Electronic Posters: Cardiovascular

Myocardial Perfusion: Experimental Models & Human Studies

Hall B Monday 14:00-16:00 Computer 32

14:00 3616. A New Quantitative Imaging Biomarker for Identifying Critical Coronary Artery Stenosis with Myocardial BOLD MRI

Sotirios A. Tsaftaris^1,2, Xiangzhi Zhou², Debiao Li^2,3, Rohan Dharmakumar<sup>2

1</sup>Electrical Engineering and Computer Science, Northwestern University, Evanston, IL, United States; ²Radiology, Northwestern University, Chicago, IL, United States; ³Biomedical Engineering, Northwestern University, Evanston, IL, United States

Blood-oxygen-level dependent (BOLD) MRI may be used for detecting myocardial oxygenation changes secondary to coronary artery stenosis (CAS). Under pharmacological stress, areas of the myocardium supplied by a stenotic coronary artery appear hypointense relative to healthy regions in BOLD images. The purpose of this work is to present a fundamentally new approach for visualizing and quantifying regional myocardial BOLD signal changes. This approach, tested in canines, relies on the statistical identification of myocardial pixels affected by CAS, correlates strongly with true flow measurements, and most importantly, leads to a significant increase in sensitivity to microvascular flow changes compared to previous approaches.

14:30 3617. Comparison of Systolic and Diastolic Myocardial Perfusion by Dynamic Contrast Enhanced MRI

Aleksandra Radjenovic¹, John D. Biglands¹, Abdulghani Larghat¹, John P. Ridgway¹, Michael Jerosch-Herold², John P. Greenwood¹, Sven Plein<sup>1

1</sup>School of Medicine, University of Leeds, Leeds, England, United Kingdom; ²Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States

Dynamic contrast-enhanced MRI was performed in 17 volunteers to simultaneously assess systolic and diastolic myocardial blood flow (MBF). At rest transmural MBF estimates were similar in systole and diastole (1.6 ± 0.42 vs 1.7 ± 0.49 ml/g/min, p>0.05). During adenosine-induced hyperaemia, MBF was significantly lower in systole than diastole (4.3 ± 0.93 vs 5.7 ± 1.7 ml/g/min, p < 0.0001). Subendocardial MBF was higher than subepicaridal MBF, apart from systole at stress where this relation was reversed. In conclusion, estimates of hyperaemic MBF differ significantly between systole and diastole, following the expected physiological pattern of preferential diastolic filling.

15:00 3618. Mouse Myocardial First-Pass Perfusion Imaging

Bram F. Coolen¹, Rik PM Moonen¹, Leonie EM Paulis¹, Tessa Geelen¹, Larry de Graaf¹, Klaas Nicolay¹, Gustav J. Strijkers<sup>1

1</sup>Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands

A method that allows myocardial first-pass perfusion measurements in mice is presented. Using a combination of segmented saturation-prepared FISP acquisition and GRAPPA parallel imaging allows a temporal resolution of one image every three heart beats with an acquisition time of less than 16 ms. First-pass perfusion images showed the influx of contrast agent into the myocardium with sufficient temporal resolution to derive semi-quantitative perfusion values. These were found significantly lower in a mouse with myocardial infarction compared to healthy control mice.

15:30 3619. Theory-Based Single-Point T₁ Mapping for Quantitative Analysis of First-Pass Cardiac Perfusion MRI: A Validation Study

Elodie Breton¹, Daniel Kim¹, Sohae Chung¹, Leon Axel<sup>1

1</sup>Research Radiology - Center for Biomedical Imaging, New York University Langone Medical Center, New York, NY, United States

Quantitative analysis of first-pass contrast-enhanced cardiac perfusion MRI requires the signal-time curve be converted to Gd-DTPA concentration-time curve. A theory-based single-point T₁ measurement method has been proposed and validated in phantoms at 1.5T. In this study at 3T, the sensitivity to B₁ variations and blood inflow of the single-point T₁ mapping method was first evaluated depending on its linear or centric k-space trajectory. Then, the centric k-space trajectory T₁ mapping pulse sequence was validated in vivo against a multi-point saturation recovery T₁ measurement method in the left ventricular myocardium and cavity.

