A novel blood-free analytical framework for the quantification of neuroinflammatory load from TSPO PET Imaging

A novel blood-free analytical framework for the quantification of neuroinflammatory load from TSPO PET Imaging | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Method Article A novel blood-free analytical framework for the quantification of neuroinflammatory load from TSPO PET Imaging Lucia Maccioni, Ludovica Brusaferri, Leonardo Barzon, Julia J. Schubert, and 17 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5924801/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Positron Emission Tomography (PET) of the 18 kDa translocator protein (TSPO) is critical for neuroinflammation studies but faces substantial methodological challenges. These include issues with arterial blood sampling for kinetic modeling, the absence of suitable reference regions, genetic polymorphisms affecting tracer affinity, altered blood-to-brain tracer delivery in inflammatory conditions, and high signal variability. This study presents a novel blood-free reference-free method for TSPO PET quantification, leveraging a logistic regression model to estimate the probability of TSPO overexpression across brain regions. Validation was performed on 323 human brain scans from five datasets and three radiotracers. The quantified TSPO topology in healthy controls showed strong concordance with the constitutive TSPO gene expression for all tracers. When using [ 11 C]PBR28 PET data, the method replicated previous findings in schizophrenia, Alzheimer’s disease, chronic pain, and XBD173 blocking. However, model extension to [ 18 F]DPA-714 and [ 11 C]-(R)-PK11195 revealed small effect sizes and high variability, suggesting the need for tracer-specific model optimization. Finally, validation in a rat model of lipopolysaccharide-induced neuroinflammation confirmed previous evidence of increased brain TSPO uptake after a systemic challenge. This novel non-invasive method provides individualized TSPO PET quantification, demonstrating broad applicability across TSPO PET tracers and imaging sites, assuming sufficient training data for model development. Nuclear Medicine & Medical Imaging blood-free quantification neuroinflammation normative modeling PET TSPO Full Text Additional Declarations The authors declare potential competing interests as follows: Dr Howes has received investigator-initiated research funding from and/or participated in advisory/ speaker meetings organized by Abbvie, Alkermes, Angellini, Autifony, Biogen, Boehringer-Ingelheim, Delix, Eli Lilly, Elysium, Heptares, Global Medical Education, Invicro, Jansenn, Karuna, Lundbeck, Merck, Neumora, Neurocrine, Ontrack/ Pangea, Otsuka, Sunovion, Teva, Recordati, Roche, Rovi and Viatris/ Mylan. He was previously a part-time employee of Lundbeck A/v. Dr Howes and Dr. Veronese have a patent for the use of dopaminergic imaging. All the other authors do not report any relevant conflict of interest. Supplementary Files SupplementaryMaterial.pdf Supplementary Material Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5924801","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Method Article","associatedPublications":[],"authors":[{"id":409221942,"identity":"fb0b59d9-8721-4c82-841d-aae3513461fa","order_by":0,"name":"Lucia Maccioni","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0002-6564-2827","institution":"Department of Information Engineering, University of Padova, Padova, Italy","correspondingAuthor":true,"prefix":"","firstName":"Lucia","middleName":"","lastName":"Maccioni","suffix":""},{"id":409222652,"identity":"ec317f01-8670-4d80-99d5-01835e264050","order_by":1,"name":"Ludovica Brusaferri","email":"","orcid":"","institution":"Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA","correspondingAuthor":false,"prefix":"","firstName":"Ludovica","middleName":"","lastName":"Brusaferri","suffix":""},{"id":409222653,"identity":"0482635d-1b14-4d09-ad23-000c95ead0bb","order_by":2,"name":"Leonardo Barzon","email":"","orcid":"","institution":"Department of Information Engineering, University of Padova, Padova, Italy","correspondingAuthor":false,"prefix":"","firstName":"Leonardo","middleName":"","lastName":"Barzon","suffix":""},{"id":409222654,"identity":"19f4c76f-c94e-41eb-a5fa-209bc6e5ade8","order_by":3,"name":"Julia J. Schubert","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Julia","middleName":"J.","lastName":"Schubert","suffix":""},{"id":409222655,"identity":"3b19071b-5dc8-44f6-bf00-ec184639daef","order_by":4,"name":"Maria A. Nettis","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Maria","middleName":"A.","lastName":"Nettis","suffix":""},{"id":409222656,"identity":"80a086c4-926d-4802-ac81-589cbaabff1b","order_by":5,"name":"Oliver