Utility of Ultrasound in the Diagnosis of Primary Sarcopenia: An Umbrella Review of Systematic Reviews

Abstract

Introduction: Primary sarcopenia is a musculoskeletal syndrome characterized by the progressive loss of muscle mass and function, and is associated with disability, frailty, falls, and increased mortality in older adults. Reference diagnostic methods, such as dual-energy X-ray absorptiometry (DXA), magnetic resonance imaging (MRI), and computed tomography (CT), have limitations related to cost, availability, or radiation exposure. Muscle ultrasound (US) has emerged as an accessible, safe, and portable alternative for assessing both muscle quantity and quality.

Objective: To evaluate the diagnostic accuracy, reliability, and degree of standardization of ultrasound for the detection of primary sarcopenia through an umbrella review of systematic reviews.

Methods: An umbrella review was conducted and prospectively registered in PROSPERO (CRD420251003631) following PRISMA 2020 guidelines. A systematic search was performed in PubMed, Scopus, and the Cochrane Library from 2000 to the present. Systematic reviews evaluating the use of ultrasound in older adults with sarcopenia or low muscle mass were included. Study selection and data extraction were performed independently and in duplicate. Methodological quality was assessed using the ROBIS tool, and overlap among reviews was evaluated using the Corrected Covered Area (CCA). Evidence was synthesized narratively using an adapted GRADE approach.

Results: Twenty-seven records were identified, of which three systematic reviews met the inclusion criteria. Overlap among reviews was moderate (CCA = 7.9%). Overall, ultrasound demonstrated moderate-to-good diagnostic performance for sarcopenia, with an area under the curve (AUC) ranging from 0.76 to 0.87, sensitivity of approximately 82%, and specificity of approximately 72%. The best diagnostic performance was observed when applying Asian Working Group for Sarcopenia (AWGS) criteria. The most consistent findings were reported for the medial gastrocnemius and rectus femoris muscles, with cutoff values ranging from 1.5 to 1.71 cm for the medial gastrocnemius and approximately 1.5 cm for the rectus femoris. Ultrasound showed a moderate correlation with DXA (r = 0.69), whereas MRI demonstrated the highest agreement with DXA (r = 0.96). High intra- and inter-rater reproducibility (ICC > 0.90) was observed when standardized acquisition protocols were applied.

Conclusions: Ultrasound is an accessible, reproducible, and safe imaging modality with moderate-to-good diagnostic accuracy for identifying primary sarcopenia. Its application to muscles such as the medial gastrocnemius and rectus femoris provides clinically useful information that complements DXA and MRI, particularly in resource-limited settings. Further standardization of acquisition protocols and validation of muscle-specific cutoff values are necessary to support its integration as a first-line diagnostic tool.