Three-dimensional Motion Tracking Research Articles

Quantification of left atrial volumes using three-dimensional wall motion tracking echocardiographic technology: comparison with cardiac magnetic resonance

Left atrium (LA) size assessment is clinically relevant, but the accuracy of two-dimensional echocardiographic (2D-echo) methods is limited. Three-dimensional (3D) echocardiography is an excellent alternative but is far from being used in daily clinical practice. Three-dimensional-wall motion tracking (3D-WMT) allows us to obtain volumes in a very simple and rapid manner. The aims of this study were to evaluate the accuracy of 3D-WMT technology to assess LA volume using cardiac magnetic resonance (CMR) as a reference method, to evaluate its reproducibility, and to determine its added clinical value to classify the LA enlargement severity. Seventy consecutive patients referred for a CMR study were prospectively enrolled. They underwent LA volume assessment by means of 2D-echo, 3D-WMT, and CMR. Inter-methods agreement was assessed. The mean age was 56 ± 18 years and 42 patients (60%) were males. Average maximal LA volume obtained by 2D-echo, 3D-WMT, and CMR were 63.33 ± 26.82, 79.80 ± 29.0, and 79.80 ± 28.99 mL, respectively. Univariate linear regression analysis showed a good correlation between 3D-WMT and CMR (r = 0.83; P < 0.001). The agreement analysis showed a similar result (ICC = 0.83; 95% CI = 0.74-0.89; P < 0.001). Furthermore, the LA enlargement degree was better evaluated with 3D-WMT than with 2D-echo. This study validates LA volume measurements obtained using the new and fast 3D-WMT technology, compared with CMR. This method is fast, accurate, and reproducible, and it allows a better classification of left LA enlargement severity compared with 2D-echo.

Two-leg alternate loading model – A different approach to biomechanical investigations of fixation methods of the injured pelvic ring with focus on the pubic symphysis

The dorsal component of the pelvic ring is considered to be the most essential element for the stability of the pelvic ring. None of the current biomechanical set-ups include the effect of shear stresses by alternating loads that the pelvic ring has to withstand during walking. We hypothesize that a biomechanical test set-up with two-leg alternate loading will lead to stress imitation at the pubic symphysis that are more similar to existing strains than other test set-ups, and would, therefore, be more adequate for biomechanical testing of fixation methods.A new biomechanical two-leg standing test set-up with an alternate pelvic loading was constructed and was validated with six human pelvises from fresh frozen cadavers. Three-dimensional motion tracking was performed. The specimens were subjected to a non-destructive quasi-static test and a non-destructive cyclic test with progressive load amplitude from 170N to 340N over 1000 cycles.The initial rotational 'range of motion' and 'mean displacement' around the vertical axis for a pre-load of 170N was about 0.3° and 0.2°, respectively, increasing by 0.1–0.2° at a load of 340N. The rotation around the vertical axis and the translation along the frontal horizontal axis confirmed the stability of the pubic symphysis. The rate of ascend of displacements decreased, once the rotation reached 1° or the translation reached 1mm.The current biomechanical test set-up was compared with previous clinical findings, and the method was found valid for measuring inter-segmentary movements at the pubic symphysis.

Real-time visual sensing system achieving high-speed 3D particle tracking with nanometer resolution

This paper presents a real-time visual sensing system, which is created to achieve high-speed three-dimensional (3D) motion tracking of microscopic spherical particles in aqueous solutions with nanometer resolution. The system comprises a complementary metal-oxide-semiconductor (CMOS) camera, a field programmable gate array (FPGA), and real-time image processing programs. The CMOS camera has high photosensitivity and superior SNR. It acquires images of 128×120 pixels at a frame rate of up to 10,000 frames per second (fps) under the white light illumination from a standard 100 W halogen lamp. The real-time image stream is downloaded from the camera directly to the FPGA, wherein a 3D particle-tracking algorithm is implemented to calculate the 3D positions of the target particle in real time. Two important objectives, i.e., real-time estimation of the 3D position matches the maximum frame rate of the camera and the timing of the output data stream of the system is precisely controlled, are achieved. Two sets of experiments were conducted to demonstrate the performance of the system. First, the visual sensing system was used to track the motion of a 2 μm polystyrene bead, whose motion was controlled by a three-axis piezo motion stage. The ability to track long-range motion with nanometer resolution in all three axes is demonstrated. Second, it was used to measure the Brownian motion of the 2 μm polystyrene bead, which was stabilized in aqueous solution by a laser trapping system.

