{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T08:52:15Z","timestamp":1791967935889,"version":"4.3.4"},"reference-count":65,"publisher":"SAGE Publications","issue":"2","license":[{"start":{"date-parts":[[2025,8,20]],"date-time":"2025-08-20T00:00:00Z","timestamp":1755648000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["J Cereb Blood Flow Metab"],"published-print":{"date-parts":[[2026,2]]},"abstract":"<jats:p>\n                    The choroid plexus (CP) is important for cerebrospinal fluid (CSF) secretion and forms the blood\u2013CSF barrier (BCSFB), which is essential for brain homeostasis. However, noninvasive methods for evaluating BCSFB function remain limited. Previously, we introduced a novel magnetic resonance imaging (MRI) technique, relaxation-exchange MRI (REXI), to quantify water exchange between CP and CSF in rats by leveraging the substantial difference in transverse relaxation times between CP tissue and CSF. Here, we adapted REXI to human applications by implementing segmented echo-planar imaging readout for enhanced acquisition speed, optimizing key parameters based on the Cram\u00e9r\u2013Rao lower bound, and refining the analysis methodology. We conducted simulations and phantom experiments for methodological validation. Subsequently, we performed a scan\u2013rescan experiment in healthy volunteers (n\u2009=\u20096, mean-age \u223c22 years), revealing relatively good repeatability in measurements of the apparent water exchange rate\n                    <jats:italic toggle=\"yes\">k<\/jats:italic>\n                    <jats:sub>BCSFB<\/jats:sub>\n                    (intraclass correlation coefficient\u2009=\u20090.84). REXI detected a 34% decrease in\n                    <jats:italic toggle=\"yes\">k<\/jats:italic>\n                    <jats:sub>BCSFB<\/jats:sub>\n                    among middle-aged healthy adults (n\u2009=\u20096, mean-age \u223c55 years) compared with young healthy adults (n\u2009=\u20099, mean-age \u223c23 years,\n                    <jats:italic toggle=\"yes\">p\u2009=\u2009<\/jats:italic>\n                    0.0048). These results demonstrate the feasibility of REXI in quantifying water exchange in human CP in vivo, providing a promising tool for future investigations of BCSFB function.\n                  <\/jats:p>","DOI":"10.1177\/0271678x251369218","type":"journal-article","created":{"date-parts":[[2025,8,20]],"date-time":"2025-08-20T11:34:06Z","timestamp":1755689646000},"page":"508-520","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":4,"title":["Feasibility of relaxation-exchange magnetic resonance imaging (REXI) for measuring water exchange across the blood\u2013CSF barrier in the human choroid plexus"],"prefix":"10.1177","volume":"46","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-2681-9062","authenticated-orcid":false,"given":"Xuetao","family":"Wu","sequence":"first","affiliation":[{"name":"State Key Laboratory of Cognitive Science and Mental Health, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 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