TRADITIONAL POSTER - ismrm

Poster Sessions
accelerated parallel imaging is affected by residual artifacts, while excessive zooming sacrifices spatial coverage. A robust combination of both methods is
optimized here (‘Zoomed imaging with GRAPPA’ - ZOOPPA) to provide high quality single-shot EPI human brain images with reasonable coverage and an
isotropic resolution of 0.65 mm.
2890. Conjugate Gradient PINOT Reconstruction with a Fast Initial Estimate
Lei Hou Hamilton 1 , Benjamin Russell Hamilton 1 , David Moratal 2 , Senthil Ramamurthy 3 , Marijn Brummer 3
1 School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States; 2 Universitat Politècnica
de València, València, Spain; 3 Emory University, United States
PINOT (Parallel Imaging and NOquist in Tandem), a fast imaging method combining SPACE-RIP and Noquist, favorably preserves edge detail at a cost of
increased SNR. PINOT involves a large matrix inversion for each read-out coordinate to combine data from all frames and coils. We use iterative conjugate
gradient (CG) to reduce this computational burden. An initial estimate based on the projection matrix’s structure allows CG-PINOT to converge quickly. We
simulate this CG-initiated PINOT (CGi-PINOT) with phantom and in vivo studies, showing it provides better reconstructed image quality with an order of
magnitude less time than direct inversion PINOT.
2891. Computationally Rapid Method for Estimating SNR of Arbitrary Parallel MRI Reconstructions
Curtis Nathan Wiens 1 , Shawn Joseph Kisch 2 , Jacob David Willig-Onwuachi 3 , Charles A. McKenzie 1,2
1 Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada; 2 Department of Medical
Biophysics, University of Western Ontario, London, Ontario, Canada; 3 Department of Physics, Grinnell College, Grinnell, IA, United
States
Existing approaches for measuring parallel MRI SNR are limited because they are not applicable to all reconstructions, require significant computation time
or need repeated image acquisitions. A new SNR estimation approach is proposed that is a hybrid of the two acquisition and multiple pseudo replica
methods. The difference of two pseudo-images is used to estimate the noise in the acquisition. This gives a computationally rapid method of measuring SNR
from a single acquisition. SNR maps using the two pseudo-image method were compared to pseudo-replica. All tests of the proposed method were on
average within ±1.75%.
2892. Virtual Coil Phase Determination Using Region Growing: Description and Application to Direct
Virtual Coil Parallel Imaging Reconstruction
Philip James Beatty 1 , Shaorong Chang 2 , Ersin Bayram 2 , Ananth Madhuranthakam 3 , Huanzhou Yu 1 , Scott
B. Reeder 4 , Jean H. Brittain 5
1 Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States; 2 GE Healthcare, Waukesha, WI, United States;
3 Applied Science Laboratory, GE Healthcare, Boston, MA, United States; 4 Departments of Radiology and Medical Physics,
University of Wisconsin-Madison, Madison, WI, United States; 5 Applied Science Laboratory, GE Healthcare, Madison, WI, United
States
Setting the phase of the virtual coil in the Direct Virtual Coil (DVC) reconstruction technique is both critical to achieving a high quality reconstruction and
challenging, especially with high channel count arrays. In this work, a region growing approach to setting the virtual coil phase is described and evaluated in
the context of the DVC technique. We demonstrate that the approach is able to generate sensible virtual coil phase even in challenging situations.
2893. Random Phase Modulation of Spatial Aliasing in Temporal Domain for Dynamic MRI
Yu Li 1 , Feng Huang 1 , Wei Lin 1 , Arne Reykowski 1
1 Advanced Concept Development, Invivo Diagnostic Imaging, Gainesville, FL, United States
In this study, we propose a new k-t space sampling trajectory for parallel dynamic MRI. This method applies random phase modulation to the spatial aliasing
of images in temporal domain. As a result, the spatial aliasing induced by k-space undersampling at every time frame has a noise pattern in temporal
dimension. By applying a temporal constraint that can be known from the priori knowledge of dynamic MRI data, the noise-like aliasing can be easily
removed. This work uses the fMRI and cardiac imaging applications as examples to demonstrate the feasibility of the proposed method.
2894. Rapid 3D Parallel Imaging of Non-Cartesian Data
Nicholas Ryan Zwart 1 , James Grant Pipe 1
1 Keller Center for Imaging Innovation, Barrow Neurological Institute, Phoenix, AZ, United States
A 3D parallel imaging reconstruction technique is presented. This technique is a coil sensitivity based method used for reconstructing undersampled
arbitrary 3D k-space trajectories. Iterations enforce receive b1-field and sampled data consistency without degridding/gridding operations improving the
computational speed compared to similar reconstruction methods. The 3D trajectory used is Spiral Projection Imaging.
2895. Improvement of Quantitative MRI Using Radial GRAPPA in Conjunction with IR-TrueFISP
Martin Kunth 1 , Nicole Seiberlich 2 , Philipp Ehses 1 , Vikas Gulani 2 , Mark Griswold 2
1 Experimentelle Physik V, Universitaet Wuerzburg, Wuerzburg, Germany; 2 Radiology, Case Western Reserve University, Cleveland,
OH, United States
While the use of IR-TrueFISP to quantify the relaxation parameters T1 and T2 and the proton density M0 has been demonstrated, these values can be
difficult to quantify in species with fast relaxation because the first points along the relaxation curve are hard to assess. This abstract explores the use of the
recently proposed technique through-time radial GRAPPA to reconstruct highly undersampled radial images acquired along the relaxation curve. In this
way, the first few points after the inversion can be assessed and the relaxation parameters more accurately quantified.