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

Monday, 22 April 2013 (14:15-16:15) Exhibition Hall

14:15 0006.   
Regional Mapping of Gas Uptake by Red Blood Cells and Tissue in the Human Lung Using Hyperpolarized Xenon-129 MRI
Kun Qing1, Kai Ruppert2, Yun Jiang3, Jaime F. Mata2, G Wilson Miller2, Yun Michael Shim4, Chengbo Wang2, Iulian C. Ruset5,6, F. William Hersman5,6, Talissa A. Altes2, and John P. Mugler, III1,2
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, 2Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, United States, 3Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, 4Medicine, Pulmonary and Critical Care, University of Virginia School of Medicine, Charlottesville, VA, United States, 5Xemed LLC, Durham, NH, United States, 6Physics, University of New Hampshire, Durham, NH, United States

We have demonstrated an imaging method that permits regional mapping of the tissue and RBC fractions of Xe129 dissolved in the human lung, as well as quantitative comparison of tissue- and RBC-based ratios among subjects. The 11-sec breath-hold acquisition was well tolerated by both healthy volunteers and subjects with obstructive lung disease. Our preliminary results, although obtained from a small number of subjects in this exploratory study, suggest marked differences in the spatial distributions of Xe129 dissolved in tissue and RBCs among healthy subjects, smokers (including those with COPD), and asthmatics.

14:35 0007.   Dynamic Imaging of the Fetal Heart Using Metric Optimized Gating
Christopher W. Roy1, Mike Seed2,3, Joshua F. P. van Amerom1,3, Bahiyah Al Nafisi2, Lars Grosse-Wortmann2,3, Shi-Joon Yoo2,3, and Christopher K. Macgowan1,3
1Medical Biophysics and Medical Imaging, University of Toronto, Toronto, Ontario, Canada, 2Labatt Family Heart Centre, Division of Cardiology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada, 3Diagnostic Imaging, The Hospital for Sick Children, University of Toronto

A metric-based image reconstruction method is developed and validated for CINE MR imaging of the fetal heart. This method, known as metric optimized gating (MOG), is adapted from a previous study of fetal blood flow. It involves oversampling k-space and then reconstructing images according to an iterative model of the subject’s cardiac cycle. Image quality is optimized through the minimization of an image metric (entropy). Here, the approach is validated in healthy adult volunteers through qualitative and quantitative comparison to gold standard ECG gating. Dynamic CINE images of a normal fetal heart are presented.

14:55 0008.   3D Hemodynamics in Intracranial Aneurysms: Influence of Size and Morphology
Susanne Schnell1, Sameer A. Ansari1,2, Parmede Vakil1,3, Marie Wasilewski1, Maria L. Carr1, Michael C. Hurley1,2, Bernard R. Bendok2, Hunt Batjer2, Timothy J. Carroll1,3, James C. Carr1, and Michael Markl1,3
1Radiology, Northwestern University, Chicago, Illinois, United States, 2Neurological Surgery, Northwestern University, Chicago, Illinois, United States, 3Biomedical Engineering, Northwestern University, Evanston, Illinois, United States

Characterization of 3D blood flow demonstrated the influence of lesion size, shape and type on aneurysm hemodynamics suggesting the potential of 4D-flow MRI to assist in the classification of individual aneurysms.

15:15 0009.   Multi-Slice Cardiac Arterial Spin Labelling Using Improved Myocardial Perfusion Quantification with Simultaneously Measured Blood Pool Input Function
Adrienne E. Campbell-Washburn1,2, Hui Zhang3, Bernard M. Siow1,3, Anthony N. Price4, Mark F. Lythgoe1, Roger J. Ordidge5, and David L. Thomas6
1Centre for Advanced Biomedical Imaging, Division of Medicine and Institute of Child Health, University College London, London, United Kingdom, 2Department of Medical Physics and Bioengineering, University College London, London, United Kingdom, 3Centre for Medical Image Computing, Department of Computer Science, University College London, London, United Kingdom, 4Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom,5Centre for Neuroscience, University of Melbourne, Melbourne, Victoria, Australia, 6Brain Repair and Rehabilitation, Institute of Neurology, University College London, London, United Kingdom

This study presents multi-slice cardiac arterial spin labelling using a new method of myocardial blood flow (MBF) quantification with blood pool magnetization measurement (“bpMBF quantification”). For bpMBF quantification, a direct measurement of the left-ventricle blood pool magnetization was used to approximate the blood input function into the Bloch equations. Simulation and in vivo results show that bpMBF quantification is robust to variations in slice-selective thickness and therefore applicable to multi-slice acquisition, whereas traditional methods are likely to underestimate multi-slice perfusion. This technique is applied to generate the first multi-slice MBF maps using cardiac arterial spin labelling.

15:35 0010.   
Joint K-T Reconstruction and Oversampled Spirals for Single-Shot 2D Spatial/1D Spectral Imaging of 13C Dynamics
Jeremy W. Gordon1, David J. Niles1, Sean B. Fain1,2, and Kevin M. Johnson1
1Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 2Radiology, University of Wisconsin-Madison, Madison, Wisconsin, United States

A least-squares based reconstruction is developed to simultaneously solve for both spatial and spectral encoding. By jointly solving both domains, spectral imaging can be performed with a spatially oversampled single-shot spiral acquisition. Simulations indicate that accurate single-shot imaging is possible with oversampling factors greater than six, even in situations of substantial T2* decay and ΔB0. With lower oversampling, two shots are required for similar accuracy. Simulations were confirmed with in-vivo experiments, showing accurate single-shot spectral imaging with an oversampling factor of 7. The proposed approach increases scan efficiency by reducing RF requirements, allowing accelerated acquisition speed and improved temporal/spatial resolution.

15:55 0011.   
A New Approach to Shimming: The Dynamically Controlled Adaptive Current Network
Chad Tyler Harris1, William B. Handler1, and Blaine A. Chronik1,2
1Physics and Astronomy, Western University, London, Ontario, Canada, 2Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada

Active magnetic shim coils, used to correct field inhomogeneities caused by susceptibility differences between tissue interfaces, are typically composed of sets of cylindrical layers, with each layer producing a magnetic field profile of a particular spherical harmonic. A radically different approach to shimming is to dynamically and adaptively control the flow of current over a given surface. This could be achieved with the use of a network of metal-oxide-semiconductor field-effect transistors (MOSFETs). In this work, we present computer simulations demonstrating the benefits that a supplementary, region specific shim coil utilizing this approach can provide, and experimental results of a proof-of-principle prototype.