The Experts below are selected from a list of 86433 Experts worldwide ranked by ideXlab platform
Christine H Lorenz - One of the best experts on this subject based on the ideXlab platform.
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3d myocardial tissue tracking with slice followed cine dense mri
Journal of Magnetic Resonance Imaging, 2008Co-Authors: Bruce S Spottiswoode, Christine H Lorenz, Xiaodong Zhong, Bongani M Mayosi, Ernesta M Meintjes, Frederick H EpsteinAbstract:Purpose To track three-dimensional (3D) myocardial tissue Motion using slice followed cine displacement encoded imaging with stimulated echoes (DENSE). Materials and Methods Slice following (SF) has previously been developed for 2D myocardial tagging to compensate for the effect of through-Plane Motion on 2D tissue tracking. By incorporating SF into a cine DENSE sequence, and applying displacement encoding in three orthogonal directions, we demonstrate the ability to track discrete elements of a slice of myocardium in 3D as the heart moves through the cardiac cycle. The SF cine DENSE tracking algorithm was validated on a moving phantom, and the effects of through-Plane Motion on 2D cardiac strain were investigated in six healthy subjects. Results A through-Plane tracking accuracy of 0.46 ± 0.32 mm was measured for a typical range of myocardial Motion using a rotating phantom. In vivo 3D measurements of cardiac Motion were consistent with prior myocardial tagging results. Through-Plane rotation in a mid-ventricularshort-axis view was shown to decrease the magnitude of the 2D end-systolic circumferential strain by 3.91 ± 0.43% and increase the corresponding radial strain by 6.01 ± 1.07%. Conclusion Slice followed cine DENSE provides an accurate method for 3D tissue tracking. J. Magn. Reson. Imaging 2008;27:1019–1027. © 2008 Wiley-Liss, Inc.
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quantification of in Plane Motion of the coronary arteries during the cardiac cycle implications for acquisition window duration for mr flow quantification
Journal of Magnetic Resonance Imaging, 1998Co-Authors: Mark B M Hofman, Samuel A Wickline, Christine H LorenzAbstract:Motion of the coronary arteries during the heart cycle can result in image blurring and inaccurate flow quantification by MR. This condition applies particularly for longer acquisition windows that are typical of breath-hold coronary flow measurements. To determine the sensitivity of the technique to in-Plane Motion of different coronary arteries, the temporal variation in coronary position was measured in a Plane perpendicular to the proximal portion of the vessel. The results indicated the presence of substantial displacement of the coronary arteries within the cardiac cycle, with a magnitude of Motion approximately twice as large for the right as for the left coronary arteries. An estimation of the resulting vessel blurring was calculated, showing that the duration of the acquisition window for high spatial resolution coronary flow acquisitions should be less than 25 to 120 msec, depending on the specific coronary artery studied. In addition, these data specify optimal acquisition window placement for high resolution coronary angiography.
Chongmin Song - One of the best experts on this subject based on the ideXlab platform.
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consistent infinitesimal finite element cell method in Plane Motion
Computer Methods in Applied Mechanics and Engineering, 1995Co-Authors: John P Wolf, Chongmin SongAbstract:Note: [189] Reference LCH-ARTICLE-1995-005 Record created on 2007-04-24, modified on 2016-08-08
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consistent infinitesimal finite element cell method out of Plane Motion
Journal of Engineering Mechanics-asce, 1995Co-Authors: Chongmin Song, John P WolfAbstract:Note: [194] Reference LCH-ARTICLE-1995-006View record in Web of Science Record created on 2007-04-24, modified on 2016-08-08
Smita Sampath - One of the best experts on this subject based on the ideXlab platform.
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effect of through Plane Motion on left ventricular rotation a study using slice following harmonic phase imaging
Magnetic Resonance in Medicine, 2013Co-Authors: David Brotman, Ziheng Zhang, Smita SampathAbstract:Non-invasive quantification of regional left ventricular (LV) rotation may improve understanding of cardiac function. Current methods employed to quantify rotation typically acquire data on a set of prescribed short-axis slices, neglecting effects due to through-Plane myocardial Motion. We combine principles of slice-following tagged imaging with harmonic phase analysis methods to account for through-Plane Motion in regional rotation measurements. We compare rotation and torsion measurements obtained using our method to those obtained from imaging datasets acquired without slice-following. Our results in normal volunteers demonstrate differences in the general trends of average and regional rotation-time plots in mid-basal slices, and of the rotation versus circumferential strain loops. We observe substantial errors in measured peak average rotation of the order of 58% for basal slices (due to change in the pattern of the curve), −6.6% for mid-ventricular slices, and −8.5% for apical slices; and an average error in base-to-apex torsion of 19% when through-Plane Motion is not considered. This study concludes that due to an inherent base-to-apex gradient in rotation that exists in the LV, accounting for through-Plane Motion is critical to the accuracy of LV rotation quantification.
Susumu Tadakuma - One of the best experts on this subject based on the ideXlab platform.
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A Study of Energy-Saving Shoes for Robot Considering Lateral Plane Motion
IEEE Transactions on Industrial Electronics, 2008Co-Authors: Hideaki Minakata, Hirokazu Seki, Susumu TadakumaAbstract:In this paper, we propose a flexible shoe system for biped robots to optimize energy consumption of the lateral Plane Motion. This shoe system is made to deform decline outside in the lateral Plane and it can absorb the kinetic energy of the robot in the lateral Plane. Furthermore, this hardware (shoes) and software (controller) can be easily applicable to the ordinary walking robot system. The effectiveness and characteristics of this system are confirmed by computer simulations and experimental results. It is confirmed that the stiffness of the shoe is a very important parameter for energy consumption by using computer simulations and experimental results.
Christopher M Powers - One of the best experts on this subject based on the ideXlab platform.
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sagittal Plane pelvis Motion influences transverse Plane Motion of the femur kinematic coupling at the hip joint
Gait & Posture, 2016Co-Authors: Jennifer J Bagwell, Thiago Yukio Fukuda, Christopher M PowersAbstract:Previous studies have suggested that internal femur rotation can influence sagittal pelvis Motion. This indicates that there may be kinematic "coupling" of these two segments. The purpose of the current study was to determine whether there is a consistent and predictable kinematic relationship between the pelvis and the femur. Sixteen healthy subjects (nine females, seven males) performed three trials of maximum anterior and posterior pelvis tilt at four different hip flexion angles (0°, 30°, 60°, and 90°). Ordinary least squares regressions were used to calculate the ratio of transverse femur Motion to sagittal pelvis Motion using the mean kinematic curves during maximum anterior and posterior pelvis tilting. R(2) values were used to assess the strength of the kinematic relationship between these segments at each hip flexion angle. The ratios of transverse femur Motion to sagittal pelvis Motion were consistent across all hip flexion angles during anterior and posterior pelvis tilting (range 0.23-0.32; R(2) values greater than 0.97). On average, for every 5° of anterior pelvis tilt there was 1.2-1.6° of internal femur rotation and the converse was true for posterior pelvis tilt and external femur rotation. Our findings suggest that altered pelvis movement in the sagittal Plane may influence transverse femur Motion. The observed coupling behavior between the pelvis and femur may have implications for musculoskeletal conditions in which excessive internal femur rotation has been deemed contributory to symptoms (i.e. femoroacetabular impingement).
