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Correlation between velocity waveforms measured using ultrasound and motion capture system. Four cycles of dorsiflexion and relaxation are shown. A & B display the axial and lateral spectrograms overlaid in yellow with the estimated velocities. (C) Joint velocity in degrees/s from motion capture system. (D) Absolute tendon velocity using vector Doppler. (E) Correlation between velocity waveforms for all trials obtained from vector Doppler and motion capture systems.
Source publication
We have developed a vector Doppler ultrasound imaging method to directly quantify the magnitude and direction of muscle and tendon velocities during movement. The goal of this study was to evaluate the feasibility of using vector Tissue Doppler Imaging (vTDI) for estimating the tibialis anterior tendon velocities during dorsiflexion in children wit...
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Context 1
... reflective plane in the beam profile phantom was placed at the 64 th element of the transducer. Figure 3 shows the correlations between the ultrasound and 3D motion capture measurements for one subject over multiple cycles of dorsiflexion and relaxation. Each cycle shows a distinct velocity peak corresponding to dorsiflexion and a higher velocity peak corresponding to the passive relaxation phase of the movement. ...
Context 2
... absolute velocities from vector Doppler showed strong correlation with the estimated absolute velocities from the 3D motion capture system as shown in Fig. 3(E) and Fig. 4. As expected, a linear relationship was observed between the joint velocity and the tendon velocity. Table 1 summarizes the R 2 values obtained over all the trials. The values over all trials are comparable with all 30 trials showing strong correlations, with peak velocity of 5.66±1.45 cm/s during dorsiflexion and peak ...
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Citations
... Once displacement is estimated, strain can be calculated by estimating differences in displacement between two points separated by a known distance. We have proposed a method for tracking muscle motion along the direction of the fascicles that can be broadly applicable even in situations where the entire muscle fascicle cannot be visualized (14,15). Our approach is inspired by the M-mode and kymography displays. ...
... Given a sequence of gray scale images (2D + time), M-mode image displays can be derived by resampling pixels along an arbitrary line or curve in the 2D image ( Fig. 2). This resampled M-mode (or curved M-mode) can be used to track motion along an arbitrary curve (14,15). Either manual operations or cross-correlation based image processing techniques can be exploited to estimate motion from these curved M-model images. ...
... These components can then be appropriately combined to get the velocity vector. We have developed a vector Doppler system for tracking muscle and tendon motion (14). We electronically split the transducer array into two apertures that were steered in different directions by programming the ultrasound transmission and reception parameters on an ultrasound system with a research interface (Sonix RP, Ultrasonix Corp., Vancouver, BC). ...
Advances in imaging methods have led to new capability to study muscle and tendon motion in vivo. Direct measurements of muscle and tendon kinematics using imaging may lead to improved understanding of musculoskeletal function. This review presents quantitative ultrasound methods for muscle dynamics that can be used to assess in vivo musculoskeletal function when integrated with other conventional biomechanical measurements.
... These advances have enabled a new methodological approach to understanding in vivo muscle function. However, these methods have primarily relied on using conventional grayscale (or B-mode) ultrasound imaging, and therefore have not fully exploited the possibilities of ultrasound to measure tissue velocities, strain and strain rate using Doppler principles, that have been shown to be valuable in evaluating cardiac muscle function [15][16] . ...
Ultrasound is an attractive modality for imaging muscle and tendon motion during dynamic tasks and can provide a complementary methodological approach for biomechanical studies in a clinical or laboratory setting. Towards this goal, methods for quantification of muscle kinematics from ultrasound imagery are being developed based on image processing. The temporal resolution of these methods is typically not sufficient for highly dynamic tasks, such as drop-landing. We propose a new approach that utilizes a Doppler method for quantifying muscle kinematics. We have developed a novel vector tissue Doppler imaging (vTDI) technique that can be used to measure musculoskeletal contraction velocity, strain and strain rate with sub-millisecond temporal resolution during dynamic activities using ultrasound. The goal of this preliminary study was to investigate the repeatability and potential applicability of the vTDI technique in measuring musculoskeletal velocities during a drop-landing task, in healthy subjects. The vTDI measurements can be performed concurrently with other biomechanical techniques, such as 3D motion capture for joint kinematics and kinetics, electromyography for timing of muscle activation and force plates for ground reaction force. Integration of these complementary techniques could lead to a better understanding of dynamic muscle function and dysfunction underlying the pathogenesis and pathophysiology of musculoskeletal disorders.
... This problem can be overcome by estimating the velocity of the object using two different ultrasound beams steered at different angles, a method known as vector Doppler. We have previously developed vector tissue Doppler imaging (vTDI) to quantitatively measure tendon and muscle kinematics in-vivo during dynamic tasks [11][12]. ...
