The time course of dynamic contrast enhancement of brain tissue depends on the intrin sic tissue characteristics of blood volume, blood flow and capillary permeability, as well as on the nature of the contrast medium and the time course of the contrast input. In the normal brain, conventional iodinated contrast media are confined solely to the vascular space of the tissue, i.e., they are non-diffusible indicators. In abnormal brain tissue, iodinated contrast will diffuse into the extravascular space as well, which will affect the time course of the enhancement. Stable xenon may also be used as a contrast medium; it approximates a freely diffusible contrast material. Analysis of dynamic iodinated contrast enhancement in rapid sequence computed tomography images of arterial vessels and corresponding parenchymal areas permits approximate correction for the input function, and thus allows an approximate calculation of blood volume and blood flow in normal and ischemic brain. Simple compartment analysis may also permit some characterization of the extravascular exchange of iodinated contrast in more abnormal brain tissue. Measurement of the time course of exhaled xenon concentrations can permit similar calculations for dynamic xenon enhancement.
"Tissue Characterization By Dynamic Contrast Enhancement Of The Brain", Proc. SPIE 0273, Application of Optical Instrumentation in Medicine IX, (16 July 1981); doi: 10.1117/12.931814; https://doi.org/10.1117/12.931814