scholarly journals Development of a CD19 PET tracer for detecting B cells in a mouse model of multiple sclerosis

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Marc Y. Stevens ◽  
Haley C. Cropper ◽  
Katherine L. Lucot ◽  
Aisling M. Chaney ◽  
Kendra J. Lechtenberg ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
B Cells ◽  
Brain Tissue ◽  
Pet Imaging ◽  
Ex Vivo ◽  
Therapeutic Success ◽  
Gamma Counting ◽  
Pet Tracer ◽  
Imaging Results ◽  
Ex Vivo Autoradiography

Abstract Background B cells play a central role in multiple sclerosis (MS) through production of injurious antibodies, secretion of pro-inflammatory cytokines, and antigen presentation. The therapeutic success of monoclonal antibodies (mAbs) targeting B cells in some but not all individuals suffering from MS highlights the need for a method to stratify patients and monitor response to treatments in real-time. Herein, we describe the development of the first CD19 positron emission tomography (PET) tracer, and its evaluation in a rodent model of MS, experimental autoimmune encephalomyelitis (EAE). Methods Female C57BL/6 J mice were induced with EAE through immunization with myelin oligodendrocyte glycoprotein (MOG1–125). PET imaging of naïve and EAE mice was performed 19 h after administration of [64Cu]CD19-mAb. Thereafter, radioactivity in organs of interest was determined by gamma counting, followed by ex vivo autoradiography of central nervous system (CNS) tissues. Anti-CD45R (B220) immunostaining of brain tissue from EAE and naïve mice was also conducted. Results Radiolabelling of DOTA-conjugated CD19-mAb with 64Cu was achieved with a radiochemical purity of 99% and molar activity of 2 GBq/μmol. Quantitation of CD19 PET images revealed significantly higher tracer binding in whole brain of EAE compared to naïve mice (2.02 ± 0.092 vs. 1.68 ± 0.06 percentage of injected dose per gram, % ID/g, p = 0.0173). PET findings were confirmed by ex vivo gamma counting of perfused brain tissue (0.22 ± 0.020 vs. 0.12 ± 0.003 % ID/g, p = 0.0010). Moreover, ex vivo autoradiography of brain sections corresponded with PET imaging results and the spatial distribution of B cells observed in B220 immunohistochemistry—providing further evidence that [64Cu]CD19-mAb enables visualization of B cell infiltration into the CNS of EAE mice. Conclusion CD19-PET imaging can be used to detect elevated levels of B cells in the CNS of EAE mice, and has the potential to impact the way we study, monitor, and treat clinical MS.

scholarly journals Development of a CD19 PET tracer for detecting B cells in a mouse model of multiple sclerosis

2020 ◽  
Author(s):  
Marc Y Stevens ◽  
Haley C Cropper ◽  
Katherine L Lucot ◽  
Aisling M Chaney ◽  
Kendra J Lechtenberg ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
B Cells ◽  
Brain Tissue ◽  
Pet Imaging ◽  
Ex Vivo ◽  
Therapeutic Success ◽  
Gamma Counting ◽  
Pet Tracer ◽  
Imaging Results ◽  
Ex Vivo Autoradiography

Abstract Background: B cells play a central role in multiple sclerosis (MS) through production of injurious antibodies, secretion of pro-inflammatory cytokines, and antigen presentation. The therapeutic success of monoclonal antibodies (mAbs) targeting B cells in some but not all individuals suffering from MS highlights the need for a method to stratify patients and monitor response to treatments in real time. Herein, we describe the development of the first CD19 positron emission tomography (PET) tracer and its evaluation in a rodent model of MS, experimental autoimmune encephalomyelitis (EAE).Methods: Female C57BL/6J mice were induced with EAE through immunisation with myelin oligodendrocyte glycoprotein (MOG1–125). PET imaging of naïve and EAE mice was performed 19 h after administration of [64Cu]CD19-mAb. Thereafter, radioactivity in organs of interest was determined by gamma counting, followed by ex vivo autoradiography of central nervous system (CNS) tissues. Anti-CD45R (B220) immunostaining of brain tissue from EAE and naïve mice was also conducted.Results: Radiolabelling of DOTA-conjugated CD19-mAb with 64Cu was achieved with a radiochemical purity of 99% and molar activity of 2 GBq/mol. Quantitation of CD19 PET images revealed significantly higher tracer binding in whole brain of EAE compared to naïve mice (2.02±0.092 vs. 1.68±0.06 percentage of injected dose per gram, %ID/g, p=0.0173). PET findings were confirmed by ex vivo gamma counting of perfused brain tissue (0.22±0.020 vs. 0.12±0.003 %ID/g, p=0.0010). Moreover, ex vivo autoradiography of brain sections corresponded with PET imaging results and the spatial distribution of B cells observed in B220 immunohistochemistry – providing further evidence that [64Cu]CD19-mAb enables visualisation of B cell infiltration into the CNS of EAE mice. Conclusion: CD19-PET imaging can be used to detect elevated levels of B cells in the CNS of EAE mice, and has the potential to impact the way we study, monitor, and treat clinical MS.

