MR-GUIDED PERCUTANEOUS ANGIOPLASTY - ASSESSMENT OF TRACKING SAFETY, CATHETER HANDLING AND FUNCTIONALITY

Purpose: Magnetic resonance (MR)-guided percutaneous vascular interven tions have evolved to a practical possibility with the advent of open- configuration MR systems and realtime tracking techniques. The purpose of this study was to assess an MR-tracking percutaneous transluminal angioplasty (PTA) catheter with regard to its safety profile and funct ionality. Methods: Real-time, biplanar tracking of the PTA catheter wa s made possible by incorporating a small radiofrequency (RF) coil in t he catheter tip and connecting it to a coaxial cable embedded in the c atheter wall. To evaluate potentially hazardous thermal effects due to the incorporation of the coil, temperature measurements were performe d within and around the coil under various scanning and tracking condi tions at 1.5 Tesla (T). Catheter force transmission and bal loon-burst pressure of the MR-tracking PTA catheter were compared with those of a standard PTA catheter. The dilatative capability of the angioplasty balloon was assessed in vitro as well as in vivo, in an isolated femor al artery segment in a swine. Results: The degree of heating at the RF coil was directly proportional to the power of the RF pulses. Heating was negligible with MR tracking, conventional spin-echo and low-flip gradient-echo sequences. Sequences with higher duty cycles, such as fa st spin echo, produced harmful heating effects. Force transmission of the MR-tracking PTA catheter was slightly inferior to that of the stan dard PTA catheter, while balloon-burst pressures were similar to those of conventional catheters. The MR-tracking PTA catheter functioned we ll both in vitro and in vivo. Conclusion: The in vivo use of an MR-tra cking PTA catheter is safe under most scanning conditions.