Ultrasonic Echo Intensity as a New Noninvasive In Vivo Biomarker of Frailty

OBJECTIVES: To investigate whether muscle quality based on echo intensity (EI) is associated with muscle strength (MS) and correlates with risk of frailty in elderly outpatients. DESIGN: Cross-sectional, experimental study. SETTING: Outpatient clinic. PARTICIPANTS: Individuals aged 20 to 90 (N = 112). Individuals aged 20 to 59 participated as controls. Those aged 60 and older participated in the experimental group and were subdivided into robust, prefrail, and frail according to the Fried frailty criteria. MEASUREMENTS: EI, muscle thickness (MT), and subcutaneous fat thickness (SFT) of the anterior compartment of the thigh were measured using ultrasound images. MS was quantified using a hand dynamometer. Participants responded to a questionnaire asking about demographic and physical characteristics, frailty criteria, and quality of life. RESULTS: There was a significant negative correlation between EI and MS (Women: correlation coefficient (r) = -.522, P <.001; Men: r = -.355, P <.001). A similar trend was found for MT but not SFT. Statistically significant differences were also found between EI values, MT, MS, and quality of life and the different stages of frailty (P <.01). CONCLUSIONS: Higher levels of EI were associated with lower levels of strength and greater frailty. These results, although needing to be replicated in larger and more-diverse populations, suggest that EI obtained using ultrasound images might be used as noninvasive imaging biomarker of frailty in elderly adults and opens the possibility of accurately testing interventions performed to prevent it.