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McCabe JJ, Evans NR, Gorey S, Bhakta S, Rudd JHF, Kelly PJ. Imaging Carotid Plaque Inflammation Using Positron Emission Tomography: Emerging Role in Clinical Stroke Care, Research Applications, and Future Directions. Cells 2023; 12:2073. [PMID: 37626883 PMCID: PMC10453446 DOI: 10.3390/cells12162073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/11/2023] [Accepted: 08/13/2023] [Indexed: 08/27/2023] Open
Abstract
Atherosclerosis is a chronic systemic inflammatory condition of the vasculature and a leading cause of stroke. Luminal stenosis severity is an important factor in determining vascular risk. Conventional imaging modalities, such as angiography or duplex ultrasonography, are used to quantify stenosis severity and inform clinical care but provide limited information on plaque biology. Inflammatory processes are central to atherosclerotic plaque progression and destabilization. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a validated technique for quantifying plaque inflammation. In this review, we discuss the evolution of FDG-PET as an imaging modality to quantify plaque vulnerability, challenges in standardization of image acquisition and analysis, its potential application to routine clinical care after stroke, and the possible role it will play in future drug discovery.
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Affiliation(s)
- John J. McCabe
- Health Research Board Stroke Clinical Trials Network Ireland, Catherine McAuley Centre, Nelson Street, D07 KX5K Dublin, Ireland; (S.G.); (P.J.K.)
- Neurovascular Unit for Applied Translational and Therapeutics Research, Catherine McAuley Centre, Nelson Street, D07 KX5K Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, D04 V1W8 Dublin, Ireland
- Stroke Service, Department of Medicine for the Elderly, Mater Misericordiae University Hospital, Eccles Street, D07 R2WY Dublin, Ireland
| | - Nicholas R. Evans
- Department of Clinical Neurosciences, Box 83, Addenbrooke’s Hospital, University of Cambridge, Hills Road, Cambridge CB2 0QQ, UK; (N.R.E.); (S.B.)
| | - Sarah Gorey
- Health Research Board Stroke Clinical Trials Network Ireland, Catherine McAuley Centre, Nelson Street, D07 KX5K Dublin, Ireland; (S.G.); (P.J.K.)
- Neurovascular Unit for Applied Translational and Therapeutics Research, Catherine McAuley Centre, Nelson Street, D07 KX5K Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, D04 V1W8 Dublin, Ireland
- Stroke Service, Department of Medicine for the Elderly, Mater Misericordiae University Hospital, Eccles Street, D07 R2WY Dublin, Ireland
| | - Shiv Bhakta
- Department of Clinical Neurosciences, Box 83, Addenbrooke’s Hospital, University of Cambridge, Hills Road, Cambridge CB2 0QQ, UK; (N.R.E.); (S.B.)
| | - James H. F. Rudd
- Division of Cardiovascular Medicine, Addenbrooke’s Hospital, University of Cambridge, Hills Road, Cambridge CB2 0QQ, UK;
| | - Peter J. Kelly
- Health Research Board Stroke Clinical Trials Network Ireland, Catherine McAuley Centre, Nelson Street, D07 KX5K Dublin, Ireland; (S.G.); (P.J.K.)
