scholarly journals Evaluation of Four Pyridine Analogs to Characterize 6-OHDA-Induced Modulation of mGluR5 Function in Rat Brain Using microPET Studies

2007 ◽  
Vol 27 (9) ◽  
pp. 1623-1631 ◽  
Author(s):  
Aijun Zhu ◽  
Xukui Wang ◽  
Meixiang Yu ◽  
Ji-Quan Wang ◽  
Anna-Liisa Brownell
Keyword(s):  
Positron Emission Tomography ◽  
Pet Imaging ◽  
Emission Tomography ◽  
Binding Potential ◽  
Sprague Dawley ◽  
Imaging Studies ◽  
Reference Tissue ◽  
Positron Emission ◽  
The Right

Micro-positron emission tomography imaging studies were conducted to characterize modulation of metabotropic glutamate subtype-5 receptor (mGluR5) function in a 6-hydroxydopamine (6-OHDA)-induced rat model of Parkinson's disease using four analogical PET ligands: 2-[11C]methyl-6-(2-phenylethynyl) pyridine ([11C]MPEP), 2-(2-(3-[11C]methoxyphenyl)ethynyl)pyridine ([11C]M-MPEP), 2-(2-(5-[11C]methoxypyridin-3-yl)ethynyl)pyridine ([11C]M-PEPy), and 3-[(2-[18F]methyl-1,3-thiazol-4-yl)ethynyl]pyridine ([18F]M-TEP). A total of 45 positron emission tomography (PET) imaging studies were conducted on nine male Sprague-Dawley rats within 4 to 6 weeks after unilateral 6-OHDA lesioning into the right medial forebrain bundle. The severity of the lesion was determined with [11C]CFT ([11C]2-β-carbomethoxy-3-β-(4-fluorophenyl)tropane), a specific and sensitive ligand for imaging dopamine transporter function. The binding potential (BP) images were processed on pixel-by-pixel basis by using a method of the distribution volume ratio with cerebellum as a reference tissue. The values for BP were determined on striatum, hippocampus, and cortex. [11C]CFT binding was decreased on the lesioned (right) striatum by 35.4% ± 13.4% compared with the intact left striatum, indicating corresponding loss of presynaptic dopamine terminals. On the same areas of the lesioned striatum, three of the four tested mGluR5 ligands showed enhanced binding characteristics. The average differences between the right and left striatum were 4.4% ± 6.5% ( P < 0.05) with [11C]MPEP, 0.1% ± 1.7% ( P > 0.05) with [11C]M-MPEP, 3.9% ± 4.6% ( P < 0.05) with [11C]M-PEPy, and 6.6% ± 2.7% ( P > 0.05) with [18F]M-TEP. The enhanced binding was also observed in the right hippocampus and cortex. These studies showed that glutamatergic neurotransmission might have a complementary role in dopaminergic degeneration, which can be evaluated by in vivo PET imaging.

P1216Evaluation of alphavbeta3 integrin-targeted positron emission tomography and photoacoustic tracer for imaging of carotid plaque in apoE–/– mice

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
Y Yao ◽  
L B Li ◽  
Y Ji ◽  
G Ma ◽  
Y Wu ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Pet Imaging ◽  
Carotid Arteries ◽  
Emission Tomography ◽  
Atherosclerotic Plaques ◽  
Positron Emission ◽  
Αvβ3 Integrins ◽  
Tracer Accumulation ◽  
The Right

