Determination of adipose tissue blood flow with local 133Xe clearance. Evaluation of a new labelling technique.

Adipose tissue blood flow was measured in six healthy, non-obese subjects with the xenon wash-out technique after labelling of the tissue by either injection of 133Xe dissolved in isotonic sodium chloride (water depot) or injection of 133Xe in gas form (gas depot). The wash-out rates were registered from four depots simultaneously. Two depots were placed above the umbilicus, and two depots were placed below the umbilicus in the abdominal, subcutaneous adipose tissue. A water depot and a gas depot were placed in the two positions, respectively. It was not possible to demonstrate any difference between the wash-out rates registered from the two depot types, and it was also not possible to demonstrate any difference between the changes in wash-out rates induced by an oral glucose load. Similarly, the tissue distribution of the water and the gas depots appeared to be similar as registered by a gamma camera. It is concluded that that the two tissue labelling modes give identical results. However, there are significant regional differences in the wash-out rates of xenon from subcutaneous, abdominal adipose tissue, the wash-out rates from infraumbilical depots being about 20% lower than from the supraumbilical depots.