- Neurovascular Unit for Applied Translational and Therapeutics Research, Catherine McAuley Centre, Nelson Street, D07 KX5K Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, D04 V1W8 Dublin, Ireland
- Stroke Service, Department of Medicine for the Elderly, Mater Misericordiae University Hospital, Eccles Street, D07 R2WY Dublin, Ireland
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Parametric Imaging of Biologic Activity of Atherosclerosis Using Dynamic Whole-Body Positron Emission Tomography. JACC. CARDIOVASCULAR IMAGING 2022; 15:2098-2108. [PMID: 36481078 DOI: 10.1016/j.jcmg.2022.05.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 04/26/2022] [Accepted: 05/11/2022] [Indexed: 01/11/2023]
Abstract
BACKGROUND For molecular imaging of atherosclerotic vessel wall activity, tracer kinetic analysis may yield improved contrast versus blood, more robust quantitative parameters, and more reliable characterization of systems biology. OBJECTIVES The authors introduce a novel dynamic whole-body positron emission tomography (PET) protocol that is enabled by rapid continuous camera table motion, followed by reconstruction of parametric data sets using voxel-based Patlak graphical analysis. METHODS Twenty-five subjects were prospectively enrolled and underwent dynamic PET up to 90 minutes after injection of 2-[18F]fluoro-2-deoxy-D-glucose (FDG). Two sets of images were generated: 1) the established standard of static standardized uptake value (SUV) images; and 2) parametric images of the metabolic rate of FDG (MRFDG) using the Patlak plot-derived influx rate. Arterial wall signal was measured and compared using the volume-of-interest technique, and its association with hematopoietic and lymphoid organ signal and atherosclerotic risk factors was explored. RESULTS Parametric MRFDG images provided excellent arterial wall visualization, with elimination of blood-pool activity, and enhanced focus detectability and reader confidence. Target-to-background ratio (TBR) from MRFDG images was significantly higher compared with SUV images (2.6 ± 0.8 vs 1.4 ± 0.2; P < 0.0001), confirming improved arterial wall contrast. On MRFDG images, arterial wall signal showed improved correlation with hematopoietic and lymphoid organ activity (spleen P = 0.0009; lymph nodes P = 0.0055; and bone marrow P = 0.0202) and increased with the number of atherosclerotic risk factors (r = 0.49; P = 0.0138), where signal from SUV images (SUVmaxP = 0.9754; TBRmaxP = 0.8760) did not. CONCLUSIONS Absolute quantification of MRFDG is feasible for arterial wall using dynamic whole-body PET imaging. Parametric images provide superior arterial wall contrast, and they might be better suited to explore the relationship between arterial wall activity, systemic organ networks, and cardiovascular risk. This novel methodology may serve as a platform for future diagnostic and therapeutic clinical studies targeting the biology of arterial wall disease.
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Molecular imaging in atherosclerosis. Clin Transl Imaging 2022. [DOI: 10.1007/s40336-022-00483-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Abstract
Purpose
As atherosclerosis is a prominent cause of morbidity and mortality, early detection of atherosclerotic plaques is vital to prevent complications. Imaging plays a significant role in this goal. Molecular imaging and structural imaging detect different phases of atherosclerotic progression. In this review, we explain the relation between these types of imaging with the physiopathology of plaques, along with their advantages and disadvantages. We also discuss in detail the most commonly used positron emission tomography (PET) radiotracers for atherosclerosis imaging.
Method
A comprehensive search was conducted to extract articles related to imaging of atherosclerosis in PubMed, Google Scholar, and Web of Science. The obtained papers were reviewed regarding precise relation with our topic. Among the search keywords utilized were "atherosclerosis imaging", "atherosclerosis structural imaging", "atherosclerosis CT scan" "positron emission tomography", "PET imaging", "18F-NaF", "18F-FDG", and "atherosclerosis calcification."
Result
Although structural imaging such as computed tomography (CT) offers essential information regarding plaque structure and morphologic features, these modalities can only detect macroscopic alterations that occur later in the disease’s progression, when the changes are frequently irreversible. Molecular imaging modalities like PET, on the other hand, have the advantage of detecting microscopic changes and allow us to treat these plaques before irreversible changes occur. The two most commonly used tracers in PET imaging of atherosclerosis are 18F-sodium fluoride (18F-NaF) and 18F-fluorodeoxyglucose (18F-FDG). While there are limitations in the use of 18F-FDG for the detection of atherosclerosis in coronary arteries due to physiological uptake in myocardium and high luminal blood pool activity of 18F-FDG, 18F-NaF PET is less affected and can be utilized to analyze the coronary arteries in addition to the peripheral vasculature.
Conclusion
Molecular imaging with PET/CT has become a useful tool in the early detection of atherosclerosis. 18F-NaF PET/CT shows promise in the early global assessment of atherosclerosis, but further prospective studies are needed to confirm its role in this area.