Assessment of area strain, twist, torsion and rotation in fetal echocardiography using three-dimensional (3D) Wall Motion Tracking Technology

Purpose: To demonstrate the possible application of 3D speckle tracking enabling to do real 3D based analysis of advanced three-dimensional myocardial motion patterns such as area strain, rotation, twist and torsion in fetal echocardiography.

Use of a real-time three-dimensional motion tracking system for measurement of intrafractional motion of the thoracic wall in dogs

To measure respiratory motion of the thoracic wall region in dogs using a real-time motion tracking system and compare the amount of respiratory motion between dogs positioned with and without a vacuum-formable cushion. 8 healthy adult mixed-breed dogs (median weight, 23 kg). Dogs were anesthetized and positioned in sternal and dorsal recumbency with and without a vacuum-formable cushion. Three-dimensional movement of anatomic landmarks was measured with a real-time motion capture system that tracked the locations of infrared light-emitting diodes attached externally to the dorsal or ventral and lateral aspects of the thoracic wall. Dogs positioned in sternal recumbency had significantly less cranial-to-caudal and left-to-right respiratory motion at the lateral aspect of the thoracic wall, compared with dogs positioned in dorsal recumbency, whether or not a cushion was used. For dogs treated in sternal recumbency, use of a cushion significantly increased the peak displacement vector (overall movement in 3-D space) for 3 of 4 marker locations on the dorsal thoracic wall. As respiratory rate increased, respiratory motion at the lateral and ventral aspects of the thoracic wall decreased when data for all dogs in dorsal recumbency were evaluated together. Associations between respiratory rate and respiratory motion suggested that the use of rapid, shallow ventilation may be beneficial for dogs undergoing highly conformal radiation treatment. These results provide a basis for further research on respiratory motion in anesthetized dogs.

Three‐dimensional motion tracking for high‐resolution optical microscopy, in vivo

When conducting optical imaging experiments, in vivo, the signal to noise ratio and effective spatial and temporal resolution is fundamentally limited by physiological motion of the tissue. A three-dimensional (3D) motion tracking scheme, using a multiphoton excitation microscope with a resonant galvanometer, (512 × 512 pixels at 33 frames s(-1)) is described to overcome physiological motion, in vivo. The use of commercially available graphical processing units permitted the rapid 3D cross-correlation of sequential volumes to detect displacements and adjust tissue position to track motions in near real-time. Motion phantom tests maintained micron resolution with displacement velocities of up to 200 μm min(-1), well within the drift observed in many biological tissues under physiologically relevant conditions. In vivo experiments on mouse skeletal muscle using the capillary vasculature with luminal dye as a displacement reference revealed an effective and robust method of tracking tissue motion to enable (1) signal averaging over time without compromising resolution, and (2) tracking of cellular regions during a physiological perturbation.

