TRADITIONAL POSTER - ismrm

2896. Maxwell's Equation Tailored Reverse Method of Obtaining Coil Sensitivity for Parallel MRI
Jin Jin 1 , Feng Liu 1 , Yu Li 1 , Ewald Weber 1 , Stuart Crozier 1
1 ITEE, The University of Queensland, St Lucia, Queensland, Australia
Poster Sessions
A new method is proposed to obtain noise-free RF coil sensitivity maps. This is highly desirable, considering the fact that the sensitivity encoding (SENSE)
method imposes ultimate dependence of successful full FOV image reconstruction on the correct sensitivity map of each individual coil. The proposed
method differs from traditional methods in that, instead of refining the measured sensitivity maps by means of numerical approximation and/or extrapolation,
it is based on physics of electromagnetics, parameterization and optimization algorithms. Preliminary simulations show substantial improvement in
sensitivity maps constructed by proposed method compared to traditional polynomial fitting method and consequently in reconstructed images.
2897. Sub-Sampling Parallel MRI with Unipolar Matrix Decoding
Doron Kwiat 1
1 DK Computer College, Tel-Aviv, Israel
A method is proposed of parallel array scan, where signals from coils are combined by a summing multiplexer and decoded by unipolar matrix inversion is
suggested, which reduces acquisition channels to a single pre-amp and A/D. The results would be, an independent individual separated signals as if acquired
through multiple acquisition channels, and yet at a total acquisition time similar to acquisition time of multiple channels, Background In a standard parallel
array technology, N coils simultaneously cover N FOVs by reading N k-space lines simultaneously over N independent data sampling channels. These k-
space lines are phase weighted to maximize SNR and then FT converted to N independent images with an increased SNR[1]. In current accelerated PI
techniques, some of K-space lines are skipped physically, and are replaced by virtual k-space substitutes using preumed spatial sensitivities of the coils in the
PE direction [2-5]. Based on the method described recently [6,7] a new scanning procedure is described here. The Method 1.Have all coils be connected
through a single summing multiplexer unit (MUX) which allows, at our discretion, selecting N-1 coils to be actively connected while a single coil is
deactivated electronically, to a single summing common output (SCO). Let the summed signal from these N-1 coils be sampled by the single acquisition
channel (ACQ) having a single pre-amp and single A/D. 2.Scan 1/Nth of the total k-space lines while having N-1 coils actively connected to the ACQ by the
MUX unit. Repeat the above scan procedure over another 1/Nth part of k-space, this time with another set of N-1 coils actively connected, and 1 coil
deactivated. Keep these scan procedures N times, until all k-space lines were acquired over all N possible permutations of selections of N-1 coils out of N. 3.
There are now exactly N summed acquisitions at our hands. Using an inverse of a unipolar matrix, these can be now decoded back to the original individual
k-space lines
Non-Cartesian Imaging Methods
Hall B Tuesday 13:30-15:30
2898. 3D Dual VENC PCMRA Using Spiral Projection Imaging
Nicholas Ryan Zwart 1 , James Grant Pipe 1
1 Keller Center for Imaging Innovation, Barrow Neurological Institute, Phoenix, AZ, United States
This work focuses on the reduction of scan time required by the phase-contrast MRA technique. The proposed method consists of a 3D variable density
spiral projection imaging trajectory (SPI) combined with a dual velocity encoding technique. SPI is a rapid imaging technique that improves acquisition
time through the intrinsic efficiency of spirals and through undersampling. The dual-VENC method improves SNR by allowing low-VENC (high SNR) data
to be reconstructed without phase aliasing of the velocity measurements.
2899. Dynamic 3D Contrast Enhanced Liver Imaging Using a Novel Hybrid Cartesian-Radial Acquisition
with Flexible Temporal and Spatial Resolution
Pascal Spincemaille 1 , Beatriu Reig 1 , Martin R. Prince 1 , Yi Wang 1
1 Radiology, Weill Cornell Medical College, New York, NY, United States
High temporal resolution dynamic contrast enhanced liver imaging is achieved using a novel k-space sampling method that samples the phase and slice
encoding plane along true radial trajectories with an angularly varying field-of-view and resolution. Combined with an adapted golden ratio view order, it
eliminates the need for accurate bolus timing and allows the retrospective selection of the optimal arterial enhancement for the detection and characterization
of liver lesions.
2900. Magnetization-Prepared Shells with Integrated RadiaL and Spirals
Yunhong Shu 1 , Matt A. Bernstein 1
1 Department of Radiology, Mayo Clinic, Rochester, MN, United States
In this work, we demonstrate the initial feasibility of combining the SWIRLS trajectory with the MP-RAGE acquisition for volumetric T1-weighted brain
imaging. The SWIRLS trajectory uses one continuous interleave to cover the surface of a spherical shell from pole-to-pole, which offer more flexibility for
magnetization prepared (MP) design than the traditional shells trajectory. Meanwhile, it also shares the advantages of shells trajectory, including optimizing
the contrast between WM and GM with reduced scan time.
2901. High-Field MRI for Non-Invasive Preclinical Imaging in Free-Breathing Mice
Prachi Pandit 1,2 , Yi Qi 2 , Kevin F. King 3 , G A. Johnson 1,2
1 Biomedical Engineering, Duke University, Durham, NC, United States; 2 Center for In Vivo Microscopy, Duke University, Durham,
NC, United States; 3 GE Healthcare, Waukesha, WI, United States
The requirements for preclinical cancer imaging are high spatial resolution, good soft tissue differentiation, excellent motion immunity, and fast and noninvasive
imaging to enable high-throughput, longitudinal studies. Here we describe a PROPELLER-based technique, which with its unique data acquisition
and reconstruction overcomes the adverse effects of physiological motion, allows for rapid setup and acquisition and provides excellent tissue contrast.