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Toward Reliable Uptake Metrics in Large Vessel Vasculitis Studies. Diagnostics (Basel) 2021; 11:diagnostics11111986. [PMID: 34829332 PMCID: PMC8617769 DOI: 10.3390/diagnostics11111986] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/18/2021] [Accepted: 10/21/2021] [Indexed: 11/16/2022] Open
Abstract
The aim of this study is to investigate the influence of sex, age, fat mass, fasting blood glucose level (FBGL), and estimated glomerular filtration rate (eGFR) on blood pool activity in patients with large vessel vasculitis (LVV). Blood pool activity was measured in the superior caval vein using mean, maximum, and peak standardized uptake values corrected for body weight (SUVs) and lean body mass (SULs) in 41 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scans of LVV patients. Sex influence on the blood pool activity was assessed with t-tests, while linear correlation analyses were used for age, fat mass, FBGL, and eGFR. Significantly higher SUVs were found in women compared with men, whereas SULs were similar between sexes. In addition, higher fat mass was associated with increased SUVs (r = 0.56 to 0.65; all p < 0.001) in the blood pool, but no correlations were found between SULs and fat mass (r = −0.25 to −0.15; all p > 0.05). Lower eGFR was associated with a higher FDG blood pool activity for all uptake values. In FDG-PET/CT studies with LVV patients, we recommend using SUL over SUV, while caution is advised in interpreting SUV and SUL measures when patients have impaired kidney function.
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Ahlman MA, Vigneault DM, Sandfort V, Maass-Moreno R, Dave J, Sadek A, Mallek MB, Selwaness MAF, Herscovitch P, Mehta NN, Bluemke DA. Internal tissue references for 18Fluorodeoxyglucose vascular inflammation imaging: Implications for cardiovascular risk stratification and clinical trials. PLoS One 2017; 12:e0187995. [PMID: 29131857 PMCID: PMC5683610 DOI: 10.1371/journal.pone.0187995] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 10/30/2017] [Indexed: 01/01/2023] Open
Abstract
Introduction 18Fluorodeoxyglucose (FDG) positron emission tomography (PET) uptake in the artery wall correlates with active inflammation. However, in part due to the low spatial resolution of PET, variation in the apparent arterial wall signal may be influenced by variation in blood FDG activity that cannot be fully corrected for using typical normalization strategies. The purpose of this study was to evaluate the ability of the current common methods to normalize for blood activity and to investigate alternative methods for more accurate quantification of vascular inflammation. Materials and methods The relationship between maximum FDG aorta wall activity and mean blood activity was evaluated in 37 prospectively enrolled subjects aged 55 years or more, treated for hyperlipidemia. Target maximum aorta standardized uptake value (SUV) and mean background reference tissue activity (blood, spleen, liver) were recorded. Target-to-background ratios (TBR) and arterial maximum activity minus blood activity were calculated. Multivariable regression was conducted, predicting uptake values based on variation in background reference and target tissue FDG uptake; adjusting for gender, age, lean body mass (LBM), blood glucose, blood pool activity, and glomerular filtration rate (GFR), where appropriate. Results Blood pool activity was positively associated with maximum artery wall SUV (β = 5.61, P<0.0001) as well as mean liver (β = 6.23, P<0.0001) and spleen SUV (β = 5.20, P<0.0001). Artery wall activity divided by blood activity (TBRBlood) or subtraction of blood activity did not remove the statistically significant relationship to blood activity. Blood pool activity was not related to TBRliver and TBRspleen (β = −0.36, P = NS and β = −0.58, P = NS, respectively) Conclusions In otherwise healthy individuals treated for hyperlipidemia, blood FDG activity is associated with artery wall activity. However, variation in blood activity may mask artery wall signal reflective of inflammation, which requires normalization. Blood-based TBR and subtraction do not sufficiently adjust for blood activity. Warranting further investigation, background reference tissues with cellular uptake such as the liver and spleen may better adjust for variation in blood activity to improve assessment of vascular activity.