Area strain: umbrales de normalidad de un nuevo parámetro en sujetos sanos

The echocardiographic technology known as three-dimensional wall motion tracking offers three-dimensional images of the myocardium and provides multiple measures of deformation, one of which is known as “area strain” (AS), which combines left ventricular longitudinal and circumferential deformations. Our aim was to describe the normal maximum systolic reference AS value in a sample of healthy subjects. Sixty consecutive subjects without known cardiovascular risk factors or diseases were enrolled, and left ventricular AS was measured. Overall mean AS was –38.87 ± 5.89%. Mean values at the level of the basal, middle, and apical segments were −38.42 ± 7.58%, −38.74 ± 6.34%, and −43.18 ± 12.81%, respectively. Thus, our results show for the first time the reference values for AS in healthy subjects. Full English text available from: www.revespcardiol.org

Area Strain: Normal Values for a New Parameter in Healthy People

The echocardiographic technology known as three-dimensional wall motion tracking offers three-dimensional images of the myocardium and provides multiple measures of deformation, one of which is known as “area strain” (AS), which combines left ventricular longitudinal and circumferential deformations. Our aim was to describe the normal maximum systolic reference AS value in a sample of healthy subjects. Sixty consecutive subjects without known cardiovascular risk factors or diseases were enrolled, and left ventricular AS was measured. Overall mean AS was –38.87 ± 5.89%. Mean values at the level of the basal, middle, and apical segments were –38.42% ± 7.58%, –38.74% ± 6.34%, and −43.18% ± 12.81%, respectively. Thus, our results show for the first time the reference values for AS in healthy subjects.

Novel Area Strain Based on Three-Dimensional Wall Motion Analysis for Assessment of Global Left Ventricular Performance after Repair of Tetralogy of Fallot

This study aimed to determine the usefulness of novel parameters of left ventricular (LV) endocardial area strain (AS) in assessing global LV performance in patients with repaired tetralogy of Fallot (TOF). Thirty patients, aged 21.7 ± 5.8 years, with repaired TOF and 25 healthy subjects aged 19.9 ± 5.5 years were studied. Three-dimensional LV wall motion tracking was performed to determine global and regional peak AS, an AS-systolic dyssynchrony index (SDI), and LV volumes and ejection fraction. The AS-SDI was derived from the dispersion of time-to-minimum segmental endocardial areas, expressed as a percentage of RR interval, using a 16-segment model. The LV global performance plot was generated by plotting peak global AS against AS-SDI. The coefficients of variations for intra- and interobserver measurement of LV global AS were 6.3% and 10.6%, respectively. Compared with controls, patients had significantly lower global AS (30.5% ± 4.5% vs. 40.9% ± 2.8%, P < .001) and greater AS-SDI (10.0% ± 2.9% vs. 4.1% ± 1.4%, P < .001). Global AS (r= 0.94, P < .001) and AS-SDI (r= -0.76, P < .001) correlated strongly with LV ejection fraction. The global performance plot identified 87% of patients (26/30) with both reduced LV global AS and LV systolic mechanical dyssynchrony. AS measurement of LV endocardium based on three-dimensional wall motion tracking is reproducible and enables convenient assessment of global LV performance using a composite representation of parameters, including global AS and an AS-derived index of mechanical dyssynchrony.

Kinematic analysis of netball goal shooting: A comparison of junior and senior players

The aim of this study was to investigate the effect of playing experience on the kinematic characteristics of the goal shooting action in netball players. Six county-level junior and six senior goal shooters took part in the study. They were asked to perform eight shots at goal and were equipped with 33 retro-reflective markers fixed to anatomical landmarks for three-dimensional motion tracking. The shot was divided into three periods: start of throw, shooting action, and release. The following variables were determined for each period: position of the ball, joint angles, timings between actions, joint angular velocities, and ranges of motion. The main results showed a significant effect of playing experience, with senior shooters showing a shorter delay between the movements involved in the shooting action, a significant difference between the right and left elbow angles at the start of forearm extension, and greater extension of the left shoulder and greater flexion of the left elbow at release compared with junior shooters. These results might help justify some of the empirical observations made by coaches and direct them in their advice to players. In particular, recommendations to junior players should focus on the simultaneity of leg and arm actions and dissociation between the right and left arms during the shooting action.

3-D phantom and in vivo cardiac speckle tracking using a matrix array and raw echo data.

