Myocardial Perfusion & Spectroscopy
Thursday 23 April 2009
Room 316A 16:00-18:00


Ulrike A. Blume and Robert G. Weiss

16:00 699. Qualitative and Quantitative Myocardial Perfusion with Arterial Spin Labeling
    Ulrike Blume1, Matthias Guenther2, Amedeo Chiribiri1, Sven Plein1,3, Tobias Schaeffter1
Division of Imaging Sciences, King's College London, London, UK; 2University Clinic of Neurology, Mannheim, Germany; 3Academic Unit of Cardiovascular Medicine, University of Leeds, Leeds, UK
    Arterial spin labelling (ASL) is an alternative to first pass imaging and can be performed without the need for contrast agent. Perfusion imaging using ASL can therefore be repeated several times and requires no timing of a bolus of contrast agent. In this study, the combination of qualitative and quantitative assessment of myocardial perfusion is presented in only two breath holds. Therefore this technique can be applied multiple times at different positions to fully assess the whole myocardium. Furthermore, a quantitative assessment can then be planned on these images and the absolute quantification of myocardial perfusion allows acquisition of high resolution perfusion-maps in one single breath hold.
16:12 700. Improved Arterial Spin Labeling After Myocardial Infarction in Mice Using Respiratory and Cardiac Gated Look-Locker Imaging with Fuzzy C-Means Clustering for T1 Estimation
    Moriel H. Vandsburger1, Robert L. Janiczek1, Brent A. French1,2, Craig H. Meyer1, Christopher M. Kramer2,3, Frederick H. Epstein1,2
Biomedical Engineering, University of Virginia, Charlottesville, VA, USA; 2Radiology, University of Virginia, Charlottesville, VA, USA; 3Medicine, University of Virginia, Charlottesville, VA, USA
    Measurment of myocardial perfusion in mouse models of acute myocardial infarction (MI) by arterial spin labeling (ASL) has never been demonstrated. We developed a cardio-respiratory gated Look-Locker spiral ASL sequence which uses a fuzzy C-means (FCM) clustering algorithm to reconstruct ASL images and assign image inversion times (TIs). This reduced motion artifacts and improved quantification of perfusion. Mice were scanned at baseline (n=7) and one day after MI (n=6). Baseline perfusion of 3.5 ± 0.3 (ml/g•min) rose after MI in the noninfarcted zone to 4.5 ± 0.4 (ml/g•min) and dropped in the infarcted zone to 1.9 ± 0.3 (ml/g•min).
16:24 701. Reconstruction of Free-Breathing Myocardial Perfusion MRI Using Simultanous Modeling of Perfusion and Motion (SMPM) and Arbitrary K-Space Sampling
    Henrik Pedersen1, Henrik B.W. Larsson1, Rasmus Larsen2
Functional Imaging Unit, Glostrup Hospital, Glostrup, Denmark; 2DTU Informatics, Technical University of Denmark, Lyngby, Denmark
    Respiratory motion of the heart represents a major practical problem in myocardial perfusion MRI, because it hampers perfusion quantification and causes residual aliasing artifacts in modern k-space undersampling techniques. This work presents a computational framework that allows simultaneous modeling of perfusion and motion (SMPM) for arbitrary k-space sampling strategies. We demonstrate the SMPM concept for a representative free-breathing myocardial perfusion data set using 1) fully sampled k-space data, 2) undersampled Cartesian k-space data, and 3) undersampled radial k-space data. Results show that the SMPM approach fits the original data well, both with fully sampled k-space data and 8-fold radial undersampling.
16:36 702. Myocardial Perfusion MRI Using SW-CG-HYPR in Canines with Improved Spatial Coverage, Resolution and SNR
    Lan Ge1, Aya Kino1, Daniel Lee1, Rohan Dharmakumar1, Mark Griswold2, Charles Mistretta3, James Carr1, Debiao Li1
Northwestern University, Chicago, IL, USA; 2Western Reserve University, OH, USA; 3University of Wisconsin-Madison, WI, USA
    The diagnostic value of myocardial perfusion MRI is limited by the low spatial coverage, resolution, SNR, and cardiac motion related image artifacts. This work compared SW-CG-HYPR method with conventional clinical protocols for myocardial perfusion and demonstrated the feasibility of SW-CG-HYPR method for detecting the myocardial territory supplied by a stenotic coronary artery using a controlled animal model. Using this method, the acquisition time per slice was reduced by a factor of 4, which should substantially reduce cardiac motion artifacts; the number of slices was doubled; the spatial resolution was improved by a factor of 2 and the SNR by >50% as compared to conventional methods.
16:48 703. First Pass Contrast Enhanced MRI Shows Disparate Manifestations in Exercise-Induced Perfusion Improvement in Non-Transmural Infracted and Remote Myocardium
    Mao-Yuan Marine Su1, B-C Lee2, Y-W Wu2, H-Y Yu3, W-C Chu4, W-Y I. Tseng5
Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan; 2Internal Medicine, National Taiwan University Hospital; 3Surgery, Natioanl Taiwan University Hospital; 4Institute of Biomedical Engineering, Natioanl Yang-Ming University; 5Center for Optoelectronic Biomedicine, National Taiwan University College of Medicine, Taipei, Taiwan
    Previous studies have demonstrated that exercise training can improve myocardial perfusion for patients with myocardial infarction (MI).However, the effect of exercise training on the non-transmural infarct myocardium and residual viable myocardium still remains unclear. Using MRI, our results suggest that the effects of exercise training on the non-transmural infarct and non-infarct remote zone might be different. In the remote zone, improvement of MPR after exercise training is mainly due to reduced coronary vascular resistance. For the residual viable myocardium in the non-transmural infarct zone, the observed increased stress perfusion might be attributed to exercise-induced angiogenesis.
