Rectus femoris (RF) ultrasound for the assessment of muscle mass in older people.

BACKGROUND Simple and reliable methods to evaluate muscle mass in older people are lacking. AIM To evaluate ultrasound as a measure of RF muscle mass and quality in healthy subjects of different ages and gender, assessing its concordance with dual energy X-ray densitometry (DEXA) and association with muscle strength and walking capacity. METHODS We selected 54 adults of both genders, aged 20-55 years and 51 adults older than 60 years. Ultrasound images of the RF were obtained at the mid-thigh to measure its thickness and ultrasonographic density using a GE Logiq e equipment. Body composition was assessed by DEXA. Quadriceps isometric strength and 12 minutes' walk were also measured and gender specific t scores for older adults were calculated using the values obtained in adults. RESULTS RF ultrasound measurements correlated significantly with lean body mass assessed by DEXA (Double energy X-ray absorptiometry). The concordance between both measures was also adequate. Older people had lower muscle mass and worse ultrasound parameters than adults. Older males with a t score for quadriceps strength of -2 or less, had a significantly higher RF grayscale density. Older males with a 12 minutes' walk t score of -2 or less and old males and females with a walking speed of 1m/s or less had a lower RF thickness. DISCUSSION There is a good concordance between RF ultrasound and DEXA. CONCLUSIONS Assessment of RF using ultrasound appears to be a reliable and accurate method to evaluate muscle mass in older people.