ISMRM 21st Annual Meeting & Exhibition 20-26 April 2013 Salt Lake City, Utah, USA

Tissue Characterization of the Myocardium: Different Insights
Tuesday 23 April 2013
Room 150 AG  13:30 - 15:30 Moderators: Peter Kellman, Jeanette Schulz-Menger

13:30 0254.   
Acute Hemorrhagic Myocardial Infarction Leads to Localized Chronic Iron Deposition: A CMR Study
Avinash Kali1,2, Ivan Cokic1, Andreas Kumar3, Richard L Q Tang1, Sotirios A. Tsaftaris4, Matthias G. Friedrich5, and Rohan Dharmakumar1
1Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, 2Department of Biomedical Engineering, University of California, Los Angeles, CA, United States, 3Québec Heart and Lung Institute, Laval University, Québec City, QC, Canada, 4Computer Science and Applications, IMT Institutions, Lucca, Italy, 5Montréal Heart Institute, Université de Montréal, Montréal, QC, Canada

The long-term fate of acute reperfusion intramyocardial hemorrhage (IMH) was studied using CMR. T2* maps and Late Gadolinium Enhancement images were acquired in patients with first STEMI at 3 days (acute) and 6 months (chronic) post-PCI, and in canines subjected to ischemia-reperfusion injury at 3 days (acute) and 56 days (chronic) post-reperfusion. Both patients and canines with acute IMH had persistent T2* losses within infarcted territories in chronic phase T2* maps. Mass spectrometry of canine myocardium showed that hemorrhagic infarctions had 10-fold higher iron content than non-hemorrhagic infarctions. In conclusion, acute IMH leads to chronic iron deposition within infarcted territories.

13:42 0255.   Quantitative T2 Mapping Visualizes Hemorrhage and Edema After Acute Myocardial Infarction in Swine
Haiyan Ding1,2, Michael Schär3,4, Elliot R. McVeigh2, Henry Halperin5, M. Muz Zviman6, Roy Beinart6, and Daniel A. Herzka7
1Biomedical Engineering, Tsinghua University, Beijing, Beijing, China, 2Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, United States,3Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins School of Medicine, Baltimore, MD, United States, 4Philips Healthcare, Cleveland, Ohio, United States, 5Medicine, Cardiology, Johns Hopkins University, Baltimore, MD, United States, 6Medicine, Cardiology, Johns Hopkins School of Medicine, Baltimore, MD, United States, 7Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States

T2 relaxation time correlates with pathologic processes within infarcted myocardial tissue, such as edema, hemorrhage and microvascular obstruction (MVO). Recently, edema detection (T2 elevation) through quantitative mapping has been shown more robust than qualitative clinical T2 W imaging. Myocardial hemorrhage (T2 reduction) evolves secondary to severe vessel obstruction. We hypothesize that following myocardial infarction (MI) and reperfusion both variations in myocardial edema and hemorrhage are detectable and distinguishable with high resolution quantitative T2 mapping. Quantitative T2 imaging should allow for detection/segmentation of hemorrhage without the temporal variability imposed by contrast-enhanced imaging.

13:54 0256.   T1 Mapping After Acute Myocardial Infarction: Multiphase Phase-Sensitive Inversion-Recovery (MpPSIR) Method as Valuable Alternative to the Modified Look-Locker Inversion Recovery (MOLLI) Method
Oliver M. Weber1,2, Javier Sanchez-Gonzalez1, Leticia Fernandez-Friera2, Gonzalo Pizarro-Sanchez2, Jesus G. Mirelis2, Rodrigo Fernandez-Jimenez2, Luis Jesus Jimenez-Borreguero2, Christian Stehning3, Valentin Fuster2, and Borja Ibañez2
1Philips Healthcare Iberia, Madrid, Spain, 2Epidemiology, Atherothrombosis & Imaging, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain, 3Philips Research, Hamburg, Germany

A method for T1 mapping of the myocardium based on the phase-sensitive inversion-recovery (mpPSIR) technique is presented. It was performed in ten patients with sub-acute myocardial infarction and provided T1 values in very good agreement with the modified Look-Locker imaging (MOLLI) sequence. With both methods, we could demonstrate differences in T1 values between normal and infarcted myocardium, both before and after administration of Gd-containing contrast agent. The novel mpPSIR methods is a valuable alternative to the MOLLI sequence.

