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Echogenicity: Implication of Rehabilitative Ultrasound Imaging
for Assessing Muscle Quality
Hadian MR. PT. PhD, Olyaei GR. PT. PhD,
Rezasoltani A. PT. PhD,Rahimeh Mahmoodi, PT. PhD candidate
Presented by: Zinat Ashnagar PhD candidate of Physiotherapy
Tehran University of Medical Sciences
IntroductionThe accumulation of connective and adipose
tissues in the muscles may result in changes of muscle quality or composition.
The computed tomography imaging serves as a
gold standard for the assessment of muscle quality and shows reduced attenuation coefficient due to augmented fat infiltration.
Muscle quality can also be assessed by using musculoskeletal ultrasound imaging.
Increases in intramuscular fibrous and adipose tissue may result in enhanced echogenicity.
Echogenicity: Capacity of a structure in the path of an ultrasound beam to reflect back sound waves.
Echogenicity can be quantified by using computer-aided gray scale analysis of ultrasound image.
Transversal ultrasound images of musculus rectusfemoris and musculus intermedius from a 28-year-old man (a)and a 69-year-old man (b).
Implications
The results of Watanabe et al. study indicate that aging-related changes in muscle quality contribute to diminishing muscle strength.
Ultrasonography is a low-cost, easily accessible, and safe method suitable for the assessment of EI as an index of muscle quality.
Echo intensity obtained from ultrasonography images reflecting muscle strength in elderly men
Clinical Interventions in Aging 2013:8 993–998
skeletal muscle US is capable of detecting neuromuscular disorders (NMDs)
Quantification of echo intensity is a more objective than visual evaluation and accurate method. Because it can achieve higher sensitivities, it is better-suited for the screening task in the diagnostic phase of children with a NMD.
SKELETAL MUSCLE ULTRASONOGRAPHY: VISUAL VERSUSQUANTITATIVE EVALUATION
Ultrasound in Med. & Biol., Vol. 32, No. 9, pp. 1315–1321, 2006
Two method s of echogenicity analysis were introduced by the literature.
Some authors have used a region of interest in the selected muscle as much of the muscle was possible without any bone or surrounding fascia
others have defined a rectangular window (100mm2) as a region of interest in the selected muscle.
Aim
The aim of this study was to assess the association between the two
mentioned methods of echogenicity analysis and to provide the reliability
of each method.
Two dimensional B-mode ultrasound imaging with 7.5 MHz linear
transducer(HS-2600, Honda Electronics, Japan)
[email protected] 16Method A
[email protected] 17Method B
Each method was repeated for three times and the mean of the trials was
calculated.
The results showed that there is a high association between two methods of echogenicity analysis (Pearson correlation coefficient: 0.883, p=0.004).
The intrarater reliability of ultrasound echogenicity was excellent for both methods (ICC: 0.981-0.984).
Method A
Min Max Mean SD ICC P
Echo.A.1 6.82 39.31 18.9376 10.29831 0.981
≤0.001
Echo.A.2 7.34 37.82 18.7160 9.95831
Echo.A.3 7.33 30.21 17.5549 8.23600
Mean.A 7.78 35.78 18.4028 9.36705
ConclusionThe findings of the current study indicate that
echogenicity is a highly reliable method for assessing muscle quality.
It seems that two methods of echogenicity analysis provide similar results of muscle quality.
Therefore, when the limited image size of ultrasound image prevents the full measurement of the cross section area of the large muscles for quantifying muscle quality, a standard selection as a sample of the whole muscle can be used.
The musculoskeletal ultrasound imaging as a safe, non-invasive and easily accessible method for muscle visualization can detect structural muscle changes.
Echo- intensity or echogenicity of an ultrasound image provides information about the muscle composition.
Conclusion
Cautionchanges in system-settings, especially increased gain, can give muscles a whiter appearance, which can be mistaken for pathologic changes.
