title: Intracoronary MR imaging using a 0.014-inch MR imaging-guidewire: toward MRI-guided coronary interventions.
abstract: OBJECTIVE
  To validate the feasibility of using a newly designed MR imaging-guidewire (MRIG) to guide angioplasty balloon placement in coronary arteries.
  
  
  METHODS
  A custom gold/sliver/Nitinol/MP35N-based, 0.014-inch MRIG was manufactured. To test its mechanical performance we used the new MRIG to catheterize the left coronary arteries of three dogs under x-ray fluoroscopy. To further validate the feasibility of using the MRIG to generate intracoronary MR imaging, we positioned the MRIG, along with a dilation-perfusion balloon catheter, into the left coronary arteries of an additional three dogs. Longitudinal and four-chamber views of cine cardiac MR images were obtained using a fast gradient recalled echo (FGRE) sequence (TR/TE/FA = 5.2 msec/1.6 msec/20 degrees , field of view [FOV] = 32 x 32 cm, thickness = 5 mm, space = 2 mm, matrix = 256 x 160, number of excites [NEX] = 0.5, and bandwidth [BW] = 32 kHz). Then three-dimensional (3D) MR coronary angiography of the left coronary arteries was obtained using a fast imaging employing steady-state acquisition (FIESTA) sequence. We subsequently used the MRIG, at a receive-only mode, to generate intracoronary MR images using FGRE (TR/TE/FA = 7.2 msec/3.5 msec/20 degrees , FOV = 18 x 18cm, thickness = 3 mm, space = 0.5 mm, matrix = 256 x 256, NEX = 0.5, and BW = 32 kHz).
  
  
  RESULTS
  In all six animals the left main coronary arteries were successfully catheterized. 3D MR imaging displayed left coronary artery branches. Intracoronary MR imaging demonstrated the inflated balloons as a "train track" or a bright, thick ring at different views.
  
  
  CONCLUSIONS
  This study demonstrates the potential of using this newly designed gold/sliver/Nitinol/MP35N-based, 0.014-inch MRIG to catheterize coronary arteries and, thus, generate intracoronary MR imaging with balloon inflation.
authors.affiliation: Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Bensheng
authors.initials: B
authors.lastname: Qiu
authors.forename: Fabao
authors.initials: F
authors.lastname: Gao
authors.forename: Parag
authors.initials: P
authors.lastname: Karmarkar
authors.forename: Ergin
authors.initials: E
authors.lastname: Atalar
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Yang
mesh_terms: D000497:Alloys; D000818:Animals; D006328:Cardiac Catheterization; D003287:Contrast Media; D003331:Coronary Vessels; D004285:Dogs; D004867:Equipment Design; D005240:Feasibility Studies; D019786:Gadolinium DTPA; D006046:Gold; D019028:Magnetic Resonance Imaging, Cine; D053783:Magnetic Resonance Imaging, Interventional / Q000295:instrumentation*; D012834:Silver
chemical_list: D000497:Alloys; D003287:Contrast Media; C013616:nitinol; D012834:Silver; D006046:Gold; D019786:Gadolinium DTPA