Tuesday 13:30-15:30 Computer 32

13:30 3620. Optimization of Spiral Pulse Sequences for First-Pass Myocardial Perfusion Imaging

Michael Salerno¹, Christopher M. Kramer², Christopher Sica³, Craig H. Meyer<sup>4

1</sup>Department of Medicine, Cardiology, University of Virginia, Charlottesville, VA, United States; ²Department of Radiology, University of Virginia, Charlottesville, VA; ³Biomedical Engineering, Hershey Medical Center, Hershey, PA; ⁴Biomedical Engineering, University of Virginia, Charlottesville, VA

Optimized Spiral Pulse Sequences may have advantages for clinical myocardial perfusion imaging. The goal of this project was to evaluate how variations in the readout duration per interleaf, number of spiral interleaves, and spatial resolution affect the image quality and artifacts for first-pass myocardial perfusion imaging using spiral trajectories in human subjects.

14:00 3621. A Fully Quantitative Pixel Based Approach for Measuring Myocardial Blood Flow in First-Pass Contrast-Enhanced Perfusion MRI: Microspheres Validation in Dogs and Feasibility Study in Humans

Li-Yueh Hsu¹, Daniel W. Groves¹, Anthony H. Aletras¹, Peter Kellman¹, Andrew E. Arai<sup>1

1</sup>National Institutes of Health, Bethesda, MD, United States

We developed a fully quantitative method to estimate myocardial blood flow (MBF) in first-pass contrast-enhanced perfusion MR images at the pixel level. The results were validated in an animal model and show that the MR perfusion estimates correlated with microspheres over a wide range of absolute MBF. To test feasibility in humans, the method was also applied to clinical perfusion MR images to estimate pixel-wise MBF at rest and during stress.

14:30 3622. First-Pass Cardiac Perfusion Imaging of the Infarcted Rat Heart

Daniel James Stuckey¹, Carolyn A. Carr¹, Stephanie Meader¹, Damian J. Tyler¹, Kieran Clarke<sup>1

1</sup>Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, Oxon, United Kingdom

We developed a first-pass cardiac perfusion imaging method which identified regions of perfusion deficit in the infarcted rat heart. Seven days after infarction, cine-MRI was combined with first-pass imaging, which acquired one image per heartbeat during Gd-DTPA bolus. Perfusion deficit at 7 days was larger in rats that went on to develop greater cardiac impairment by 42 days, and provided a more accuracy early indicator of the extent of myocardial infarction than ejection fraction. First-pass MRI will be useful for evaluation of rodent models of human disease and experimental therapies, including cytokine and stem-cell mediated angiogenesis in the infarcted heart.

15:00 3623. Myocardial Perfusion MRI at 3.0T with Sliding-Window Conjugate-Gradient HYPR for the Detection of Coronary Artery Disease

Heng Ma¹, Lan Ge², Dong Xu¹, Qing Tang¹, Han Li¹, Yu Zhang¹, Jiabin Liu¹, Qi Yang¹, Jing An³, Lixin Jin⁴, Renate Jerecic⁴, Xiangying Du¹, Kuncheng Li¹, Debiao Li<sup>2

1</sup>Xuanwu Hospital, Capital Medical University, Beijing, China; ²Radiology, Northwestern University, Chicago, IL, United States; ³Siemens Mindit Magnetic Resonance Ltd, Shenzhen, China; ⁴Siemens Ltd, Healthcare Sector, China

SW-CG-HYPR is a promising method to improve the myocardial perfusion MR imaging with reduced acquisition window, increased spatial coverage, improved spatial resolution and SNR. In this work, 10 patients with suspected CAD were scanned at 3.0T with SW-CG-HYPR. Our initial results show that myocardial perfusion MRI at 3.0T with SW-CG-HYPR is feasible in a clinical population, and has high image quality and diagnostic accuracy in patients with suspected CAD.

