{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,18]],"date-time":"2026-10-18T16:24:47Z","timestamp":1792340687403,"version":"4.4.0"},"reference-count":39,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2020,6,1]],"date-time":"2020-06-01T00:00:00Z","timestamp":1590969600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["2R01 EB002711"],"award-info":[{"award-number":["2R01 EB002711"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["5R01 EB008706"],"award-info":[{"award-number":["5R01 EB008706"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["5R01 EB011654"],"award-info":[{"award-number":["5R01 EB011654"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2020,8]]},"abstract":"<jats:sec><jats:title>Purpose<\/jats:title><jats:p>Prospective motion correction is arguably the \u201csilver bullet\u201d solution for magnetic resonance imaging (MRI) studies impacted by motion, applicable to almost any pulse sequence and immune from the spin history artifacts introduced by a moving object. In prospective motion correction, the magnetic field gradients and radio frequency waveforms are adjusted in real time in response to measured head motion so as to maintain the head in a stationary reference frame relative to the scanner. Vital for this approach are accurate and rapidly sampled head pose measurements, which may be obtained optically using cameras. However, most optical methods are limited by the need to attach physical markers to the skin, which leads to decoupling of head and marker motion and reduces the effectiveness of correction. In this work we investigate the feasibility and initial performance of a stereo\u2010optical motion tracking method which does not require any attached markers.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>The method relies on detecting distinctive natural features or amplified features (using skin stamps) directly on the forehead in multiple camera views, and then deriving pose estimates via a 3D\u20102D registration between the skin features and a database of forehead landmarks. To demonstrate the feasibility and potential accuracy of the marker\u2010free method for discrete (step\u2010wise) head motion, we performed out\u2010of\u2010bore and in\u2010bore experiments using robotically and manually controlled phantoms in addition to in\u2010bore testing on human volunteers. We also developed a convenient out\u2010of\u2010bore test bed to benchmark and optimize the motion tracking performance.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>For out\u2010of\u2010bore phantom tests, the pose estimation accuracy (compared to robotic ground truth) was 0.14\u00a0mm and 0.23\u00a0degrees for incremental translation and rotation, respectively. For arbitrary motion, the pose accuracy obtained using the smallest forehead feature patch was equivalent to 0.21\u00a0\u00b1\u00a00.11\u00a0mm positional accuracy in the striatum. For in\u2010bore phantom experiments, the accuracy of rigid\u2010body motion parameters (compared to wireless MR\u2010sensitive markers) was 0.08\u20130.41\u00a0\u00b1\u00a00.18\u00a0mm\/0.05\u20130.3\u00a0\u00b1\u00a00.12\u00a0deg and 0.14\u20130.16\u00a0\u00b1\u00a00.12\u00a0mm\/0.08\u20100.17\u00a0\u00b1\u00a00.08\u00a0deg for the small and large feature patches, respectively. In vivo results in human volunteers indicated sub\u2010millimeter and sub\u2010degree pose accuracy for all rotations and translations except the depth direction (max error 1.8\u00a0mm) when compared to a registration\u2010based approach.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>In both bench\u2010top and in vivo experiments we demonstrate the feasibility of using very small feature patches directly on the skin to obtain high accuracy head pose measurements needed for motion\u2010correction in MRI brain studies. The optical technique uses in\u2010bore cameras and is consistent with the limited visibility of the forehead afforded by head coils used in brain imaging. Future work will focus on optimization of the technique and demonstration in prospective motion correction.<\/jats:p><\/jats:sec>","DOI":"10.1002\/mp.14199","type":"journal-article","created":{"date-parts":[[2020,4,24]],"date-time":"2020-04-24T06:15:40Z","timestamp":1587708940000},"page":"3321-3331","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Marker\u2010free optical stereo motion tracking for in\u2010bore MRI and PET\u2010MRI application"],"prefix":"10.1002","volume":"47","author":[{"given":"Andre Z.","family":"Kyme","sequence":"first","affiliation":[{"name":"School of Biomedical Engineering Faculty of Engineering and Computer Science University of Sydney Sydney Australia"},{"name":"The Brain &amp; Mind Centre University of Sydney Sydney Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Murat","family":"Aksoy","sequence":"additional","affiliation":[{"name":"Department of Radiology Stanford University USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David L.","family":"Henry","sequence":"additional","affiliation":[{"name":"The Brain &amp; Mind Centre University of Sydney Sydney Australia"},{"name":"Faculty of Health Sciences University of Sydney Sydney Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Roland","family":"Bammer","sequence":"additional","affiliation":[{"name":"Department of Radiology Stanford University USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Julian","family":"Maclaren","sequence":"additional","affiliation":[{"name":"Department of Radiology Stanford University USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2020,6]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.24314"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.neuroimage.2013.08.006"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.neuroimage.2010.06.017"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.1910310307"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1002\/hbm.21192"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.22448"},{"key":"e_1_2_8_8_1","first-page":"281","article-title":"Performance characteristics of a head immobilization device for PET imaging","volume":"40","author":"Mawlawi O","year":"1999","journal-title":"J Nucl Med"},{"key":"e_1_2_8_9_1","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_10_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.20288"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.23230"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.10012"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.21038"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.22176"},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.23228"},{"key":"e_1_2_8_16_1","unstructured":"KymeA.PhD dissertation.University of Sydney;2012."},{"key":"e_1_2_8_17_1","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0048088"},{"key":"e_1_2_8_18_1","doi-asserted-by":"publisher","DOI":"10.1007\/s10334-012-0320-0"},{"key":"e_1_2_8_19_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.22076"},{"key":"e_1_2_8_20_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.26838"},{"key":"e_1_2_8_21_1","doi-asserted-by":"publisher","DOI":"10.1109\/TRPMS.2018.2878978"},{"key":"e_1_2_8_22_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.neuroimage.2006.01.039"},{"key":"e_1_2_8_23_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/48\/8\/301"},{"key":"e_1_2_8_24_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.24845"},{"key":"e_1_2_8_25_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/60\/5\/2047"},{"key":"e_1_2_8_26_1","doi-asserted-by":"publisher","DOI":"10.1109\/TMI.2014.2332821"},{"key":"e_1_2_8_27_1","doi-asserted-by":"publisher","DOI":"10.1023\/B:VISI.0000029664.99615.94"},{"key":"e_1_2_8_28_1","doi-asserted-by":"publisher","DOI":"10.1017\/CBO9780511811685"},{"key":"e_1_2_8_29_1","doi-asserted-by":"publisher","DOI":"10.1177\/027836402761412467"},{"key":"e_1_2_8_30_1","unstructured":"Bouguet Complete Camera Calibration Toolbox for Matlabhttp:\/\/www.vision.caltech.edu\/bouguetj\/calib_doc\/. 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