Passive catheter tracking using MRI: comparison of conventional and magnetization-prepared FLASH.
OBJECTIVE
To compare a magnetization-prepared gradient-echo (GRE) sequence with a conventional GRE sequence for visualizing contrast agent-filled catheters.


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.


CONCLUSIONS
This study shows that IR-FLASH is a better technique for passive tracking of contrast agent-filled catheters than conventional FLASH.
Department of Radiology, Northwestern University, Chicago, Illinois, USA.
Jordin D
JD
Green
Reed A
RA
Omary
J Paul
JP
Finn
Richard
R
Tang
Yongzhong
Y
Li
James
J
Carr
Debiao
D
Li
D000818:Animals; D002404:Catheterization; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D015641:Radiography, Interventional / Q000379:methods; D013552:Swine