TABLE 2.

Pitfalls and suggested solutions for different MUS analyzing methods

Pitfall	Muscles	Solution
Visual assessment
Background optical illusion effect	Upper extremity, mainly FCR	Combine visual with quantitative assessment for objective measurements and prevent underestimation of EI
Observer estimation error	Tibialis anterior, rectus abdominis	Familiarize the observer with different effects of age, BMI, and sex on MUS images; elderly, higher BMI, and female sex will result in higher EI
Quantitative assessment
Fatty degeneration	Tibialis anterior, medial gastrocnemius	Exclude muscle parts with fatty degeneration in ROI and note visual finding in final results
Inadequate ROI placement	Vastus lateralis, tibialis anterior	Exclude the (deeper) parts of muscles with lower EI due to attenuation artifact
Inhomogeneous EI structure	All	Note this finding as a remark in final results and/or use visual assessment

Abbreviations: EI, echogenicity.