Question 1388
{"accessible":false,"alternatives":[{"id":6919,"text":"Alzheimer disease"},{"id":6920,"text":"multiple system atrophy - cerebellum (MSA-C)"},{"id":6921,"text":"normal pressure hydrocephalus"},{"id":6922,"text":"Parkinson disease"},{"id":6923,"text":"Wernicke encephalopathy"}],"archived":false,"correctAlternativeId":6922,"explanation":"\u003cp\u003eThe swallow-tail sign describes the normal axial imaging appearance of nigrosome-1 within the substantia nigra on high-resolution T2*/SWI weighted MRI. Absence of the sign (absent swallow-tail sign) is reported to have a diagnostic accuracy of greater than 90% for Parkinson disease and dementia with Lewy bodies but can be challenging to distinguish from a suboptimal scan and requires high-resolution targetted scans. This has made it difficult to add to routine clinical scanning in many practices.\u0026nbsp;\u003c/p\u003e","id":1388,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/1388","nextQuestionPath":null,"relatedArticles":[],"alsoUsedIn":[{"id":502,"kind":"Course","title":"Neurodegenerative Learning Pathway - page 502","link":"https://radiopaedia.org/courses/neurodegenerative-learning-pathway/pages/502"},{"id":1059,"kind":"Course","title":"Neurodegenerative Learning Pathway - page 1059","link":"https://radiopaedia.org/courses/neurodegenerative-learning-pathway/pages/1059"}],"stem":"\u003cp\u003eThe swallow-tail sign is\u0026nbsp;an MRI feature helpful in diagnosing which of the following diseases?\u0026nbsp;\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/1388"}],"attemptsPercentages":[{"alternativeId":"6922","percentage":85},{"alternativeId":"6920","percentage":9},{"alternativeId":"6921","percentage":1},{"alternativeId":"6919","percentage":3},{"alternativeId":"6923","percentage":2}],"promptToLogin":false,"questionManager":false,"articleId":"swallow-tail-sign-substantia-nigra"}