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KMID : 0357220120240020066
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Journal of Korean Society Physical Therapy
2012 Volume.24 No. 2 p.66 ~ p.72
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Distortion Correction in Magnetic Resonance Images on the Measurement of Muscle Cross-sectional Area
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Hong Cheol-Pyo
Lee Dong-Hoon
Park Ji-Won
Han Bong-Soo
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Abstract
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Purpose: The purpose of this study is to explore the importance of the image distortion correction in the cross sectional area measurement for the iliopsas muscle, tensor fasciae latae muscle, gluteus maximus muscle and the knee extensor muscles, by using (magnetic resonance imaging) MRI.
Methods: This study was performed using an open 0.32T MRI system. To estimate the image distortion, T1 images for an AAPM homogeneity/linearity phantom were acquired, and the region in which the maximum geometric distortion was less than or equal to the pixel size (1.6 mm) of the images, it was defined as the distortion correction-free region. The T2 images for a human subject’s pelvis and thigh in normal positions were obtained. Then, after the regions of interest in the pelvis and thigh were moved into the distortion correction-free region, T2 images for the pelvis and thigh were scanned with the same imaging parameters used in the previous T2 imaging. The cross-sectional areas were measured in the two T2 images that were obtained in the normal position, and the distortion correction-free region, as well as the area error caused by geometric image distortion was calculated.
Results: The geometrical distortion is gradually increased, from the magnet center to the outer region, in axial and coronal plane. The cross-sectional area error of gluteus maximus muscle and the knee extensors was as high as 9.27% and 3.16 % in before and after distortion correction, respectively.
Conclusion: The cross-sectional area of the muscles that suffered from the geometrical distortion is necessary to correct for the estimation of the intervention.
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KEYWORD
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Muscle measurement, Magnetic resonance imaging, Cross-section area, Distortion correction
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