{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,31]],"date-time":"2026-01-31T16:28:31Z","timestamp":1769876911107,"version":"3.49.0"},"reference-count":24,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2002,11,4]],"date-time":"2002-11-04T00:00:00Z","timestamp":1036368000000},"content-version":"vor","delay-in-days":3,"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":[[2002,11]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Head motion within an applied magnetic field alters the effective shim within the brain, causing geometric distortions in echo planar imaging (EPI). Even if subtle, change in shim can lead to artifactual signal changes in timecourse EPI acquisitions, which are typically performed for functional MRI (fMRI) or diffusion tensor imaging. Magnetic field maps acquired before and after head motions of clinically realistic magnitude indicate that motion\u2010induced changes in magnetic field may cause translations exceeding 3 mm in the phase\u2010encoding direction of the EPI images. The field maps also demonstrate a trend toward linear variations in shim changes as a function of position within the head, suggesting that a real\u2010time, first\u2010order correction may compensate for motion\u2010induced changes in magnetic field. This article presents a navigator pulse sequence and processing method, termed a \u201cshim NAV,\u201d for real\u2010time detection of linear shim changes, and a shim\u2010compensated EPI pulse sequence for dynamic correction of linear shim changes. In vivo and phantom experiments demonstrate the detection accuracy of shim NAVs in the presence of applied gradient shims. Phantom experiments demonstrate reduction of geometric distortion and image artifact using shim\u2010compensated EPI in the presence of applied gradient shims. In vivo experiments with intentional interimage subject motion demonstrate improved alignment of timecourse EPI images when using the shim NAV\u2010detected values to update the shim\u2010compensated EPI acquisition in real time. Magn Reson Med 48:771\u2013780, 2002. \u00a9 2002 Wiley\u2010Liss, Inc.<\/jats:p>","DOI":"10.1002\/mrm.10259","type":"journal-article","created":{"date-parts":[[2002,11,5]],"date-time":"2002-11-05T14:07:43Z","timestamp":1036505263000},"page":"771-780","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":72,"title":["Real\u2010time autoshimming for echo planar timecourse imaging"],"prefix":"10.1002","volume":"48","author":[{"given":"Heidi A.","family":"Ward","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stephen J.","family":"Riederer","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"suffix":"Jr.","given":"Clifford R.","family":"Jack","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2002,12,2]]},"reference":[{"key":"e_1_2_6_2_2","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910310307"},{"key":"e_1_2_6_3_2","doi-asserted-by":"publisher","DOI":"10.1016\/S1076-6332(05)80074-1"},{"key":"e_1_2_6_4_2","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910350312"},{"key":"e_1_2_6_5_2","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1097-0193(1999)8:2\/3<80::AID-HBM2>3.0.CO;2-C"},{"key":"e_1_2_6_6_2","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910140112"},{"key":"e_1_2_6_7_2","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910360316"},{"key":"e_1_2_6_8_2","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910390210"},{"key":"e_1_2_6_9_2","doi-asserted-by":"publisher","DOI":"10.1002\/jmri.1880080423"},{"key":"e_1_2_6_10_2","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1522-2594(200003)43:3<459::AID-MRM19>3.0.CO;2-1"},{"key":"e_1_2_6_11_2","doi-asserted-by":"publisher","DOI":"10.1002\/1522-2594(200009)44:3<457::AID-MRM17>3.0.CO;2-R"},{"key":"e_1_2_6_12_2","doi-asserted-by":"publisher","DOI":"10.1148\/radiology.173.1.2781017"},{"key":"e_1_2_6_13_2","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910340514"},{"key":"e_1_2_6_14_2","doi-asserted-by":"publisher","DOI":"10.1364\/JOSAA.14.002692"},{"key":"e_1_2_6_15_2","doi-asserted-by":"publisher","DOI":"10.1006\/cbmr.1996.0014"},{"key":"e_1_2_6_16_2","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1522-2594(199912)42:6<1014::AID-MRM4>3.0.CO;2-F"},{"key":"e_1_2_6_17_2","unstructured":"WardHA RiedererSJ JackCRJr.Feasibility of real\u2010time auto\u2010shimming. 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