ABSTRACT
Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a specialized technique for both imaging and quantitatively measuring changes in vascular function using standard magnetic resonance imaging systems as described in the previous chapter. DCE-MRI involves the periodic acquisition of T1-weighted images before, during, and aer injection of a gadolinium-labeled contrast agent such as gadopentetate dimeglumine. Contrast agents used in MRI aect the observed image signal by shortening the longitudinal (T1) and transverse (T2) relaxation time for protons that are in the vicinity of the contrast agent. e change over time in signal intensity in a voxel or region of interest in this time series can then be related to contrast agent concentration in that tissue. e observed enhancement curves in tissue and plasma can then be used to estimate various physiological parameters [1-4]. Figure 17.1 shows a typical time course for contrast agent uptake in sample tissue and in arterial plasma. Generally, contrast agents used with MRI are classied based on the eects they have on dierent compartments, including intravascular space (arterial-capillary and venous spaces), extracellular extravascular space (EES), the recticuloendothelial system, and the parenchymal cells of various organs [5]. In this chapter, we restrict our discussion to imaging and analysis techniques used for gadolinium-based contrast agents that distribute within the intravascular space and then rapidly diuse to the EES of perfused tissues. A representative sampling of FDA-approved contrast agents available for clinical use in the United States is summarized in Table 17.1.
