Measuring muscle and subcutaneous adipose tissue: agreement and reliability between dietetic-led ultrasound and magnetic resonance imaging.

Ultrasound and MRI showed minimal bias for quadricep muscle thickness at the right quadricep 2/3 point.

• The mean difference between measures was 0.04 mm (SD = 2.68 mm) at the right quadricep 2/3 point
• This was described as showing 'minimal bias'
• The study used a cross-sectional design with 35 healthy participants
• Bland-Altman analyses were performed to assess agreement

Mean differences for quadricep muscle thickness and cross-sectional area between ultrasound and MRI were small across all measured sites.

• Mean differences for quadricep muscle thickness ranged from -1.41 to 0.04 mm
• Mean differences for quadricep cross-sectional area (CSA) ranged from -0.07 to 0.05 cm²
• Intraclass correlation coefficient (ICC) and Bland-Altman analyses were used to assess agreement
• Measurements were taken at 5 sites including bicep and quadriceps locations

High ICC values were obtained for muscle and subcutaneous adipose thickness at all five sites when comparing ultrasound with MRI.

• ICC values of >0.90 were obtained for muscle and subcutaneous adipose thickness at all 5 sites
• Measurements were taken at both bicep and quadriceps sites
• Both muscle thickness and subcutaneous adipose thickness were assessed
• 35 healthy participants were included in the cross-sectional study

Inter- and intra-operator reliability of ultrasound measurements was high.

• ICC values of >0.90 were obtained for both inter- and intra-operator reliability of ultrasound
• Ultrasound images were taken by two researchers to enable inter-operator reliability assessment
• Reliability was assessed alongside agreement with MRI during the same research visit
• Intraclass correlation coefficient analyses were used to assess reliability

Ultrasound was evaluated as a bedside tool for body composition assessment against MRI as a reference method in a clinical research context.

• MRI is described as costly and routinely inaccessible in clinical practice
• Ultrasound is described as a 'noninvasive, bedside tool for body composition assessment'
• Both muscle thickness and cross-sectional area (CSA) as well as subcutaneous adipose tissue thickness were measured
• Measurements were taken at the bicep and quadriceps in 35 healthy participants
• Both MRI and ultrasound assessments were conducted during the same research visit