title: Interventional magnetic resonance angiography with no strings attached: wireless active catheter visualization.
abstract: Active instrument visualization strategies for interventional MR angiography (MRA) require vascular instruments to be equipped with some type of radiofrequency (RF) coil or dipole RF antenna for MR signal detection. Such visualization strategies traditionally necessitate a connection to the scanner with either coaxial cable or laser fibers. In order to eliminate any wire connection, RF resonators that inductively couple their signal to MR surface coils were implemented into catheters to enable wireless active instrument visualization. Instrument background to contrast-to-noise ratio was systematically investigated as a function of the excitation flip angle. Signal coupling between the catheter RF coil and surface RF coils was evaluated qualitatively and quantitatively as a function of the catheter position and orientation with regard to the static magnetic field B0 and to the surface coils. In vivo evaluation of the instruments was performed in interventional MRA procedures on five pigs under MR guidance. Cartesian and projection reconstruction TrueFISP imaging enabled simultaneous visualization of the instruments and vascular morphology in real time. The implementation of RF resonators enabled robust visualization of the catheter curvature to the very tip. Additionally, the active visualization strategy does not require any wire connection to the scanner and thus does not hamper the interventionalist during the course of an intervention.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Essen, MR-Center, Essen, Germany. HHQuick@uni-essen.de
authors.forename: Harald H
authors.initials: HH
authors.lastname: Quick
authors.forename: Michael O
authors.initials: MO
authors.lastname: Zenge
authors.forename: Hilmar
authors.initials: H
authors.lastname: Kuehl
authors.forename: Gernot
authors.initials: G
authors.lastname: Kaiser
authors.forename: Stephanie
authors.initials: S
authors.lastname: Aker
authors.forename: Sandra
authors.initials: S
authors.lastname: Massing
authors.forename: Silke
authors.initials: S
authors.lastname: Bosk
authors.forename: Mark E
authors.initials: ME
authors.lastname: Ladd
mesh_terms: D000818:Animals; D002404:Catheterization; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007083:Iliac Artery / Q000033:anatomy & histology; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D013686:Telemetry / Q000295:instrumentation* / Q000379:methods; D014159:Transducers