Question 2968
{"accessible":false,"alternatives":[{"id":14445,"text":"2D Fourier transformation"},{"id":14446,"text":"high amplitude frequency encoding gradient during TE"},{"id":14447,"text":"TE \u003c 5ms"},{"id":14448,"text":"uniform magnetic field within the voxel"}],"archived":false,"correctAlternativeId":14448,"explanation":"\u003cp\u003eThe magnetic field within the voxel of interest must be near perfectly uniform. Separation of metabolites relies on accurate frequency reading. Frequency shift should be solely due to chemical shift and not secondary to field non-uniformity.\u003c/p\u003e\u003cp\u003eA 1D Fourier transform is required to convert time-based data into frequency-based data.\u003c/p\u003e\u003cp\u003eThere is NO frequency encoding gradient at readout in PRESS sequences.\u003c/p\u003e\u003cp\u003ePRESS sequences have longer TE times due to the multiple 180 degree RF pulses needed to select the voxel.\u003c/p\u003e","id":2968,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/2968","nextQuestionPath":"/articles/echo-time/questions/2966","relatedArticles":[{"id":1630,"title":"MR spectroscopy","link":"/articles/mr-spectroscopy-1?lang=us"},{"id":16504,"title":"Fourier transform","link":"/articles/fourier-transform?lang=us"},{"id":22558,"title":"MRI physics","link":"/articles/mri-physics?lang=us"},{"id":57795,"title":"Fourier transformation","link":"/articles/fourier-transformation-1?lang=us"}],"alsoUsedIn":[{"id":1928,"kind":"Course","title":"Imaging Physics: MRI - page 1928","link":"https://radiopaedia.org/courses/imaging-physics-mri/pages/1928"}],"stem":"\u003cp\u003eWhich of the following is required in point resolved spectroscopy (PRESS)?\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/2968"}],"attemptsPercentages":[{"alternativeId":"14446","percentage":20},{"alternativeId":"14445","percentage":12},{"alternativeId":"14448","percentage":56},{"alternativeId":"14447","percentage":12}],"promptToLogin":false,"questionManager":false,"articleId":"echo-time"}