Dynamic Susceptibility MRI: Data Acquisition and Analysis
DSC-MRI involves the serial acquisition of MR images of a tissue of interest (e.g., a tumor) before and a£er an intravenous injection of a contrast agent (CA). As the CA traverses a tissue under investigation, the native relaxation times (T1, T2, and T2∗)
of tissue water decrease to an extent that is determined by the concentration of the agent and the geometry of the tissue structures containing the CA. By considering a set of images acquired before, during, and a£er a CA infusion, the signal intensity time course for individual voxels can be related to changes in CA concentration. By œtting the DSC-MRI data to an appropriate pharmacokinetic model, physiological parameters relating to blood volume (BV), blood §ow (BF), and mean transit time (MTT) can be extracted [1-3]. DSC-MRI is most commonly used to assess hemodynamics within normal and/or tumor-bearing brain tissue, but its applicability in noncerebral tumors (e.g., breast and prostate) is also under investigation [4,5]. Abnormal angiogenesis is a hallmark of most cancer types and DSC-MRI is particularly well-suited for the noninvasive evaluation of morphological and functional characteristics of a developing vascular network. Indeed, DSC-MRI derived tumor hemodynamic maps have demonstrated a correlation with brain tumor grade [2,6-8] and treatment response [9-11].