... Vector TDI estimates velocity components of the rectus femoris muscle, based on measurements taken from two or more independent directions by electronically splitting an array transducer into multiple apertures. Our previous work [11][12] details the implementation of vTDI. Briefly, a 5-14 MHz linear array transducer with 38mm field of view was used. ...
We have developed an office based vector tissue Doppler imaging (vTDI) that can be used to quantitatively measure muscle kinematics using ultrasound. The goal of this preliminary study was to investigate if vTDI measures are repeatable and can be used robustly to measure and understand the kinematics of the rectus femoris muscle during a drop jump task. Data were collected from 8 healthy volunteers. Vector TDI along with a high speed camera video was used to better understand the dynamics of the drop jump. Our results indicate that the peak resultant vector velocity of the rectus femoris immediately following landing was repeatable across trials (intraclass correlation coefficient=0.9).The peak velocity had a relatively narrow range in 6 out of 8 subjects (48-62 cm/s), while in the remaining two subjects it exceeded 70 cm/s. The entire drop jump lasted for 1.45 0.27 seconds. The waveform of muscle velocity could be used to identify different phases of the jump. Also, the movement of the ultrasound transducer holder was minimal with peak deflection of 0.91 0.54 degrees over all trials. Vector TDI can be implemented in a clinical setting using an ultrasound system with a research interface to better understand the muscle kinematics in patients with ACL injuries.
... Such a system has the ability to perform experiments in a clinical setting with simultaneous imaging. Preliminary studies have characterized the accuracy of this vector Doppler system [5] and also shown the feasibility of measuring muscle and tendon velocities in vivo [6][7]. However, characterizing the beam overlap regions due to change in various parameters has not been studied. ...
... Assessment of muscle and tendon kinematics could have applications in understanding various gait and neuromuscular disorders and clinically monitoring treatment response. Vector Doppler can measure musculoskeletal motion in real time with high temporal resolution and without the need for any landmarks [7]. It could complement traditional electromyography, 3D motion capture systems and other joint kinematic modalities. ...
1 Abstract—We have developed a vector Doppler system based on an array transducer using a clinical ultrasound scanner with a research interface. In this system, vector Doppler is performed by splitting the array transducer into transmit and receives sub- apertures, which are then steered to obtain velocity estimates at different Doppler angles. The goal of this study was to characterize the size of the overlap region between the transmit and receive beams in both axial and lateral directions. We studied the effect of vector Doppler geometry, beam steering angle, aperture size and the depth of focus on the size of beam overlap region. Our results show that change in these parameters has minimal effect on the axial widths when a single transmit beam and two steered receive beams are used. However, the lateral widths tend to decrease with depth under all the factors under consideration. The average deviation of the beam widths was about 7% and 17% along the axial and lateral directions respectively over all 48 scenarios under consideration. Preliminary experiments on tissue did not substantially affect the beam overlap region.
Currently evidence-based practice has given scientific weight to the physical therapist profession; it is essential that all medical professional and physical therapists know the usefulness of new tools that optimize the effectiveness of their interventions and allow the growing of the scientific knowledge base. The use of ultrasound imaging (USI) by physiotherapists has evolved in recent years, consolidating as an increasingly standardized technique, low cost compared to other imaging techniques, quickly of execution, feasible and reliable tool. USI offers a wide range of opportunities in clinical practice as well as in different research areas.
Therefore, ultrasound has been currently used as a diagnostic tool by physicians and in recent years there has been an expansion of the use of ultrasound equipment by non-physicians professionals such as physical therapist or physical trainers, who incorporates USI as a means of assessing musculoskeletal system architecture and composition, musculoskeletal changes in dysfunction, pain or injury conditions, as an interventional technique assisting echo-guided procedures or using the visual real-time information as a biofeedback in control motor approaches, as guiding tool in clinical decisions as well as to improve the understanding of tissue adaptations to exercise or movement.
The purpose of this article is to review and provide an overview about the currently research of the USI applications and their benefits for the diagnosis and management in individuals with musculoskeletal conditions.
Objective:
Injuries to the hands, wrists, and fingers often involve damage to the tendons. The ability to measure tendon movements during the rehabilitation process can provide clinicians with important information in the quantification of tendon injuries. Conventionally, the tendon is considered a single spring-like structure during force transmission, and its twisted structure is neglected. Recently, clinicians believed that the twisted fiber structure (which enables tendon rotation during movement) of the tendon can provide it with a degree of elasticity and improve the efficiency of force transmission. However, observation of the hand tendon rotation in vivo by using the current imaging modalities is difficult.
