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Larsson HBW, Law I, Andersen TL, Andersen FL, Fischer BM, Vestergaard MB, Larsson TSW, Lindberg U. Brain perfusion estimation by Tikhonov model-free deconvolution in a long axial field of view PET/CT scanner exploring five different PET tracers. Eur J Nucl Med Mol Imaging 2024; 51:707-720. [PMID: 37843600 PMCID: PMC10796558 DOI: 10.1007/s00259-023-06469-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 10/03/2023] [Indexed: 10/17/2023]
Abstract
PURPOSE New total-body PET scanners with a long axial field of view (LAFOV) allow for higher temporal resolution due to higher sensitivity, which facilitates perfusion estimation by model-free deconvolution. Fundamental tracer kinetic theory predicts that perfusion can be estimated for all tracers despite their different fates given sufficiently high temporal resolution of 1 s or better, bypassing the need for compartment modelling. The aim of this study was to investigate whether brain perfusion could be estimated using model-free Tikhonov generalized deconvolution for five different PET tracers, [15O]H2O, [11C]PIB, [18F]FE-PE2I, [18F]FDG and [18F]FET. To our knowledge, this is the first example of a general model-free approach to estimate cerebral blood flow (CBF) from PET data. METHODS Twenty-five patients underwent dynamic LAFOV PET scanning (Siemens, Quadra). PET images were reconstructed with an isotropic voxel resolution of 1.65 mm3. Time framing was 40 × 1 s during bolus passage followed by increasing framing up to 60 min. AIF was obtained from the descending aorta. Both voxel- and region-based calculations of perfusion in the thalamus were performed using the Tikhonov method. The residue impulse response function was used to estimate the extraction fraction of tracer leakage across the blood-brain barrier. RESULTS CBF ranged from 37 to 69 mL blood min-1 100 mL of tissue-1 in the thalamus. Voxelwise calculation of CBF resulted in CBF maps in the physiologically normal range. The extraction fractions of [15O]H2O, [18F]FE-PE2I, [11C]PIB, [18F]FDG and [18F]FET in the thalamus were 0.95, 0.78, 0.62, 0.19 and 0.03, respectively. CONCLUSION The high temporal resolution and sensitivity associated with LAFOV PET scanners allow for noninvasive perfusion estimation of multiple tracers. The method provides an estimation of the residue impulse response function, from which the fate of the tracer can be studied, including the extraction fraction, influx constant, volume of distribution and transit time distribution, providing detailed physiological insight into normal and pathologic tissue.
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Affiliation(s)
- Henrik Bo Wiberg Larsson
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital-Rigshospitalet, Valdemar Hansens Vej 13, 2600, Glostrup, Denmark.
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Ian Law
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Thomas L Andersen
- Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Flemming L Andersen
- Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Barbara M Fischer
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Mark B Vestergaard
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital-Rigshospitalet, Valdemar Hansens Vej 13, 2600, Glostrup, Denmark
| | - Tanne S W Larsson
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital-Rigshospitalet, Valdemar Hansens Vej 13, 2600, Glostrup, Denmark
| | - Ulrich Lindberg
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital-Rigshospitalet, Valdemar Hansens Vej 13, 2600, Glostrup, Denmark
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Marques TR, Veronese M, Owen DR, Rabiner EA, Searle GE, Howes OD. Specific and non-specific binding of a tracer for the translocator-specific protein in schizophrenia: an [11C]-PBR28 blocking study. Eur J Nucl Med Mol Imaging 2021; 48:3530-3539. [PMID: 33825022 PMCID: PMC8440284 DOI: 10.1007/s00259-021-05327-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 03/21/2021] [Indexed: 11/24/2022]
Abstract
OBJECTIVE The mitochondrial 18-kDa translocator protein (TSPO) is expressed by activated microglia and positron emission tomography enables the measurement of TSPO levels in the brain. Findings in schizophrenia have shown to vary depending on the outcome measure used and this discrepancy in TSPO results could be explained by lower non-displaceable binding (VND) in schizophrenia, which could obscure increases in specific binding. In this study, we have used the TSPO ligand XBD173 to block the TSPO radioligand [11C]-PBR28 and used an occupancy plot to quantify VND in patients with schizophrenia. METHODS A total of 7 patients with a diagnosis of schizophrenia were recruited for this study. Each patient received two separate PET scans with [11C]PBR28, one at baseline and one after the administration of the TSPO ligand XBD173. All patients were high-affinity binders (HABs) for the TSPO gene. We used an occupancy plot to quantify the non-displaceable component (VND) using 2TCM kinetic estimates with and without vascular correction. Finally we computed the VND at a single subject level using the SIME method. RESULTS All patients showed a global and generalized reduction in [11C]PBR28 uptake after the administration of XBD173. Constraining the VND to be equal for all patients, the population VND was estimated to be 1.99 mL/cm3 (95% CI 1.90 to 2.08). When we used vascular correction, the fractional TSPO occupancy remained similar. CONCLUSIONS In schizophrenia patients, a substantial component of the [11C]PBR28 signal represents specific binding to TSPO. Furthermore, the VND in patients with schizophrenia is similar to that previously reported in healthy controls. These results suggest that changes in non-specific binding between schizophrenia patients and healthy controls do not account for discrepant PET findings in this disorder.
