TE-switched double-contrast enhanced visualization of vascular system and instruments for MR-guided interventions.

A visualization principle for MR-guided vascular interventions based on the concerted use of two contrast agents is introduced. The first contrast agent, consisting of small paramagnetic iron oxide particles, was administered intravenously to shorten T(1), and even more so T *(2), of the blood for extended time periods. The second agent, a monomeric gadolinium complex, was added to a solution in an interventional device, such as a percutaneous-transluminal-angioplasty (PTA) balloon, to reduce T(1) with only minor additional effects on T *(2). With appropriate T(1)- and T *(2)-weighting the vascular tree (TE <3 ms) and the device (TE > or =8 ms) could be selectively imaged (TR <20 ms). Potentially, both images could be simultaneously updated in the subsecond range. Whereas a visualization of thin structures like guidewires was found to require pulse-sequence optimization, a successful visualization of a PTA balloon in a swine aorta in vivo was possible with standard sequences.