Identification of landmarks |
• Appropriate training is needed for consistent identification of landmarks. |
• Standardized protocols on how to identify anatomical landmarks for measurement are lacking. |
• Reporting standards (in publications) are lacking for landmarking. |
• Reliability testing for landmarking is either lacking or included within the entire data acquisition process (i.e., probe placement, image analysis). |
Reliability testing |
• Reporting on reliability testing is often lacking. |
• Standardization on how a reliability test is performed and what is included in the testing procedure is lacking. |
• Intra- and interreliability tests are either both lacking or only one of the two tests is performed using ultrasound and published in research studies. |
Muscle site |
• Different muscles are often measured across different studies (rectus femoris vs. vastus lateralis, upper limb vs. lower limb, or a combination). |
• Different methods are used for muscle quantity assessment (i.e., cross-sectional area vs. muscle layer thickness). |
• Best site to capture muscle groups consistently are unclear (i.e. mid-thigh versus 2/3 femur length versus 3/5 femur length) |
Image acquisition and analysis |
• Form of analysis varies across studies (i.e., muscle layer thickness, cross-sectional area, echogenicity). Some studies use a combination of these methods. |
• Different body composition phenotypes present distinct challenges (e.g., obese individuals may have indistinguishable fascial boundaries, fatty infiltration may affect muscle thickness). |
• Fluid status may affect measurements: use of minimal versus maximal compression. |
Equipment use |
• Appropriate use and reporting of curvilinear versus linear probes |
• Identification of a minimal level of resolution for echogenicity |
• Software choice for image analysis varies |
Normative data and interpretation of results |
• Limited studies that provide a healthy, homogeneous cohort for comparison |
• Measurement reporting is essential for longitudinal evaluation but is currently missing in the literature. |
• Identification of the smallest detectable change for clinically meaningful longitudinal analysis is needed. |