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Affiliation(s)
- Tiago Reis Marques
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences (LMS), Hammersmith Hospital, Imperial College London, London, UK.
- Psychiatric Imaging Group, Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK.
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London, UK.
| | - Mattia Veronese
- Centre for Neuroimaging Sciences, Institute of Psychiatry, King's College London, London, UK
| | - David R Owen
- Division of Brain Sciences, Department of Medicine, Imperial College, London, UK
| | - Eugenii A Rabiner
- Centre for Neuroimaging Sciences, Institute of Psychiatry, King's College London, London, UK
- Invicro, London, UK
| | | | - Oliver D Howes
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences (LMS), Hammersmith Hospital, Imperial College London, London, UK
- Psychiatric Imaging Group, Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London, UK
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3
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Nettis MA, Veronese M, Nikkheslat N, Mariani N, Lombardo G, Sforzini L, Enache D, Harrison NA, Turkheimer FE, Mondelli V, Pariante CM. PET imaging shows no changes in TSPO brain density after IFN-α immune challenge in healthy human volunteers. Transl Psychiatry 2020; 10:89. [PMID: 32152285 PMCID: PMC7063038 DOI: 10.1038/s41398-020-0768-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 02/18/2020] [Accepted: 02/24/2020] [Indexed: 12/22/2022] Open
Abstract
Depression is associated with peripheral inflammation, but its link with brain microglial activity remains unclear. In seven healthy males, we used repeated translocator protein-Positron Emission Tomography (TSPO-PET) dynamic scans with [11C]PBR28 to image brain microglial activation before and 24 h after the immune challenge interferon (IFN)-α. We also investigated the association between changes in peripheral inflammation, changes in microglial activity, and changes in mood. IFN-α administration decreased [11C]PBR28 PET tissue volume of distribution (Vt) across the brain (-20 ± 4%; t6 = 4.1, p = 0.01), but after correction for radioligand free-plasma fraction there were no longer any changes (+23 ± 31%; t = 0.1, p = 0.91). IFN-α increased serum IL-6 (1826 ± 513%, t6 = -7.5, p < 0.001), IL-7 (39 ± 12%, t6 = -3.6, p = 0.01), IL-10 (328 ± 48%, t6 = -12.8, p < 0.001), and IFN-γ (272 ± 64%, t6 = -7.0, p < 0.001) at 4-6 h, and increased serum TNF-α (49 ± 7.6%, t6 = -7.5, p < 0.001), IL-8 (39 ± 12%, t6 = -3.5, p = 0.013), and C-reactive protein (1320 ± 459%, t6 = -7.2, p < 0.001) at 24 h. IFN-α induced temporary mood changes and sickness symptoms after 4-6 h, measured as an increase in POMS-2 total mood score, confusion and fatigue, and a decrease in vigor and friendliness (all p ≤ 0.04). No association was found between changes in peripheral inflammation and changes in PET or mood measures. Our work suggests that brain TSPO-PET signal is highly dependent of inflammation-induced changes in ligand binding to plasma proteins. This limits its usefulness as a sensitive marker of neuroinflammation and consequently, data interpretation. Thus, our results can be interpreted as showing either that [11C]PBR28 is not sensitive enough under these conditions, or that there is simply no microglial activation in this model.
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Affiliation(s)
- M A Nettis
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, Department of Psychological Medicine, London, UK.
- National Institute for Health and Research Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London, London, UK.
| | - M Veronese
- National Institute for Health and Research Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London, London, UK
- Institute of Psychiatry, Psychology and Neuroscience, King's College London Department of Neuroimaging, London, UK
| | - N Nikkheslat
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, Department of Psychological Medicine, London, UK
| | - N Mariani
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, Department of Psychological Medicine, London, UK
| | - G Lombardo
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, Department of Psychological Medicine, London, UK
| | - L Sforzini
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, Department of Psychological Medicine, London, UK
- Universita' degli Studi di Milano, Psychiatry Unit, Department of Biomedical and Clinical Sciences, Luigi Sacco Hospital, Milan, Italy
| | - D Enache
- Karolinska Institute, Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Stockholm, Sweden
| | - N A Harrison
- Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK
| | - F E Turkheimer
- National Institute for Health and Research Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London, London, UK
- Institute of Psychiatry, Psychology and Neuroscience, King's College London Department of Neuroimaging, London, UK
| | - V Mondelli
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, Department of Psychological Medicine, London, UK
- National Institute for Health and Research Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London, London, UK
| | - C M Pariante
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, Department of Psychological Medicine, London, UK
- National Institute for Health and Research Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London, London, UK
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Dahoun T, Calcia MA, Veronese M, Bloomfield P, Reis Marques T, Turkheimer F, Howes OD. The association of psychosocial risk factors for mental health with a brain marker altered by inflammation: A translocator protein (TSPO) PET imaging study. Brain Behav Immun 2019; 80:742-750. [PMID: 31112791 DOI: 10.1016/j.bbi.2019.05.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 05/16/2019] [Indexed: 12/11/2022] Open
Abstract
Psychiatric disorders associated with psychosocial risk factors, including depression and psychosis, have been shown to demonstrate increased microglia activity. Whilst preclinical studies indicate that psychosocial stress leads to increased levels of microglia in the frontal cortex, no study has yet been performed in humans. This study aimed at investigating whether psychosocial risk factors for depression and/or psychosis would be associated with alterations in a brain marker expressed by microglia, the translocator specific protein (TSPO) in humans. We used [11C]-PBR28 Positron Emission Tomography on healthy subjects exposed to childhood and adulthood psychosocial risk factors (high-risk group, N = 12) and age- and sex-matched healthy controls not exposed to childhood and adulthood psychosocial risk factors (low-risk group, N = 12). The [11C]-PBR28 volume of distribution (VT) and Distribution Volume Ratio (DVR) were measured in the total gray matter, and frontal, parietal, temporal, occipital lobes. Levels of childhood trauma, anxiety and depression were measured using respectively the Childhood Trauma Questionnaire, State-anxiety questionnaire and Beck Depression Inventory. Compared to the low-risk group, the high-risk group did not exhibit significant differences in the mean [11C]-PBR28 VT (F(1,20) = 1.619, p = 0.218) or DVR (F(1,22) = 0.952, p = 0.340) on any region. There were no significant correlations between the [11C]-PBR28 VT and DVRs in total gray matter and frontal lobe and measures of childhood trauma, anxiety and depression. Psychosocial risk factors for depression and/or psychosis are unlikely to be associated with alterations in [11C]-PBR28 binding, indicating that alterations in TSPO expression reported in these disorders is unlikely to be caused by psychosocial risk factors alone.
