A RAPID 2D TIME-RESOLVED VARIABLE-RATE K-SPACE SAMPLING MR TECHNIQUE FOR PASSIVE CATHETER TRACKING DURING ENDOVASCULAR PROCEDURES

A new, fast, 2D MR imaging technique allowing passive catheter visuali zation adequate for use as a tool for guiding the movement of a cathet er during endovascular procedures is described. This imaging technique samples low spatial frequencies more often than high spatial frequenc ies; it also uses both k-space view sharing and temporal interpolation , Unlike other techniques for passive visualization that exploit magne tic-susceptibility-induced artifacts, we have adopted a strategy that takes advantage of the T-1-shortening effect of paramagnetic contrast agents, such as Gd-DTPA and a projection dephaser, This not only permi ts visualization of the entire catheter length but also minimizes the risk of intravascular heating. Using this method, a temporal frame rat e of up to eight images per second and a tip localization accuracy of +/- 1 mm (root mean square difference) can be achieved.