Agreement between dual energy X-ray absorptiometry and opto-electronic volumetry for measurement of forearm volume.

BACKGROUND Lymphedema is commonly assessed by measuring the increase in volume of the affected region using methods that are not only accurate and sensitive but also applicable for use in clinical practice. Opto-electronic volumetry (Perometer™) is a rapid and convenient technique recommended as a reference method for this purpose, while the use of dual-energy X-ray absorptiometry is becoming more common. We report here a method agreement study between DXA and perometry for the measurement of forearm volume. METHODS Perometric measurements were performed on both whole arms, in the horizontal plane, of a group of healthy young participants. Perometric data were obtained for 4 and 5 mm slices between the malleoli to the anticubital fossa crease. The DXA-measured masses (bone mineral, fat, and lean) for the same forearm region were obtained using recently published algorithms. Perometric and DXA-measured volumes were compared using correlation and limits of agreement analysis. RESULTS DXA-computed volumes were highly and significantly correlated (r=0.986; p<0.0001) with those measured by perometry. The mean bias between the methods was extremely small; 0.7% underestimation by DXA with limits of agreement of 6.3 to -7.7% (DXA-perometry). CONCLUSIONS This study has demonstrated a high degree of concordance between DXA computed limb volumes and those measured by the reference method of perometry. The relatively small limits of agreement suggest that these methods can be used interchangeably.