Abstract Background Cardiovascular disease is the leading cause of death in the world. The majority of cardiovascular events result from the rupture of vulnerable atherosclerotic plaques, which are characterized by high and active macrophage content. The integrin αVβ3 is expressed by activated macrophages and endothelial cells in atherosclerotic lesions and thus is a marker of high-risk plaques. Therefore, 89Zr-RGD-melanin nanoparticle (MNP) positron emission tomography (PET)/photoacoustic imaging (PAI) imaging of αVβ3 expression in plaques might provide a novel noninvasive biomarker of plaque vulnerability. Purpose In this study, the intrinsic photoacoustic signals and the native strong chelating properties with metal ions of MNP, positron-emitting metal ions 89Zr and αVβ3 integrins targeting ability of cyclic c (RGDfC) peptide was employed to construct an efficient nanoplatform. And we evaluated the feasibility of 89Zr-RGD-MNP PET/PAI of αVβ3 expression in vivo and in vitro. Methods We conjugated αVβ3 integrins, cyclic c (RGDfC) peptide, to MNP and chelated the long-lived positron-emitting nuclide 89Zr. The bio-stability and targeting action was detected in macrophages. And the PET/PAI imaging was performed in apoE−/− mice with partial carotid ligation leading to atherosclerosis. In PET imaging, tracer uptake was measured in the stenotic areas of the carotid arteries, as well as on the contralateral side at different time points in vivo. In PAI, photoacoustic signal was measured in the atherosclerosis of the carotid arteries in vivo. Melanin staining and immunohistochemistry of αVβ3 expression were detected in atherosclerosis of the carotid arteries. Results 89Zr-RGD-MNP showed excellent bio-stability and targeting action. PET imaging showed specific tracer accumulation at plaques in the left carotid artery, confirmed by competitive receptor blocking studies and the contrast in the right carotid artery. In the biodistribution studies, the left carotid (5.29%±0.78%) showed higher uptake than the right carotid (2.11%±1.55%). PAI showed the PA signal in the surgery group (452±85 a.u.) were stronger than the control (156±45 a.u.) and blocking group (254±66 a.u). The result was consistent with PET imaging and the presence of nanoparticles, as indicated by pathological examinations. These results presented good in vivo multimodality imaging (PET/PAI) properties. Conclusions We have developed 89Zr-labeled atherosclerotic plaques imaging agents based on the natural melanin nanoparticle. 89Zr-RGD-MNP demonstrates specific tracer accumulation in mice atherosclerotic carotid plaques. In this model, its uptake was associated with αVβ3 expression. 89Zr-RGD-MNP is a potential tracer for noninvasive imaging in atherosclerosis. Acknowledgement/Funding National Natural Science Foundation of China 81770452, 81470401

scholarly journals Investigating the in vivo biodistribution of extracellular vesicles isolated from various human cell sources using positron emission tomography

2021 ◽  
Author(s):  
Zachary T Rosenkrans ◽  
Anna S Thickens ◽  
John A Kink ◽  
Eduardo Aluicio-Sarduy ◽  
Jonathan W Engle ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Positron Emission Tomography ◽  
Pet Imaging ◽  
Human Cell ◽  
Emission Tomography ◽  
Imaging Studies ◽  
Nsg Mice ◽  
Positron Emission ◽  
Cell Sources

Noninvasive imaging is a powerful tool for understanding the in vivo behavior of drug delivery systems and successfully translating promising platforms into the clinic. Extracellular vesicles (EVs), nano-sized vesicles with a lipid bilayer produced by nearly all cell types, are emerging platforms for drug delivery. To date, the biodistribution of EVs has been insufficiently investigated, particularly using nuclear imaging-based modalities such as positron emission tomography (PET). Herein, we developed positron-emitting radiotracers to investigate the biodistribution of EVs isolated from various human cell sources using PET imaging. Chelator conjugation did not impact EVs size and subsequent radiolabeling was found to be highly efficient and stable with Zr-89 (t1/2 = 78.4 h). In vivo tracking of EVs isolated from bone marrow-derived mesenchymal stromal cells (BMSCs EVs), primary human macrophages (Mϕ EVs), and a melanoma cell line (A375 EVs) were performed in immunocompetent ICR mice. Imaging studies revealed excellent in vivo circulation for all EVs, with a half-life of approximately 12 h. Significantly higher liver uptake was observed for Mϕ EVs, evidencing the tissue tropism of EV and highlighting the importance of carefully choosing EVs cell sources for drug delivery applications. Conversely, the liver, spleen, and lung uptake of the BMSC EVs and A375 EVs was relatively low. We also investigated the impact of immunodeficiency on the biodistribution of BMSC EVs using NSG mice. The spleen uptake drastically increased in NSG mice, which could confound results of therapeutic studies employing this mouse models. Lastly, PET imaging studies in a melanoma tumor model demonstrated efficient tumor uptake of BMSC EVs following intravenous injection. Overall, these imaging studies evidenced the potential of EVs as carriers to treat a variety of diseases, such as cancer or in regenerative medicine applications, and the necessity to understand EVs tropism to optimize their therapeutic deployment.