Wednesday 13:30-15:30 Computer 32

13:30 3624. Myocardial Perfusion Imaging with Variable Density Spiral Trajectories

Michael Salerno¹, Christopher M. Kramer², Craig H. Meyer<sup>3

1</sup>Department of Medicine, Cardiology, University of Virginia, Charlottesville, VA, United States; ²Department of Radiology, University of Virginia, Charlottesville, VA; ³Biomedical Engineering, University of Virginia, Charlottesville, VA

Variable density (VD) spiral trajectories are an efficient method for data acquisition and may be advantageous for first pass myocardial perfusion imaging. By only partially correcting the variable density, k-space is weighted by a smooth function which reduces Gibbs Ringing. This strategy is employed to further reduce dark-rim artifacts for spiral myocardial perfusion imaging.

14:00 3625. Rapid Quantification of Arterial Input Function and Myocardial T1 Changes in Mice During Contrast Agent Injection

Wen Li^1,2, Wei Li^1,2, Chris Flask^2,3, Mark Griswold^2,3, Xin Yu<sup>1,2

1</sup>Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States; ²Case Center for Imaging Research, Case Western Reserve University, Cleveland, OH, United States; ³Department of Radiology, Case Western Reserve University, Cleveland, OH, United States

A modified ECG-triggered saturation recovery Look-Locker (MSRLL) method was developed for quantification of arterial input function via rapid T1 mapping in dynamic contrast enhanced MRI (DCE-MRI) studies. High temporal resolution (< 2 min) was achieved by acquiring only the low spatial frequency lines. High spatial frequency lines acquired before contrast were used to generate composite images with higher spatial resolution. Validation was performed by comparing T1 values measured with SRLL and MSRLL method in both phantom and in vivo mouse heart. The in vivo application of MSRLL in DCE-MRI studies was demonstrated in mouse heart. These results suggest that MSRLL may provide a robust method for rapid T1 mapping of blood and myocardium in cardiac DCE-MRI studies.

14:30 3626. The Contribution of Cardiac Motion to Dark Rim Artifacts in Myocardial Perfusion Scans

Li Zhao¹, Michael Salerno², Christopher M. Kramer, ²³, Craig H. Meyer<sup>1,3

1</sup>Biomedical Enginnering, University of Virginia, Charlottesville, VA, United States; ²Medicine, University of Virginia, Charlottesville, VA, United States; ³Radiology, University of Virginia, Charlottesville, VA, United States

The Dark Rim artifacts in adenosine stress perfusion imaging are not completely understood, with Gibb’s ringing and cardiac motion thought to be contributing factors. In this work we provide strong support to the idea that dark rim artifacts come from motion by experimental data, and it also shows that these artifacts are more significant in some portions of the cardiac cycle than in others. Moreover, a 1D motion model is developed and used to predict how dark rim artifacts vary over the cardiac cycle.

15:00 3627. A Comprehensive MR Examination of the Heart in Less Than 25 Minutes Using a Semi-Automated Image Acquisition Prototype

Michaela Schmidt¹, Giso von der Recke², Peter Speier³, Saurabh Shah⁴, Carmel Hayes³, David Hardung², Heyder Omran⁵, Edgar Mueller<sup>6

1</sup>MR Application Development, Healthcare Sector, Siemens AG , Erlangen, Germany; ²St.-Marien-Hospital , Bonn, Germany; ³MR Application Development, Healthcare Sector, Siemens AG, Erlangen, Germany; ⁴MR R&D, Healthcare Sector, Siemens AG, Chicago, IL, United States; ⁵St.-Marien-Hospital, Bonn, Germany; ⁶MR Application Development, Healthcare Sector, Siemens AG, erlangen, Germany

In this study we evaluated a prototype designed for simplicity and speed in CMR examinations. Sixty five patients with suspected ischemic heart disease were imaged with the prototype. The prototype offers, among others, user guidance and patient-centric parameters, simplified, marker-based localization of the heart and automatic FOV calculation. Two users were experienced in and one user was inexperienced in CMR imaging. Without reducing the accuracy and quality of the result, examination times below 25 minutes could be achieved for the experienced users, the beginner managed to successfully complete cardiac examinations with excellent image quality in around 30 minutes.

