Sarcopenia Staging and Screening
The utility of diagnostic ultrasound to detect age-related muscle dysfunction
Harris-Love MO, Adams B, Ismail C, Hernandez HJ, McIntosh V, Yang J, Chacko L, Blackman MR, Garra BS, 2015 (doi: 10.13140/RG.2.1.1331.3763)
Sonography can be used to characterize skeletal muscle morphology and morphometry in both clinical and research settings. Quantitative ultrasound remains a useful clinical and research imaging option to examine skeletal muscle in muscular dystrophy and sarcopenia. This imaging modality provides a non-invasive, inexpensive method to assess muscle morphology and estimate tissue and body composition without the use of ionizing radiation. Findings from our group and other investigators have shown that quantitative ultrasound methods provide viable proxy measures for lean body mass.
Diagnostic ultrasound image of the rectus femoris region of interest and the corresponding grayscale histogram analysis values.
Muscle quality may surpass muscle mass as a determinant of strength in some patient populations
Ismail C, Zabal J, Hernandez HJ, Woletz P, Manning H, Teixeira C, DiPietro L, Blackman MR, Harris-Love MO, 2015. (doi: 10.3389/fphys.2015.00302)
Our recent work suggests that age and muscle echogenicity, are significantly associated with scaled peak force production in the women that participated in our study. In contrast, DXA measures of lean body mass (LBM) are not significantly associated with scaled peak force generation in our participants. The higher total BF% of the Normal LBM subgroup may have conferred a protective effect against low muscle mass, but not myosteatosis. The women in the Normal LBM subgroup exhibit higher BMI values and echogenicity levels, but lower scaled peak force values in comparison to the Low LBM group.
The exemplar images above depict the diagnostic ultrasound transverse muscle images on the left and the grayscale histograms on the right. The bottom ultrasound image shows greater hyperechoic properties in comparison to the top image. The comparatively hyperechoic image characteristics of the bottom image correspond to grayscale histogram data with a wider distribution and a shift to the right which is associated with larger grayscale values. The grayscale value of the bottom image is 66.9 and may indicate a greater proportion of intramuscular adipose tissue in comparison to the top image (grayscale value, 35.6).
Exemplar ultrasound images of the rectus femoris and axial computed tomography CT images of the mid-thigh in two study participants. Mean grayscale measures of echogenicity at the rectus femoris of the dominant leg were derived from longitudinal ultrasound images and axial CT scans were obtained from the same anatomical plane at the mid-thigh.
Rectus femoris echogenicity has construct validity of as a surrogate measure of muscle quality
Harris-Love MO, Avila NA, Adams B, et al., 2018. (doi: 10.3390/jcm7100340)
Our findings in a sample of older, predominantly African American men indicate that rectus femoris echogenicity is strongly associated with CT scan estimates of IMAT at the mid-thigh. Moreover, our data suggest that echogenicity and CT scan estimates of IMAT are similarly associated with postprandial glucose values and HDL values, as well as hand grip strength, and knee extension (180°/s) strength values adjusted for body size.
The exemplar images show the rectus femoris and axial computed tomography CT images of the mid-thigh in two study participants. The images featured in Panel (A–C) depict a study participant with 15% cross-sectional fat mass and 7% intra- and intermuscular adipose tissue (IMAT). In contrast, the images in Panel (D–F) show a study participant with 66% cross-sectional fat mass and 40% IMAT (Hounsfield units: −190 to −30 for adipose tissue, 0 to +30 for low density muscle, and +31 to +100 for normal density muscle tissue)