Question 2955
{"accessible":false,"alternatives":[{"id":14390,"text":"decreasing TE"},{"id":14391,"text":"decreasing TR"},{"id":14392,"text":"increasing bandwidth"},{"id":14393,"text":"increasing flip angle"}],"archived":false,"correctAlternativeId":14390,"explanation":"\u003cp\u003eDecreasing TE will result in earlier sampling of the free induction decay curve. This will provide higher signal values.\u003c/p\u003e\u003cp\u003eDecreasing TR reduces the time for longitudinal recovery. The magnitude of longitudinal recovery determines the magnitude of signal at the next radiofrequency pulse. A reduction in TR, especially to shorter than the T1 of tissues, will reduce signal.\u003c/p\u003e\u003cp\u003eSignal-to-noise = 1/ √bandwidth. Increasing bandwidth reduces signal-to-noise.\u003c/p\u003e\u003cp\u003eIn spin echo sequences, with long TR values, increasing flip angle will increase signal. This is not always the case in gradient echo sequences. Increasing flip angles above the Ernst angle will decrease signal.\u003c/p\u003e","id":2955,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/2956","nextQuestionPath":null,"relatedArticles":[{"id":14045,"title":"Signal-to-noise ratio (MRI)","link":"/articles/signal-to-noise-ratio-mri?lang=us"},{"id":14587,"title":"Echo time","link":"/articles/echo-time?lang=us"},{"id":14588,"title":"Repetition time","link":"/articles/repetition-time?lang=us"},{"id":18339,"title":"Gradient echo sequences","link":"/articles/gradient-echo-sequences-1?lang=us"},{"id":34994,"title":"Ernst angle","link":"/articles/ernst-angle?lang=us"},{"id":22558,"title":"MRI physics","link":"/articles/mri-physics?lang=us"},{"id":60748,"title":"Effect of gradient strength and bandwidth on slice thickness","link":"/articles/effect-of-gradient-strength-and-bandwidth-on-slice-thickness?lang=us"}],"alsoUsedIn":[{"id":1927,"kind":"Course","title":"Imaging Physics: MRI - page 1927","link":"https://radiopaedia.org/courses/imaging-physics-mri/pages/1927"}],"stem":"\u003cp\u003eWhich of the following changes in isolation will produce higher signal values in gradient echo imaging?\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/2955"}],"attemptsPercentages":[{"alternativeId":"14391","percentage":15},{"alternativeId":"14392","percentage":14},{"alternativeId":"14393","percentage":32},{"alternativeId":"14390","percentage":39}],"promptToLogin":false,"questionManager":false,"articleId":"flip-angle"}