Thursday 13:30-15:30 Computer 32

13:30 3628. High Resolution 3D Cardiac Perfusion Imaging Using Compartment-Based k-T PCA

Viton Vitanis¹, Robert Manka, ^1,2, Henrik Pedersen³, Peter Boesiger¹, Sebastian Kozerke<sup>1

1</sup>Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland; ²German Heart Institute Berlin, Berlin, Germany; ³Functional Imaging Unit, Glostrup Hospital, Glostrup, Denmark

k-t PCA is an extension of k-t SENSE aiming at improving reconstruction of non-periodic dynamic images. It is based on a decomposition of the training and undersampled data into a temporally and a spatially invariant term using principal component analysis. In this abstract, a compartment based k-t PCA reconstruction approach is presented, which aims at improving highly undersampled, high-resolution 3D myocardial perfusion imaging by constraining the temporal content of different compartments in the image series based on the bolus arrival times and prior knowledge about the perfusion curves.

14:00 3629. Highly Accelerated 3D SSFP First-Pass Myocardial Perfusion at 3T Using a 32-Channel Coil

Matteo Milanesi¹, Thomas K. Foo², Luca Marinelli², Christopher J. Hardy², Dan W. Rettmann³, Wei Sun⁴, Stephen Garnier⁴, Ersin Bayram⁴, Piergiorgio Masci¹, Vincenzo Positano¹, Luigi Landini⁵, Massimo Lombardi<sup>1

1</sup>"G. Monasterio" Foundation, Pisa, Italy; ²Global Research Center, General Electric, Niskayuna, NY, United States; ³Applied Science Laboratory, GE Healthcare, Rochester, MN, United States; ⁴GE Healthcare, Milwaukee, WI, United States; ⁵Department of Information Engineering, University of Pisa, Italy

This study presents a new highly accelerated 3d saturation recovery first-pass perfusion using balanced steady state free precession (Fiesta) pulse sequence. Saturation was carried out through a 8ms adiabatic BIR4 radio frequency pulse. Acquisition was carried out at 3Tesla using a 32 channel cardiac coil, which allow 4-fold acceleration factor. Good image quality and CNR was obtained in three subjects anticipating a clinical validation of this pulse sequence

14:30 3630. Myocardial T1 During Multiple Bolus Injections

Christian Stehning¹, Timothy Lockie², Eike Nagel³, Masaki Ishida³, Sven Plein<sup>3

1</sup>Philips Research Europe, Hamburg, Germany; ²Cardiovascular Division, King's College, London, United Kingdom; ³Division of Imaging Sciences, King's College, London, United Kingdom

MR first pass perfusion imaging via the dynamic enhancement after intravenous contrast injection has become a valuable clinical tool for the assessment of myocardial perfusion. The aim of the present study was to investigate whether such a saturation effect of myocardial T1 has to be taken into account in MR-based perfusion studies involving multiple injections of Gd-DTPA.

15:00 3631. Magnetic Resonance Quantification of Myocardial Perfusion with a Minimally Constrained Deconvolution Model

Omar El-Sherif^1,2, Robert Z. Stodilka^1,2, Nathan A. Pack^3,4, Edward VR Dibella^3,4, James A. White⁵, Robert Terry Thompson^1,2, Frank S. Prato<sup>1,2

1</sup>Imaging, Lawson Health Research Institute, London, Ontario, Canada; ²Medical Biophysics, University of Western Ontario, London, Ontario, Canada; ³Department of Bioengineering, University of Utah, Salt Lake City, UT, United States; ⁴Radiology, Utah Center for Advanced Imaging Research, Salt Lake City, UT, United States; ⁵Cardiology, London Health Sciences Centre, London, Ontario, Canada

We introduce a novel minimally constrained myocardial perfusion analysis technique. The technique has been implemented on dynamic contrast enhanced magnetic resonance images, obtained from 10 patients with hypertrophic cardiomyopathy. Regional myocardial perfusion estimates were directly compared to both the Fermi perfusion model and a 2 compartment perfusion model. The results indicate that there is discrepancy between Fermi and 2 compartment models during stress exams. However our technique correlates well with the Fermi model during both stress and rest exams.

