As one of the key geriatric syndromes, sarcopenia, a generalized skeletal muscle disorder, needs little introduction. The progressive decline in muscle function, mass, and strength affects all aspects of life, leading not only to physical challenges but also to psychological, social, and financial burdens [1]. Despite significant advancements in understanding its aetiology, definition, and screening guidelines over the past decade, several critical issues persist. Historically, the focus was primarily on measuring muscle quantity. However, in the past decade, it has become evident that assessing muscle quality is equally indispensable [2, 3]. Consequently, when measuring muscle mass, both muscle quantity and quality should be considered [1]. Although the exact definition of muscle quality is still debated, for the purposes of this review, muscle quality will be understood as the relative presence of various components within muscle mass, such as muscle, vascular, fibrous, and adipose tissues. Unfortunately, it remains unclear which specific ‘quality’ parameters should be prioritized, and no universally accepted cut-off points exist. While methods like dual-energy X-ray absorptiometry (DXA) and bio-impedance analysis (BIA) have established cut-off values for muscle quantity, they do not provide measures for muscle quality. In contrast, techniques like computed tomography (CT) and magnetic resonance imaging (MRI) can assess both muscle quantity and quality but lack defined cut-off points and are not feasible for routine clinical use [4]. To address this limitation, ultrasound (US) has emerged as a promising alternative. Ultrasound has proven to be an accurate, reliable, and repeatable technique for measuring muscle mass across various populations [5–8]. It is an affordable, non-invasive method that is portable and can be used at the bedside. Ultrasound measurements are strongly correlated with those obtained through MRI [9–11], CT [12], and DXA [13–16]. However, to facilitate widespread comparative studies, standardization of techniques and measurements is crucial. The first step toward this standardization was the publication of the SARCUS (SARCopenia through UltraSound) article, which set forth consensus guidelines for the ultrasonographic assessment of muscle [17]. This article outlined key anatomical landmarks and introduced an instructional video for accurate measurement procedures [18].

The aim of this study is to update the current literature on sarcopenia and standardize the use of ultrasound (US) methods for measuring muscle mass. The focus will be on ultrasonographic parameters for assessing muscle quality, and new measurement points and anatomical landmarks will be introduced, particularly for smaller muscle groups. Additionally, through SARCUS (SARCopenia through UltraSound), the study aims to expand internationally accepted measurement techniques and guidelines for evaluating muscle quality. The ultimate goal is to promote the widespread and effective use of ultrasound in the diagnosis and management of sarcopenia.

Research Methodology This study will employ a systematic approach combining both a literature review and an empirical assessment of muscle mass measurement techniques using ultrasound (US). The methodology is outlined as follows: Literature Review: A comprehensive review of current literature will be conducted to evaluate the existing methods for measuring muscle mass and quality, including techniques like dual-energy X-ray absorptiometry (DXA), bio-impedance analysis (BIA), computed tomography (CT), and magnetic resonance imaging (MRI). This review will focus on understanding the limitations of current methods and the need for a standardized approach in clinical practice, with particular emphasis on muscle quality. Ultrasound Standardization: The study will focus on refining the use of ultrasound for measuring muscle mass and quality. Following the SARCUS (SARCopenia through UltraSound) framework, the research will establish and expand upon standardized anatomical landmarks and measurement points for different muscle groups, including both large muscles (e.g., quadriceps) and smaller muscles with specific functions (e.g., swallowing muscles). Parameters such as muscle thickness (MT), pennation angle (PA), fascicle length (Lf), echo-intensity (EI), and cross-sectional area (CSA) will be assessed and standardized. Data Collection: Ultrasound measurements will be taken from a sample population consisting of healthy individuals as well as those diagnosed with sarcopenia, in accordance with established inclusion criteria. The measurement protocol will involve a series of ultrasonographic scans on predefined anatomical sites for each participant. The data will be collected at multiple time points to assess repeatability and reliability. Data Analysis: The collected ultrasound data will be analyzed for consistency, reproducibility, and correlation with other methods such as MRI, CT, and DXA. Statistical tests such as intra-class correlation coefficients (ICCs) will be used to evaluate the reliability of the ultrasound measurements. Descriptive statistics and inferential analyses will be conducted to identify any significant differences between groups (healthy vs. sarcopenic) and to establish thresholds for muscle quality parameters. Protocol Development and Recommendations: Based on the findings from the data collection and analysis phases, the study will propose updated standardized protocols for ultrasound-based muscle mass and quality assessment. Recommendations for clinical implementation, particularly in the diagnosis and management of sarcopenia, will also be provided. Ethical Considerations: The study will adhere to ethical guidelines, ensuring informed consent is obtained from all participants. Ethical approval will be sought from the relevant institutional review boards before data collection begins.

Girişimsel Çalışma Dizaynı / Pilot / Feasibility Study