ABSTRACT
This chapter explains the concentration of the bone imaging agents in bone lesions on the basis of increased blood flow and/or bone formation. As Charkes et al. have pointed out, as blood flow is increased the uptake of a bone imaging agent increases linearly up to some point. Further nonphysiologic increase in blood flow results in a nonlinear increase or plateau in uptake. The understanding of how bone imaging agents deposit in bone requires that we assemble all the known facts and attempt to make a reasonable model that is consistent with the available data. The model should then be directly tested and revised if necessary in order to fit the observed behavior of the system. From the standpoint of bone imaging, the soft tissue background is of great importance because it represents the "noise" level above which the bone "signal" must be detected.