Myocardial Visibility: Experimental Models

Hall B Monday 14:00-16:00 Computer 33

14:00 3632. Imaging of Inflammation Using VSOP and T2* Mapping in a Mouse Model of Myocardial Infarction

Andrea Protti¹, Alexander Sirker¹, Xuebin Dong¹, Marcelo Andia², Ajay M. Shah¹, Rene Botnar<sup>2

1</sup>Cardiovascular Division, King’s College London BHF Centre of Excellence, London, United Kingdom; ²Division of Imaging Sciences, King’s College London BHF Centre of Excellence, London, United Kingdom

In this work, we sought to investigate the merits of a very small superparamagnetic iron oxide particle (VSOP) for direct imaging of inflammation in a mouse model of MI and to quantify T2* using multi echo gradient echo images. The combined use of a very small iron-oxide particle, VSOP, and the use of short to long TE acquisition to generate T2* mapping allowed the quantitative assessment of VSOP uptake in the infarct zone.

14:30 3633. Studying Indirect Ca²⁺ Alterations Following Myocardial Infarction in a Murine Model Using T₁-Mapping Manganese-Enhanced MRI

Benjamin Waghorn^1,2, Jimei Liu¹, Nathan Yanasak¹, Tom C.-C. Hu<sup>1,2

1</sup>Department of Radiology, Medical College of Georgia, Augusta, GA, United States; ²Nuclear and Radiological Engineering and Medical Physics Programs, Georgia Institute of Technology, Atlanta, GA, United States

Intracellular calcium (Ca²⁺) overloading that occurs during myocardial ischemia-reperfusion is known to exacerbate injuries. This study demonstrates the use of cardiac T₁-mapping manganese-enhanced MRI for identifying and quantifying regional differences in tissue Mn²⁺, and therfore inferred Ca²⁺, handling that occur after a myocardial infarction (MI) in the murine model. Regional alterations in Mn²⁺ efflux were detected, suggesting changes in NCX activity and altered Mn²⁺ content in ischemic tissue, consistent with changes in Ca²⁺ handling post-MI. This technique could potentially be developed to provide and indirect in vivo assessment of Ca²⁺ handling alterations.

15:00 3634. MR Tagging on Healthy and MI Mice Model, an EF Vs Strain Study

Andrea Protti¹, Alexander Sirker¹, Ajay M. Shah¹, Rene Botnar<sup>2

1</sup>Cardiovascular Division, King’s College London BHF Centre of Excellence, London, United Kingdom; ²Division of Imaging Sciences, King’s College London BHF Centre of Excellence, London, United Kingdom

In this study we sought to investigate radial and circumferential strain in a mouse model of myocardial infarction (MI) 3 weeks post left anterior diagonal (LAD) coronary artery ligation and healthy control mice using 2D SPAMM technique. Strain was correlated with ejection fraction (EF) and left ventricular (LV) infarct size. MR tagging analysis provided important information on LV regional contraction and allowed assessment of wall motion alterations in MI mice.

15:30 3635. From Men to Mice: Theoretical Considerations for Edema Imaging at Ultra-High Magnetic Fields

Jurgen E. Schneider¹, Steffen Bohl¹, Erica Dall'Armellina¹, Stefan K. Piechnik¹, Matthew D. Robson¹, Stefan Neubauer<sup>1

1</sup>Cardiovascular Medicine, University of Oxford, Oxford, Oxon, United Kingdom

T2-weighted magnetic resonance imaging (T2w-MRI) has been shown to visualize and to quantify edema in the acutely infarcted myocardium of humans and animal models. Based on relaxation time measurements, we quantitatively demonstrate that the achievable T2-contrast between normal and ischemia-reperfusion injured myocardium in mice at 9.4T is only 60% of the contrast in patients with acute myocardial infarction undergoing CMR at 3T.

