Contrast and Resolution Considerations in Keyhole MFU: Application to Dynamic Studies of Contrast Media Kinetics

This report presents a quantitative evaluation of the effect of the keyhole technique on contrast-enhanced dynamic MRI; specifically, the effect of the observed region of interest (ROI) on keyhole images was evaluated in comparison with a complete set of data. The limiting condition of the quantitative use of the keyhole approach was defined and exemplified. Results obtained by simulations, as well as on MR images, indicated that object size and noise level determine the minimum keyhole size and maximum size of the ROI, so that if keyhole parameters are properly selected, a quantitative analysis of MRI gives the same signal intensity as complete data acquisition. In this case the time resolution increases by factor N/L.