title: 3D coronary motion tracking in swine models with MR tracking catheters.
abstract: OBJECTIVE
  To develop MR-tracked catheters to delineate the three-dimensional motion of coronary arteries at high spatial and temporal resolution.
  
  
  METHODS
  Catheters with three tracking microcoils were placed into nine swine. During breath-holds, electrocardiographic (ECG)-synchronized 3D motion was measured at varying vessel depths. 3D motion was measured in American Heart Association left anterior descending (LAD) segments 6-7, left circumflex (LCX) segments 11-15, and right coronary artery (RCA) segments 2-3, at 60-115 beats/min heart rates. Similar-length cardiac cycles were averaged. Intercoil cross-correlation identified early systolic phase (ES) and determined segment motion delay.
  
  
  RESULTS
  Translational and rotational motion, as a function of cardiac phase, is shown, with directionality and amplitude varying along the vessel length. Rotation (peak-to-peak solid-angle RCA approximately 0.10, LAD approximately 0.06, LCX approximately 0.18 radian) occurs primarily during fast translational motion and increases distally. LCX displacement increases with heart rate by 18%. Phantom simulations of motion effects on high-resolution images, using RCA results, show artifacts due to translation and rotation.
  
  
  CONCLUSIONS
  Magnetic resonance imaging (MRI) tracking catheters quantify motion at 20 fps and 1 mm(3) resolution at multiple vessel depths, exceeding that available with other techniques. Imaging artifacts due to rotation are demonstrated. Motion-tracking catheters may provide physiological information during interventions and improve imaging spatial resolution.
authors.affiliation: Cardiology, Massachusetts General Hospital, Boston, Massachusetts, USA. eschmidt3@partners.org
authors.forename: Ehud J
authors.initials: EJ
authors.lastname: Schmidt
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Yoneyama
authors.forename: Charles L
authors.initials: CL
authors.lastname: Dumoulin
authors.forename: Robert D
authors.initials: RD
authors.lastname: Darrow
authors.forename: Eric
authors.initials: E
authors.lastname: Klein
authors.forename: Andrew J M
authors.initials: AJ
authors.lastname: Kiruluta
authors.forename: Motoya
authors.initials: M
authors.lastname: Hayase
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization / Q000295:instrumentation* / Q000379:methods; D003331:Coronary Vessels / Q000033:anatomy & histology* / Q000502:physiology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000295:instrumentation* / Q000379:methods; D019028:Magnetic Resonance Imaging, Cine / Q000295:instrumentation*; D023421:Models, Animal; D009038:Motion; D009068:Movement; D013552:Swine; D014159:Transducers