Question 2308
{"accessible":true,"alternatives":[{"id":11425,"text":"cerebrospinal fluid"},{"id":11423,"text":"gray matter"},{"id":11420,"text":"skin"},{"id":11422,"text":"skull"},{"id":11421,"text":"subcutaneous fat"},{"id":11424,"text":"white matter"}],"archived":false,"correctAlternativeId":11425,"explanation":"\u003cp\u003eCerebrospinal fluid is closest in density to water which, by definition, has an HU density of zero.\u003c/p\u003e","id":2308,"imageUrl":"https://prod-images-static.radiopaedia.org/images/23778587/4d3e5643d4688b982b7cef2b2a2cfa_big_gallery.jpeg","imageAttribution":{"kind":"case","rID":46232},"imageAttributionCaseInfo":{"title":"Normal CT head","contributor_name":"Derek Smith","contributor_param":"dereks","case_rid":46232,"case_param":"normal-ct-head-1"},"firstQuestionPath":"/questions/2308","nextQuestionPath":"/articles/hounsfield-unit/questions/2307","relatedArticles":[{"id":58893,"title":"Cerebrospinal fluid","link":"/articles/cerebrospinal-fluid-1?lang=us"}],"alsoUsedIn":[{"id":1377,"kind":"Course","title":"Head CT: Graphic Novel - page 1377","link":"https://radiopaedia.org/courses/head-ct-graphic-novel/pages/1377"}],"stem":"\u003cp\u003eWhat normal finding on a head CT has an HU measurement closest to zero?\u003c/p\u003e","menuLinks":[{"text":"Report problem with question","url":"https://docs.google.com/forms/d/e/1FAIpQLSfO3soWYhOjJ7yErSysyCe5V4A1CqW7WK3rDA7MtAkecMGqNw/viewform?entry.1624461248\u0026entry.553583435=https://radiopaedia.org/questions/2308"}],"attemptsPercentages":[{"alternativeId":"11424","percentage":2},{"alternativeId":"11422","percentage":0},{"alternativeId":"11425","percentage":90},{"alternativeId":"11420","percentage":1},{"alternativeId":"11423","percentage":3},{"alternativeId":"11421","percentage":4}],"promptToLogin":false,"questionManager":false,"articleId":"hounsfield-unit"}