CATHETER VISUALIZATION USING LOCALLY INDUCED, ACTIVELY CONTROLLED FIELD INHOMOGENEITIES

A new technique for visualization of interventional devices using MR i s presented, A prototype catheter was equipped with a thin copper wire loop, leading from the proximal end to the tip and back, A small curr ent (10-150 mA) through these two parts of a wire induces a local magn etic field along the catheter, Introduction of this catheter into the main magnetic field of the MR imager locally disturbs the homogeneity of the magnetic field, Image locations within the locally induced fiel ds appear dark due to signal loss, and the extent of this effect can b e varied during the procedure by simply adjusting the current, Differe nt dedicated wire configurations allow visualization of the catheter i n its whole length or in parts, i.e., with markers for balloons, Fast gradient echo sequences that provide a bright signal from inflowing bl ood are used for rapid imaging.