13:06 0257.   
Combined Saturation/Inversion Recovery Sequences for Improved Evaluation of Scar and Diffuse Fibrosis in Patients with Arrhythmia or Heart Rate Variability
Sebastian Weingärtner1,2, Mehmet Akçakaya1, Kraig V. Kissinger1, Beth Goddu1, Sophie J. Berg1, Warren J. Manning1, and Reza Nezafat1
1Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States, 2Computer Assisted Clinical Medicine, University Medical Center Mannheim, Heidelberg University, Mannheim, Germany

We propose magnetization preparation which combines saturation and inversion pulses, for improved Late Gadolinium enhancement imaging and T1 mapping in the presence of arrhythmia and heart rate variability. A saturation pulse right after the detection of the R-wave erases the magnetization history and is followed by an inversion time to enhance T1-weighted contrast. A 3D free breathing LGE sequence using this preparation scheme was shown to provide artifact free LGE images in the presence of arrhythmia. In T1 mapping this preparation enabled an optimal imaging efficiency, resulting in rapid, heart rate invariant T1 maps of improved quality.

13:18 0258.   Three-Dimensional MOLLI for Myocardial T1 Mapping Using Respiratory Navigation and Inversion Time Gating -permission withheld
Tobias Voigt1, Tobias Schaeffter2, Rene M. Botnar2, Jouke Smink3, and Markus Henningsson2
1Clinical Research Europe, Philips Research, London, London, United Kingdom, 2Division of Imaging Sciences, King's College London, London, London, United Kingdom, 3Philips Healthcare, Best, Best, Netherlands

In this work, a free breathing three dimensional MOLLI implementation using respiratory navigation and novel inversion time gating is presented. Mapping of T1 has been applied in patients with diffuse fibrosis showing differences in quantitative values between disease and control groups. Probably the most widely used cardiac T1 mapping method is MOLLI. MOLLI is acquired in a breath hold which limits spatial resolution and restricts coverage to a single slice. Free breathing three dimensional T1 mapping of the whole ventricle as introduced in this work can be performed using respiratory navigation and inversion time gating, resulting in high-quality T1 maps.

13:30 0259.   Assessment of Myocardial Radiofrequency Ablation Lesions with 3D High Resolution Free-Breathing T2 Mapping
Daniel A. Herzka1, Haiyan Ding2,3, Farhad Pashakhanloo3, Karl H. Schuleri4, Aravindan Kolandaivelu4, Elliot R. McVeigh3, Henry Halperin5, M. Muz Zviman4, and Roy Beinart4
1Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States, 2Biomedical Engineering, Tsinghua University, Beijing, China, 3Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, United States, 4Department of Medicine, Cardiology, Johns Hopkins School of Medicine, Baltimore, MD, United States, 5Department of Medicine, Cardiology, Johns Hopkins University, Baltimore, MD, United States

Radiofrequency ablation (RFA) has become first-line therapy for many cardiac arrhythmias. Differentiating between viable myocardium and injured tissue (necrosis or edema) in both ventricles and atria following RFA can help in predicting the recurrence of arrhythmias. High-resolution MR imaging techniques such as late gadolinium enhancement (LGE) are well-established for the delineation of lesions. More recently, quantitative techniques such as T2 mapping have been demonstrated for the evaluation of acute injury. Here we present, high-resolution, 3 dimensional (3D) whole-heart free-breathing T2 mapping for the post-procedural detection of RF ablation lesions and correlate the results to high-resolution in vivo LGE and ex vivo images.