Cousins","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Oliver","middleName":"","lastName":"Cousins","suffix":""},{"id":409222657,"identity":"fdea178b-a7b4-4c51-b3bb-ac7fb57b8ef0","order_by":6,"name":"Ivana Rosenzweig","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Ivana","middleName":"","lastName":"Rosenzweig","suffix":""},{"id":409222658,"identity":"ddfdb21d-acb4-4c0d-98a9-0e5513481a36","order_by":7,"name":"Yuya Mizuno","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Yuya","middleName":"","lastName":"Mizuno","suffix":""},{"id":409222659,"identity":"c4bb86d6-8cd5-4aad-9961-127ea1e42f2d","order_by":8,"name":"Marta Vicente-Rodríguez","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Marta","middleName":"","lastName":"Vicente-Rodríguez","suffix":""},{"id":409222660,"identity":"32511f51-c798-4fc3-97a3-a36e853c56c2","order_by":9,"name":"Nisha Singh","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Nisha","middleName":"","lastName":"Singh","suffix":""},{"id":409222661,"identity":"71f2ec41-ccee-43bd-8bc4-f4fd742f2504","order_by":10,"name":"Tiago R. Marques","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Tiago","middleName":"R.","lastName":"Marques","suffix":""},{"id":409222854,"identity":"af803601-aec9-46d9-b805-7d887a1e12a2","order_by":11,"name":"Neil A. Harrison","email":"","orcid":"","institution":"Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK","correspondingAuthor":false,"prefix":"","firstName":"Neil","middleName":"A.","lastName":"Harrison","suffix":""},{"id":409222855,"identity":"d9ca3bf0-8565-481d-8920-3a2403c25d86","order_by":12,"name":"Tim Fryer","email":"","orcid":"","institution":"Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK","correspondingAuthor":false,"prefix":"","firstName":"Tim","middleName":"","lastName":"Fryer","suffix":""},{"id":409222856,"identity":"c3762dfb-838a-4786-bee9-c92c7b71a246","order_by":13,"name":"Edward T. Bullmore","email":"","orcid":"","institution":"Department of Psychiatry, School of Clinical Medicine, University of Cambridge, Cambridge, UK","correspondingAuthor":false,"prefix":"","firstName":"Edward","middleName":"T.","lastName":"Bullmore","suffix":""},{"id":409227756,"identity":"1268dd57-c3dc-40f1-82fb-771ed084aa12","order_by":14,"name":"Diana Cash","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Diana","middleName":"","lastName":"Cash","suffix":""},{"id":409227757,"identity":"3f06aa1c-54e0-41d1-9fc0-33ad2d4db96d","order_by":15,"name":"Valeria Mondelli","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Valeria","middleName":"","lastName":"Mondelli","suffix":""},{"id":409227758,"identity":"191a7afd-1075-4fc6-bdab-5ea306c6a5fd","order_by":16,"name":"Carmine Pariante","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Carmine","middleName":"","lastName":"Pariante","suffix":""},{"id":409227759,"identity":"3d96ffac-90c7-4f9f-af28-fb6130201328","order_by":17,"name":"Oliver Howes","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Oliver","middleName":"","lastName":"Howes","suffix":""},{"id":409227760,"identity":"cc081c65-6350-4b19-94e2-a6c537154e6f","order_by":18,"name":"Federico E. Turkheimer","email":"","orcid":"","institution":"Institute of Psychology, Psychiatry and Neuroscience, King’s College London, London, UK","correspondingAuthor":false,"prefix":"","firstName":"Federico","middleName":"E.","lastName":"Turkheimer","suffix":""},{"id":409227761,"identity":"d12790ed-0e45-469d-b371-ff6a3f2c57c2","order_by":19,"name":"Marco L. Loggia","email":"","orcid":"","institution":"Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA","correspondingAuthor":false,"prefix":"","firstName":"Marco","middleName":"L.","lastName":"Loggia","suffix":""},{"id":409227762,"identity":"70b90757-983d-419b-b775-7365950f4ea6","order_by":20,"name":"Mattia Veronese","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+klEQVRIiWNgGAWjYLCCBCS2HAMDYwMDD4MEHvXMjA3IWoxhWvDoAWpB5iaCeTwMuK3RbT9//MGDGobEfunDxx58+GOTvuF2c9uDNwwWdbi0mJ1JBjrsGEPizL60dMOZbWm5G+4cbDecg8dhZgdAWtgYjA3O8JhJ8zYczt1wI7FNGp9fzM4/Bmr5x2BsD9Ly58//dAOCWm4AbUlsY5Az4AFqYWA7kECElseGMxL7JOQkzrClSfa2JRvOvJEI9IuBhGQDToclPvj445sND38P8zGJH3/s5PlupD978Kaijh+XLVCA6go2BgYDAhrQARuJ6kfBKBgFo2CYAwA/rVNOptE2MwAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0003-3562-0683","institution":"Department of Information Engineering, University of Padova, Padova, Italy","correspondingAuthor":true,"prefix":"","firstName":"Mattia","middleName":"","lastName":"Veronese","suffix":""}],"badges":[],"createdAt":"2025-01-29 