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Affiliation(s)
- Tarik Dahoun
- Psychiatric Imaging Group MRC London Institute of Medical Sciences, Hammersmith Hospital, London W12 0NN, UK; Institute of Clinical Sciences, Faculty of Medicine, Imperial College, Hammersmith Hospital, London W12 0NN, UK; Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford OX37 JX, UK
| | - Marilia A Calcia
- Institute of Psychiatry, Neurology and Neuroscience (IoPPN), King's College London, London SE5 8AF, UK
| | - Mattia Veronese
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Neurology and Neuroscience (IoPPN), King's College London, London SE5 8AF, UK
| | - Peter Bloomfield
- Psychiatric Imaging Group MRC London Institute of Medical Sciences, Hammersmith Hospital, London W12 0NN, UK; Institute of Clinical Sciences, Faculty of Medicine, Imperial College, Hammersmith Hospital, London W12 0NN, UK
| | - Tiago Reis Marques
- Psychiatric Imaging Group MRC London Institute of Medical Sciences, Hammersmith Hospital, London W12 0NN, UK; Institute of Clinical Sciences, Faculty of Medicine, Imperial College, Hammersmith Hospital, London W12 0NN, UK; Institute of Psychiatry, Neurology and Neuroscience (IoPPN), King's College London, London SE5 8AF, UK
| | - Federico Turkheimer
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Neurology and Neuroscience (IoPPN), King's College London, London SE5 8AF, UK
| | - Oliver D Howes
- Psychiatric Imaging Group MRC London Institute of Medical Sciences, Hammersmith Hospital, London W12 0NN, UK; Institute of Clinical Sciences, Faculty of Medicine, Imperial College, Hammersmith Hospital, London W12 0NN, UK; Institute of Psychiatry, Neurology and Neuroscience (IoPPN), King's College London, London SE5 8AF, UK.
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5
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Veronese M, Reis Marques T, Bloomfield PS, Rizzo G, Singh N, Jones D, Agushi E, Mosses D, Bertoldo A, Howes O, Roncaroli F, Turkheimer FE. Kinetic modelling of [ 11C]PBR28 for 18 kDa translocator protein PET data: A validation study of vascular modelling in the brain using XBD173 and tissue analysis. J Cereb Blood Flow Metab 2018; 38:1227-1242. [PMID: 28580888 PMCID: PMC6434448 DOI: 10.1177/0271678x17712388] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The 18 kDa translocator protein (TSPO) is a marker of microglia activation in the central nervous system and represents the main target of radiotracers for the in vivo quantification of neuroinflammation with positron emission tomography (PET). TSPO PET is methodologically challenging given the heterogeneous distribution of TSPO in blood and brain. Our previous studies with the TSPO tracers [11C]PBR28 and [11C]PK11195 demonstrated that a model accounting for TSPO binding to the endothelium improves the quantification of PET data. Here, we performed a validation of the kinetic model with the additional endothelial compartment through a displacement study. Seven subjects with schizophrenia, all high-affinity binders, underwent two [11C]PBR28 PET scans before and after oral administration of 90 mg of the TSPO ligand XBD173. The addition of the endothelial component provided a signal compartmentalization much more consistent with the underlying biology, as only in this model, the blocking study produced the expected reduction in the tracer concentration of the specific tissue compartment, whereas the non-displaceable compartment remained unchanged. In addition, we also studied TSPO expression in vessels using 3D reconstructions of histological data of frontal lobe and cerebellum, demonstrating that TSPO positive vessels account for 30% of the vascular volume in cortical and white matter.