Cardiac motion has been tracked using various methods, which vary in their invasiveness and dimensionality. One such noninvasive modality for cardiac motion tracking is ultrasound. Three-dimensional ultrasound motion tracking has been demonstrated using detected data at low volume rates. However, the effects of volume rate, kernel size, and data type (raw and detected) have not been sufficiently explored. First comparisons are made within the stated variables for 3-D speckle tracking. Volumetric data were obtained in a raw, baseband format using a matrix array attached to a high parallel receive beam count scanner. The scanner was used to acquire phantom and human in vivo cardiac volumetric data at 1000-Hz volume rates. Motion was tracked using phase-sensitive normalized cross-correlation. Subsample estimation in the lateral and elevational dimensions used the grid-slopes algorithm. The effects of frame rate, kernel size, and data type on 3-D tracking are shown. In general, the results show improvement of motion estimates at volume rates up to 200 Hz, above which they become stable. However, peak and pixel hopping continue to decrease at volume rates higher than 200 Hz. The tracking method and data show, qualitatively, good temporal and spatial stability (for independent kernels) at high volume rates.

Validation of a single camera three-dimensional motion tracking system

The ability to analyze human movement is an essential tool of biomechanical analysis for both sport and clinical applications. Traditional 3D motion capture technology limits the feasibility of large scale data collections and therefore the ability to address clinical questions. Ideally, the measurement system/protocol should be non-invasive, mobile, generate nearly instantaneous feedback to the clinician and athlete, and be relatively inexpensive. The retro-grate reflector (RGR) is a new technology that allows for three-dimensional motion capture using a single camera. Previous studies have shown that orientation and position information recorded by the RGR system has high measurement precision and is strongly correlated with a traditional multi-camera system across a series of static poses. The technology has since been refined to record moving pose information from multiple RGR targets at sampling rates adequate for assessment of athletic movements. The purpose of this study was to compare motion data for a standard athletic movement recorded simultaneously with the RGR and multi-camera (Motion Analysis Eagle) systems. Nine subjects performed three single-leg land-and-cut maneuvers. Thigh and shank three-dimensional kinematics were collected with the RGR and Eagle camera systems simultaneously at 100 Hz. Results showed a strong agreement between the two systems in all three planes, which demonstrates the ability of the RGR system to record moving pose information from multiple RGR targets at a sampling rate adequate for assessment of human movement and supports the ability to use the RGR technology as a valid 3D motion capture system.

Annealed particle filter based on particle swarm optimization for articulated three-dimensional human motion tracking

Three-dimensional articulated human motion tracking is challenging due to the high-dimensional parameter space and poor image observations. When particle swarm optimization (PSO) is used for human motion tracking, due to unreliable image likelihood, particles may be misled and be unable to find the most plausible pose space. This paper proposes a new PSO-based algorithm for human motion tracking, annealed PSO-based particle filter (APSOPF). The sampling covariance and annealing factor are incorporated into the velocity-updating equation of PSO; they are initialized with appropriate values at the beginning of the PSO iteration, and decreased (annealed) in reasonable steps. Through the sampling covariance, the motion prior is introduced into APSOPF, constraining particles to the most likely region of pose space and reducing the generation of invalid particles. By adopting decreasing coefficients in the updating principle, the leading effects of the local and global best on particles decrease with generations, making particles preserve their own divergence and self-exploration capabilities before convergence. Hence the problem of insufficiently reliable image likelihood can be mitigated in some degree. We compare APSOPF quantitatively with an annealed particle filter and a standard particle filter on the challenging HumanEvaI data set. Experimental results show that the proposed algorithm achieves lower estimation error in tracking real-world 3-D human motion.

