Body fat content can be predicted in vivo in mice using a modified dual-energy X-ray absorptiometry technique

The introduction of transgenic mice as animal models in medical research ha s increased the need for methods to study the phenotype of mice. The aim of the present study was to develop and evaluate a method for in vivo predict ion of fat content in living mice. We combined a modified dual-energy X-ray technique with an image analysis procedure. This combined procedure calcul ates the percentage of fat area, defined as the percentage of the total are a of the mice consisting of > 50% fat. A high correlation between the perce ntage of fat area and dissected adipose tissue was seen in both male and fe male mice (males, r = 0.92, P < 0.001; females, r = 0.88, P < 0.001). A hig h correlation was also seen between the percentage of fat area and serum le vels of leptin (males, r = 0.95, P < 0.001; females, r = 0.86, P < 0.001). An additional experiment demonstrated a very strong correlation between the percentage of fat area and total body fat as determined by chemical extrac tion (r = 0.97, P < 0.001). In summary, the percentage of fat area, as meas ured with the dual-energy X-ray/image combined procedure, provides a good i n vivo estimation of total body fat content in mice.