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Affiliation(s)
- Mattia Veronese
- Department of Neuroimaging, IoPPN,
King’s College London, London, UK
| | - Tiago Reis Marques
- Department of Psychosis Studies, IoPPN,
King’s College London, London, UK
- Institute of Clinical Sciences, Imperial
College London, London, UK
| | | | - Gaia Rizzo
- Department of Information Engineering,
Padova University, Padova, Italy
| | - Nisha Singh
- Department of Neuroimaging, IoPPN,
King’s College London, London, UK
| | - Deborah Jones
- Department of Cellular Pathology,
Salford Royal Foundation Trust, Salford, UK
| | - Erjon Agushi
- Division of Neuroscience and
Experimental Psychology, University of Manchester, UK
| | - Dominic Mosses
- Division of Neuroscience and
Experimental Psychology, University of Manchester, UK
| | - Alessandra Bertoldo
- Department of Information Engineering,
Padova University, Padova, Italy
- Padua Neuroscience Center, University of
Padova, Padova, Italy
| | - Oliver Howes
- Department of Psychosis Studies, IoPPN,
King’s College London, London, UK
- Institute of Clinical Sciences, Imperial
College London, London, UK
| | - Federico Roncaroli
- Division of Neuroscience and
Experimental Psychology, University of Manchester, UK
| | - Federico E Turkheimer
- Department of Neuroimaging, IoPPN,
King’s College London, London, UK
- Federico E Turkheimer, Centre for
Neuroimaging Sciences, IoPPN, King’s College London, P089, De Crespigny Park,
Denmark Hill, London SE5 8AF, UK.
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Arakawa Y, Nai Y, Shidahara M, Furumoto S, Seki C, Okamura N, Tashiro M, Kudo Y, Yanai K, Gonda K, Watabe H. Prediction of the Clinical SUV Ratio in Amyloid PET Imaging Using a Biomathematic Modeling Approach Toward the Efficient Development of a Radioligand. J Nucl Med 2017; 58:1285-1292. [DOI: 10.2967/jnumed.116.183566] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 12/07/2016] [Indexed: 11/16/2022] Open
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7
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Tonietto M, Rizzo G, Veronese M, Fujita M, Zoghbi SS, Zanotti-Fregonara P, Bertoldo A. Plasma radiometabolite correction in dynamic PET studies: Insights on the available modeling approaches. J Cereb Blood Flow Metab 2016; 36:326-39. [PMID: 26661202 PMCID: PMC4759680 DOI: 10.1177/0271678x15610585] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 07/09/2015] [Indexed: 11/17/2022]
Abstract
Full kinetic modeling of dynamic PET images requires the measurement of radioligand concentrations in the arterial plasma. The unchanged parent radioligand must, however, be separated from its radiometabolites by chromatographic methods. Thus, only few samples can usually be analyzed and the resulting measurements are often noisy. Therefore, the measurements must be fitted with a mathematical model. This work presents a comprehensive analysis of the different models proposed in the literature to describe the plasma parent fraction (PPf) and of the alternative approaches for radiometabolite correction. Finally, we used a dataset of [(11)C]PBR28 brain PET data as a case study to guide the reader through the PPf model selection process.
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Affiliation(s)
- Matteo Tonietto
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Gaia Rizzo
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Mattia Veronese
- Department of Neuroimaging, IoPPN, King's College London, London, UK
| | - Masahiro Fujita
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, MD, USA
| | - Sami S Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, MD, USA
| | - Paolo Zanotti-Fregonara
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, MD, USA INCIA UMR-CNRS 5287, Université de Bordeaux, Bordeaux, France
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Su Y, Blazey TM, Snyder AZ, Raichle ME, Hornbeck RC, Aldea P, Morris JC, Benzinger TLS. Quantitative amyloid imaging using image-derived arterial input function. PLoS One 2015; 10:e0122920. [PMID: 25849581 PMCID: PMC4388540 DOI: 10.1371/journal.pone.0122920] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 02/24/2015] [Indexed: 11/19/2022] Open
Abstract
Amyloid PET imaging is an indispensable tool widely used in the investigation, diagnosis and monitoring of Alzheimer’s disease (AD). Currently, a reference region based approach is used as the mainstream quantification technique for amyloid imaging. This approach assumes the reference region is amyloid free and has the same tracer influx and washout kinetics as the regions of interest. However, this assumption may not always be valid. The goal of this work is to evaluate an amyloid imaging quantification technique that uses arterial region of interest as the reference to avoid potential bias caused by specific binding in the reference region. 21 participants, age 58 and up, underwent Pittsburgh compound B (PiB) PET imaging and MR imaging including a time-of-flight (TOF) MR angiography (MRA) scan and a structural scan. FreeSurfer based regional analysis was performed to quantify PiB PET data. Arterial input function was estimated based on coregistered TOF MRA using a modeling based technique. Regional distribution volume (VT) was calculated using Logan graphical analysis with estimated arterial input function. Kinetic modeling was also performed using the estimated arterial input function as a way to evaluate PiB binding (DVRkinetic) without a reference region. As a comparison, Logan graphical analysis was also performed with cerebellar cortex as reference to obtain DVRREF. Excellent agreement was observed between the two distribution volume ratio measurements (r>0.89, ICC>0.80). The estimated cerebellum VT was in line with literature reported values and the variability of cerebellum VT in the control group was comparable to reported variability using arterial sampling data. This study suggests that image-based arterial input function is a viable approach to quantify amyloid imaging data, without the need of arterial sampling or a reference region. This technique can be a valuable tool for amyloid imaging, particularly in population where reference normalization may not be accurate.
