Question 2934
{"accessible":false,"alternatives":[{"id":14293,"text":"free induction decay"},{"id":14294,"text":"gradient echo"},{"id":14295,"text":"T1 relaxation"},{"id":14296,"text":"T2 weighting"},{"id":14297,"text":"TE (time of echo)"}],"archived":false,"correctAlternativeId":14293,"explanation":"\u003cp\u003eLoss of the transverse magnetization vector over time is known as free induction decay or T2*. This occurs due to dephasing of spins secondary to spin-spin interactions and local magnetic field inhomogeneities.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eA gradient echo is created using sequential frequency encoding gradients with opposite orientations. This causes a reaccumulation of transverse magnetization during readout.\u003c/p\u003e\u003cp\u003eT1 relaxation refers to the longitudinal recovery of the net magnetization vector over time. This is not the primary cause of loss of transverse magnetization.\u003c/p\u003e\u003cp\u003eT2 weighting describes the contrast contribution in an image based on both the T1 and T2 relaxation rates of tissues as well as the image parameters TE and TR.\u003c/p\u003e\u003cp\u003eTE is the period of time between the initial radiofrequency pulse in a sequence and the sampling of the signal from the slice. The TE determines the degree of T2 contrast within an image.\u003c/p\u003e","id":2934,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/2962","nextQuestionPath":"/articles/gradient-echo-sequences-1/questions/542","relatedArticles":[{"id":6315,"title":"T1 relaxation time","link":"/articles/t1-relaxation-time?lang=us"},{"id":14587,"title":"Echo time","link":"/articles/echo-time?lang=us"},{"id":5852,"title":"T1 weighted image","link":"/articles/t1-weighted-image?lang=us"},{"id":16493,"title":"Free induction decay","link":"/articles/free-induction-decay?lang=us"},{"id":16494,"title":"T2 relaxation","link":"/articles/t2-relaxation?lang=us"},{"id":6345,"title":"T2 weighted image","link":"/articles/t2-weighted-image?lang=us"}],"alsoUsedIn":[{"id":1926,"kind":"Course","title":"Imaging Physics: MRI - page 1926","link":"https://radiopaedia.org/courses/imaging-physics-mri/pages/1926"}],"stem":"\u003cp\u003eLoss of the transverse magnetization vector over time is known as what?\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/2934"}],"attemptsPercentages":[{"alternativeId":"14296","percentage":15},{"alternativeId":"14294","percentage":1},{"alternativeId":"14295","percentage":9},{"alternativeId":"14293","percentage":72},{"alternativeId":"14297","percentage":4}],"promptToLogin":false,"questionManager":false,"articleId":"gradient-echo-sequences"}