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Affiliation(s)
- Mark A. Ahlman
- Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States of America
- * E-mail:
| | - Davis M. Vigneault
- Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States of America
- Institute of Biomedical Engineering, Department of Engineering, University of Oxford, Oxford, United Kingdom
- Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, United States of America
| | - Veit Sandfort
- Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States of America
| | - Roberto Maass-Moreno
- Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States of America
| | - Jenny Dave
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Ahmed Sadek
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Marissa B. Mallek
- Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States of America
| | - Mariana A. F. Selwaness
- Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States of America
| | - Peter Herscovitch
- PET Research Department, National Institutes of Health, Bethesda, MD, United States of America
| | - Nehal N. Mehta
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - David A. Bluemke
- Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States of America
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Evans NR, Tarkin JM, Buscombe JR, Markus HS, Rudd JHF, Warburton EA. PET imaging of the neurovascular interface in cerebrovascular disease. Nat Rev Neurol 2017; 13:676-688. [PMID: 28984315 DOI: 10.1038/nrneurol.2017.129] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cerebrovascular disease encompasses a range of pathologies that affect different components of the cerebral vasculature and brain parenchyma. Large artery atherosclerosis, acute cerebral ischaemia, and intracerebral small vessel disease all demonstrate altered metabolic processes that are key to their pathogenesis. Although structural imaging techniques such as MRI are the mainstay of clinical care and research in cerebrovascular disease, they have limited ability to detect these pathophysiological processes in vivo. By contrast, PET can detect and quantify metabolic processes that are relevant to each facet of cerebrovascular disease. Information obtained from PET studies has helped to shape the understanding of key concepts in cerebrovascular medicine, including vulnerable atherosclerotic plaque, salvageable ischaemic penumbra, neuroinflammation and selective neuronal loss after ischaemic insult. PET has also helped to elucidate the relationships between chronic hypoxia, neuroinflammation, and amyloid-β deposition in cerebral small vessel disease. This Review describes how PET-based imaging of metabolic processes at the neurovascular interface has contributed to our understanding of cerebrovascular disease.
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Affiliation(s)
- Nicholas R Evans
- Department of Clinical Neurosciences, University of Cambridge, Box 83, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Jason M Tarkin
- Division of Cardiovascular Medicine, Department of Medicine, University of Cambridge, Box 157, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - John R Buscombe
- Department of Nuclear Medicine, Box 219, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge CB2 0QQ, UK
| | - Hugh S Markus
- Department of Clinical Neurosciences, University of Cambridge, Box 83, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - James H F Rudd
- Division of Cardiovascular Medicine, Department of Medicine, University of Cambridge, Box 157, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Elizabeth A Warburton
- Department of Clinical Neurosciences, University of Cambridge, Box 83, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
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The Uptake of 18F-FDG by Renal Allograft in Kidney Transplant Recipients Is Not Influenced by Renal Function. Clin Nucl Med 2017; 41:683-7. [PMID: 27405040 DOI: 10.1097/rlu.0000000000001298] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
PURPOSE OF THE REPORT F-FDG PET/CT has been recently proposed as a noninvasive tool for the diagnosis of renal allograft acute rejection (AR) in kidney transplant recipients (KTRs). Still, the influence of kidney function on F-FDG uptake by renal grafts remains unknown. PATIENTS AND METHODS We retrospectively identified all KTRs who underwent at least one F-FDG PET/CT. Kidney transplant recipients with documented pyelonephritis or AR were excluded. Estimated glomerular filtration rate (eGFR) was assessed using chronic kidney disease (CKD)-EPI equation. Mean standardized uptake values (SUVmean) of renal graft cortex and aorta were measured in 4 and 1 volumes of interest, respectively. Spearman rank correlation coefficient (ρ) and analysis of variance (ANOVA) were performed. RESULTS Eighty-two KTRs underwent F-FDG PET/CT for tumor staging (n = 46), suspected infection (n = 11), or fever of unknown origin (n = 25). Mean eGFR was 50 ± 19 mL/min per 1.73 m, including CKD stage 1 (n = 3), stage 2 (n = 21), stage 3a (n = 20), stage 3b (n = 29), and stage 4 (n = 9). Mean kidney and aorta SUVmean were 1.8 ± 0.2 and 1.7 ± 0.3, respectively. No significant correlation was observed between eGFR and kidney SUVmean (ρ, 0.119; P, 0.28) or aorta SUVmean (ρ, -0.144; P, 0.20). ANOVA showed no difference of kidney (P, 0.62) and aorta (P, 0.85) SUVmean between CKD groups. Mean coefficient of variation (on the basis of kidney SUVmean of >3 consecutive F-FDG PET/CT in 15 patients with no significant change of eGFR) reached 13.1%. CONCLUSIONS The uptake of F-FDG by renal allografts within an hour postinjection is not significantly impacted by CKD.
