ELECTRONIC POSTER - ismrm

15:00 3611. An Optimal Physiologic Model for Study of Murine Cardiac Function Under
Inhalational Anesthesia
Christakis Constantinides 1 , Richard Mean 1 , Laurence W. Hedlund 2
1 Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus; 2 Radiology, Duke
University Medical Center, Durham, NC, United States
While cardiac mechanical functional studies initially focused on large mammals and the human, the mouse emerged as the preferred
animal species for research in recent years. Albeit evidence supports that bioenergetically and hemodynamically the mouse scales
linearly with larger mammals and humans, important physiological questions still remain for the appropriateness of this model for
extrapolation of conclusions to man. Since the complete characterization of the mouse and human genomes in 2002 and 2003
respectively, there has been a plethora of transgenic mouse studies targeting the cardiovascular system. Equally important were noninvasive
imaging studies of such animals for phenotypic and genotypic screening, often conducted under inhalational anesthesia.
Anesthetics, however, are known to cause severe cardio-depression with adverse physiological effects on hormonal release, centrally
to the heart and peripherally to the vasculature, at the cellular level, affecting calcium entry through L-type Ca2+ channels, the
calcium binding sensitivity of the contractile proteins to calcium, and on conduction and excitability. The objective of this study was
to determine the isoflurane dose in normal mice for optimal physiological status (respiration, cardiac function, and metabolism) for a
period of 1-2 hours post-induction, facilitating migration of such work to the non-invasive imaging platform of MRI, with tremendous
potential for future basic science towards the phenotypic screening of transgenic mice and translational research.
Thursday 13:30-15:30 Computer 31
13:30 3612. The Patho-Physiological Sensitivity of Cardiac MR Elastography: Preliminary
Results.
Thomas Elgeti 1 , Mark Beling 2 , Dieter Klatt 1 , Sebastian Papazoglou 1 , Sebastian Hirsch 1 ,
Kerstin Riek 1 , Bernd Hamm 1 , Jürgen Braun 3 , Ingolf Sack 1
1 Institut für Radiologie, Charité Universitätsmedizin , Berlin, Germany; 2 Klinik und Poliklinik für Kardiologie,
Charité Universitätsmedizin , Berlin, Germany; 3 Institut für Medizinische Informatik und Biometrie, Charité
Universitätsmedizin , Berlin, Germany
MR Elastography (MRE) is capable to directly measure tissue stiffness. This is particularly interesting for cardiac applications, since
the cardiac shear modulus changes over the cardiac cycle. It is known, that increasing myocardial stiffness yields decrease of wave
amplitudes in MRE. Therefore, left ventricular shear wave amplitudes were measured in 11 healthy volunteers and 11 patients with
relaxation abnormalities. It is observed, that shear wave amplitudes are significantly lower in the left ventricle of patients. This result
indicates the sensitivity of amplitude-based cardiac MRE to identify increased myocardial stiffness.
14:00 3613. Relationship Between Mitral Velocity and Mitral Flow Time-Profiles During
Ventricular Filling
June Cheng-Baron 1 , Jessica M. Scott 2 , Ben T. Esch 2 , Mark J. Haykowsky 2 , John V.
Tyberg 3 , Richard B. Thompson 1
1 Biomedical Engineering, University of Alberta, Edmonton, AB, Canada; 2 Physical Therapy, University of
Alberta, Edmonton, AB, Canada; 3 Cardiac Sciences, University of Calgary, Calgary, AB, Canada
It has been shown that blood velocity waveforms measured at the conventional mitral leaflet tips location do not match mitral flow
waveforms. In this study we quantify the relationship between velocity profiles at several points along the inflow path and volumetric
flow, illustrating the dependence of commonly derived diastolic parameters (E/A ratio, deceleration time) on the measurement
approach. Velocity profiles and derived parameters vary significantly over small (1 cm) intervals and are distinct from flow profiles.
Velocity-time curves above the conventional leaflet tip location (in the atrium) are less susceptible to measurement error and are most
similar to flow curves.
14:30 3614. Cine DENSE and Manganese-Enhanced Cardiac MRI Demonstrate That ENOS
Does Not Play a Determining Role in Modulating the Effects of ß-Adrenergic Stimulation
Moriel H. Vandsburger 1 , Brent A. French 1 , Xiaodong Zhong 1,2 , Christopher M. Kramer 1 ,
Frederick H. Epstein 1
1 University of Virginia, Charlottesville, VA, United States; 2 MR R&D Collaborations, Siemens Healthcare,
Atlanta, GA, United States
Dynamic manganese-enhanced MRI and cine DENSE MRI can be used to probe calcium flux and contractile function in vivo in the
mouse heart. Using these methods, we sought to elucidate the role of endothelial nitric oxide synthase (eNOS) in modulating calcium
flux and contractile function. Counter to the prevailing opinion, which suggests that eNOS inhibits basal calcium flux, we found that
eNOS does not play a role in modulating either calcium flux or contractile function at baseline, during β-adrenergic stimulation, or
during muscarinic inhibition of β-adrenergic stimulation.