title: Truly hybrid interventional MR/X-ray system: investigation of in vivo applications.
abstract: OBJECTIVE
  The purpose of this study was to provide in vivo demonstrations of the functionality of a truly hybrid interventional x-ray/magnetic resonance (MR) system.
  
  
  METHODS
  A digital flat-panel x-ray system (1,024(2) array of 200 microm pixels, 30 frames per second) was integrated into an interventional 0.5-T magnet. The hybrid system is capable of MR and x-ray imaging of the same field of view without patient movement. Two intravascular procedures were performed in a 22-kg porcine model: placement of a transjugular intrahepatic portosystemic shunt (TIPS) (x-ray-guided catheterization of the hepatic vein, MR fluoroscopy-guided portal puncture, and x-ray-guided stent placement) and mock chemoembolization (x-ray-guided subselective catheterization of a renal artery branch and MR evaluation of perfused volume).
  
  
  RESULTS
  The resolution and frame rate of the x-ray fluoroscopy images were sufficient to visualize and place devices, including nitinol guidewires (0.016-0.035-inch diameter) and stents and a 2.3-F catheter. Fifth-order branches of the renal artery could be seen. The quality of both real-time (3.5 frames per second) and standard MR images was not affected by the x-ray system. During MR-guided TIPS placement, the trocar and the portal vein could be easily visualized, allowing successful puncture from hepatic to portal vein.
  
  
  CONCLUSIONS
  Switching back and forth between x-ray and MR imaging modalities without requiring movement of the patient was demonstrated. The integrated nature of the system could be especially beneficial when x-ray and MR image guidance are used iteratively.
authors.affiliation: Department of Radiology, Stanford University, Calif 94305, USA.
authors.forename: R
authors.initials: R
authors.lastname: Fahrig
authors.forename: K
authors.initials: K
authors.lastname: Butts
authors.forename: Z
authors.initials: Z
authors.lastname: Wen
authors.forename: R
authors.initials: R
authors.lastname: Saunders
authors.forename: S T
authors.initials: ST
authors.lastname: Kee
authors.forename: D Y
authors.initials: DY
authors.lastname: Sze
authors.forename: B L
authors.initials: BL
authors.lastname: Daniel
authors.forename: F
authors.initials: F
authors.lastname: Laerum
authors.forename: N J
authors.initials: NJ
authors.lastname: Pelc
mesh_terms: D000818:Animals; D016461:Chemoembolization, Therapeutic; D004867:Equipment Design; D005471:Fluoroscopy / Q000295:instrumentation; D007680:Kidney Neoplasms / Q000628:therapy; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D023421:Models, Animal; D019168:Portasystemic Shunt, Transjugular Intrahepatic; D015642:Radiology, Interventional / Q000295:instrumentation*; D013552:Swine