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

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

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

scholarly journals Imaging Cardiovascular and Lung Macrophages With the Positron Emission Tomography Sensor 64 Cu-Macrin in Mice, Rabbits, and Pigs

2020 ◽  
Vol 13 (10) ◽  
Author(s):  
Matthias Nahrendorf ◽  
Friedrich Felix Hoyer ◽  
Anu E. Meerwaldt ◽  
Mandy M.T. van Leent ◽  
Max L. Senders ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Flow Cytometry ◽  
Confocal Microscopy ◽  
Pet Imaging ◽  
Near Infrared ◽  
Emission Tomography ◽  
Imaging Biomarker ◽  
Positron Emission ◽  
Pulmonary Macrophages

Background: Macrophages, innate immune cells that reside in all organs, defend the host against infection and injury. In the heart and vasculature, inflammatory macrophages also enhance tissue damage and propel cardiovascular diseases. Methods: We here use in vivo positron emission tomography (PET) imaging, flow cytometry, and confocal microscopy to evaluate quantitative noninvasive assessment of cardiac, arterial, and pulmonary macrophages using the nanotracer 64 Cu-Macrin—a 20-nm spherical dextran nanoparticle assembled from nontoxic polyglucose. Results: PET imaging using 64 Cu-Macrin faithfully reported accumulation of macrophages in the heart and lung of mice with myocardial infarction, sepsis, or pneumonia. Flow cytometry and confocal microscopy detected the near-infrared fluorescent version of the nanoparticle ( VT680 Macrin) primarily in tissue macrophages. In 5-day-old mice, 64 Cu-Macrin PET imaging quantified physiologically more numerous cardiac macrophages. Upon intravenous administration of 64 Cu-Macrin in rabbits and pigs, we detected heightened macrophage numbers in the infarcted myocardium, inflamed lung regions, and atherosclerotic plaques using a clinical PET/magnetic resonance imaging scanner. Toxicity studies in rats and human dosimetry estimates suggest that 64 Cu-Macrin is safe for use in humans. Conclusions: Taken together, these results indicate 64 Cu-Macrin could serve as a facile PET nanotracer to survey spatiotemporal macrophage dynamics during various physiological and pathological conditions. 64 Cu-Macrin PET imaging could stage inflammatory cardiovascular disease activity, assist disease management, and serve as an imaging biomarker for emerging macrophage-targeted therapeutics.

scholarly journals Kinetic Modeling of the Serotonin 5-HT1B Receptor Radioligand [11C]P943 in Humans

2009 ◽  
Vol 30 (1) ◽  
pp. 196-210 ◽  
Author(s):  
Jean-Dominique Gallezot ◽  
Nabeel Nabulsi ◽  
Alexander Neumeister ◽  
Beata Planeta-Wilson ◽  
Wendol A Williams ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Arterial Input Function ◽  
Human Subjects ◽  
Emission Tomography ◽  
Binding Potential ◽  
Noninvasive Methods ◽  
Reference Tissue ◽  
Positron Emission ◽  
Tissue Models

[11C]P943 is a new radioligand recently developed to image and quantify serotonin 5-Hydroxytryptamine (5-HT1B) receptors with positron emission tomography (PET). The purpose of this study was to evaluate [11C]P943 for this application in humans, and to determine the most suitable quantification method. Positron emission tomography data and arterial input function measurements were acquired in a cohort of 32 human subjects. Using arterial input functions, compartmental modeling, the Logan graphical analysis, and the multilinear method MA1 were tested. Both the two tissue-compartment model and MA1 provided good fits of the PET data and reliable distribution volume estimates. Using the cerebellum as a reference region, BPND binding potential estimates were computed. [11C]P943 BPND estimates were significantly correlated with in vitro measurements of the density of 5-HT1B receptors, with highest values in the occipital cortex and pallidum. To evaluate noninvasive methods, two- and three-parameter graphical analyses, Simplified Reference Tissue Models (SRTM and SRTM2), and Multilinear Reference Tissue Models (MRTM and MRTM2) were tested. The MRTM2 model provided the best correlation with MA1 binding-potential estimates. Parametric images of the volume of distribution or binding potential of [11C]P943 could be computed using both MA1 and MRTM2. The results show that [11C]P943 provides quantitative measurements of 5-HT1B binding potential.

scholarly journals Linearized Reference Tissue Parametric Imaging Methods: Application to [11C]DASB Positron Emission Tomography Studies of the Serotonin Transporter in Human Brain

2003 ◽  
Vol 23 (9) ◽  
pp. 1096-1112 ◽  
Author(s):  
Masanori Ichise ◽  
Jeih-San Liow ◽  
Jian-Qiang Lu ◽  
Akihiro Takano ◽  
Kendra Model ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Human Brain ◽  
Positron Emission Tomography Imaging ◽  
Emission Tomography ◽  
Binding Potential ◽  
Parametric Imaging ◽  
Reference Tissue ◽  
Parametric Images ◽  
Positron Emission ◽  
Tissue Models

