Question 2947
{"accessible":false,"alternatives":[{"id":14353,"text":"acquisition time"},{"id":14354,"text":"motion artifact"},{"id":14355,"text":"phase errors"},{"id":14356,"text":"signal-to-noise ratio"},{"id":14357,"text":"spatial resolution"}],"archived":false,"correctAlternativeId":14355,"explanation":"\u003cp\u003eHalf Fourier imaging (or fractional NEX) utilizes the phase conjugate symmetry of k-space to create an anatomically accurate image whilst only filling half of k-space.\u003c/p\u003e\u003cp\u003eThis reduces the number of phase encoding steps required. A reduction in phase encoding steps reduces acquisition time (which in turn reduces the likelihood of motion artifact) at the expense of signal-to-noise. Despite a reduction in signal to noise (≈ √2) the matrix size (spatial resolution) remains the same.\u003c/p\u003e\u003cp\u003eAny phase errors encountered during k-space filling, will, however, propagate through to the final image as they are not averaged out by the now unfilled second half of k-space.\u003c/p\u003e","id":2947,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/2967","nextQuestionPath":"/articles/acquisition-time/questions/2943","relatedArticles":[{"id":14045,"title":"Signal-to-noise ratio (MRI)","link":"/articles/signal-to-noise-ratio-mri?lang=us"},{"id":16504,"title":"Fourier transform","link":"/articles/fourier-transform?lang=us"},{"id":18820,"title":"k-space","link":"/articles/k-space-1?lang=us"},{"id":48589,"title":"Motion artifact","link":"/articles/motion-artifact-2?lang=us"},{"id":22558,"title":"MRI physics","link":"/articles/mri-physics?lang=us"},{"id":57797,"title":"Inverse Fourier transformation","link":"/articles/inverse-fourier-transformation-1?lang=us"},{"id":57795,"title":"Fourier transformation","link":"/articles/fourier-transformation-1?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\u003eHalf Fourier imaging results in an increase in...\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/2947"}],"attemptsPercentages":[{"alternativeId":"14354","percentage":6},{"alternativeId":"14353","percentage":13},{"alternativeId":"14355","percentage":50},{"alternativeId":"14356","percentage":20},{"alternativeId":"14357","percentage":11}],"promptToLogin":false,"questionManager":false,"articleId":"acquisition-time"}