Electronic Posters : Pulse Sequences, Reconstruction & Analysis
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Pulse Sequences & Applications

Monday May 9th
Exhibition Hall  14:00 - 16:00 Computer 112

14:00 4353.   Superbalanced Steady State Free Precession 
Oliver Bieri1
1Department of Medical Radiology, Radiological Physics, University of Basel Hospital, Basel, Switzerland

Finite radio-frequency (RF) pulses can give raise to considerable signal deviations from the “common” steady-state free precession (SSFP) theory in the transient and steady state, which may impair the accuracy of SSFP-based quantification techniques. Here, a generic approach for intrinsic compensation of finite RF pulse effects is introduced, based on balancing transverse relaxation effects during finite RF excitation (similar to flow or motion compensation of gradient moments), resulting in a superbalanced SSFP sequence free of finite RF pulse effects in the transient and in the steady state, irrespective of the RF pulse duration, relaxation times and flip angles.

14:30 4354.   Measurement of Cerebral Metabolic Rate of Oxygen (CMRO2) using qBOLD Technique in Resting State 
Xiang He1, Dmitriy A. Yablonskiy2, and Kyongtae Ty Bae1
1Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2Mallinckrodt Institute of Radiology, Washington Uninversity in St Louis, St Louis, Missouri, United States

MRI-based quantitative BOLD (qBOLD) method allows for non-invasive regional measurement of OEF. In this study, we have developed and implemented an ASL-qBOLD technique to determine quantitative in vivo absolute CMRO2 maps of the brain in the human brain in the resting state. We demonstrated that imaging artifacts can be effectively minimized by incorporating techniques such as over-sampling and navigator echoes. In addition, high SNR in blood flow measurement can be achieved by averaging the perfusion MR signal along the qBOLD echo train. Application of these methods facilitates a robust estimation of absolute CMRO2 in the brain baseline state.

15:00 4355.   Dynamic 3D Visualization of Vocal Tract Shaping during Speech 
Yinghua Zhu1, Yoon-Chul Kim1, Michael I Proctor1, Shrikanth S Narayanan1, and Krishna S Nayak1
1Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, CA, United States

We reconstruct the 3D dynamics of vocal tract based on 1) parallel 2D real-time imaging of 15 repetitions of a speech productions /asa/, /aʃa/, /ala/ and /ara/, with the synchronized noise-cancelled audios recorded simultaneously, and 2) alignment of the 2D real-time movies using dynamic time warping based on the recorded audio tracks, with mel-frequency cepstral coefficients as the acoustic feature to analyze. The resulting 3D movies show several vocal tract features that cannot be seen in single 2D slice, and therefore present unique value to speech research.

15:30 4356.   Measurement of eye pO2 using T1 mapping has precision ~8 mmHg and shows oxygenation gradient between retina and lens 
Nicholas G Dowell1, Edward H Hughes2, and Paul S Tofts1
1Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, Sussex, United Kingdom, 2Sussex Eye Hospital, Brighton, Sussex, United Kingdom

A new technique is presented that precisely measures T1 (within subject variability ~40 ms) and hence pO2 (precision ~8 mmHg) in the human eye. A pixel-by-pixel calculation of T1 allows the measurement of a T1 and pO2 gradient through the eye that gives useful information about regional variation in oxygenation. We overcome the difficulties of eye movement and image distortion by employing an audio/visual cue for participants and through the careful implementation of the TrueFISP acquisition sequence. This new method of assessing oxygen concentration of the eye will benefit the study of a range of eye conditions such as retinopathy or assessing the therapeutic value of surgical procedures such as vitrectomy (removal and replacement of vitreous humour).

Electronic Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the video presentation.
Pulse Sequences - Methods

Wednesday May 11th
Exhibition Hall  13:30 - 15:30 Computer 113

13:30 4357.   Retrospective Reconstruction of Black-Blood Golden Ratio Radial Imaging for Visualization of Heart Valves at Arbitrary Dynamic Time Points 
Claudia Prieto1, and Tobias Schaeffter1
1Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom

Accurate visualization of the valve leaflet morphology is needed for the assessment of valvular heart disease. Accurate synchronization of the imaging sequence with the opening and closing of the valve is required. We propose the use of the golden ratio radial trajectory to retrospectively select and reconstruct a high-spatial resolution black-blood image at any specific time-point over the valves dynamics. In a first step, the acquired data is used to reconstruct a dynamic sequence with high-temporal resolution. This information is then used to select the right timing for a high-spatial resolution reconstruction from the same data.

