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Imaging
method, caution has to be exercised according to the signal-to-noise quantitative information about regional tissue contraction, relaxation
ratio.
11
In order to provide a robust signal, an offset of 8mm has been and inactivity during functional movements in realtime; and tissue
used. As for the strain parameter, which is an integration method, a activation pattern correlated to the EMG activity pattern. The
drift in the signal may be another factor to consider. Furthermore, the technique seems suitable for functional studies of healthy or injured
frame rate of the registration needs to be considered in relation to muscles or can be applied to athletic training and rehabilitation and
the speed of movement to be registered. The consequence of a low neuro-motor affected muscles. n
frame rate may result in missing parts of the tissue dynamic during
the movement. All registrations need to be considered in terms of
Michael Peolsson is a Researcher/Lecturer in Medical
insonation angle deviations. This is because velocities are calculated
Engineering with a focus on ultrasonic visualisation of
along the axial direction of the probe and the direction of muscle skeletal muscle dynamics at the School for Technology
contractions often deviates from the axial direction. As a
and Health at the Royal Institute of Technology in
Stockholm in Sweden. His most recent research concerns
consequence, all calculations are indirect and relative.
the development of new ultrasonic imaging modalities
applied to muscles and biomedical multimodal data
Conclusions
modelling. He received a BSc in nursing from University
College of Skövde in Sweden, an MSc in electrical
This article has described a tool that makes it possible to visualise
engineering and applied physics and biomedical engineering from the Institute of
and quantify regional musculoskeletal tissue activity. TVI can Technology at Linköping University and a PhD in communication from the Department of
contribute in the following ways: identification of regional active and
Communication Studies at Linköping University. After his dissertation, Dr Peolsson worked
as a researcher in the Department of Rehabilitation Medicine at Linköping University
passive tissue segments; identification of intra- and inter-muscular
Hospital, concentrating on applications of ultrasonics to skeletal muscle dynamics,
co-ordination patterns; mapping of the muscle activation and to medical thermography, microdialysis studies and studies on clinical databases.
some extent the degree of contraction/relaxation; visual and
1. Brodin LA, Clin Physiol Funct Imaging, 2004; 24(3):147–55. 5. Mannion AF, et al., J Appl Physiol, 2008;104(4): 1192–1201. 2001.
2. Sutherland GR, et al., J Am Soc Echocardiogr, 6. Peolsson M, et al., BMC Musculoskel Disord, 2008;9:127–41. 8. Heimdal A, et al., J Am Soc Echocardiogr, 1998;11:1013–19.
2004;17(7):788–802. 7. Stoylen A, Strain rate imaging of the left ventricle by ultrasound. 9. D’Hooge J, et al., IEEE Trans Med Imaging, 2002;21(9):1022–30.
3. Grubb NR, et al., Radiology, 1995;194(3):837–42. Feasibility, clinical validation and physiological aspects, Trondheim: 10. Fukunaga T, et al., J Appl Physiol, 1997;82(1):354–8.
4. Pulkovski N, et al., Muscle Nerve, 2008;37:638–49. NTNU, Norwegian University of Science and Technology, 11. D’Hooge J, et al., Eur J Echocardiogr, 2000;1(3):154–70.
Editor’s Recommendations
Beliefs About Back Pain Predict the Recovery Rate Abdominal Muscle Size and Symmetry at Rest and During
Over 52 Consecutive Weeks Abdominal Hollowing Exercises in Healthy Control Subjects
Elfering A, Mannion AF, Jacobshagen N, et al., Scand J Work Environ Health, 2009 Oct 2 Mannion AF, Pulkovski N, Toma V, Sprott H, J Anat, 2008;213(2):173–82.
(Epub ahead of print).
The symmetry of, and physical characteristics influencing, the
This study examined the course of low-back pain over 52 weeks thickness of the lateral abdominal muscles at rest and during
following current pain at baseline. Initial beliefs about the inevitability abdominal exercises were examined in 57 healthy subjects. M-
of the pain’s negative consequences and fear avoidance beliefs mode ultrasound images were recorded from the abdominal
were examined as potential risk factors for persistent low-back pain. muscles at rest and during abdominal hollowing exercises in hook-
On a weekly basis over a period of one year, 264 participants lying. The fascial lines bordering the transversus abdominis,
reported both the intensity and frequency of their low-back pain and obliquus internus and obliquus externus were digitised and the
the degree to which it impaired their work performance. In a absolute thickness, relative thickness, contraction ratio and
multilevel regression analysis, predictor variables included initial asymmetry for each of these parameters were determined for each
low-back pain intensity, age, gender, body mass index, muscle. Both at rest and during hollowing, obliquus internus was
anxiety/depression, participation in sport, heavy workload, time (one the thickest and transversus abdominis the thinnest muscle. There
to 52 weeks) and scores on the ‘back beliefs’ and “fear-avoidance were no significant differences between left and right sides for
beliefs” questionnaires. The group mean values for both the intensity group mean thicknesses of any muscle; however, individual
and frequency of weekly low-back pain and the impairment of work asymmetries were evident, with mean values for the different
performance due to such pain showed a recovery within the first 12 muscles ranging from 11 to 26%; asymmetry was much less for the
weeks. In a multilevel regression of 9,497 weekly measurements, contraction ratios (mean % side differences 5–14% depending on
greater weekly low-back pain and impairment were predicted by muscle). Body mass was the most significant positive predictor of
higher levels of work-related fear avoidance beliefs. A significant absolute muscle thickness, for all muscles at rest and during
interaction between time and the scores on both the work-related hollowing, accounting for 30–44% variance. Body mass index
fear avoidance and back beliefs questionnaires indicated faster explained 20–30% variance in transversus abdominis contraction
recovery and pain relief over time in those who reported less fear ratio (negative relationship). The influence of these confounders
avoidance and fewer negative beliefs. In conclusion, negative beliefs must be considered in comparative studies of healthy controls and
about the inevitability of adverse consequences of low-back pain back pain patients, unless groups are very carefully matched.
and work-related fear avoidance beliefs are independent risk factors Asymmetries observed in patients should be interpreted with
for poor recovery from low-back pain. n caution, as they are also common in healthy subjects. n
106 EUROPEAN MUSCULOSKELETAL REVIEW
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