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Affiliation(s)
- Yi Su
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Knight Alzheimer’s Disease Research Center (ADRC), Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail:
| | - Tyler M. Blazey
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Abraham Z. Snyder
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Marcus E. Raichle
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Russ C. Hornbeck
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Knight Alzheimer’s Disease Research Center (ADRC), Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Patricia Aldea
- Knight Alzheimer’s Disease Research Center (ADRC), Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - John C. Morris
- Department of Neurology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Knight Alzheimer’s Disease Research Center (ADRC), Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Tammie L. S. Benzinger
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Knight Alzheimer’s Disease Research Center (ADRC), Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Neurosurgery, Washington University School of Medicine, Saint Louis, Missouri, United States of America
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9
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Daniela P, Orazio S, Alessandro P, Mariano NF, Leonardo I, Pasquale Anthony DR, Giovanni F, Carlo C. A survey of FDG- and amyloid-PET imaging in dementia and GRADE analysis. BIOMED RESEARCH INTERNATIONAL 2014; 2014:785039. [PMID: 24772437 PMCID: PMC3977528 DOI: 10.1155/2014/785039] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 01/29/2014] [Indexed: 12/25/2022]
Abstract
PET based tools can improve the early diagnosis of Alzheimer's disease (AD) and differential diagnosis of dementia. The importance of identifying individuals at risk of developing dementia among people with subjective cognitive complaints or mild cognitive impairment has clinical, social, and therapeutic implications. Within the two major classes of AD biomarkers currently identified, that is, markers of pathology and neurodegeneration, amyloid- and FDG-PET imaging represent decisive tools for their measurement. As a consequence, the PET tools have been recognized to be of crucial value in the recent guidelines for the early diagnosis of AD and other dementia conditions. The references based recommendations, however, include large PET imaging literature based on visual methods that greatly reduces sensitivity and specificity and lacks a clear cut-off between normal and pathological findings. PET imaging can be assessed using parametric or voxel-wise analyses by comparing the subject's scan with a normative data set, significantly increasing the diagnostic accuracy. This paper is a survey of the relevant literature on FDG and amyloid-PET imaging aimed at providing the value of quantification for the early and differential diagnosis of AD. This allowed a meta-analysis and GRADE analysis revealing high values for PET imaging that might be useful in considering recommendations.
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Affiliation(s)
- Perani Daniela
- Nuclear Medicine Department, Vita-Salute San Raffaele University, San Raffaele Hospital and Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
| | - Schillaci Orazio
- Nuclear Medicine Department, University of Rome “Tor Vergata” and IRCCS Neuromed, 86077 Pozzilli, Italy
| | - Padovani Alessandro
- Department of Medical and Experimental Sciences, Unit of Neurology, Brescia University, 25123 Brescia, Italy
| | - Nobili Flavio Mariano
- Department of Neuroscience Ophthalmology and Genetics, University of Genoa, 16132 Genoa, Italy
| | - Iaccarino Leonardo
- Nuclear Medicine Department, Vita-Salute San Raffaele University, San Raffaele Hospital and Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
| | | | - Frisoni Giovanni
- IRCCS Centro San Giovanni di Dio Fatebenefratelli, and Memory Clinic and LANVIE, Laboratory of Neuroimaging of Aging, University Hospitals and University of Geneva, 1225 Geneva, Switzerland
| | - Caltagirone Carlo
- University of Rome Tor Vergata and IRCSS S. Lucia, 00142 Rome, Italy
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10
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Su Y, D'Angelo GM, Vlassenko AG, Zhou G, Snyder AZ, Marcus DS, Blazey TM, Christensen JJ, Vora S, Morris JC, Mintun MA, Benzinger TLS. Quantitative analysis of PiB-PET with FreeSurfer ROIs. PLoS One 2013; 8:e73377. [PMID: 24223109 PMCID: PMC3819320 DOI: 10.1371/journal.pone.0073377] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 07/27/2013] [Indexed: 11/19/2022] Open
Abstract
In vivo quantification of β-amyloid deposition using positron emission tomography is emerging as an important procedure for the early diagnosis of the Alzheimer's disease and is likely to play an important role in upcoming clinical trials of disease modifying agents. However, many groups use manually defined regions, which are non-standard across imaging centers. Analyses often are limited to a handful of regions because of the labor-intensive nature of manual region drawing. In this study, we developed an automatic image quantification protocol based on FreeSurfer, an automated whole brain segmentation tool, for quantitative analysis of amyloid images. Standard manual tracing and FreeSurfer-based analyses were performed in 77 participants including 67 cognitively normal individuals and 10 individuals with early Alzheimer's disease. The manual and FreeSurfer approaches yielded nearly identical estimates of amyloid burden (intraclass correlation = 0.98) as assessed by the mean cortical binding potential. An MRI test-retest study demonstrated excellent reliability of FreeSurfer based regional amyloid burden measurements. The FreeSurfer-based analysis also revealed that the majority of cerebral cortical regions accumulate amyloid in parallel, with slope of accumulation being the primary difference between regions.
