Passive catheter tracking using MRI: Comparison of conventional and magnetization-prepared FLASH

Abstract

Purpose: To compare a magnetization-prepared gradientecho (GRE) sequence with a conventional GRE sequence for visualizing contrast agent-filled catheters. Materials and Methods: Passive visualization of endovascular catheters using MRI was compared between two imaging sequences: 1) inversion recovery (IR)-fast low angle shot (FLASH), and 2) conventional FLASH. Two-dimensional projection images of the catheters filled with 4% diluted contrast agent in a phantom and the aorta of swine were obtained with each sequence with a temporal resolution of two frames per second. We compared background suppression and catheter visibility using the catheter-to-background signal ratio and the ratings of two radiologists. Results: In the phantom, IR-FLASH allowed for a 200% increase in catheter-to -background ratio (p < 0.01) and improved depiction of catheters over conventional FLASH. In swine, the IR-FLASH images showed a statistically significant improvement of 80% {p < 0.001} over conventional FLASH in all comparisons of the catheter-to-background signal ratio, and an improvement of 160% {p < 0.05} in comparison with the radiologists' observations. Conclusion: This study shows that IR-FLASH is a better technique for passive tracking of contrast agent-filled catheters than conventional FLASH. © 2002 Wiley-Liss, Inc.