a-novel-application-of-musculoskeletal-ultrasound-imaging

A Novel Application of Musculoskeletal Ultrasound Imaging

Ultrasound is an attractive modality for imaging muscle and tendon  motion during dynamic tasks and can provide a complementary methodological  approach ...

George Mason University

We have developed a vector tissue Doppler imaging (TDI) system based on a clinical scanner that can be used to measure muscle velocities independent of the direction of motion. This method overcomes the limitations of conventional Doppler ultrasound, which can only measure velocity components along the ultrasound beam. In this study, we utilized this method to investigate the rectus femoris muscle velocities during a patellar tendon jerk test. Our goal was to investigate whether the muscle elongation velocities during a brisk tendon tap fall within the normal range of velocities that are expected due to rapid stretch of limb segments. In a preliminary study, we recruited six healthy volunteers (three men and three women) following informed consent. The stretch reflex response to tendon tap was evaluated by measuring: (1) the tapping force using an accelerometer instrumented to the neurological hammer (2) the angular velocities of the knee extension and flexion using a electrogoniometer (3) reflex activation using electromyography (EMG) and (4) muscle elongation, extension and flexion velocities using vector TDI. The passive joint angular velocity was linearly related to the passive muscle elongation velocity (R(2)=0.88). The maximum estimated joint angular velocity corresponding to muscle elongation due to tendon tap was less than 8.25 radians/s. This preliminary study demonstrates the feasibility of vector TDI for measuring longitudinal muscle velocities and indicates that the muscle elongation velocities during a clinical tendon tap test are within the normal range of values for rapid limb stretch encountered in daily life. With further refinement, vector TDI could become a powerful method for quantitative evaluation of muscle motion in musculoskeletal disorders.

Measurement of rectus femoris muscle velocities during patellar tendon jerk using vector tissue doppler imaging.

We have developed a vector Doppler system using a clinical ultrasound scanner with a research interface. In this system, vector Doppler estimation is performed by electronically dividing a linear array transducer into a transmit sub-aperture and two receive sub-apertures. The receive beams are electronically steered, and two velocity components are estimated from echoes received from the beam overlap region. The velocity vector is reconstructed from these two estimates. The goal of this study was to characterize this vector Doppler system in vitro using a string phantom with a pulsatile velocity waveform. We studied the effect of four parameters on the estimation error: beam steering angle, angle of the velocity vector, depth of the scatterer relative to the beam overlap region and the transmit focus depth. Our results show that changing these parameters have minimal effect on the velocity and angle estimates, and robust velocity vector estimates can be obtained under a variety of conditions. The mean velocity error was less than 0.06 x pulse repetition frequency. The velocity estimates are sensitive to the Doppler estimation method. Our results indicate that vector Doppler using a linear array transducer is feasible for a wide range of imaging parameters. Such a system would facilitate the investigation of complex blood flow and tissue motion in human subjects.

Experimental characterization of a vector Doppler system based on a clinical ultrasound scanner.

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 with cerebral palsy who have foot drop. Our preliminary results from this study show that tendon velocities estimated using vTDI have a strong linear correlation with the joint angular velocity estimated using a conventional 3D motion capture system. We observed a peak tendon velocity of 5.66Â±1.45 cm/s during dorsiflexion and a peak velocity of 8.83Â±2.13 cm/s during the passive relaxation phase of movement. We also obtained repeatable results from the same subject 3 weeks apart. Direct measurements of muscle and tendon velocities may be used as clinical outcome measures and for studying efficiency of movement control.

Measurement of tendon velocities using vector tissue Doppler imaging: a feasibility study.

Tendon jerk (TJ) is one of the most commonly used clinical tests in differential diagnosis of human motor disorders. There remains some ambiguity in the physiological interpretation of the test, especially with respect to its association to the functional status of patients. The TJ test inputs a non-physiological stimuli, but it is unclear to what degree the kinematics generated during the TJ test exceed the ranges that muscles encounter in activities of daily living (ADLs). The aim of our pilot study was to determine the range of angular knee kinematics (angular velocities and accelerations) corresponding to the muscle stretch elicited by TJ. We measured the longitudinal kinematics (velocities and accelerations) of the rectus femoris muscle in vivo using vector tissue Doppler imaging, an ultrasound-based method, and measured the angular kinematics of the knee in response to tendon taps with an electrogoniometer. We concluded that muscle longitudinal elongation accelerations elicited during the standard TJ test exceed angular accelerations (104.40-4534.20 radsâ»Â²) encountered in typical ADLs, but the velocities (0.82-6.21 radsâ»Â¹) elicited do not exceed those elicited by ADLs.

Knee joint angular velocities and accelerations during the patellar tendon jerk.

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.

Article	Year
Measurement of rectus femoris muscle velocities during patellar tendon jerk using vector tissue doppler imaging. Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference\| PubMed ID: 19963547	2009
Experimental characterization of a vector Doppler system based on a clinical ultrasound scanner. Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference\| PubMed ID: 19965161	2009
Measurement of tendon velocities using vector tissue Doppler imaging: a feasibility study. Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference\| PubMed ID: 21096066	2010
Knee joint angular velocities and accelerations during the patellar tendon jerk. Journal of neuroscience methods\| PubMed ID: 21549755	2011
Real-time measurement of rectus femoris muscle kinematics during drop jump using ultrasound imaging: a preliminary study. Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference\| PubMed ID: 23367014	2012

Avinash Eranki

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