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Imaging
Functional Musculoskeletal Ultrasound
Michael Peolsson and Lars-Åke Brodin
School for Technology and Health, Royal Institute of Technology, Stockholm
Abstract
Although the muscular component in various medical conditions is frequent, its impact is often difficult to confirm. The background of
this article concerns the need for tools to qualitatively and quantitatively describe musculoskeletal tissue dynamics and co-ordination
during realtime procedures. Tissue velocity ultrasound offers such possibilities. An ultrasound system equipped with tissue velocity
imaging (TVI) was used. Registrations were analysed post-process by a research software package. TVI offers four modes to describe
tissue activities: tissue velocity, displacement, strain and strain rate. Electromyography (EMG) was used to identify muscle rest and activity.
These parameters described different aspects of tissue dynamics. The main finding is that TVI has the sensitivity to visualise and quantify
musculoskeletal tissue activity and dynamics. Discrimination between active and passive tissue segments is possible. Both intra- and
inter-muscular co-ordination patterns are identified and described. A good correlation is found between tissue activity and EMG activity.
TVI is a sensitive method to describe muscle tissue dynamics as a function of muscle performance in realtime. It is possible to scrutinise
both intra-muscular and inter-muscular co-ordination patterns.
Keywords
Ultrasound, musculoskeletal, tissue velocity imaging (TVI), tissue Doppler imaging (TDI), strain rate, intra-muscular co-ordination,
inter-muscular co-ordination
Disclosure: The authors have no conflicts of interest to declare.
Received: 15 September 2009 Accepted: 24 September 2009
Correspondence: Michael Peolsson, Hälsans Nya verktyg, Platensgatan 29, Box 1224, SE-581 12 Linköping, Sweden. E:
Mikael.Peolsson@sth.kth.se
The muscular component in various medical conditions is often results suggested a less dynamic trapezius muscle among most
difficult to diagnose. Electromyography (EMG) is probably the most trapezius myalgia patients after pain provocation compared with
widely used tool to study muscle function and for a long time has healthy controls.
contributed considerable information in various ways. However, so
far few methods allow investigation of musculoskeletal dynamics. Methods
Tissue velocity imaging (TVI) or the similar tissue Doppler imaging Four Tissue Velocity Imaging Parameters
(TDI) is a relatively new ultrasound (US)-based method that was Describing Tissue Activity
originally developed to study tissue dynamics in the heart muscle.
1,2
Muscle tissue is an elastic entity and therefore undergoes dynamic
The image resolution of US systems has improved tremendously changes during neuro-motor innervations. The interpretation of the
over the last few years. Both comparatively cheap computing power results from the TVI calculations relies on the incompressibility
for image processing and the proliferating plethora of imaging principle, which means that if the muscle volume is prevailed during
techniques are rapidly adding new qualitative improvements and activity, the compression in one of several directions is compensated
quantitative possibilities, not only of anatomical landmarks and by concomitant elongations in the others.
7
demarcation but also of functional parameters.
Two fundamental concepts can be used to describe muscle tissue
TVI is an umbrella concept that describes different aspects of dynamics: tissue movement and tissue deformation. When a constant
muscle tissue dynamics. Grubb et al.
3
pioneered the musculoskeletal force affects the tissues, no tissue acceleration is present. In this case,
application field of TVI to identify phases in maximal voluntary the velocity of the parameters and displacement provides information.
contractions and to separate active from passive movements. If a tissue accelerates or decelerates, force affects the muscle tissue;
Pulkowski et al.
4
used TVI in order to identify the onset of muscle as per usual, the tissue response will be either compression or
activation according to isokinetic and isometric knee extensions and elongation. To convey information about tissue deformation, the
reported good validity and reliability against EMG. Mannion et al.
5
variables strain and strain rate are used.
8,9
Strain is the degree of tissue
used the same technique and successfully identified the onset of deformation compared with rest (%), and strain rate is the rate at
abdominal muscle feed-forward activity. Peolsson et al.
6
used TVI which this deformation occurs (dimensionless 1/s). Thus, strain can be
to investigate trapezius muscle dynamics after pain provocation seen as the degree of muscle thickening/thinning, while strain rate is
among trapezius myalgia patients and non-pain controls. The the rate at which this thickening/thinning occurs.
102 © TOUCH BRIEFINGS 2009
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