Young Investigator Award Presentations

Monday 22 April 2013

Kun Qing¹, Kai Ruppert², Yun Jiang³, Jaime F. Mata², G Wilson Miller², Yun Michael Shim⁴, Chengbo Wang², Iulian C. Ruset^5,6, F. William Hersman^5,6, Talissa A. Altes², and John P. Mugler, III^1,2
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.

Christopher W. Roy¹, Mike Seed^2,3, Joshua F. P. van Amerom^1,3, Bahiyah Al Nafisi², Lars Grosse-Wortmann^2,3, Shi-Joon Yoo^2,3, and Christopher K. Macgowan^1,3
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.

Susanne Schnell¹, Sameer A. Ansari^1,2, Parmede Vakil^1,3, Marie Wasilewski¹, Maria L. Carr¹, Michael C. Hurley^1,2, Bernard R. Bendok², Hunt Batjer², Timothy J. Carroll^1,3, James C. Carr¹, and Michael Markl^1,3
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.

Adrienne E. Campbell-Washburn^1,2, Hui Zhang³, Bernard M. Siow^1,3, Anthony N. Price⁴, Mark F. Lythgoe¹, Roger J. Ordidge⁵, and David L. Thomas^6
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.

Jeremy W. Gordon¹, David J. Niles¹, Sean B. Fain^1,2, and Kevin M. Johnson^1
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.

Chad Tyler Harris¹, William B. Handler¹, and Blaine A. Chronik^1,2
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.