb Protoc 2013; 2013:685-99. [PMID: 23906907 DOI: 10.1101/pdb.top069864] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Imaging mouse models of cancer with reporter transgenes has become a relatively common experimental approach in the laboratory, which allows noninvasive and longitudinal investigation of diverse aspects of tumor biology in vivo. Our goal here is to outline briefly the principles of the relevant imaging modalities, emphasizing particularly their strengths and weaknesses and what the researcher can expect in a practical sense from each of these techniques. Furthermore, we discuss how relatively subtle modifications in the way reporter transgene expression is regulated in the cell underpin the ability of reporter transgenes as a whole to provide readouts on such varied aspects of tumor biology in vivo.
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Affiliation(s)
- Scott K Lyons
- Department of Molecular Imaging, CRUK Cambridge Research Institute, Li Ka Shing Centre, Cambridge CB2 0RE, United Kingdom
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Lasnon C, Quak E, Briand M, Gu Z, Louis MH, Aide N. Contrast-enhanced small-animal PET/CT in cancer research: strong improvement of diagnostic accuracy without significant alteration of quantitative accuracy and NEMA NU 4-2008 image quality parameters. EJNMMI Res 2013; 3:5. [PMID: 23327687 PMCID: PMC3563455 DOI: 10.1186/2191-219x-3-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 01/09/2013] [Indexed: 02/05/2023] Open
Abstract
Background The use of iodinated contrast media in small-animal positron emission tomography (PET)/computed tomography (CT) could improve anatomic referencing and tumor delineation but may introduce inaccuracies in the attenuation correction of the PET images. This study evaluated the diagnostic performance and accuracy of quantitative values in contrast-enhanced small-animal PET/CT (CEPET/CT) as compared to unenhanced small animal PET/CT (UEPET/CT). Methods Firstly, a NEMA NU 4–2008 phantom (filled with 18F-FDG or 18F-FDG plus contrast media) and a homemade phantom, mimicking an abdominal tumor surrounded by water or contrast media, were used to evaluate the impact of iodinated contrast media on the image quality parameters and accuracy of quantitative values for a pertinent-sized target. Secondly, two studies in 22 abdominal tumor-bearing mice and rats were performed. The first animal experiment studied the impact of a dual-contrast media protocol, comprising the intravenous injection of a long-lasting contrast agent mixed with 18F-FDG and the intraperitoneal injection of contrast media, on tumor delineation and the accuracy of quantitative values. The second animal experiment compared the diagnostic performance and quantitative values of CEPET/CT versus UEPET/CT by sacrificing the animals after the tracer uptake period and imaging them before and after intraperitoneal injection of contrast media. Results There was minimal impact on IQ parameters (%SDunif and spillover ratios in air and water) when the NEMA NU 4–2008 phantom was filled with 18F-FDG plus contrast media. In the homemade phantom, measured activity was similar to true activity (−0.02%) and overestimated by 10.30% when vials were surrounded by water or by an iodine solution, respectively. The first animal experiment showed excellent tumor delineation and a good correlation between small-animal (SA)-PET and ex vivo quantification (r2 = 0.87, P < 0.0001). The second animal experiment showed a good correlation between CEPET/CT and UEPET/CT quantitative values (r2 = 0.99, P < 0.0001). Receiver operating characteristic analysis demonstrated better diagnostic accuracy of CEPET/CT versus UEPET/CT (senior researcher, area under the curve (AUC) 0.96 versus 0.77, P = 0.004; junior researcher, AUC 0.78 versus 0.58, P = 0.004). Conclusions The use of iodinated contrast media for small-animal PET imaging significantly improves tumor delineation and diagnostic performance, without significant alteration of SA-PET quantitative accuracy and NEMA NU 4–2008 IQ parameters.
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