A Novel Method For Assessing Leg Compartmental Body Composition Using Dual Energy X-ray Absorptiometry

Abstract

PURPOSE: Manual segmentation using dual energy X-ray absorptiometry (DXA) is a valid method for quantifying contralateral tissue asymmetries of the body but has not been used to quantify body composition in the ipsilateral upper leg compartments. The purpose of this study was to examine the reliability and validity of DXA to quantify fat and lean composition in the anterior and posterior compartments of the upper leg. METHODS: Twenty-one (10 male/11 female) college athletes (X[Combining Overline]age= 20±1y) were assessed for total and regional body composition. Segmentation of the anterior and posterior thigh compartments was accomplished by scanning participants lying on their right and left side. Each scan was manually segmented and analyzed by 3 technicians using custom regions of interest (ROIs) created from bony landmarks on the femur. Caudal and distal borders of the ROI were made at the level of the greater trochanter and lateral epicondyle. A line was drawn down the middle of the femur to create an anterior and posterior ROI to quantify tissue composition between compartments. To validate this new segmentation method, lateral scan measures were compared with total body frontal scan measures of upper leg compartments for fat, lean and total tissue masses. Independent t-tests assessed these compositional comparisons. Intra-class correlation coefficients (ICC) and coefficients of variation (CV) were calculated to assess reliability. RESULTS: All comparisons of total, lean and fat tissue masses between the frontal and lateral DXA scans were non-significant (p-value: 0.14 to 0.64). ICCs were high for all composition measures between- and within-testers, ranging from 0.983 to 0.999 and 0.954 to 0.999, respectively, with low variation across measures (all CVs: <5%). CVs between- and within-testers, respectively, for segmented total composition were ≤4.8% and ≤3.8% and compartmental composition were ≤3.5% and ≤2.7%. CONCLUSIONS: This study demonstrated that DXA measures using custom ROIs to assess anterior and posterior upper leg fat, lean, and total masses are valid and reliable. Future studies are needed to determine the clinical usefulness of these measures with regard to prevention or rehabilitation of sports-related injury. Funded by University of Minnesota CTRS Mini Pilot Funding Program