13:42 0260.   The Dual-IR Sequence Improves the Inter-Observer Correlation in Post-Ablation Atrial Scar Size Measurements Compared to the Traditional IR Sequence.
Sarah Anne Peel1, Aruna Arujuna1,2, James Harrison1,2, Zhong Chen1,2, Kawal Rhode1, Jaswinder Gill1,2, Reza Razavi1,2, Tobias Schaeffter1, and Rene M. Botnar1
1Imaging Sciences and Bioengineering, King's College London, London, United Kingdom, 2Department of Cardiology, Guy’s and St. Thomas’ NHS Foundation Trust, London, United Kingdom

In 11 patients, the dual-IR and IR sequences were compared for late gadolinium enhancement imaging of atrial wall scar 3 months after radiofrequency ablation for atrial fibrillation. The dual-IR sequence at 20 minutes post-contrast produced a two-fold higher inter-observer correlation for post-ablation atrial scar size measurements compared to the IR sequence at 25 minutes.

13:54 0261.   Is Fat-Suppression Necessary to Evaluate Remodeling in the Left Atrium with Late Gadolinium Enhancement?
Dana C. Peters1, Jaime L. Shaw2, James William Goldfarb3, and Warren J. Manning4,5
1Diagnostic Radiology, Yale Medical School, New Haven, CT, United States, 2Biomedical Engineering, UCLA, Los Angeles, CA, United States, 3,Department of Research and Education, St. Francis Hospital, Roslyn, NY, United States, 4Medicine, Beth Israel Deaconess Medical Center, Boston, MA, United States, 5Radiology, Harvard Medical School, Boston, MA, United States

High spatial resolution LGE is currently used to evaluate left atrial (LA) remodeling and scar. LGE uses fat-suppression, which is considered necessary for visualizing enhancement due to scar/remodeling, since the thin LA wall is covered in fat. To understand the impact of fat-suppression on image quality and identification of LGE, we compared water-only and water-fat opposed-phased LGE images, obtained from dual-echo Dixon LGE scans of 12 patients prior to a 1st PVI. Agreement was found in 87% of regions, using an 18 region model of the LA. We conclude that fat-suppression may not be an absolute requirement.

14:06 0262.   A New Method for Accurate Myocardial T1 Mapping Using Variable Angle Long Echo Train Relaxometric Imaging (VALERI)
Thanh D. Nguyen1, Mitchell A. Cooper1,2, Pascal Spincemaille1, Jonathan W. Weinsaft3, Martin R. Prince1, and Yi Wang1,2
1Radiology, Weill Cornell Medical College, New York, NY, United States, 2Biomedical Engineering, Cornell University, Ithaca, NY, United States, 3Cardiology, Weill Cornell Medical College, New York, NY, United States

We propose to develop an inversion recovery single shot fast spin echo based T1 mapping sequence called Variable Angle Long Echo train Relaxometric Imaging (VALERI). This technique provides more accurate T1 when compared with the more widely used Modified Look Locker Imaging (MOLLI) sequence.

14:18 0263.   Myocardial ATP Turnover Rates in the in vivo Hearts with Post-Infarction Remodeling
Qiang Xiong1, Pengyuan Zhang1, Lei Ye1, Jinfeng Tian1, Cory Swingen1, Albert Jang1, J. Thomas Vanghan1, and Jianyi Zhang1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, United States

A novel indirect magnetization saturation transfer (MST) approach is developed to allow measurement of ATP→Pi reaction rate without quantification of inorganic phosphate (Pi) levels, thus avoided the primary barrier for applications in in vivo heart. With the new approach, myocardial ATP→Pi reaction rate was measured in Normal and post-infarct hearts with or without stem cell therapy. The data suggested that the ATP→Pi rate is a sensitive bioenergetic index that is tightly correlated to cardiac workload as well as the severity of post-infarction left ventricular remodeling based on a swine model of post-infarction LV remodeling.