14:00 4358.   Highly Efficient Isotropic Whole-Heart Imaging using Radial Phase Encoding PAWS 
Christoph Kolbitsch1, Claudia Prieto1, Jouke Smink2, and Tobias Schaeffter1
1Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom, 2Philips Healthcare, Best, Netherlands

The major challenges for 3D whole-heart MRI are long acquisition times and respiratory motion. Here a fast and highly efficient 3D whole-heart acquisition scheme is presented. It combines the ideas of Radial Phase Encoding(RPE) allowing for high acceleration factors and Phase Ordering with Automatic Window Selection(PAWS) yielding high navigator efficiency. A new phase encoding scheme is proposed to ensure a short scan time for isotropic high resolution images. Volunteer scans show a strong decrease in scan time for RPE-PAWS compared to a respiratory gated Cartesian scan and indicate a better depiction of small structures such as the coronary arteries.

14:30 4359.   Five-Dimensional Free-Breathing Cardiac MRI Using a 3D Cones Trajectory 
Holden H Wu1,2, Dwight G Nishimura2, Michael V McConnell1,2, and Bob S Hu2,3
1Cardiovascular Medicine, Stanford University, Stanford, CA, United States, 2Electrical Engineering, Stanford University, Stanford, CA, United States, 3Palo Alto Medical Foundation, Palo Alto, CA, United States

Conventional methods for imaging cardiac function seek to suspend or effectively eliminate respiratory motion to avoid image artifacts. However, in many disease states, including pericardial constriction and diastolic dysfunction, it is precisely the changes in cardiac function associated with changes in respiration that can reflect the pathophysiology. In this work, we present a comprehensive free-breathing technique for capturing the five-dimensional state of the heart, including volumetric spatial information, cardiac phase information, and respiratory phase information. This proposed technique collects data using the 3D cones readout trajectory to reduce scan time and provide robustness to motion/flow effects.

15:00 4360.   Ultra Fast Volumetric Functional Imaging using Single Shot Concentric Shells Trajectories 
Benjamin Zahneisen1, Thimo Grotz1, Maxim Zaitsev1, and Juergen Hennig1
1University Hospital Freiburg, Freiburg, Germany

MR-encephalography (MREG) has been shown to allow extremely fast and highly sensitive monitoring of functional activation. Recently, it has been shown that the use of a 3D rosette trajectory provides whole brain coverage with an acquisition time of 23ms. However, the rosette trajectory has a very non-uniform k-space sampling density and suffers from off-resonance artifacts. Here, we propose the use of a single shot, variable density, concentric shells trajectory for ultra-fast functional imaging. The method yields very good spatial localization of BOLD-activation. The high sampling rate allows the real time observation of dynamic changes of the BOLD-response (dynamic retinotopic mapping).

Thursday May 12th
  13:30 - 15:30 Computer 113

13:30 4361.   Improved through slice resolution in continuously moving table MRI by using a modified helical trajectory 
Florian Hoffmann1, Philipp Ehses2, Michael Völker2, Felix A Breuer2, Martin Blaimer2, and Peter M Jakob1,2
1Department of Experimental Physics 5, University of Würzburg, Würzburg, Bayern, Germany, 2Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany

One of the first continuously moving table experiments was helical MRI. It uses a radial readout with a linearly increasing projection angle. Helical MRI requires a linear interpolation reconstruction otherwise the table movement provokes artifacts. However, this smears details into neighboring slices. In this work, the angular sampling was modified based on the golden ratio approach. As k-space is covered almost uniformly at any time it is possible to vary the projection number during a sliding window reconstruction or to apply a KWIC-filter. This results in an improved through-slice resolution as demonstrated by phantom and in vivo experiments.

14:00 4362.   3D Fast Spin Echo Novel view ordering for variable TE 
Mitsuharu Miyoshi1, Naoyoki Takei1, Ananth J Madhuranthakam2, and Hiroyuki Kabasawa1
1Global Applied Science Laboratory, GE Healthcare Japan, Hino, Tokyo, Japan, 2Global Applied Science Laboratory, GE Healthcare, Boston, MA, United States

3D Fast Spin Echo with variable flip angle uses low flip angle refocus pulses and long echo trains. The effective TE of FSE corresponds to echo train number of k-space center. To make TE flexible, novel view ordering methods were developed in this paper. Phantom and volunteer were scanned with conventional and novel view orderings. Ringing, blur, signal intensity and contrast were measured and compared.

14:30 4363.   Fast Susceptibility Weighted Imaging (SWI) using Readout-Segmented (RS)-EPI 
Samantha J Holdsworth1, Rafael O'Halloran1, Stefan Skare2, and Roland Bammer1
1Department of Radiology, Stanford University, Palo Alto, CA, United States, 2Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden

The most commonly used SWI acquisition uses a 3D gradient echo (GRE) sequence, however due to the inefficient coverage of k-space per TR, 3D GRE suffers from a long scan time and even subtle motion can considerably hamper the quality of final SWI image. 3D SAP-EPI has been used as a much faster and motion-robust technique than 3D GRE for SWI. Here, we implement Readout-Segmented (RS)-EPI as an alternative. Due to the unidirectional distortions and reduction of blurring compared to 3D SAP-EPI, we show that 3D RS-EPI is a promising technique for the acquisition of fast SWI images.