scholarly journals Imaging and Methotrexate Response Monitoring of Systemic Inflammation in Arthritic Rats Employing the Macrophage PET Tracer [18F]Fluoro-PEG-Folate

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Durga M. S. H. Chandrupatla ◽  
Gerrit Jansen ◽  
Elise Mantel ◽  
Philip S. Low ◽  
Takami Matsuyama ◽  
...  
Keyword(s):  
Systemic Inflammation ◽  
Pet Imaging ◽  
Ex Vivo ◽  
Folate Receptor ◽  
Tracer Uptake ◽  
Response Monitoring ◽  
Distribution Analysis ◽  
Pet Tracer ◽  
Systemic Inflammatory Disease ◽  
Before And After

Background. In rheumatoid arthritis, articular inflammation is a hallmark of disease, while the involvement of extra-articular tissues is less well defined. Here, we examined the feasibility of PET imaging with the macrophage tracer [18F]fluoro-PEG-folate, targeting folate receptorβ(FRβ), to monitor systemic inflammatory disease in liver and spleen of arthritic rats before and after methotrexate (MTX) treatment.Methods. [18F]Fluoro-PEG-folate PET scans (60 min) were acquired in saline- and MTX-treated (1 mg/kg, 4x) arthritic rats, followed by tissue resection and radiotracer distribution analysis. Liver and spleen tissues were stained for ED1/ED2-macrophage markers and FRβexpression.Results. [18F]Fluoro-PEG-folate PET and ex vivo tissue distribution studies revealed a significant (p<0.01) 2-fold lower tracer uptake in both liver and spleen of MTX-treated arthritic rats. Consistently, ED1- and ED2-positive macrophages were significantly (p<0.01) decreased in liver (4-fold) and spleen (3-fold) of MTX-treated compared with saline-treated rats. Additionally, FRβ-positive macrophages were also significantly reduced in liver (5-fold,p<0.005) and spleen (3-fold,p<0.01) of MTX- versus saline-treated rats.Conclusions. MTX treatment reduced activated macrophages in liver and spleen, as markers for systemic inflammation in these organs. Macrophage PET imaging with [18F]fluoro-PEG-folate holds promise for detection of systemic inflammation in RA as well as therapy (MTX) response monitoring.

Increased ex vivo antigen presentation profile of B cells in multiple sclerosis

2016 ◽  
Vol 23 (6) ◽  
pp. 802-809 ◽  
Author(s):  
Amandine Mathias ◽  
Guillaume Perriard ◽  
Mathieu Canales ◽  
Charlotte Soneson ◽  
Mauro Delorenzi ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
B Cells ◽  
Immunological Synapse ◽  
Ex Vivo ◽  
Neurological Diseases ◽  
Human Leukocyte ◽  
Blood Monocytes ◽  
Model Framework ◽  
Hla Dr ◽  
Activation Profile

Background: Multiple sclerosis (MS) is thought to be T cell mediated but the mechanisms eliciting such a dysregulated adaptative immune response remain enigmatic. Objective: To examine the activation profile of antigen-presenting cells (APCs) in MS. Methods: A total of 98 study subjects were enrolled including patients suffering from relapsing–remitting, secondary- and primary-progressive (PP) MS, other inflammatory neurological diseases, and healthy controls. Blood monocytes and B cells were stimulated using specific ligands of toll-like receptors (TLRs) or inflammasomes or Epstein–Barr virus (EBV) particles. Their activation profile was determined before or after stimulation by flow cytometry (CD40, CD80, CD83, CD86, and human leukocyte antigen–antigen D related (HLA-DR)) and Luminex assay, measuring the concentration of eight cytokines in culture supernatants. Differences among groups were assessed in a linear model framework. Results: We demonstrate that relapsing MS patients exhibit an increased expression of HLA-DR and CD40 ex vivo, mostly at the surface of B cells. Specific stimulations of TLR or inflammasomes enhance the expression of components of the immunological synapse and the cytokine secretion but without differences between categories of study subjects. Conclusion: These data suggest that the activation profile of B cells is increased in MS. However, the perception of the danger signal by B lymphocytes and monocytes does not seem to be different in MS patients as compared to control subjects.

