Association between echo intensity and attenuation of skeletal muscle in young and older adults: a comparison between ultrasonography and computed tomography

Abstract

BackgroundSkeletal muscle experiences both quantitative and qualitative changes with aging. Echo intensity (EI) of the skeletal muscle obtained by ultrasonography (US) has been considered to reflect muscle quality. This technique is noninvasive, easily accessible, and is relatively inexpensive than that of other imaging techniques such as computed tomography (CT). Previous studies have reported that EI is related to several physical performances. However, few studies have investigated the validity of EI against other imaging methods in case of imaging of the skeletal muscle. We compared quantitative and qualitative indices evaluated by the US and CT imaging systems to strengthen their validity.Participants and methodsA total of 40 adults participated in this study: 19 young (10 men and 9 women; their mean (±SD) age was 22.7±1.5 years) and 21 older adults (13 men and 8 women; their mean age was 70.6±4.8 years). Both thighs of each participant were evaluated using US and CT imaging systems.ResultsWith respect to the US indices, the young group had significantly higher muscle thickness (MT) of the front thigh (P<0.001) and lower EI (P=0.001) than that of the older group. With respect to the CT indices, the cross-sectional area (CSA) and mean CT value (Hounsfield unit [HU]) of the muscle were found to be significantly higher in the young group (P<0.001) than that of the older group, whereas the percentage of low-density muscle area (%LDMA) was found to be significantly higher in the older group (P<0.001) than that of the young group. A significant, strong, and positive correlation was observed between MT and CSA, which reflects the muscle quantity (r=0.774; P<0.001). With respect to the indices of muscle quality, we found significant and moderate correlations between EI and CT values (r=−0.502; P<0.001) and between EI and %LDMA (r=0.441; P<0.001). However, these correlations were found to be decreased in the older group [between EI and CT value (r=−0.363; P=0.018) and between EI and %LDMA (r=0.257; P=0.100)].ConclusionResults of this study indicate that the EI is moderately associated with muscle attenuation as assessed by CT, which means that higher EI at least partly reflects intramuscular lipid infiltration.

Application of ultrasound for muscle assessment in sarcopenia: 2020 SARCUS update

“…Quadriceps muscle (rectus femoris and vastus intermedius bellies) was evaluated at 30% (proximal or distal was not described) between the anterior superior iliac spine and the proximal end of the patella, in a supine position, for muscle thickness and echo-intensity [47]; at 50% between the anterior superior iliac spine and the proximal end of the patella, in a supine position, for muscle thickness of both bellies [48,49] and echo-intensity of rectus femoris alone [48]; at 30% (proximal or distal was not described) between the anterior superior iliac spine and the proximal end of the patella, in a supine position, for muscle thickness and echo-intensity [50]; at 50% between the anterior superior iliac spine and the lateral epicondyle of the femur, in a standing position, for echo-intensity [51]; at 50% between the greater trochanter and the knee cleft (left or right was not described), in a supine position with the knees in 10°, for muscle thickness, cross-sectional area and echo-intensity and pennation angle [52]; at 15 cm proximal of the superior border of the patella, in a sitting position, for muscle thickness and echo-intensity [53].…”

Acute effect of multiple sets of fatiguing resistance exercise on muscle thickness, echo intensity, and extracellular-to-intracellular water ratio

“…However, it is not clear what exactly the increase of EI after exercise means (Fujikake et al 2009). In resting state, higher value of EI is related to higher proportion of intramuscular adipose, fibrous, or connective tissues (Pillen et al 2009;Watanabe et al 2018). In animal model, focal edema and inflammation fibers were observed several days after eccentric exercise (Sudo and Kano 2009).…”

Muscle Quality, Measured by Ultrasound-Derived Corrected Echo Intensity, Does not Affect Changes in Cross-sectional Area of the Vastus Lateralis Following Recumbent Rest

“…Muscle quality measures derived from CT and sonography have been shown to be significantly different, although related. 28 The CT radiologic density value is primarily affected by the presence of intramuscular fat and water content, 62 whereas EI may also be influenced by the presence of fibrous tissue and other connective tissue. 63 Previous research has suggested that EI may be a more effective indicator of muscle quality than radiologic density.…”