Methods:
In this study, a 40-MHz high-frequency vector Doppler imaging (HFVDI) was used to visualize the movement of the hand tendon during muscle contraction. The performance of HFVDI was verified using a rotation phantom experiment. Two human experiments were designed in the present study: 1) participants were allowed to bend their distal and proximal interphalangeal (DIP and PIP) joints of fingers freely and 2) the PIP joint of the finger was fixed such that only the DIP could be moved. The HFVDIs of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendons were obtained in the transverse and longitudinal views to observe the movements of the hand tendon during finger movements.
Results:
The average longitudinal displacements of the FDS and FDP were approximately 3×4 mm for free bending of the finger; however, it was reduced when only the DIP was moved. The rotational phenomenon of the FDS and FDP tendons was observed in the transverse view, which demonstrated the different rotational behaviors of the FDS and FDP fibers during muscle contraction.
Conclusion:
All the results validated the potential of HFVDI as a novel tool for visualizing tendon rotation and would be useful in providing quantitative information regarding tendon function to determine the rehabilitation process following injuries.
We have developed two ultrasound-based methods, vector tissue Doppler imaging (vTDI) and curved M-mode (cMM), to directly quantify the magnitude of muscle and tendon velocities. The goal of this study was to investigate the repeatability of the vTDI and cMM system in measuring tendon velocities in vivo and cross validate between these two independent methods. We performed a preliminary study on children with cerebral palsy (CP) who have foot drop (inadequate dorsiflexion during swing phase of gait), and were undergoing treatment using a functional electrical stimulation device. While vTDI estimated peak instantaneous velocity during dorsiflexion, cMM estimated displacement, from which a mean dorsiflexion velocity could be derived. The peak velocities from vTDI and mean velocity from cMM showed strong correlations with peak and mean joint angle velocities from 3D motion capture (R2 =0.81 and 0.78, respectively) for all four cases over multiple trials, and the vTDI estimates were consistent with the cMM estimates. These preliminary results demonstrate that direct ultrasonic measurements of muscle and tendon velocities may be used as clinical outcome measures and for studying patients with gait related disorders like CP.
Recently there have been major advances in the electro-mechanical design of upper extremity prosthetics. However, the development of control strategies for such prosthetics has lagged significantly behind. Conventional noninvasive myoelectric control strategies rely on the amplitude of electromyography (EMG) signals from flexor and extensor muscles in the forearm. Surface EMG has limited specificity for deep contiguous muscles because of cross talk and cannot reliably differentiate between individual digit and joint motions. We present a novel ultrasound imaging based control strategy for upper arm prosthetics that can overcome many of the limitations of myoelectric control. Real time ultrasound images of the forearm muscles were obtained using a wearable mechanically scanned single element ultrasound system, and analyzed to create maps of muscle activity based on changes in the ultrasound echogenicity of the muscle during contraction. Individual digit movements were associated with unique maps of activity. These maps were correlated with previously acquired training data to classify individual digit movements. Preliminary results using ten healthy volunteers demonstrated this approach could provide robust classification of individual finger movements with 98% accuracy (precision 96-100% and recall 97-100% for individual finger flexions). The change in ultrasound echogenicity was found to be proportional to the digit flexion speed (R2=0.9), and thus our proposed strategy provided a proportional signal that can be used for fine control. We anticipate that ultrasound imaging based control strategies could be a significant improvement over conventional myoelectric control of prosthetics.
Frictional resistance to tendon gliding is minimized by surrounding loose areolar tissue. During periods of prolonged immobilization, for example, post-tendon-repair, adhesions can form between these two adjacent tissues, thereby limiting tendon function. Anti-adhesive agents can be applied during surgery to prevent adhesion formation, whilst reportedly providing some reduction in friction during in vitro tendon-bony pulley investigations. This bio-tribological study evaluates whether application of these agents can improve the lubrication between the tendon and surrounding tissue, thus potentially reducing the risk of re-rupturing the tendon at the repair site. The use of bovine synovial fluid (BSF) enabled an approximation of the in vivo lubrication regime, and subsequent comparison of the performance of three synthetic agents (50 mg/ml 5-fluorouracil; 5 mg/ml hyaluronic acid; ADCON-T/N). Coefficient of friction data was recorded and then compared with the Stribeck curve. BSF generated a fluid film that separated the two surfaces, giving rise to optimal lubrication conditions. This efficient regime was also generated following application of each anti-adhesion agent. The use of phosphate-buffered saline solution in generating only a boundary lubrication regime highlighted the effectiveness of the agents in reducing friction. Hyaluronic acid (5 mg/ml) was marginally deemed the most effective anti-adhesive agent at lubricating the tendon. Subsequently, it is concluded that the application of anti-adhesive agents post-surgery has secondary, tribological benefits that serve to reduce friction, and thus potentially the risk of failure, at the tendon repair site.
