三、翻译正常骨显像部分的第一段: The most important feature in a normal bone imaging is symmetry about the mid-line in the sagittal plane. The left and right halves of the skeleton should be virtually mirror images of each other. There should be uniform uptake of tracer throughout most of the skeleton. Clear visualization of the whole skeleton should be obtained, with particular attention paid to ensure there are no areas of omission such as the upper femur. The count rate is highest in those parts of the skeleton that are metabolically most active, and these areas generally contain a high per­ centage of trabecular bone and are subject to considerable stress, e.g. the axial skeleton. Diphosphonate that is not taken up by the skeleton is excreted via the urinary tract, and in normal study the kidneys are clearly visualized.