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Quantification of Muscle Tissue Properties by Modeling the Statistics of Ultrasound Image Intensities Using a Mixture of Gamma Distributions in Children With and Without Cerebral Palsy
Author(s) -
Sikdar Siddhartha,
Diao Guoqing,
Turo Diego,
Stanley Christopher J.,
Sharma Abhinav,
Chambliss Amy,
Laughrey Loretta,
Aralar April,
Damiano Diane L.
Publication year - 2018
Publication title -
journal of ultrasound in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 91
eISSN - 1550-9613
pISSN - 0278-4297
DOI - 10.1002/jum.14566
Subject(s) - medicine , cerebral palsy , ultrasound , radiology , biomedical engineering , physical medicine and rehabilitation
Objectives To investigate whether quantitative ultrasound (US) imaging, based on the envelope statistics of the backscattered US signal, can describe muscle properties in typically developing children and those with cerebral palsy (CP). Methods Radiofrequency US data were acquired from the rectus femoris muscle of children with CP (n = 22) and an age‐matched cohort without CP (n = 14) at rest and during maximal voluntary isometric contraction. A mixture of gamma distributions was used to model the histogram of the echo intensities within a region of interest in the muscle. Results Muscle in CP had a heterogeneous echo texture that was significantly different from that in healthy controls ( P < .001), with larger deviations from Rayleigh scattering. A mixture of 2 gamma distributions showed an excellent fit to the US intensity, and the shape and rate parameters were significantly different between CP and control groups ( P < .05). The rate parameters for both the single gamma distribution and mixture of gamma distributions were significantly higher for contracted muscles compared to resting muscles, but there was no significant interaction between these factors (CP and muscle contraction) for a mixed‐model analysis of variance. Conclusions Ultrasound tissue characterization indicates a more disorganized architecture and increased echogenicity in muscles in CP, consistent with previously documented increases in fibrous infiltration and connective tissue changes in this population. Our results indicate that quantitative US can be used to objectively differentiate muscle architecture and tissue properties.