A novel non-bridging external fixator construct versus volar angular stable plating for the fixation of intra-articular fractures of the distal radius—A biomechanical study

Non-bridging external fixation has recently been introduced as an alternative to volar angular stable plating for the fixation of unstable intra-articular distal radial fractures. The purpose of this study was to biomechanically compare a new non-bridging external fixator construct to volar angular stable plate fixation in a dorsally comminuted intra-articular fracture model of the distal radius. Five pairs of fresh frozen human cadaveric radii were randomly supplied with either a non-bridging external fixator or a stainless steel volar locking plate. A three-fragmental AO 23-C2.1 fracture was created by removing a 15 degrees dorsal wedge with remaining volar cortical contact and by an intra-articular osteotomy lateral to the lister-tubercle. Physiological load transfer via the wrist was simulated by means of a custom-made seesaw. For biomechanical testing, the bones were loaded in cyclic axial compression. Starting at 100N, the load was monotonically increased at 0.025 degrees N per cycle until failure of the construct. Motion of the lunate and scaphoid fragments with respect to the radial diaphysis was acquired by optical three-dimensional (3D) motion tracking. Plastic wedge deformation was determined after 2000, 4000 and 6000 cycles. The amplitude of wedge motion at the beginning of the test as a measure for construct stiffness was significantly lower for the fixator group (P=0.003, power=0.99). Plastic wedge deformation after 2000, 4000 and 6000 cycles was found significantly lower for the external fixator (repeated measures analysis of variance (ANOVA), P=0.009, power=0.86). Displacement of the intra-articular gap was found below 0.6mm (mean) for both groups (P>0.05). The study revealed superior biomechanical properties of the proposed non-bridging external fixation compared to volar locked plating in an unstable intra-articular fracture model with volar cortical support. However, both fixation techniques seem to apply sufficient stabilisation to restore and retain anatomy after fracture of the most distal part of the radius and should be individually chosen according to distinct criteria.

Investigation of a chaotic double pendulum in the Basic Level Physics Teaching Laboratory

First-year physics students at the Technical University of Budapest carry out a wide range of measurements in the Basic Level Physics Teaching Laboratory. One of the most exciting experiments is the investigation of a chaotic double pendulum by a V-scope, a powerful three-dimensional motion tracking system. After a brief introduction to the V-scope apparatus, the measurement carried out by the students, typical results of data analysis and the experiences are presented.

The use of ergonomic spoons by people with cerebral palsy: effects on food spilling and movement kinematics

The effects of adapted spoons on food spilling and movement kinematics (movement duration, dysfluency) were examined in people with tetraparetic cerebral palsy (CP). We varied the thickness of the spoon's handle (diameters of 1, 3, and 5cm), the substance with which the spoon was filled (sugar or water), and the size of the bowl into which the spoon had to be emptied (diameter 5 or 11cm). Ten adolescents with tetraparesis (five males, five females; mean age 17y 2mo [SD 1y 3mo]; range 14y 7mo‐18y 6mo) and 12 healthy comparison participants (four males, eight females; mean age 25y 6mo [SD 3y 0mo]; range 20y 0mo‐30y 0mo) participated. Four participants with tetraparesis could walk independently, while the other six sat unstrapped in a wheelchair. The task consisted of picking up and transporting the filled spoon and emptying it into a bowl. Movements of the hand were recorded by a three‐dimensional motion tracking device. When the spoon's handle was thickened participants with CP were faster in picking up the spoon and transporting it to the bowl, in particular when the spoon was filled with water. Importantly, this faster performance did not lead to increased spilling. These results are the first systematic test of the supposed beneficial effect of adapted spoons on movement performance in people with CP.

The use of ergonomic spoons by people with cerebral palsy: effects on food spilling and movement kinematics

