title: Fiber-optic stethoscope: a cardiac monitoring and gating system for magnetic resonance microscopy.
abstract: A fundamental problem associated with using the conventional electrocardiograph (ECG) to monitor a subject's cardiac activity during magnetic resonance imaging (MRI) is the distortion of the ECG due to electromagnetic interference. This problem is particularly pronounced in MR microscopy (MRI of small animals at microscopic resolutions (< 0.03 mm(3))) because the strong, rapidly-switching magnetic field gradients induce artifacts in the animal's ECG that often mimic electrophysiologic activity, impairing the use of the ECG for cardiac monitoring and gating purposes. The fiber-optic stethoscope system offers a novel approach to measuring cardiac activity that, unlike the ECG, is immune to electromagnetic effects. The fiber-optic stethoscope is perorally inserted into the esophagus of small animals to optically detect pulsatile compression of the esophageal wall. The optical system is shown to provide a robust cardiac monitoring and gating signal in rats and mice during routine cardiac MR microscopy.
authors.affiliation: Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Anja C S
authors.initials: AC
authors.lastname: Brau
authors.forename: Charles T
authors.initials: CT
authors.lastname: Wheeler
authors.forename: Laurence W
authors.initials: LW
authors.lastname: Hedlund
authors.forename: G Allan
authors.initials: GA
authors.lastname: Johnson
mesh_terms: D000818:Animals; D004562:Electrocardiography / Q000295:instrumentation*; D004945:Esophagoscopy; D005336:Fiber Optic Technology; D006325:Heart Atria / Q000033:anatomy & histology*; D006339:Heart Rate / Q000502:physiology; D006352:Heart Ventricles / Q000033:anatomy & histology*; D006439:Hemodynamics / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D051379:Mice; D008810:Mice, Inbred C57BL; D008853:Microscopy / Q000295:instrumentation*; D009200:Myocardial Contraction / Q000502:physiology; D055100:Optical Fibers; D051381:Rats; D019023:Stethoscopes