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KMID : 0858520120160010055
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Journal of the Korean Society of Magnetic Resonance in Medicine
2012 Volume.16 No. 1 p.55 ~ p.66
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Head Motion Detection and Alarm System during MRI scanning
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Pae Chong-Won
Park Hae-Jeong
Kim Dae-Jin
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Abstract
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Purpose: During brain MRI scanning, subject’s head motion can adversely affect MRI images. To minimize MR image distortion by head movement, we developed an optical tracking system to detect the 3-D movement of subjects.
Materials and Methods: The system consisted of 2 CCD cameras, two infrared illuminators, reflective sphere-type markers, and frame grabber with desktop PC. Using calibration which is the procedure to calculate intrinsic/extrinsic parameters of each camera and triangulation, the system was desiged to detect 3-D coordinates of subject’s head movement. We evaluated the accuracy of 3-D position of reflective markers on both test board and the real MRI scans.
Results: The stereo system computed the 3-D position of markers accurately for the test board and for the subject with glasses with attached optical reflective marker, required to make regular head motion during MRI scanning. This head motion tracking didn’t affect the resulting MR images even in the environment varying magnetic gradient and several RF pulses.
Conclusion: This system has an advantage to detect subject’s head motion in real-time. Using the developed system, MRI operator is able to determine whether he/she should stop or intervene in MRI acquisition to prevent more image distortions.
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KEYWORD
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Magnetic resonance imaging, Functional MRI, Head motion, Motion detection
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