Tuesday 13:30-15:30 Computer 33

13:30 3636. Feasibility of 3D Late Enhancement Imaging in Mice with Totally Occluded Left Anterior Ascending (LAD) Artery on a Clinical 1.5T MR Scanner

Christian Kremser¹, Jakob Völkl², Bernhard Haubner², Michael Schocke¹, Bernhard Metzler<sup>2

1</sup>Dept. of Radiology, Innsbruck Medical University, Innsbruck, Tyrol, Austria; ²Dept. of Internal Medicine III (Cardiology), Innsbruck Medical University, Innsbruck, Tyrol, Austria

Delayed enhancement cardiac magnetic resonance imaging is frequently used to detect and quantify the size of myocardial infarction. In this study we demonstrate the feasibility of 3D late enhancement imaging in a mouse model on a clinical 1.5T whole body MR scanner and compare the obtained results with 2D sequences as used for clinical applications and histologic sections.

14:00 3637. Ex Vivo and in Vivo MR Imaging of Ischemia Reperfusion Injury in Mouse Hearts Using Microparticles of Iron Oxide Targeting VCAM-1

Erica Dall'Armellina¹, Craig A. Lygate¹, Martina McAteer¹, Steffen Bohl¹, Lee-Anne Stork¹, Stefan Neubauer¹, Robin P. Choudhury¹, Jurgen E. Schneider<sup>1

1</sup>Cardiovascular Medicine, University of Oxford, Oxford, Oxon, United Kingdom

Ischemia-reperfusion (IR) injury is an important cause of tissue damage in vascular syndromes of the heart, but sensitive markers of early inflammation in reversible myocardial injury are lacking. Our study demonstrates that antibody-conjugated microparticles of iron oxide (MPIO) targeting VCAM-1 enable molecular MR imaging of endothelial activation in murine IR hearts.

14:30 3638. A Fast Black Blood Sequence for 4D Cardiac MEMRI of Mouse Heart

William Lefrançois¹, Sylvain Miraux, Guillaume Calmettes, François Vigneron², Jean-Michel Franconi, Philippe Diolez, Eric Thiaudière

¹Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS-Univ. Bordeaux 2, Bordeaux, Gironde, France, Metropolitan; ²INSERM U828, Avenue du Haut Lévêque, Bordeaux, France

This study aimed to develop a new method enabling a fast time-resolved cine 2D and cine 3D (4D) black blood imaging of mouse heart. This sequence has been applied to Manganese-Enhancement MRI (MEMRI) studies i.e. with Mn²⁺ infusion to improve contrast. This new method provided time- and space-resolved 3D images, respectively (200 µm) ³ and one image every 12 ms, for the first time within 30 minutes only. Lastly, associated to manganese infusion, this sequence appeared to be particularly adequate for studying cardiac pathologies such as ischemia on animal models.

15:00 3639. Black-Blood Preparation Improves Accuracy in Murine Phase-Contrast Cine MRI at Ultra-High Mag-Netic Fields

Erica Dall'Armellina¹, Bernd Jung², Hannah Barnes³, Stefan Neubauer¹, Michael Markl², Jurgen E. Schneider<sup>1

1</sup>Cardiovascular Medicine, University of Oxford, Oxford, Oxon, United Kingdom; ²Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany; ³University of Oxford, Cardiovascular Medicine, Oxford, Oxon, United Kingdom

Tissue Phase Mapping (TPM) is a well-established technique to assess regional cardiac function in humans and in animal models such as mice. While TPM-studies in humans required suppression of the dominant blood signal in order to provide an accurate measurement of myocardial velocities, the murine studies were conducted without blood suppression. We show that bright-blood contrast can impact on both, absolute velocities and motion pattern, which can potentially and erroneously be identified as a local impairment of cardiac function.