scholarly journals Evaluation of [68Ga]Ga-NODAGA-RGD for PET Imaging of Rat Autoimmune Myocarditis

2021 ◽  
Vol 8 ◽  
Author(s):  
Arghavan Jahandideh ◽  
Mia Ståhle ◽  
Jenni Virta ◽  
Xiang-Guo Li ◽  
Heidi Liljenbäck ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Ex Vivo ◽  
Cell Surface Receptor ◽  
Myocardial Inflammation ◽  
Autoimmune Myocarditis ◽  
Inflammatory Lesions ◽  
Pet Tracer ◽  
Freund’S Adjuvant ◽  
Freund's Adjuvant

The 68Gallium-labeled 1,4,7-triazacyclononane-1-glutaric acid-4,7-diacetic acid conjugated radiolabelled arginine-glycine-aspartic acid peptide ([68Ga]Ga-NODAGA-RGD) is a positron emission tomography (PET) tracer binding to cell surface receptor αvβ3 integrin that is upregulated during angiogenesis and inflammation. We studied whether αvβ3 targeting PET imaging can detect myocardial inflammation in a rat model of autoimmune myocarditis. To induce myocarditis, rats (n = 8) were immunized with porcine cardiac myosin in complete Freund's adjuvant on days 0 and 7. Control rats (n = 8) received Freund's adjuvant alone. On day 21, in vivo PET/CT imaging with [68Ga]Ga-NODAGA-RGD followed by ex vivo autoradiography and immunohistochemistry were carried out. Inflammatory lesions were detected histologically in the myocardium of 7 out of 8 immunized rats. In vivo PET images showed higher [68Ga]Ga-NODAGA-RGD accumulation in the myocardium of rats with inflammation than the non-inflamed myocardium of control rats (SUVmean 0.4 ± 0.1 vs. 0.1 ± 0.02; P = 0.00006). Ex vivo autoradiography and histology confirmed that [68Ga]Ga-NODAGA-RGD uptake co-localized with inflammatory lesions containing αvβ3 integrin-positive capillary-like structures. A non-specific [68Ga]Ga-DOTA-(RGE)2 tracer showed 76% lower uptake than [68Ga]Ga-NODAGA-RGD in the inflamed myocardium. Our results indicate that αvβ3 integrin-targeting [68Ga]Ga-NODAGA-RGD is a potential PET tracer for the specific detection of active inflammatory lesions in autoimmune myocarditis.

scholarly journals Synthesis of 68Ga-Labeled cNGR-Based Glycopeptides and In Vivo Evaluation by PET Imaging

Pharmaceutics ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2103
Author(s):  
Barbara Gyuricza ◽  
Judit P. Szabó ◽  
Viktória Arató ◽  
Noémi Dénes ◽  
Ágnes Szűcs ◽  
...  
Keyword(s):  
Tissue Distribution ◽  
Pet Imaging ◽  
Ex Vivo ◽  
Distribution Data ◽  
Melanoma Tumor ◽  
In Vivo Evaluation ◽  
Imaging Results ◽  
Ngr Peptide ◽  
Ex Vivo Tissue

Tumor hypoxia induces angiogenesis, which is required for tumor cell survival. The aminopeptidase N receptor (APN/CD13) is an excellent marker of angiogenesis since it is overexpressed in angiogenic blood vessels and in tumor cells. Asparagine-glycine-arginine (NGR) peptide analogs bind selectively to the APN/CD13 recepto, therefore, they are important vector molecules in the development of a PET radiotracer which is capable of detecting APN-rich tumors. To investigate the effect of glycosylation and pegylation on in-vivo efficacy of an NGR-based radiotracer, two 68Ga-labeled radioglycopeptides were synthesized. A lactosamine derivative was applied to glycosylation of the NGR derivative and PEG4 moiety was used for pegylation. The receptor targeting potential and biodistribution of the radiopeptides were evaluated with in vivo PET imaging studies and ex vivo tissue distribution studies using B16-F10 melanoma tumor-bearing mice. According to these studies, all synthesized radiopeptides were capable of detecting APN expression in B16-F10 melanoma tumor. In addition, lower hepatic uptake, higher tumor-to background (T/M) ratio and prolonged circulation time were observed for the novel [68Ga]-10 radiotracer due to pegylation and glycosylation, resulting in more contrasting PET imaging. These in vivo PET imaging results correlated well with the ex vivo tissue distribution data.

