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Quantification of Skeletal Muscle Fibrosis at Different Healing Stages Using Sonography
Author(s) -
Hu Ching-Fang,
Chen Carl Pai-Chu,
Tsai Wen-Chung,
Hu Li-Lin,
Hsu Chih-Chin,
Tseng Shih-Ting,
Shau Yio-Wha
Publication year - 2012
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 - 10.7863/jum.2012.31.1.43
Subject(s) - medicine , fibrosis , intensity (physics) , gastrocnemius muscle , decibel , pathology , anatomy , nuclear medicine , skeletal muscle , physics , quantum mechanics , audiology
Objectives This study attempted to quantify the degree of muscle fibrosis on sonograms of injured gastrocnemius muscles at different healing stages in a rat model. Correlations between the quantifications and histologic assessments of the injured muscles were also determined. Methods Sonograms and histologic findings of gastrocnemius muscle fibrosis were obtained during the second, third, and fourth weeks after surgically induced lesions in the right gastrocnemius muscles of 15 Wistar rats. The echo intensity, reflecting the degree of brightness on a sonogram, was divided into 256 gray levels instead of decibels. The mean echo intensity of each pixel in the region of interest was calculated as a summation of the echo intensities in all pixels divided by the pixel numbers in the region. To control individual variations among the rats, we calculated a K value, defined as the difference in the mean echo intensity between normal and affected muscles. Results Significant correlations ( r > 0.7; P < .05) between mean echo intensity and K values and the fibrous tissue percentage were identified. The mean echo intensity in the injured gastrocnemius muscles was significantly ( P = .029) greater than that in the normal muscles 3 weeks after injury. In histologic assessments, muscle fibrosis was most prominent 3 weeks after injury. However, the differences in fibrosis at different healing stages were not significant. Conclusions Mean echo intensity and K values can reflect the extent of fibrosis in affected muscles and may be valuable for quantifying muscle fibrosis in clinical practice.