{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T07:52:57Z","timestamp":1790236377901,"version":"4.1.0"},"reference-count":24,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2020,2,22]],"date-time":"2020-02-22T00:00:00Z","timestamp":1582329600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001711","name":"swiss national science foundation","doi-asserted-by":"publisher","award":["PP00P2_163683 and PP00P2_190093"],"award-info":[{"award-number":["PP00P2_163683 and PP00P2_190093"]}],"id":[{"id":"10.13039\/501100001711","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R01AG054473 and R01AG052414"],"award-info":[{"award-number":["R01AG054473 and R01AG052414"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>[18F]FPEB is a positron emission tomography (PET) radiopharmaceutical used for imaging the abundance and distribution of mGluR5 in the central nervous system (CNS). Efficient radiolabeling of the aromatic ring of [18F]FPEB has been an ongoing challenge. Herein, five metal-free precursors for the radiofluorination of [18F]FPEB were compared, namely, a chloro-, nitro-, sulfonium salt, and two spirocyclic iodonium ylide (SCIDY) precursors bearing a cyclopentyl (SPI5) and a new adamantyl (SPIAd) auxiliary. The chloro- and nitro-precursors resulted in a low radiochemical yield (&lt;10% RCY), whereas both SCIDY precursors and the sulfonium salt precursor produced [18F]FPEB in the highest RCYs of 25% and 36%, respectively. Preliminary PET\/CT imaging studies with [18F]FPEB were conducted in a transgenic model of Alzheimer\u2019s Disease (AD) using B6C3-Tg(APPswe,PSEN1dE9)85Dbo\/J (APP\/PS1) mice, and data were compared with age-matched wild-type (WT) B6C3F1\/J control mice. In APP\/PS1 mice, whole brain distribution at 5 min post-injection showed a slightly higher uptake (SUV = 4.8 \u00b1 0.4) than in age-matched controls (SUV = 4.0 \u00b1 0.2). Further studies to explore mGluR5 as an early biomarker for AD are underway.<\/jats:p>","DOI":"10.3390\/molecules25040982","type":"journal-article","created":{"date-parts":[[2020,2,27]],"date-time":"2020-02-27T03:21:16Z","timestamp":1582773676000},"page":"982","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Revisiting the Radiosynthesis of [18F]FPEB and Preliminary PET Imaging in a Mouse Model of Alzheimer\u2019s Disease"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1217-764X","authenticated-orcid":false,"given":"Cassis","family":"Varlow","sequence":"first","affiliation":[{"name":"Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada"},{"name":"Institute of Medical Science, University of Toronto, Toronto, ON M5S1A8, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Emily","family":"Murrell","sequence":"additional","affiliation":[{"name":"Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0066-219X","authenticated-orcid":false,"given":"Jason P.","family":"Holland","sequence":"additional","affiliation":[{"name":"Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital &amp; Department of Radiology, Harvard Medical School, Boston, MA 02114, USA"},{"name":"Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alina","family":"Kassenbrock","sequence":"additional","affiliation":[{"name":"Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital &amp; Department of Radiology, Harvard Medical School, Boston, MA 02114, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Whitney","family":"Shannon","sequence":"additional","affiliation":[{"name":"Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada"},{"name":"Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N OX2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steven H.","family":"Liang","sequence":"additional","affiliation":[{"name":"Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital &amp; Department of Radiology, Harvard Medical School, Boston, MA 02114, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2087-5125","authenticated-orcid":false,"given":"Neil","family":"Vasdev","sequence":"additional","affiliation":[{"name":"Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada"},{"name":"Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital &amp; Department of Radiology, Harvard Medical School, Boston, MA 02114, USA"},{"name":"Department of Psychiatry, University of Toronto, Toronto, ON M5T-1R8, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4227-5371","authenticated-orcid":false,"given":"Nickeisha A.","family":"Stephenson","sequence":"additional","affiliation":[{"name":"Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada"},{"name":"Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital &amp; Department of Radiology, Harvard Medical School, Boston, MA 02114, USA"},{"name":"Department of Chemistry, The University of West Indies at Mona, Kingston 7, Jamaica"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,2,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1151","DOI":"10.1007\/s00259-015-3301-5","article-title":"Metabotropic glutamate receptor 5\u2014A promising target in drug development and neuroimaging","volume":"43","author":"Pillai","year":"2016","journal-title":"Eur. 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