17:00 704. Measurements of Myocardial Perfusion and Metabolism with MR: Validation Study with PET in a Canine Model
    Kyle Stephan McCommis1, Thomas A. Goldstein1, Dana R. Abendschein2, Bernd Misselwitz3, Robert J. Gropler1, Jie Zheng1
Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA; 2Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA; 3Bayer Schering Pharma AG, Berlin, Germany
    In this ongoing study, MRI methods to quantify myocardial perfusion and oxygenation were validated in a canine model at rest and during pharmacologically induced hyperemia by PET imaging. The MRI methods can quantify myocardial blood flow (MBF), blood volume (MBV), oxygen extraction (OEF), and oxygen consumption (MVO2). A black-blood turbo spin-echo sequence was used to measure the myocardial T2, and a 2-compartment model was used to measure hyperemic myocardial OEF. MBF/MBV were determined with a turboFLASH perfusion sequence. MVO2 was determined with Fick’s law. The MRI results in MBF, OEF, and MVO2 agreed well with the “gold standard” PET measurements.
17:12 705. In Vivo Assessment of Calcium Influx in Alpha-Dystrobrevin Knock-Out Mouse by Manganese-Enhanced MRI
    Wen Li1,2, Jia Zhong1,2, Ya Chen1,2, Laurie Castel3, Ming Lu1,2, Wei Li1,2, David van Wagoner3, Xin Yu1,2
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA; 2Case Center for Imaging Research, Case Western Reserve University, Cleveland, OH, USA; 3Department of Molecular Cardiology, Cleveland Clinic, Cleveland, OH, USA
    This study aims to explore the sensitivity of MEMRI in detecting changes of calcium handling in an α-dystrobrevin knockout mouse model, which showed higher calcium influx through the L-type calcium channel from whole cell patch clamp studies. Intraperitoneal injection of 12.6 μmol MnCl2 led to a 37% signal enhancement for both knockout and control groups. The increased calcium influx in knockout mice was reflected by significantly earlier and faster (19.4 vs 13.3 min-1) signal enhancement in MEMRI experiment. This study suggests that in vivo MEMRI is sensitive to subtle changes of calcium influx associated with disruption in signaling gene.
17:24 706. New Methods for the Quantification of Myocardial Oxygen Consumption with 17O MRI
    Kyle Stephan McCommis1, Xiang He1, Dana R. Abendschein2, Pradeep M. Gupte3, Robert J. Gropler1, Jie Zheng1
Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA; 2Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA; 3Rockland Technimed Ltd, Airmont, NY, USA
    A new MRI method is presented to calculate the myocardial oxygen consumption rate (MVO2) using 17O-enriched blood. Initial in vivo study was performed in normal dogs, as well as in one dog with a severe coronary stenosis. A cardiac T -weighted imaging sequence was developed to monitor myocardial T signals with and without the presence of metabolic H217O water. Various doses of 17O-blood were injected intravenously, followed by the injection of 16O-blood. MVO2 can then be quantified using a simplified model.
17:36 707. High Energy Phosphate Cardiac Energetics Are Abnormal in Primary Biliary Cirrhosis Patients in the Absence of Functional or Anatomical Abnormalities on Structural MRI
    Kieren Grant Hollingsworth1, David EJ Jones2, Jessie Pairman2, Katherine Wilton2, Roy Taylor1, Julia Lindsay Newton2, Andrew Mark Blamire1
Newcastle Magnetic Resonance Centre, Newcastle University, Newcastle, Tyne and Wear, UK; 2Institute of Cellular Medicine, Newcastle University, Newcastle, Tyne and Wear, UK
    Primary Biliary Cirrhosis is an autoimmune liver disease affecting females from middle age. A follow-up study of 770 PBC patients studies indicated an increased risk of cardiac-related death. Phosphorus MRS and anatomical imaging for cardiac morphology were acquired to look for cardiac metabolic stress and dysfunction. For 15 PBC patients, the PCr/ATP ratio was significantly reduced compared to age and weight-matched control subjects, but there was no difference in left ventricle morphology, suggesting metabolic stress only. There was no correlation between PCr/ATP ratio, fatigue severity or age, suggesting that cardiac metabolic stress is a systemic feature of the disease.
17:48 708. 31P TRIple TR Saturation Transfer (TRIST) in the Human Heart at 3T
    Michael Schär1,2, AbdEl Monem El-Sharkawy1, Paul A. Bottomley1,3, Robert G. Weiss1,3
Russel H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; 2Philips Healthcare, Cleveland, OH, USA; 3Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
    A new saturation transfer method to measure the pseudo-first-order rate constant kf of the creatine kinase (CK) reaction employing just two fully-relaxed and one short-TR acquisition is presented. This TRIST method is validated by comparison with conventional progressive saturation kf measures in the human calf. It is then combined with 1D chemical shift imaging to obtain the first 3T measures of CK kinetics in the normal human skeletal muscle and heart.