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Affiliation(s)
- Yi Su
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Knight Alzheimer's Disease Research Center, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail:
| | - Gina M. D'Angelo
- Division of Biostatistics, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Neurology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Andrei G. Vlassenko
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Knight Alzheimer's Disease Research Center, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Gongfu Zhou
- Division of Biostatistics, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Abraham Z. Snyder
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Neurology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Daniel S. Marcus
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Knight Alzheimer's Disease Research Center, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Tyler M. Blazey
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Jon J. Christensen
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Shivangi Vora
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - John C. Morris
- Department of Neurology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Knight Alzheimer's Disease Research Center, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Mark A. Mintun
- Avid Radiophamaceuticals, Philadelphia, Pennsylvania, United States of America
| | - Tammie L. S. Benzinger
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Knight Alzheimer's Disease Research Center, Washington University School of Medicine, Saint Louis, Missouri, United States of America
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11
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Ikoma Y, Edison P, Ramlackhansingh A, Brooks DJ, Turkheimer FE. Reference region automatic extraction in dynamic [(11)C]PIB. J Cereb Blood Flow Metab 2013; 33:1725-31. [PMID: 23921900 PMCID: PMC3824180 DOI: 10.1038/jcbfm.2013.133] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 06/16/2013] [Accepted: 07/10/2013] [Indexed: 11/09/2022]
Abstract
The positron emission tomography (PET) radiotracer [(11)C]Pittsburgh Compound B (PIB) is a marker of amyloid plaque deposition in brain, and binding potential is usually quantified using the cerebellum as a reference where the specific binding is negligible. The use of the cerebellum as a reference, however, has been questioned by the reported cerebellar [(11)C]PIB retention in familial Alzheimer's disease (AD) subjects. In this work, we developed a supervised clustering procedure for the automatic extraction of a reference region in [(11)C]PIB studies. Supervised clustering models each gray matter voxel as the linear combination of three predefined kinetic classes, normal and lesion gray matter, and blood pool, and extract reference voxels in which the contribution of the normal gray matter class is high. In the validation with idiopathic AD subjects, supervised clustering extracted reference voxels mostly in the cerebellum that indicated little specific [(11)C]PIB binding, and total distribution volumes of the extracted region were lower than those of the cerebellum. Next, the methodology was applied to the familial AD cohort where the cerebellar amyloid load had been demonstrated previously, resulting in higher binding potential compared with that obtained with the cerebellar reference. The supervised clustering method is a useful tool for the accurate quantification of [(11)C]PIB studies.
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Affiliation(s)
- Yoko Ikoma
- Biophysics Group, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
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12
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Edison P, Carter SF, Rinne JO, Gelosa G, Herholz K, Nordberg A, Brooks DJ, Hinz R. Comparison of MRI based and PET template based approaches in the quantitative analysis of amyloid imaging with PIB-PET. Neuroimage 2012; 70:423-33. [PMID: 23261639 DOI: 10.1016/j.neuroimage.2012.12.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 11/10/2012] [Accepted: 12/10/2012] [Indexed: 11/15/2022] Open
Abstract
RATIONALE [(11)C]Pittsburgh compound-B (PIB) has been the most widely used positron emission tomography (PET) imaging agent for brain amyloid. Several longitudinal studies evaluating the progression of Alzheimer's disease (AD), and numerous therapeutic intervention studies are underway using [(11)C]PIB PET as an AD biomarker. Quantitative analysis of [(11)C]PIB data requires the definition of regional volumes of interest. This investigation systematically compared two data analysis routes both using a probabilistic brain atlas with 11 bilateral regions. Route 1 used individually segmented structural magnetic resonance images (MRI) for each subject while Route 2 used a standardised [(11)C]PIB PET template. METHODS A total of 54 subjects, 20 with probable Alzheimer's disease (AD), 14 with amnestic Mild Cognitive Impairment (MCI) and 20 age-matched healthy controls, were scanned at two imaging centres either in London (UK) or in Turku (Finland). For all subjects structural volumetric MRI and [(11)C]PIB PET scans were acquired. Target-to-cerebellum ratios 40 min to 60 min post injection were used as outcome measures. Regional read outs for grey matter target regions were generated for both routes. Based on a composite neocortical, frontal, posterior cingulate, combined posterior cingulate and frontal cortical regions, scans were categorised into either 'PIB negative' (PIB-) or 'PIB positive' (PIB+) using previously reported cut-off target-to-cerebellar ratios of 1.41, 1.5 and 1.6, respectively. RESULTS Target-to-cerebellum ratios were greater when defined with a [(11)C]PIB PET template than with individual MRIs for all cortical regions regardless of diagnosis. This difference was highly significant for controls (p<0.001, paired samples t-test), less significant for MCIs and borderline for ADs. Assignment of subjects to raised or normal categories was the same with both routes with a 1.6 cut-off while with lower cut off using frontal cortex, and combined frontal cortex and posterior cingulate demonstrated similar results, while posterior cingulate alone demonstrated significantly higher proportion of controls as amyloid positive by Route 2. CONCLUSIONS Definition of cortical grey matter regions is more accurate when individually segmented MRIs (Route 1) were used rather than a population-based PET template (Route 2). The impact of this difference depends on the grey-to-white matter contrast in the PET images; specifically seen in healthy controls with high white matter and low grey matter uptake. When classifying AD, MCI and control subjects as normal or abnormal using large cortical regions; discordance was found between the MRI and template approach for those few subjects who presented with cortex-to-cerebellum ratios very close to the pre-assigned cut-off. However, posterior cingulate alone demonstrated significant discordance in healthy controls using template based approach. This study, therefore, demonstrates that the use of a [(11)C]PIB PET template (Route 2) is adequate for clinical diagnostic purposes, while MRI based analysis (Route 1) remains more appropriate for clinical research.
