ABSTRACT
In this chapter, the theory of computed tomography (CT) tumor perfusion measurement will be discussed. Because blood attenuates X-rays uniformly on the scale of the spatial resolution of a CT scanner, flowing blood cannot be differentiated from stationary blood. To measure tumor perfusion with CT, contrast is injected intravenously, to ‘label’ the blood. Assuming that the injected contrast is uniformly mixed with blood, tracing blood through the tumor circulation is equivalent to tracking a bolus of contrast through the tumor. As such, we can make use of the extensive literature on tracer kinetics modeling in the measurement of CT tumor perfusion. Note that ‘tumor’ in this discussion can be broadened to include peritumoral and normal tissue, since the same consideration would apply in their cases; furthermore we can use the terms perfusion and blood flow interchangeably. Also, in the diagnosis of tumor or the study of tumor biology, it is highly advantageous that besides perfusion we can measure additional functional parameters, as discussed in the following section, in the same study.