14:08:36","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":true,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-5924801/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5924801/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":75284842,"identity":"083be3a6-4e7a-438f-8c44-0eb0fb6fbb19","added_by":"auto","created_at":"2025-02-03 04:15:49","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1465866,"visible":true,"origin":"","legend":"","description":"","filename":"MainManuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5924801/v1_covered_6953952e-24c3-4a8b-a33f-431339957ff0.pdf"},{"id":75284269,"identity":"068bc70b-535e-4b21-9a56-5542c8168d85","added_by":"auto","created_at":"2025-02-03 04:07:46","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1115201,"visible":true,"origin":"","legend":"\u003cp\u003eSupplementary Material\u003c/p\u003e","description":"","filename":"SupplementaryMaterial.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5924801/v1/367e46310dded534c0eae73c.pdf"}],"financialInterests":"The authors declare potential competing interests as follows: Dr Howes has received investigator-initiated research funding from and/or participated in advisory/ speaker meetings organized by Abbvie, Alkermes, Angellini, Autifony, Biogen, Boehringer-Ingelheim, Delix, Eli Lilly, Elysium, Heptares, Global Medical Education, Invicro, Jansenn, Karuna, Lundbeck, Merck, Neumora, Neurocrine, Ontrack/ Pangea, Otsuka, Sunovion, Teva, Recordati, Roche, Rovi and Viatris/ Mylan. He was previously a part-time employee of Lundbeck A/v. Dr Howes and Dr. Veronese have a patent for the use of dopaminergic imaging. All the other authors do not report any relevant conflict of interest.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eA novel blood-free analytical framework for the quantification of neuroinflammatory load from TSPO PET Imaging\u003c/strong\u003e\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"University of Padua","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"blood-free quantification, neuroinflammation, normative modeling, PET, TSPO","lastPublishedDoi":"10.21203/rs.3.rs-5924801/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5924801/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePositron Emission Tomography (PET) of the 18 kDa translocator protein (TSPO) is critical for neuroinflammation studies but faces substantial methodological challenges. These include issues with arterial blood sampling for kinetic modeling, the absence of suitable reference regions, genetic polymorphisms affecting tracer affinity,\u0026nbsp;altered blood-to-brain tracer delivery in inflammatory conditions, and high signal variability. This study presents a novel blood-free reference-free method for TSPO PET quantification, leveraging a logistic regression model to estimate the probability of TSPO overexpression across brain regions. Validation was performed on 323 human brain scans from five datasets and three radiotracers. The quantified TSPO topology in healthy controls\u0026nbsp;showed strong concordance\u0026nbsp;with the constitutive TSPO gene expression for all tracers. When using [\u003csup\u003e11\u003c/sup\u003eC]PBR28 PET data, the method replicated previous findings in schizophrenia, Alzheimer’s disease, chronic pain, and XBD173 blocking. However, model extension to [\u003csup\u003e18\u003c/sup\u003eF]DPA-714 and [\u003csup\u003e11\u003c/sup\u003eC]-(R)-PK11195 revealed small effect sizes and high variability, suggesting the need for tracer-specific model optimization. Finally, validation in a rat model of lipopolysaccharide-induced neuroinflammation confirmed previous evidence of increased brain TSPO uptake after a systemic challenge.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis novel non-invasive method provides individualized TSPO PET quantification, demonstrating broad applicability across TSPO PET tracers and imaging sites, assuming sufficient training data for model development.\u003c/p\u003e","manuscriptTitle":"A novel blood-free analytical framework for the quantification of neuroinflammatory load from TSPO PET Imaging","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-03 04:07:42","doi":"10.21203/rs.3.rs-5924801/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"7f5dec36-84fe-461d-9f90-55ee0722aca3","owner":[],"postedDate":"February 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":43670242,"name":"Nuclear Medicine \u0026 Medical Imaging"}],"tags":[],"updatedAt":"2025-02-03T04:07:42+00:00","versionOfRecord":[],"versionCreatedAt":"2025-02-03 04:07:42","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5924801","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5924801","identity":"rs-5924801","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}