15:00 4364.   Golden Step Phase Encoding: Simultaneous real-time and ECG gated-Cine Parallel MRI with Retrospective Selection of Temporal Resolution, Acceleration Rate and Acquisition Duration 
J. Andrew Derbyshire1, Haris Saybasili1, Liheng Guo2, Ozan Sayin2, Peter Kellman1, Robert J. Lederman1, and Daniel A. Herzka2
1National Heart, Lung and Blood Institute, NIH, Bethesda, MD, United States, 2Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, United States

Golden Step phase encoding provides close-to-uniform sampling of k-space for any number of consecutive TRs. We demonstrate a MR imaging strategy that allows simultaneous real-time and ECG-gated Cine imaging from a single acquisition. In particular, multiple sets of images with differing temporal resolutions may be reconstructed with arbitrary acceleration rates at arbitrary temporal positions from a single Cartesian acquisition. Furthermore, the gated Cine reconstructions can be performed from acquisitions comprising an arbitrary number of heartbeats, permitting the reconstruction of images even from incomplete breath-holds.


Electronic Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the video presentation.
Pulse Sequences - Water & Fat

Thursday May 12th
Exhibition Hall  13:30 - 15:30 Computer 114

13:30 4365.   Simultaneous T2 and Lipid Quantitation using IDEAL-CPMG 
Robert Leonard Janiczek1,2, Giulio Gambarota2, Christopher D.J. Sinclair1, Tarek A Yousry1, John S. Thornton1, Xavier Golay1, and Rexford D. Newbould1,2
1University College London, London, United Kingdom, 2GSK Clinical Imaging Centre, London, United Kingdom

The muscle damage associated with neuromuscular diseases commonly contains both inflammation and fat infiltration. This fatty infiltration mimics the lengthened T2 of inflamed muscle as the T2 of fat, T2,f, is longer than the T2 of water, T2,w, in healthy skeletal muscle. IDEAL-CPMG is presented that overcomes this problem by combining iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with a Carr-Purcell-Meiboom-Gill (CPMG) readout. IDEAL-CPMG results in fat and water images with multiple T2-weightings, enabling measurement of T2,w, and T2,f from the water and fat isolated signals along with a T2-corrected fat fraction.

14:30 4366.   Rapid Fat-Water-Separated Cardiac Cine Imaging Using Concentric Rings and k-t BLAST 
Holden H Wu1,2, Taehoon Shin2, Dwight G Nishimura2, and Michael V McConnell1,2
1Cardiovascular Medicine, Stanford University, Stanford, CA, United States, 2Electrical Engineering, Stanford University, Stanford, CA, United States

Cine MRI is routinely used to assess cardiac function. In many situations, it is also desirable to have complementary information identifying fat signal to characterize masses, detect fatty infiltration and arrhythmogenic right ventricular dysplasia, and visualize pericardial disease. In this work we present a rapid imaging technique using the concentric rings readout trajectory to efficiently encode chemical shift information for fat/water separation and k-t BLAST acceleration to flexibly balance spatial and temporal sampling requirements. Experimental results demonstrate that co-registered 2D fat/water cines can be obtained at 1.78-mm in-plane spatial resolution and 41-ms temporal resolution within a 10-hearbeat single-breath-hold scan.

15:00 4367.   T2/PD Weighted Water and Fat Seperation on Low-field Scanner 
Cong Zhao1, Guobin Li1, Dehe Weng1, Weijun Zhang1, Mathias Nittka2, and Vladimir Jellus2
1Siemens Mindit Magnet Resonance Co. Ltd, ShenZhen, GuangDong, China, People's Republic of, 2Siemens Healthcare Sector, Erlangen, Germany

On low field system, Dixon technique is preferred for its robustness and reliability on T1 weighted imaging. However, for T2/PD weighted imaging, TSE based Dixon suffers from a sever artifacts due to system limitations of low-field scanner. In this abstract, origin of the artifacts is analyzed. An optimized TSE Dixon acquisition scheme is also proposed. A clinical acceptable PD/T2 weighted water/fat separation result is therefore feasible on low-field scanner.