The effects of adapted spoons on food spilling and movement kinematics (movement duration, dysfluency) were examined in people with tetraparetic cerebral palsy (CP). We varied the thickness of the spoon's handle (diameters of 1, 3, and 5cm), the substance with which the spoon was filled (sugar or water), and the size of the bowl into which the spoon had to be emptied (diameter 5 or 11cm). Ten adolescents with tetraparesis (five males, five females; mean age 17y 2mo [SD 1y 3mo]; range 14y 7mo-18y 6mo) and 12 healthy comparison participants (four males, eight females; mean age 25y 6mo [SD 3y 0mo]; range 20y 0mo-30y 0mo) participated. Four participants with tetraparesis could walk independently, while the other six sat unstrapped in a wheelchair. The task consisted of picking up and transporting the filled spoon and emptying it into a bowl. Movements of the hand were recorded by a three-dimensional motion tracking device. When the spoon's handle was thickened participants with CP were faster in picking up the spoon and transporting it to the bowl, in particular when the spoon was filled with water. Importantly, this faster performance did not lead to increased spilling. These results are the first systematic test of the supposed beneficial effect of adapted spoons on movement performance in people with CP.

A 3D motion-tracking method in graphonomic research: possible applications in future handwriting recognition studies

A three-dimensional (3D) motion tracking method as applied in graphonomic research is described. In addition to movements of the writing stylus, rotations of joints in the arm, hand, and index finger are recorded in a straightforward manner by making use of rigid bodies that define the position and orientation of the segments of a writer's arm and his or her pen. The method is developed in a visually-oriented, component-based programming environment which simplifies further software development and facilitates the use of the method alongside existing research paradigms. A modest example of the method and possible applications in future handwriting recognition studies are discussed.

Three-dimensional motion tracking with volumetric phase contrast MR velocity imaging.

Motion tracking based on single-slice cine-phase contrast magnetic resonance imaging data has limitations. In the presence of nontrivial three-dimensional motion and deformation, volumetric data are necessary for accurate reconstruction of material point trajectories. A three-dimensional Fourier tracking method that uses volumetric data for motion tracking is presented. The method reconstructs a material point trajectory by computing its various harmonics. For any given temporal sampling rate, a frequency domain perspective of the tracking problem indicates that the method is accurate in estimating all reconstructible harmonics of a trajectory. The algorithm incorporates an intra-voxel linear spatial model into the integration to address potential tracking performance degradation due to possibly reduced spatial resolution, which may be most relevant in the slice direction (z) if the volumetric data are obtained as multiple two-dimensional slices. The tracking method was evaluated on computer-generated data sets that simulated various motion patterns. The method was also tested with two sets of in vitro data obtained using a phantom, one acquired as multiple two-dimensional slices and the other using a three-dimensional sequence capable of higher spatial resolution in the z direction. These studies demonstrated that the algorithm can achieve high sub-voxel tracking accuracy.

Deformation of femoral nails with intramedullary insertion.

Current methods of distal interlocking of intramedullary femoral nails are dependent on image intensification. However, radiation exposure to the patient, the operating room staff, and the surgeon remains a concern. Proximally mounted, radiation-free aiming systems for distal interlocking of femoral nails have reportedly failed because of nail deformation with insertion. To better understand this deformation, a three-dimensional magnetic motion tracking system was used to determine the position of the distal interlocking hole following nail insertion. The amount and direction of deformation of commercially available small-diameter implants (unslotted 9-mm nails inserted without reaming) and large-diameter implants (slotted 13-mm nails inserted with reaming) from a single manufacturer were analyzed. Measurements of deformation (three translations and three angles), based on the center of the distal transverse locking hole, were performed on 10 paired intact human cadaveric femora before and after insertion. The technique produced the following results for the small and large-diameter nails, respectively: lateral translations of 18.1+/-10.0 mm (mean+/-SD, range: 47.8 mm) and 21.5+/-7.9 mm (range: 26.4 mm), dorsal translations of -3.1+/-4.3 mm (range: 15.2 mm) and 0.4+/-9.8 mm (range: 30.1 mm), and rotation about the longitudinal axes of -0.1+/-0.2 degrees (range: 0.7 degrees) and 10.0+/-3.1 degrees (range: 7.8 degrees). This technique is useful for measuring insertion-related femoral nail deformation. The data for the nails tested suggest that a simple aiming arm, mounted on the proximal end of the femoral nail alone, will not sufficiently provide accurate distal aiming.