scholarly journals Synthesize of a novel 89Zr labeled HER2 affibody and its application study in tumor PET imaging

2020 ◽  
Author(s):  
Yuping Xu ◽  
Lizhen Wang ◽  
Donghui Pan ◽  
Junjie Yan ◽  
Xinyu Wang ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Ex Vivo ◽  
Growth Factor Receptor ◽  
Immunohistochemical Analysis ◽  
In Vivo Studies ◽  
Her2 Overexpression ◽  
Potential Candidate ◽  
Synthesis Time ◽  
Ex Vivo Autoradiography

Abstract Background: Human epidermal growth factor receptor-2 (HER2) is an important biomarker for tumor diagnosis and therapy. Affibody is an ideal vector for preparing HER2 specific probes due to the advantages such as high affinity and rapid blood clearance etc. 89Zr is a novel PET imaging isotope with long half-lives and suitable for tracking biological processes for longer periods. In this study, a novel 89Zr labeled HER2 affibody, 89Zr-DFO-MAL-Cys-MZHER2, was synthesized and its imaging properties were also evaluated. Results: The precursors, DFO-MAL-Cys-MZHER2, were obtained with the yields of nearly 50%. The yields of 89Zr -DFO-MAL-Cys-MZHER2 were 90.2±1.9% and the radiopurities were more than 95%. The total synthesis time was only 30 minutes. The probes were stable in PBS and serum. The tracer accumulated in HER2 overexpression human ovarian cancer SKOV-3 cells. In vivo studies in mice bearing tumors showed that the probe highly retained in SKOV-3 xenografts even for 48 hours. The tumors were visualized with good contrast to normal tissue. ROI analysis revealed that the average uptakes in the tumor were greater than 5 %ID/g. On the contrary, the counterparts of MCF-7 tumors kept low levels of （~1%ID/g）. The outcome was consistent with the immunohistochemical analysis and ex vivo autoradiography. The probe quickly cleared from the blood and normal organs, and mainly excreted through the urinary system. Conclusion: The novel HER2 affibody for PET imaging was easily prepared with satisfactory labeling yield and radiochemical purity. 89Zr-DFO-MAL-MZHER is a potential candidate for monitoring HER2 expression and may play specific roles in clinical cancer theranostics.

scholarly journals Evaluating the association between hybrid magnetic resonance positron emission tomography and cardiac-related outcomes in cardiac sarcoidosis

2022 ◽  
Author(s):  
MariaGiovanna Trivieri ◽  
Philip M Robson ◽  
Vittoria Vergani ◽  
Gina LaRocca ◽  
Angelica M Romero-Daza ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Pet Imaging ◽  
Fdg Pet ◽  
Cardiac Sarcoidosis ◽  
Characteristic Curve ◽  
Cardiac Resynchronization ◽  
Pet Tracer ◽  
Imaging Results ◽  
18F Fdg

