title: In vivo real-time intravascular MRI.
abstract: OBJECTIVE
  The Magnetic resonance imaging (MRI) is an emerging technology for catheter-based imaging and interventions. Real-time MRI is a promising methodfor overcoming catheter and physiologic motion for intravascular imaging.
  
  
  METHODS
  All imaging was performed on a 1.5 T Signa MRI scanner with high-speed gradients. Multiple catheter coils were designed and constructed, including low-profile, stub-matched coils. Coil sensitivity patterns and SNR measurements were compared. Real-time imaging was performed with an interleaved spiral sequence using a dedicated workstation, providing real-time data acquisition, image reconstruction and interactive control and display. Real-time "black-blood" imaging was achieved through incorporation of off-slice saturation pulses. The imaging sequence was tested in a continuous flow phantom and then in vivo in the rabbit aorta using a 2 mm catheter coil.
  
  
  RESULTS
  The real-time intravascular imaging sequence achieved 120-440 micron resolution at up to 16 frames per second. Low-profile stub-tuned catheter coils achieved similar SNR to larger traditional coil designs. In the phantom experiments, addition of real-time black-blood saturation pulses effectively suppressed the flow signal and allowed visualization of the phantom wall. In vivo experiments clearly showed real-time intravascular imaging of the rabbit aortic wall with minimal motion artifacts and effective blood signal suppression.
  
  
  CONCLUSIONS
  Real-time imaging with low-profile coil designs provides significant enhancements to intravascular MRI.
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, CA 94305-5233, USA.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Rivas
authors.forename: Krishna S
authors.initials: KS
authors.lastname: Nayak
authors.forename: Greig C
authors.initials: GC
authors.lastname: Scott
authors.forename: Michael V
authors.initials: MV
authors.lastname: McConnell
authors.forename: Adam B
authors.initials: AB
authors.lastname: Kerr
authors.forename: Dwight G
authors.initials: DG
authors.lastname: Nishimura
authors.forename: John M
authors.initials: JM
authors.lastname: Pauly
authors.forename: Bob S
authors.initials: BS
authors.lastname: Hu
mesh_terms: D000818:Animals; D001011:Aorta / Q000473:pathology; D001161:Arteriosclerosis / Q000473:pathology; D016477:Artifacts; D002404:Catheterization / Q000295:instrumentation*; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D011673:Pulsatile Flow; D011817:Rabbits