The authors developed and applied two new linearized reference tissue models for parametric images of binding potential ( BP) and relative delivery ( R1) for [11C]DASB positron emission tomography imaging of serotonin transporters in human brain. The original multilinear reference tissue model (MRTMO) was modified (MRTM) and used to estimate a clearance rate ( k′2) from the cerebellum (reference). Then, the number of parameters was reduced from three (MRTM) to two (MRTM2) by fixing k′2. The resulting BP and R1 estimates were compared with the corresponding nonlinear reference tissue models, SRTM and SRTM2, and one-tissue kinetic analysis (1TKA), for simulated and actual [11C]DASB data. MRTM gave k′2 estimates with little bias (<1%) and small variability (<6%). MRTM2 was effectively identical to SRTM2 and 1TKA, reducing BP bias markedly over MRTMO from 12–70% to 1–4% at the expense of somewhat increased variability. MRTM2 substantially reduced BP variability by a factor of two or three over MRTM or SRTM. MRTM2, SRTM2, and 1TKA had R1 bias <0.3% and variability at least a factor of two lower than MRTM or SRTM. MRTM2 allowed rapid generation of parametric images with the noise reductions consistent with the simulations. Rapid parametric imaging by MRTM2 should be a useful method for human [11C]DASB positron emission tomography studies.

Direct Observation of Hydroxyapatite Nanoparticles In Vivo

2012 ◽  
Vol 503-504 ◽  
pp. 688-691 ◽  
Author(s):  
Wei Zhou ◽  
Jun Zheng
Keyword(s):  
Positron Emission Tomography ◽  
Real Time ◽  
Pet Imaging ◽  
Three Dimensional ◽  
Transverse Plane ◽  
Emission Tomography ◽  
Hydroxyapatite Nanoparticles ◽  
Positron Emission ◽  
Dimensional Reconstruction

While nano-hydroxyapatite (nano-HAP) has been well known for series of amazing properties in chemical or physical, the controversy on the risks of its applications has also been existed. The worries of nano-HAP applications in preclinic and clinic indicate the blank researches of nano-HAP pharmacodynamics. It is important and necessary to trace and clarify the localizations of HAP nanoparticles in vivo. In the present paper, 18F is used as radiotracer for Positron Emission Tomography (PET) imaging of HAP nanoparticles. Through the transverse plane slices and three-dimensional reconstruction pictures, it is very clear to observe the localization of nano-HAP in vivo at real time. Most nano-HAP particles were noted in organs lump, liver, spleen, stomach and existed for period of time. Therefore, PET can be a new powerful technique for tracing nano-biomaterial and their pharmacodynamics researches.

scholarly journals An activatable PET imaging radioprobe is a dynamic reporter of myeloperoxidase activity in vivo

2019 ◽  
pp. 201818434 ◽  
Author(s):  
Cuihua Wang ◽  
Edmund Keliher ◽  
Matthias W. G. Zeller ◽  
Gregory R. Wojtkiewicz ◽  
Aaron D. Aguirre ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Positron Emission Tomography ◽  
Pet Imaging ◽  
Competitive Inhibition ◽  
Emission Tomography ◽  
Myeloperoxidase Activity ◽  
Positron Emission ◽  
Emerging Therapies ◽  
Rheumatological Diseases

Myeloperoxidase (MPO) is a critical proinflammatory enzyme implicated in cardiovascular, neurological, and rheumatological diseases. Emerging therapies targeting inflammation have raised interest in tracking MPO activity in patients. We describe18F-MAPP, an activatable MPO activity radioprobe for positron emission tomography (PET) imaging. The activated radioprobe binds to proteins and accumulates at sites of MPO activity. The radioprobe18F-MAPP has a short blood half-life, remains stable in plasma, does not demonstrate cytotoxicity, and crosses the intact blood–brain barrier. The18F-MAPP imaging detected sites of elevated MPO activity in living mice embedded with human MPO and in mice induced with chemical inflammation or myocardial infarction. The18F-MAPP PET imaging noninvasively differentiated varying amounts of MPO activity, competitive inhibition, and MPO deficiency in living animals, confirming specificity and showing that the radioprobe can quantify changes in in vivo MPO activity. The radiosynthesis has been optimized and automated, an important step in translation. These data indicate that18F-MAPP is a promising translational candidate to noninvasively monitor MPO activity and inflammation in patients.

Sign in / Sign up

Export Citation Format

Share Document