{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T12:54:33Z","timestamp":1780491273323,"version":"3.54.1"},"reference-count":16,"publisher":"Springer Science and Business Media LLC","issue":"6","license":[{"start":{"date-parts":[[2021,1,28]],"date-time":"2021-01-28T00:00:00Z","timestamp":1611792000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2021,1,28]],"date-time":"2021-01-28T00:00:00Z","timestamp":1611792000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"name":"JSPS KAKENHI","award":["19K11310"],"award-info":[{"award-number":["19K11310"]}]}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Dysphagia"],"published-print":{"date-parts":[[2021,12]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Understanding bolus flow patterns in swallowing (rheology, the study of flow) is fundamental to assessment and treatment of dysphagia. These patterns are complex and poorly understood. A liquid swallow is typically biphasic, including air, so the actual bolus has both liquid and gas phases. We report a novel observation of annular two-phase flow (a ring of liquid around a core of air) as thin liquids passed through the upper esophageal sphincter (UES). Dynamic CT was performed on 27 healthy asymptomatic volunteers swallowing liquid barium in a semi-reclining position. Each subject swallowed 3, 10, and 20\u00a0ml of either thin (14 subjects) or thick liquid (13 subjects). Sagittal and axial images were analyzed. Flow patterns in the UES were assessed on cross-sectional images. Annular flow was seen in the majority of subjects with thin liquid but few with thick liquid swallows. The percentage of Annular flow during UES opening was 3\u00a0ml 58%, 10\u00a0ml 58%, 20\u00a0ml 56% in thin and 3\u00a0ml 0%, 10\u00a0ml 4%, 20\u00a0ml 1% in thick. Annular flow was usually observed from the second or third frames after onset of UES opening. The other pattern, Plug flow was seldom seen with thin but was typical with thick liquid swallows. Annular flow was the most common pattern for thin liquids (but not thick liquids) passing through the UES. Annular flow has been defined as a liquid continuum adjacent to the channel wall with a gas continuum (core) in the center of the channel. The two regions are demarcated by a gas\u2013liquid interface. Annular flow is typical for two-phase gas\u2013liquid flow in a vertical or inclined channel. It results from the interaction of viscosity with cohesive and adhesive forces in the two phases. We infer that the difference in flow pattern between thin liquid\u2013air and thick liquid\u2013air boluses resulted from the differing magnitudes of viscous forces.<\/jats:p>","DOI":"10.1007\/s00455-020-10241-9","type":"journal-article","created":{"date-parts":[[2021,1,28]],"date-time":"2021-01-28T09:47:54Z","timestamp":1611827274000},"page":"1088-1094","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Annular Flow in the Upper Esophageal Sphincter Demonstrated with Dynamic 320-row Area Detector Computed Tomography"],"prefix":"10.1007","volume":"36","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9781-9359","authenticated-orcid":false,"given":"Yoko","family":"Inamoto","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eiichi","family":"Saitoh","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeffrey B.","family":"Palmer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2021,1,28]]},"reference":[{"key":"10241_CR1","doi-asserted-by":"publisher","first-page":"1469","DOI":"10.1016\/0016-5085(89)90391-0","volume":"97","author":"P Jacob","year":"1989","unstructured":"Jacob P, Kahrilas PJ, Logemann JA, Shah V, Ha T. Upper esophageal sphincter opening and modulation during swallowing. Gastroenterology. 1989;97:1469\u201378.","journal-title":"Gastroenterology"},{"key":"10241_CR2","first-page":"G748","volume":"257","author":"IJ Cook","year":"1989","unstructured":"Cook IJ, Dodds WJ, Dantas RO, et al. Opening mechanisms of the human upper esophageal sphincter. Am J Physiol. 1989;257:G748\u201359.","journal-title":"Am J Physiol"},{"key":"10241_CR3","doi-asserted-by":"publisher","first-page":"52","DOI":"10.1016\/0016-5085(88)90290-9","volume":"95","author":"PJ Kahrilas","year":"1988","unstructured":"Kahrilas PJ, Dodds WJ, Dent J, Logemann JA, Shaker R. Upper esophageal sphincter function during deglutition. Gastroenterology. 1988;95:52\u201362.","journal-title":"Gastroenterology"},{"key":"10241_CR4","doi-asserted-by":"publisher","first-page":"133","DOI":"10.1007\/PL00009527","volume":"12","author":"G Ali","year":"1997","unstructured":"Ali G, Wallace KL, Luanda TM, Hunt DR, Decarle DJ, Cook IJ. 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Am J Physiol Gastrointest Liver Physiol. 2003;285:G1037\u201348.","journal-title":"Am J Physiol Gastrointest Liver Physiol"},{"key":"10241_CR7","doi-asserted-by":"publisher","first-page":"4","DOI":"10.1016\/B978-0-08-015797-9.50005-4","volume-title":"Annular two-phase flow","author":"GF Hewitt","year":"1970","unstructured":"Hewitt GF, Hall-Taylor NS. Regimes of flow. In: Annular two-phase flow. Oxford, New York, 1970:4\u201320."},{"key":"10241_CR8","doi-asserted-by":"crossref","unstructured":"Inamoto Y, Saitoh E. Morphologic and kinematic analysis of swallowing using multislice CT. In Dysphagia Diagnosis and Treatment. Springer, 2017:333\u2013349.","DOI":"10.1007\/174_2017_123"},{"key":"10241_CR9","doi-asserted-by":"publisher","first-page":"419","DOI":"10.1007\/s00455-017-9870-7","volume":"33","author":"Y Inamoto","year":"2018","unstructured":"Inamoto Y, Saitoh E, Ito Y, Kagaya H, et al. The Mendelsohn maneuver and its effects on swallowing: kinematic analysis in three-dimensions using dynamic area detector CT. Dysphagia. 2018;33:419\u201330.","journal-title":"Dysphagia"},{"key":"10241_CR10","doi-asserted-by":"publisher","first-page":"1679","DOI":"10.1148\/rg.246045065","volume":"24","author":"JF Barrett","year":"2004","unstructured":"Barrett JF, Keat N. Artifacts in CT: recognition and avoidance. RadioGraphics. 2004;24:1679\u201391.","journal-title":"RadioGraphics"},{"key":"10241_CR11","doi-asserted-by":"publisher","DOI":"10.1007\/s00455-019-10074-1","author":"S Patel","year":"2019","unstructured":"Patel S, McAuley WJ, Cook MT, Sun Y, Hamdy S, Liu F. The Swallowing characteristics of thickeners, Jellies and yoghurt observed using an in vitro model. 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