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Affiliation(s)
- P Edison
- Division of Neuroscience, Imperial College London, Hammersmith Campus, London, UK.
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13
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Shibuya K, Funaki Y, Hiraoka K, Yoshikawa T, Naganuma F, Miyake M, Watanuki S, Sato H, Tashiro M, Yanai K. [(11)C]Doxepin binding to histamine H1 receptors in living human brain: reproducibility during attentive waking and circadian rhythm. Front Syst Neurosci 2012; 6:45. [PMID: 22701403 PMCID: PMC3371597 DOI: 10.3389/fnsys.2012.00045] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 05/21/2012] [Indexed: 11/13/2022] Open
Abstract
Molecular imaging in neuroscience is a new research field that enables visualization of the impact of molecular events on brain structure and function in humans. While magnetic resonance-based imaging techniques can provide complex information at the level of system, positron emission tomography (PET) enables determination of the distribution and density of receptor and enzyme in the human brain. Previous studies using [(11)C]raclopride and [(11)C]FLB457 revealed that the release of neuronal dopamine was increased in human brain by psychostimulants or reward stimuli. Following on from these previous [(11)C]raclopride studies, we examined whether the levels of neuronal release of histamine might change [(11)C]doxepin binding to the H1 receptors under the influence of physiological stimuli. The purpose of the present study was to evaluate the test-retest reliability of quantitative measurement of [(11)C]doxepin binding between morning and afternoon and between resting and attentive waking conditions in healthy human subjects. There was a trend for a decrease in [(11)C]doxepin binding during attentive calculation tasks compared with that in resting conditions, but the difference (less than 10%) was not significant. Similarly, the binding potential of [(11)C]doxepin in the cerebral cortex was slightly higher in the morning than that in the afternoon, but it was also insignificant. These data suggest that higher histamine release during wakefulness could not decrease the [(11)C]doxepin binding in the brain. This study confirmed the reproducibility and reliability of [(11)C]doxepin in the previous imaging studies to measure the H1 receptor.
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Affiliation(s)
- Katsuhiko Shibuya
- Department of Pharmacology, Tohoku University Graduate School of Medicine Sendai, Japan
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14
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Sato K, Fukushi K, Shinotoh H, Shimada H, Tanaka N, Hirano S, Irie T. A short-scan method for k(3) estimation with moderately reversible PET ligands: application of irreversible model to early-phase PET data. Neuroimage 2012; 59:3149-58. [PMID: 22079452 DOI: 10.1016/j.neuroimage.2011.10.087] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 10/08/2011] [Accepted: 10/25/2011] [Indexed: 10/15/2022] Open
Abstract
Long dynamic scans (60-120 min) are often required for estimating the k(3) value, an index of receptor density, by positron emission tomography (PET). However, the precision of k(3) is usually low in kinetic analyses for reversible PET ligands compared with irreversible ligands. That is largely due to unstable estimation of the dissociation rate constant, k(4). We propose a novel '3P+' method for estimating k(3) of moderately reversible ligands, where a 3-parameter model without k(4) is applied to early-phase PET data to obtain a good model-fit of k(3) estimation. By using [(11)C] Pittsburgh compound B (PIB) (k(4) = 0.018/min) as an example of a moderately reversible ligand, the 3P+ method simulation with a 28 min PET scan yielded less than 3% k(3) relative bias with a +100% k(3) change. In [(11)C]PIB PET scans of 15 normal controls (NC) and nine patients with Alzheimer's disease (AD), the 3P+ method provided a precise k(3) estimate (mean SE of 13.6% in parietal cortex; covariance matrix method). The results revealed linear correlations (r = 0.964) of parietal k(3) values in 24 subjects between 28minute 3P+ method and conventional 90 minute 4-parameter method. A good separation of k(3) between NC and AD groups (P < 0.001; t-test) was replicated in 28 minute 3P+ method. The short-scan 3P+ method may be a practical alternative method for analyzing reversible ligands.
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Affiliation(s)
- Koichi Sato
- Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 260-8555, Japan.
