title: Magnetically assisted remote-controlled endovascular catheter for interventional MR imaging: in vitro navigation at 1.5 T versus X-ray fluoroscopy.
abstract: OBJECTIVE
  To compare in vitro navigation of a magnetically assisted remote-controlled (MARC) catheter under real-time magnetic resonance (MR) imaging with manual navigation under MR imaging and standard x-ray guidance in endovascular catheterization procedures in an abdominal aortic phantom.
  
  
  METHODS
  The 2-mm-diameter custom clinical-grade microcatheter prototype with a solenoid coil at the distal tip was deflected with a foot pedal actuator used to deliver 300 mA of positive or negative current. Investigators navigated the catheter into branch vessels in a custom cryogel abdominal aortic phantom. This was repeated under MR imaging guidance without magnetic assistance and under conventional x-ray fluoroscopy. MR experiments were performed at 1.5 T by using a balanced steady-state free precession sequence. The mean procedure times and percentage success data were determined and analyzed with a linear mixed-effects regression analysis.
  
  
  RESULTS
  The catheter was clearly visible under real-time MR imaging. One hundred ninety-two (80%) of 240 turns were successfully completed with magnetically assisted guidance versus 144 (60%) of 240 turns with nonassisted guidance (P < .001) and 119 (74%) of 160 turns with standard x-ray guidance (P = .028). Overall mean procedure time was shorter with magnetically assisted than with nonassisted guidance under MR imaging (37 seconds ± 6 [standard error of the mean] vs 55 seconds ± 3, P < .001), and time was comparable between magnetically assisted and standard x-ray guidance (37 seconds ± 6 vs 44 seconds ± 3, P = .045). When stratified by angle of branch vessel, magnetic assistance was faster than nonassisted MR guidance at turns of 45°, 60°, and 75°.
  
  
  CONCLUSIONS
  In this study, a MARC catheter for endovascular navigation under real-time MR imaging guidance was developed and tested. For catheterization of branch vessels arising at large angles, magnetically assisted catheterization was faster than manual catheterization under MR imaging guidance and was comparable to standard x-ray guidance.
authors.affiliation: From the Department of Radiology and Biomedical Imaging, School of Medicine, University of California-San Francisco, 185 Berry St, Suite 350, Campus Box 0946, San Francisco, CA 94107-5705.
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Losey
authors.forename: Prasheel
authors.initials: P
authors.lastname: Lillaney
authors.forename: Alastair J
authors.initials: AJ
authors.lastname: Martin
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Cooke
authors.forename: Mark W
authors.initials: MW
authors.lastname: Wilson
authors.forename: Bradford R H
authors.initials: BR
authors.lastname: Thorne
authors.forename: Ryan S
authors.initials: RS
authors.lastname: Sincic
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Arenson
authors.forename: Maythem
authors.initials: M
authors.lastname: Saeed
authors.forename: Steven W
authors.initials: SW
authors.lastname: Hetts
mesh_terms: D002404:Catheterization / Q000295:instrumentation*; D057785:Catheters; D057510:Endovascular Procedures / Q000295:instrumentation*; D004867:Equipment Design; D005471:Fluoroscopy / Q000295:instrumentation; D053783:Magnetic Resonance Imaging, Interventional / Q000295:instrumentation*; D008280:Magnetics; D019047:Phantoms, Imaging