Objectives: To evaluate an extended hybrid MR/PET imaging strategy in cardiac sarcoidosis (CS) employing qualitative and quantitative assessment of PET tracer uptake, and to evaluate its association with cardiac-related outcomes. Background: Invasive endomyocardial biopsy is the gold standard to diagnose CS, but it has poor sensitivity due to the patchy distribution of disease. Imaging with hybrid late gadolinium enhancement (LGE) MR and 18F-fluorodexyglucose (18F-FDG) PET allows simultaneous assessment of myocardial injury and disease activity and has shown promise for improved diagnosis of active CS based on the combined positive imaging outcome, MR(+)PET(+). Methods: 148 patients with suspected CS were enrolled for hybrid MR/PET imaging. Patients were classified based on presence/absence of LGE (MR+/MR-), presence/absence of 18F-FDG (PET+/PET-), and pattern of 18F-FDG uptake (focal/diffuse) into the following categories: MR(+)PET(+)FOCAL, MR(+)PET(+)DIFFUSE, MR(+)PET(-), MR(-)PET(+)FOCAL, MR(-)PET(+)DIFFUSE, MR(-)PET(-). Patients classified as MR(+)PET(+)FOCAL were designated as having active CS [aCS(+)], while all others were considered as having inactive or absent CS and designated aCS(-). Quantitative values of standard uptake value (SUVmax), target-to-background ratio (TBRmax), target-to-normal-myocardium ratio (TNMRmax) and T2 were measured. Occurrence of a cardiac-related clinical outcome was defined as any of the following during the 6-month period after imaging: cardiac arrest, ventricular arrhythmia, complete heart block, need for cardiac resynchronization/defibrillator/pacemaker/monitoring device (CRT-D, ICD/WCD, or ILR). MR/PET imaging results were compared to the presence of the composite clinical outcome. Results: Patients designated aCS(+) had more than 4-fold increased odds of meeting the clinical endpoint compared to aCS(-) (unadjusted odds ratio 4.8; 95% CI 2.0-11.4; p<0.001). TNMRmax achieved an area under the receiver operating characteristic curve of 0.90 for separating aCS(+) from aCS(-). Conclusions: Hybrid MR/PET imaging with an extended image-based classification of CS was statistically associated with clinical outcomes in CS. TNMRmax had high sensitivity and excellent specificity for quantifying the imaging-based classification of active CS.

138 In vivo localization of genetically engineered natural killer cells against glioblastoma using PET imaging

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A151-A151
Author(s):  
Yeonhee Yun ◽  
Jiao Wang ◽  
Karen Pollok ◽  
Tony Sinn ◽  
Randy Brutkiewicz ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Nk Cells ◽  
Natural Killer ◽  
Pet Imaging ◽  
Nk Cell ◽  
Ex Vivo ◽  
Killing Activity ◽  
Gamma Counting

BackgroundGlioblastoma (GBM) is a deadly brain malignancy with a dismal prognosis. While immunotherapy holds great promise for GBM treatment, most have failed due to a suppressive tumor microenvironment (TME). Antigen heterogeneity and adenosine signaling are two immunosuppressive mechanisms in GBM. The CD73-adenosine axis plays a multifaceted role in GBM pathogenesis and drives the dysfunction of NK cells in GBM TME.1,3 Our NKG2D-chimeric antigen receptor (CAR)-natural killer (NK) cells have shown anti-tumor activity when combined with CD73 blockade in vivo.2 To further extend the potency of these cells against GBM and address antigen heterogeneity in GBM, we combined the local blockade of CD73 with multi-antigen-targeting engineered NK cells. In order to improve treatment assessment, PET/MR imaging was employed to enable detailed, non-invasive assessment of tumor progression. Imaging assessment of adoptively-transferred CAR- NK cells was also developed to determine the fate of NK cell delivery to the tumor site over time.MethodsWe generated multifunctional engineered NK (E-NK) cells that express an anti-CD73 scFv, which is cleavable by GBM-associated proteases, an NKG2D-CAR, as well as a GD2 CAR, which can actively target the GD2 antigen overexpressed on GBM (Figure 1A). For E-NK cell radiolabeling, zirconium-89 (89Zr, ½ life = 78 Hr) radiotracer was attached covalently to the E-NK cell surface via conjugation with DFO-Bz-NCS in a range of doses from 50–600 µCi.ResultsAn optimal balance between labeling efficiency and cell viability was attained at 120 µCi 89Zr resulting in 39% labeling efficiency and 46% cell viability over for 48 hours. After labeling, the NK cells maintained their in vitro killing activity against GBM cells (figure 1B). The 89Zr labeled E-NK cells were administered intravenously in mice containing intracranial GBM10 tumors at week 5 post-implant. PET imaging was performed at 1 and 2 days later and gamma imaging ex vivo at 4 days. Free 89Zr was visible diffusely throughout the body with low levels in the brain. The majority of 89Zr labeled E-NK cell groups localized to the lungs with detectable activity elsewhere in various organs (figure 1C and 1D).Abstract 138 Figure 1PET imaging and gamma counting of the engineered NK cellsFigure 1 (A) Multifunctional, responsive CAR constructs; (B) In vitro killing activity against GBM43 cells after co-incubation with 89Zr labeled NK cells at an E:T ratio of 10 for 4 h with LDH assay (N=3); (C) & (D) In vivo PET imaging and ex vivo gamma counting with 89Zr at week 5 in 10 mice during 4 days, GBM intracranial implantation to NSG male mouse, 89Zr, 89Zr + NK cell, or 89Zr + E NK cell (7 × 106 cells with 500 µCi) was administered through intravenous injection, Qimage was used for the PET/MRI co-registration and analysisConclusionsWe generated multifunctional E-NK cells which showed the improved killing of GBM cells using novel targeting approaches, including the blockade of CD73-mediated adenosinergic signaling. We also optimized E-NK cell radiolabeling with 89Zr for GB10 therapy in vitro and in vivo fate mapping against a xenograft of patient-derived GBM.AcknowledgementsWe gratefully acknowledge the Walther Oncology Embedding Program, Indiana University Simon Cancer Center, and In Vivo Therapeutics Core.ReferencesWang J, Matosevic S. NT5E/CD73 as correlative factor of patient survival and natural killer cell infiltration in glioblastoma. J Clin Med 2019;8(10):1526.Wang J, Lupo KB, Chambers AM, Matosevic S. Purinergic targeting enhances immunotherapy of CD73+ solid tumors with piggyBac-engineered chimeric antigen receptor natural killer cells. J Immunother Cancer 2018;6(1):136.Yan A, Joachims ML, Thompson LF, Miller AD, Canoll PD, Bynoe MS. CD73 promotes glioblastoma pathogenesis and enhances its chemoresistance via A2B adenosine receptor signaling. J Neurosci 2019;39(22):4387.Flink J, Muzi M, Peck M, Krohn K. Multimodality brain tumor imaging: mr imaging, PET, and PET/MR imaging. J Nucl 2015;5(10):1554–1561.

