Errors in bone blood flow measured with microspheres due to sample preparation technique

An experiment was carried out to examine the effect of boiling the carcass on the subsequent microsphere content of the skeleton. Intracardiac injections of radioactive microspheres were made in five rabbits and the animals killed humanely. The tibia and femur were then removed from one lower limb by dissection, and from the other after boiling it in a pressure cooker. The mean radioactivity in the bones was significantly less following boiling: 61% (SD 14) of the control tibia and 56% (SD 11) of the control femur. As a methodological check, the radioactivity in the bones of left and right legs was compared after both had been removed by boiling. In three animals, the mean activity (left compared with right) was 101% (SD 6) in the tibia and 100% (SD 3) in the femur. Boiling the carcass led to a substantial reduction in the microsphere content of the bones and cannot be recommended as a method of sample preparation for quantitative bone blood flow work.