{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T02:58:49Z","timestamp":1772074729814,"version":"3.50.1"},"reference-count":13,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2006,11,30]],"date-time":"2006-11-30T00:00:00Z","timestamp":1164844800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Magnetic Resonance in Med"],"published-print":{"date-parts":[[2007,1]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The consistency of off\u2010axis MRI with non\u2010Cartesian sequences across a large number of scanners is highly variable. Improper timing alignment of the gradient fields, data acquisition system, and real\u2010time frequency demodulation reference signal, which are necessary for off\u2010axis imaging, is an important source of this variability. In addition, eddy currents and anisotropic gradient delays cause deviations in <jats:italic>k<\/jats:italic>\u2010space trajectories that in turn make the demodulation reference signals inaccurate. A method is presented to quickly measure the timing error in the frequency demodulation reference signal and separate it from anisotropic gradient delays. <jats:italic>k<\/jats:italic>\u2010Space deviations, as measured with a previous gradient calibration technique, are shown to be a second source of demodulation phase errors that degrade image quality. Using the timing delay and <jats:italic>k<\/jats:italic>\u2010space deviations, a retrospective phase correction is applied to each <jats:italic>k<\/jats:italic>\u2010space sample before the data are regridded during reconstruction. The timing delays of four MR scanners were measured to be 4.2\u20137.5 \u03bcs below the manufacturer's suggested delay. Significant degradation in 3D radial (3D projection reconstruction (PR)) knee and breast images are retrospectively corrected while a partial prospective correction is applied for spiral imaging. The method allows for more consistent performance of non\u2010Cartesian sequences across multiple scanners without operator intervention. Magn Reson Med 57:206\u2013212, 2007. \u00a9 2006 Wiley\u2010Liss, Inc.<\/jats:p>","DOI":"10.1002\/mrm.21092","type":"journal-article","created":{"date-parts":[[2006,11,30]],"date-time":"2006-11-30T16:46:58Z","timestamp":1164905218000},"page":"206-212","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":26,"title":["Consistent non\u2010cartesian off\u2010axis MRI quality: Calibrating and removing multiple sources of demodulation phase errors"],"prefix":"10.1002","volume":"57","author":[{"given":"Youngkyoo","family":"Jung","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yogesh","family":"Jashnani","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Richard","family":"Kijowski","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Walter F.","family":"Block","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2006,11,30]]},"reference":[{"key":"e_1_2_8_2_2","doi-asserted-by":"publisher","DOI":"10.1109\/TMI.1986.4307732"},{"key":"e_1_2_8_3_2","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.10212"},{"key":"e_1_2_8_4_2","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1522-2594(199911)42:5<963::AID-MRM17>3.0.CO;2-L"},{"key":"e_1_2_8_5_2","doi-asserted-by":"publisher","DOI":"10.1088\/0022-3719\/10\/3\/004"},{"key":"e_1_2_8_6_2","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910360402"},{"key":"e_1_2_8_7_2","unstructured":"PaulyJ ConollyS NishimuraD MacovskiA.Slice\u2010selective excitation for very short T2species. 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