Systematically Evaluating DOTATATE and FDG as PET Immuno-Imaging Tracers of Cardiovascular Inflammation

2021 ◽  
Author(s):  
Yohana C. Toner ◽  
Adam A. Ghotbi ◽  
Sonum Naidu ◽  
Ken Sakurai ◽  
Mandy M.T. Leent ◽  
...  
Keyword(s):  
Animal Models ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Ex Vivo ◽  
Somatostatin Receptor ◽  
Small Animal ◽  
Inflammatory Cells ◽  
Gamma Counting ◽  
Pet Tracer

Abstract The somatostatin receptor 2-binding PET tracer DOTATATE is emerging as an alternative to 18F-FDG to assess cardiovascular inflammation. The strengths and weaknesses of each tracer and their different specificity for inflammatory cells still need to be fully elucidated. In this manuscript, we employed mouse and rabbit animal models of inflammation. In mice, 64Cu-DOTATATE’s pharmacokinetics and timed biodistribution were determined in control (C57BL/6) and atherosclerotic (Apoe−/−) mice by ex vivo gamma counting. In vivo PET/CT, combined with ex vivo flow cytometry and gamma counting, was used to evaluate the quantification of cardiovascular inflammation by 64Cu-DOTATATE and 18F-FDG and the tracers’ cellular specificity in control versus infarcted and atherosclerotic mice. In a translational PET/MRI rabbit study, we then compared DOTATATE labeled with short-lived radioisotope 68Ga and 18F-FDG for the assessment of aortic inflammation, combined with ex vivo radiometric assays and near-infrared imaging of macrophage burden. In infarcted mice, in vivo 64Cu-DOTATATE PET showed higher differential uptake than 18F-FDG between infarcted and remote myocardium (p=0.0286), and with respect to controls (p=0.0286; n=4-6). In atherosclerotic mice, 64Cu-DOTATATE PET aortic signal, but not 18F-FDG, was higher compared to controls (p=0.0286; n=4). In both models, 64Cu-DOTATATE demonstrated preferential accumulation in macrophages with respect to other myeloid cells, while 18F-FDG uptake was less cell-specific. The translational rabbit PET/MRI study showed significantly higher aortic accumulation of both 68Ga-DOTATATE and 18F-FDG in atherosclerotic compared to control animals (p=0.0002 and p=0.0159, respectively; n=10-32). In conclusion, we introduce a workflow integrating in vivo PET and ex vivo immunological and radioactivity counting assays to characterize DOTATATE and 18F-FDG as inflammation tracers in small animal models of cardiovascular disease. Our results support the use of DOTATATE to assess cardiovascular inflammation, as alternative and complement to 18F-FDG. In addition, our study establishes a comprehensive and robust framework for the thorough assessment and comparison of novel and validated PET immuno-tracers in the cardiovascular arena.

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