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Evans NR, Tarkin JM, Chowdhury MM, Warburton EA, Rudd JHF. PET Imaging of Atherosclerotic Disease: Advancing Plaque Assessment from Anatomy to Pathophysiology. Curr Atheroscler Rep 2016; 18:30. [PMID: 27108163 PMCID: PMC4842219 DOI: 10.1007/s11883-016-0584-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Atherosclerosis is a leading cause of morbidity and mortality. It is now widely recognized that the disease is more than simply a flow-limiting process and that the atheromatous plaque represents a nidus for inflammation with a consequent risk of plaque rupture and atherothrombosis, leading to myocardial infarction or stroke. However, widely used conventional clinical imaging techniques remain anatomically focused, assessing only the degree of arterial stenosis caused by plaques. Positron emission tomography (PET) has allowed the metabolic processes within the plaque to be detected and quantified directly. The increasing armory of radiotracers has facilitated the imaging of distinct metabolic aspects of atherogenesis and plaque destabilization, including macrophage-mediated inflammatory change, hypoxia, and microcalcification. This imaging modality has not only furthered our understanding of the disease process in vivo with new insights into mechanisms but has also been utilized as a non-invasive endpoint measure in the development of novel treatments for atherosclerotic disease. This review provides grounding in the principles of PET imaging of atherosclerosis, the radioligands in use and in development, its research and clinical applications, and future developments for the field.
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Affiliation(s)
- Nicholas R Evans
- Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Jason M Tarkin
- Division of Cardiovascular Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK
| | - Mohammed M Chowdhury
- Division of Vascular and Endovascular Surgery, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK
| | - Elizabeth A Warburton
- Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0QQ, UK
| | - James H F Rudd
- Division of Cardiovascular Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK
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Chen W, Dilsizian V. PET assessment of vascular inflammation and atherosclerotic plaques: SUV or TBR? J Nucl Med 2015; 56:503-4. [PMID: 25722451 DOI: 10.2967/jnumed.115.154385] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 02/06/2015] [Indexed: 11/16/2022] Open
Affiliation(s)
- Wengen Chen
- University of Maryland, School of Medicine, Baltimore, Maryland
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Monitoring plaque inflammation in atherosclerotic rabbits with an iron oxide (P904) and (18)F-FDG using a combined PET/MR scanner. Atherosclerosis 2013; 228:339-45. [PMID: 23582588 DOI: 10.1016/j.atherosclerosis.2013.03.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 03/08/2013] [Accepted: 03/11/2013] [Indexed: 12/26/2022]
Abstract
PURPOSE The aim of this study was to compare the ability of (18)F-FDG PET and iron contrast-enhanced MRI with a novel USPIO (P904) to assess change in plaque inflammation induced by atorvastatin and dietary change in a rabbit model of atherosclerosis using a combined PET/MR scanner. MATERIALS AND METHODS Atherosclerotic rabbits underwent USPIO-enhanced MRI and (18)F-FDG PET in PET/MR hybrid system at baseline and were then randomly divided into a progression group (high cholesterol diet) and a regression group (chow diet and atorvastatin). Each group was scanned again 6 months after baseline imaging. R2* (i.e. 1/T2*) values were calculated pre/post P904 injection. (18)F-FDG PET data were analyzed by averaging the mean Standard Uptake Value (SUVmean) over the abdominal aorta. The in vivo imaging was then correlated with matched histological sections stained for macrophages. RESULTS (18)F-FDG PET showed strong FDG uptake in the abdominal aorta and P904 injection revealed an increase in R2* values in the aortic wall at baseline. At 6 months, SUVmean values measured in the regression group showed a significant decrease from baseline (p = 0.015). In comparison, progression group values remained constant (p = 0.681). R2* values showed a similar decreasing trend in the regression group suggesting less USPIO uptake in the aortic wall. Correlations between SUVmean or Change in R2* value and macrophages density (RAM-11 staining) were good (R(2) = 0.778 and 0.707 respectively). CONCLUSION This experimental study confirms the possibility to combine two functional imaging modalities to assess changes in the inflammation of atherosclerotic plaques. (18)F-FDG-PET seems to be more sensitive than USPIO P904 to detect early changes in plaque inflammation.
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