Departmental Oral Examination (Thesis Title: "Measurement of the Arterial Input Function from Radial MR Projections")
Physics and Astronomy
DCE-MRI provides a non-invasive method to probe the health status of tissue and help identify diseases, such as cancer. Biologically relevant information is extracted by fitting the data to a pharmacokinetic model. The accuracy of the fit parameters is highly sensitive to the quality of the input curves: the contrast-time curve in the tissue of interest, and the arterial input function, which characterizes the contrast kinetics of a blood vessel feeding the tissue. The AIF is difficult to measure in pre-clinical studies in mice due to their small body size and limited number of vessels of sufficient size. As a result, several groups use a population averaged AIF from the literature. This curve does not account for inter or intra individual differences, and is specific to a particular injection protocol.
This thesis presents a projection-based measurement that measures the AIF from a single trajectory in k-space, which provides a temporal resolution equal to the repetition time (TR). The projection-based AIF allows for acquisition of DCE-MRI data between successive measurements, while maintaining a high temporal resolution of both data sets. A dual-coil experimental platform is set up to acquire a projection-based AIF in the mouse tail, concurrently with DCE-MRI data at a tumour implanted on the hind flank. The results show that an AIF, with a temporal resolution of 100 ms, may be acquired in the mouse tail. Using this curve in the model fit provided K_trans = 0.145 min^-1, and v_e = 0.269. These values are consistent with other studies involving tumours.