Real-time MR imaging-guided passive catheter tracking with use of gadolinium-filled catheters.
OBJECTIVE
To test the hypothesis that real-time magnetic resonance (MR) imaging-guided passive catheter tracking is feasible with use of dilute gadolinium (Gd)-filled catheters, to determine the optimal Gd concentration required for tracking, and to measure catheter tip tracking accuracy.


METHODS
The authors tested a real-time, T1-weighted, two-dimensional, spoiled gradient-recalled echo MR imaging sequence suitable for tracking catheters. In a yogurt phantom, the authors placed 5-F catheters filled with 2%-12% Gd solutions. MR imaging was performed with and without use of a projection dephaser that suppressed background signal. The authors measured signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and enhancement ratio to determine the optimal Gd concentration for catheter depiction. Catheter tip tracking accuracy was measured in an acrylic phantom with use of linear regression analysis, with goodness of fit assessed statistically with the F test.


RESULTS
Peak catheter SNR, CNR, and enhancement ratios were obtained with 4%-6% Gd concentrations. Tip tracking accuracy was determined to be +/- 0.41 mm (R2 = 0.99; P < .0001). MR imaging reconstructions were displayed up to 3.1 frames/sec.


CONCLUSIONS
Accurate MR imaging-guided passive catheter tracking was feasible in real-time with use of dilute Gd-filled catheters. This technique may have application in MR imaging-guided endovascular procedures.
Omary
R A
RA
Department of Radiology, University of Wisconsin-Madison Medical School, USA. romary@radiology.northwestern.edu
Unal
O
O
Koscielski
D S
DS
Frayne
R
R
Korosec
F R
FR
Mistretta
C A
CA
Strother
C M
CM
Grist
T M
TM
D002404:Catheterization; D003287:Contrast Media / Q000008:administration & dosage*; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D015641:Radiography, Interventional / Q000379:methods
D003287:Contrast Media; D019786:Gadolinium DTPA