This work presents an investigation into catheter visualization and localization using 19F nuclear magnetic resonance (NMR) in conjunction with proton imaging. For this purpose, the imaging capabilities of a standard system were extended to allow for 19F excitation and signal detection. Two modes of operation were implemented: 1) a real-time tracking mode that provides tip tracking and automatic slice position updates interleaved with real-time, interactive proton imaging; and 2) a non-real-time catheter length visualization mode in which the entire length of a catheter can be assessed. Initial phantom experiments were conducted with the use of an angiographic balloon catheter filled with the blood substitute perfluorooctylbromide (PFOB). Using limited bandwidth excitation centered at the resonances of the CF2 groups of PFOB, we found that sufficient signal could be received to facilitate tip tracking during catheter motion and length visualization for various catheter configurations. The present approach is considered a promising alternative to existing methods, which either are associated with safety concerns (if active markers are employed) or suffer from insufficient, direction-dependent contrast (if passive visualization is used). Furthermore, our approach enables visualization of the entire length of the catheter. The proposed method provides a safe technique that, unlike electrical or optical devices, does not require modification of commercially available catheters.
Copyright 2004 Wiley-Liss, Inc.