Muscle Echogenicity and Changes Related to Age and Body Mass Index

Muscle fibers are lost and replaced by fat- and fibrous-tissue infiltration during aging. This process decreases muscle quality and influences tissue appearance on ultrasound images over time. Increased muscle "echogenicity" represents changes caused by fat- and fibrous-tissue infiltration and can be quantified with recently developed software.

To investigate skeletal muscle quality through echogenicity, estimates according to participant's body mass index (BMI) and age were taken.

This was a cross-sectional study performed at the Pennington Biomedical Research Center, Baton Rouge, Louisiana with 117 participants (57 men and 60 women), with mean age (±SD) 38.9 ± 17.0 years and BMI 28.6 ± 6.2 kg/m². All participants were examined by ultrasound (LOGIQ GE Healthcare), using a 5.0-MHz linear transducer. Participants had muscle thickness measured by ultrasound at 4 anatomic locations (biceps and triceps brachial, femoral quadriceps, and calf triceps). Echogenicity was analyzed with specific software (Pixel Health) that evaluated the image in gray scale.

According to BMI, 41% of participants were obese. There was a positive correlation between age and thigh-muscle echogenicity (r_p = 0.534, P < .0001) and a negative correlation between thigh-muscle echogenicity and thickness (r_p = -0.395, P <.0001). There was high muscle echogenicity in participants with overweight and obesity aged 50 years or older (P < .05).

Older age and higher BMI were associated with stronger echogenicity signals and smaller muscle thickness. People with overweight, obesity, and/or older than 50 years old have reduced muscle quality with smaller muscle thickness, as observed with ultrasound.