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15
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Edison P, Hinz R, Ramlackhansingh A, Thomas J, Gelosa G, Archer HA, Turkheimer FE, Brooks DJ. Can target-to-pons ratio be used as a reliable method for the analysis of [11C]PIB brain scans? Neuroimage 2012; 60:1716-23. [PMID: 22306804 DOI: 10.1016/j.neuroimage.2012.01.099] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 12/16/2011] [Accepted: 01/18/2012] [Indexed: 11/17/2022] Open
Abstract
RATIONALE (11)C]PIB is the most widely used PET imaging marker for amyloid in dementia studies. In the majority of studies the cerebellum has been used as a reference region. However, cerebellar amyloid may be present in genetic Alzheimer's (AD), cerebral amyloid angiopathy and prion diseases. Therefore, we investigated whether the pons could be used as an alternative reference region for the analysis of [(11)C]PIB binding in AD. The aims of the study were to: 1) Evaluate the pons as a reference region using arterial plasma input function and Logan graphical analysis of binding. 2) Assess the power of target-to-pons ratios to discriminate controls from AD subjects. 3) Determine the test-retest reliability in AD subjects. 4) Demonstrate the application of target-to-pons ratio in subjects with elevated cerebellar [(11)C]PIB binding. METHODS 12 sporadic AD subjects aged 65 ± 4.5 yrs with a mean MMSE 21.4 ± 4 and 10 age-matched control subjects had [(11)C]PIB PET with arterial blood sampling. Three additional subjects (two subjects with pre-symptomatic presenilin-1 mutation carriers and one probable familial AD) were also studied. Object maps were created by segmenting individual MRIs and spatially transforming the gray matter images into standard stereotaxic MNI space and then superimposing a probabilistic atlas. Cortical [(11)C]PIB binding was assessed with an ROI (region of interest) analysis. Parametric maps of the volume of distribution (V(T)) were generated with Logan analysis. Additionally, parametric maps of the 60-90 min target-to-cerebellar ratio (RATIO(CER)) and the 60-90 min target-to-pons ratio (RATIO(PONS)) were computed. RESULTS All three approaches were able to differentiate AD from controls (p<0.0001, nonparametric Wilcoxon rank sum test) in the target regions with RATIO(CER) and RATIO(PONS) differences higher than V(T) with use of an arterial input function. All methods had a good reproducibility (intraclass correlation coefficient>0.83); RATIO(CER) performed best closely followed by RATIO(PONS). The two subjects with presenilin-1 mutations and the probable familial AD case showed no significant differences in cortical binding using RATIO(CER), but the RATIO(PONS) approach revealed higher [(11)C]PIB binding in cortex and cerebellum. CONCLUSION This study established 60-90 min target-to-pons RATIOs as a reliable method of analysis in [(11)C]PIB PET studies where cerebellum is not an appropriate reference region.
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Affiliation(s)
- P Edison
- Medical Research Council Clinical Sciences Centre and Division of Neuroscience, Hammersmith Hospital, Imperial College, London, UK.
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16
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Edison P, Hinz R, Brooks DJ. Technical aspects of amyloid imaging for Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2011; 3:25. [PMID: 21888692 PMCID: PMC3226280 DOI: 10.1186/alzrt87] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
[11C]Pittsburgh Compound B positron emission tomography has now been extensively used to evaluate the amyloid load in different types of dementia and has become a powerful research tool in the field of neurodegenerative diseases. In the present short review we discuss the properties of amyloid imaging agent [11C]Pittsburgh Compound B, the different modalities of molecular imaging, image processing and data analysis, and newer amyloid imaging agents.
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Affiliation(s)
- Paul Edison
- Medical Research Council Clinical Sciences Centre and Division of Neuroscience, Imperial College London, Cyclotron Building, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
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17
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Multi-graphical analysis of dynamic PET. Neuroimage 2009; 49:2947-57. [PMID: 19931403 DOI: 10.1016/j.neuroimage.2009.11.028] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 11/01/2009] [Accepted: 11/11/2009] [Indexed: 11/22/2022] Open
Abstract
In quantitative dynamic PET studies, graphical analysis methods including the Gjedde-Patlak plot, the Logan plot, and the relative equilibrium-based graphical plot (RE plot) (Zhou Y., Ye W., Brasić J.R., Crabb A.H., Hilton J., Wong D.F. 2009b. A consistent and efficient graphical analysis method to improve the quantification of reversible tracer binding in radioligand receptor dynamic PET studies. Neuroimage 44(3):661-670) are based on the theory of a compartmental model with assumptions on tissue tracer kinetics. If those assumptions are violated, then the resulting estimates may be biased. In this study, a multi-graphical analysis method was developed to characterize the non-relative equilibrium effects on the estimates of total distribution volume (DV(T)) from the RE plot. A novel bi-graphical analysis method using the RE plot with the Gjedde-Patlak plot (RE-GP plots) was proposed to estimate DV(T) for the quantification of reversible tracer kinetics that may not be at relative equilibrium states during PET study period. The RE-GP plots and the Logan plot were evaluated by 19 [(11)C]WIN35,428 and 10 [(11)C]MDL100,907 normal human dynamic PET studies with brain tissue tracer kinetics measured at both region of interest (ROI) and pixel levels. A 2-tissue compartment model (2TCM) was used to fit ROI time activity curves (TACs). By applying multi-graphical plots to the 2TCM fitted ROI TACs which were considered as the noise-free tracer kinetics, the estimates of DV(T) from the RE-GP plots, the Logan plot, and the 2TCM fitting were equal to each other. For the measured ROI TACs, there was no significant difference between the estimates of the DV(T) from the RE-GP plots and those from 2TCM fitting (p=0.77), but the estimates of the DV(T) from the Logan plot were significantly (p<0.001) lower, 2.3% on average, than those from 2TCM fitting. There was a highly linear correlation between the ROI DV(T) from the parametric images (Y) and those from the ROI kinetics (X) by using the RE-GP plots (Y=1.01X+0.23, R(2)=0.99). For the Logan plot, the ROI estimates from the parametric images were 13% to 83% lower than those from ROI kinetics. The computational time for generating parametric images was reduced by 69% on average by the RE-GP plots in contrast to the Logan plot. In conclusion, the bi-graphical analysis method using the RE-GP plots was a reliable, robust and computationally efficient kinetic modeling approach to improve the quantification of dynamic PET.
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