MR versus fluoroscopic guidance of a catheter/guidewire system: In vitro comparison of steerability

Abstract

Our purpose in this study was to evaluate the steerability of a combined catheter guidewire system with MR tracking in an open-configuration .5T MR system and compare it with fluoroscopic guidance. Experiments were performed with an aorta-shaped glass phantom with different-size branches connected to a roller flow pump to simulate pulsatile flow. A .035" guidewire was used in conjunction with a 5F Cobra 2-shaped catheter. For active MR guidance, a small RF coil was incorporated into the tips of all devices. In addition to fluoroscopic guidance, we used MR tracking devices to selectively catheterize all branches in the .5T open magnet (Signa SP, GEMS). Time requirements for the latter were compared with those needed under conventional angiographic conditions using standard catheters and guidewires. Active MR tracking permitted the simultaneous real time (4 updates/sec) guidance of both guidewire and catheter. Under MR guidance, all branch vessels were successfully catheterized. We found no significant differences in time requirements between guidance with the MR tracking device and fluoroscopic guidance. However, cannulation under fluoroscopic guidance with standard angiography devices required significantly less time (P < .05). Selective catheterization of small branch vessels is possible with active MR tracking of a combined catheter/guidewire system. Limitations of MR tracking device material and design result in a considerable lengthening of the cannulation procedures.

Passive catheter visualization in magnetic resonance–guided endovascular therapy using multicycle projection dephasers

“…In addition, MR may potentially enhance therapies (6) by acquiring functional information for monitoring, e.g., real‐time perfusion imaging during thrombolysis (7). For these reasons, several research groups are exploring the potential for MR imaging in guiding and or monitoring endovascular therapy (6, 8–16).…”

13C imaging—a new diagnostic platform

“…MRI-based active catheter tracking methods [44,45] may suffer from practical limitations, such as hampered mechanical properties as well as tissue heating caused by the catheter RF-coils [46,47]. Passive tracking methods based on susceptibility-artifacts induced by dysprosium oxide markers depict dis-crete points along the catheter only [48], and the use of catheter contrast agents with short T 1 relaxation times may suffer from insufficient signal difference between catheter and surrounding tissue [49].…”

Passive catheter tracking during interventional MRI using hyperpolarized 13C

“…Active catheter-tracking methods may suffer from limited steerability in tortuous blood vessels due to the nonflexible mechanical properties of incorporated RF coils (26). Placing a catheter with attached RF coils within the body may also produce harmful heating effects if pulse sequences with high RF duty cycles are used (25).…”