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Three-dimensional Motion (three-dimensional + motion)
Selected AbstractsVerification of skin-based markers for 3-dimensional kinematic analysis of the equine tarsal jointEQUINE VETERINARY JOURNAL, Issue 8 2004S. KHUMSAP Summary Reasons for performing study: Kinematic studies are usually based on tracking markers attached to the skin. However, complex joints, such as the tarsal joint, function in 3-dimensions (3D), and have therefore necessitated application of the invasive bone pin technique, limiting kinematic studies to the research laboratory. This study investigates the feasibility of using skin-based markers for 3D analysis of tarsal joint motion. Hypothesis: Three-dimensional motions of the tarsal joint can be measured with an acceptable degree of accuracy using skin markers. Methods: Retroreflective markers were attached over the tibial and metatarsal segments. Markers were tracked automatically at trot. Three-dimensional skin correction algorithms were used for correction of skin displacement, and 3D motions derived from the corrected (CSD) and uncorrected (USD) skin displacement were compared with data from a previous study in which those motions were described using bone-fixed markers (BFM) by correlation, root mean square errors (RMS) and shape agreement (SA) of the curves. Results: The RMS of BFM and CSD were smaller than those of BFM and USD for all motions. The correlation coefficients of BFM and CSD were higher than those of BFM and USD. SA was good or fair for all motions except internal/external rotation and medial/lateral translation. Conclusions and potential relevance: With appropriate correction for skin movement relative to skeletal landmarks, skin markers can identify tarsal 3D motions for flexion/extension, abduction/adduction, cranial/caudal translation, and proximal/distal translation, allowing analysis and comparison of information between horses during swing and stance phases. [source] 3D coronary motion tracking in swine models with MR tracking cathetersJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2009Ehud J. Schmidt PhD Abstract Purpose To develop MR-tracked catheters to delineate the three-dimensional motion of coronary arteries at high spatial and temporal resolution. Materials and Methods Catheters with three tracking microcoils were placed into nine swine. During breath-holds, electrocardiographic (ECG)-synchronized 3D motion was measured at varying vessel depths. 3D motion was measured in American Heart Association left anterior descending (LAD) segments 6,7, left circumflex (LCX) segments 11,15, and right coronary artery (RCA) segments 2,3, at 60,115 beats/min heart rates. Similar-length cardiac cycles were averaged. Intercoil cross-correlation identified early systolic phase (ES) and determined segment motion delay. Results Translational and rotational motion, as a function of cardiac phase, is shown, with directionality and amplitude varying along the vessel length. Rotation (peak-to-peak solid-angle RCA ,0.10, LAD ,0.06, LCX ,0.18 radian) occurs primarily during fast translational motion and increases distally. LCX displacement increases with heart rate by 18%. Phantom simulations of motion effects on high-resolution images, using RCA results, show artifacts due to translation and rotation. Conclusion Magnetic resonance imaging (MRI) tracking catheters quantify motion at 20 fps and 1 mm3 resolution at multiple vessel depths, exceeding that available with other techniques. Imaging artifacts due to rotation are demonstrated. Motion-tracking catheters may provide physiological information during interventions and improve imaging spatial resolution. J. Magn. Reson. Imaging 2009;29:86,98. © 2008 Wiley-Liss, Inc. [source] Kinematics of the ACL-deficient canine knee during gait: Serial changes over two yearsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2004Scott Tashman Abstract The ACL-deficient dog is a model for investigating the development and progression of mechanically driven osteoarthrosis of the knee. ACL loss creates dynamic instability in the ACL-deficient knee which presumably leads to progressive joint degeneration, but the nature of this instability over the time course of disease development is not well understood. The goal of this study was to characterize three-dimensional motion of the canine knee during gait, before and serially for two years after ACL transection. Canine tibial-femoral kinematics were assessed during treadmill gait before and serially for two years after ACL transection (ACL-D group; 18 dogs) or sham transection (ACL-I group; five dogs). Kinematic data was collected at 250 frames/s using a biplane video-radiographic system. Six degree-of-freedom motions of the tibia relative to the femur were calculated, and values immediately prior to pawstrike as well as the maximum, minimum, midpoint and range of motion during early/mid stance were extracted. Between-group differences relative to baseline (pre-transection) values, as well as changes over time post-transection, were determined with a repeated-measures ANCOVA. In the ACL-D group, peak anterior tibial translation (ATT) increased by 10 mm (p < 0.001), and did not change over time (p = 0.76). Pre-pawstrike ATT was similar to ACL-intact values early on (2,4 months) but then increased significantly over time, by 3.5 mm (p < 0.001). The range of ab/adduction motion nearly doubled after ACL loss (from 3.3° to 6.1°). The magnitude (midpoint) of knee adduction also increased significantly over time (mean increase 3.0°; p = 0.036). All changes occurred primarily between 6 and 12 months. There were no significant differences between groups in the transverse plane, and no significant changes over time in the ACL-I group. In summary, peak anterior tibial translation and coronal-plane instability increased immediately after ACL loss, and did not improve with time. ATT just prior to pawstrike and mean knee adduction throughout stance became progressively more abnormal with time, with the greatest changes occurring between 6 and 12 months after ACL transection. This may be due to overload failure of secondary restraints such as the medial meniscus, which has been reported to fail in a similar timeframe in the ACL-deficient dog. The relationships between these complex mechanical alterations and the rate of OA development/progression are currently under investigation. © 2004 Published by Elsevier Ltd. on behalf of Orthopaedic Research Society. [source] Simulation of microalgae growth in limiting light conditions: Flow effectAICHE JOURNAL, Issue 5 2002J. Pruvost Effect of hydrodynamical conditions on a microalgae culture growth was investigated in a photobioreactor with annular light chambers, with the focus on the relation between the cell displacement and the amount of light received by microorganisms, by comparing two different flow conditions in light chambers: an axial flow generating a poor radial mixing and a 3-D swirling motion. To determine microorganism trajectories, a Lagrangian approach was retained, allowing light received to be considered from a single microalga point of view. The light distribution was calculated using Beer,Lambert law, and a biological modeling of the culture growth was proposed, with consideration of light/dark cycle effects induced by cell displacement in the depth of the culture. Finally, batch cultures of Porphyridium purpureum were simulated for both hydrodynamical conditions in light chambers. The advantage of applying a three-dimensional motion to generate cell renewal in front of the light source, allowing microorganisms to use light more efficiently, is clearly shown. [source] | ||||||||||