Magnetic resonance imaging measurement reproducibility for calf muscle and adipose tissue volume

Purpose: To describe a new semiautomated method for segmenting and measuring the volume of the muscle, bone, and adipose (subcutaneous and intermuscular) tissue in calf muscle compartments using magnetic resonance (MR) images and determine the intrarater and interrater reproducibility of the measures. Materials and Methods: Proton-density weighted MR images were acquired from the right calf of 21 subjects. Three raters segmented and measured the volumes of bones, adipose tissue, and five individual muscle compartments. Two raters repeated the segmentations. The intra- and interrater reproducibility of the measures (intraclass correlation coefficients; ICC) were determined using generalizability theory. Results: All ICC values were greater than 0.96. The average standard error of the mean (SEM) of all measures was 1.21 cm³ and none were greater than 2.3 cm³. Essentially all variation (≥97% for all measures) was due to subject differences, indicating low error in the measurements. Conclusion: The volumetric measurements for the bones, adipose tissue, and muscle in each of the compartments using MRI were highly reproducible. MRI can provide quantitative, reproducible volumetric measures of bone, adipose tissue, and individual muscle compartments in the calf. We believe these methods can be used to quantify specific muscle or adipose volumetric measures for other clinical or research purposes.