Electronic Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the video presentation.
Dynamic Imaging & Compressed Sensing
Monday May 9th
Exhibition Hall  14:00 - 16:00 Computer 115

14:00 4368.   Combination of Compressed Sensing, Parallel Imaging and Partial Fourier for Highly-Accelerated 3D First-Pass Cardiac Perfusion MRI 
Li Feng1,2, Jian Xu3,4, Daniel Kim2, Leon Axel2, Daniel K Sodickson2, and Ricardo Otazo2
1Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States, 2Department of Radiology, New York University School of Medicine, New York, NY, United States, 3Siemens Medical Solutions USA, 4Polytechnic Institute of NYU, Brooklyn, NY, United States

First-pass myocardial perfusion MRI is a promising technique for assessing ischemic heart diseases. 3D whole-heart coverage per heartbeat is desirable to overcome the volumetric coverage limitations of multislice 2D techniques. Highly accelerated imaging is required to reduce the long acquisition time per heartbeat of 3D perfusion MRI scans. In this work, we combine compressed sensing, parallel imaging and partial Fourier imaging to enable previously inaccessible accelerations. We demonstrate feasibility of whole-heart 3D perfusion MRI with 24-fold acceleration using the combined approach.

14:30 4369.   Accelerated Multi-TI Spiral MRI using Compressed Sensing with Temporal Constraints 
Xiao Chen1, Michael Salerno2,3, Frederick H Epstein2, and Craig H Meyer1
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, 2Radiology, University of Virginia, Charlottesville, VA, United States, 3Cardiology, University of Virginia, Charlottesville, VA, United States

We proposed to accelerate multi-TI spiral MRI using compressed sensing by exploiting temporal sparsity. Look-Locker inversion-recovery images of the mouse heart were acquired and different spiral sampling patterns were investigated. Rate-2 acceleration led to excellent image quality, with artifacts becoming more prominent at higher acceleration rates. A sampling pattern employing rotations of angularly-uniformly spaced interleaves provided better image quality compared to randomly selected interleaves.

15:00 4370.   Golden Angle radial cardiac imaging without ECG gating using nonconvex Compressed Sensing 
André Fischer1,2, Nicole Seiberlich3, Mark A Griswold3, Peter M Jakob1,2, and Felix A Breuer1
1Research Center Magnetic Resonance Bavaria (MRB) e.V., Wuerzburg, Germany, 2Department of Experimental Physics 5, University of Wuerzburg, Wuerzburg, Germany,3Department of Radiology, University Hospitals, Cleveland, Ohio, United States

Real-time imaging with high spatial and high temporal resolution is of great interest in cardiac imaging. Golden angle radial imaging allows to retrospectively selecting the temporal resolution by grouping a certain number of temporally adjacent projections to a timeframe. In this work, a Compressed Sensing based technique is presented to reconstruct a Golden angle radially undersampled real-time cardiac dataset. Thereby, the sparse differences of the individual timeframes to a temporally averaged composite image of the dataset were CS reconstructed. By exploiting the joint sparsity of the receiver array, accurate reconstructions of a dataset exhibiting PVCs could be obtained from 24 projections.

15:30 4371.   Local versus Global Low-Rank Promotion in Dynamic MRI Series Reconstruction 
Joshua Trzasko1, and Armando Manduca1
1Mayo Clinic, Rochester, MN, United States

Recent works have suggested that dynamic MRI series reconstructions can be significantly improved by promoting low-rank structure in the estimated image series. However, when there exists a significant discrepancy between the spatial and temporal dimensions of the image series, low-rank approximations begin to lose their efficacy, resulting in either inadequate noise removal or temporal blurring. In this work, we present a generalization of the low-rank recovery paradigm, which we call Locally Low Rank (LLR) image recovery, that promotes low-rank structure locally rather than globally. As demonstrated, this migration can improve both the efficacy of noise removal and temporal signal fidelity.

Tuesday May 10th
  13:30 - 15:30 Computer 115

13:30 4372.   On the Spatiotemporal Bandwidth of Cardiac Motion 
Marijn E Brummer1, Mireia Sanz-Blasco2, Sumati Krishnan3, Lei Hou Hamilton4, Senthil Ramamurthy3, and David Moratal5
1Pediatrics and Radiology, Emory University, Atlanta, GA, United States, 2Universitat Politècnica de València, València, Spain, 3Pediatrics, Emory University, Atlanta, GA, United States, 4Bioengineering, Georgia Institute of Technology, Atlanta, GA, United States, 5Center for Biomaterials and Tissue Engineering, Universitat Politècnica de València, València, Spain

In theoretical and experimental spatiotemporal spectral analyses of two elementary models of motion, commonly encountered in dynamic cardiac imaging, temporal Nyquist frequencies were observed for each spatial frequency component. Temporal Nyquist rates were found higher for high spatial frequencies. These results open new perspectives on efficient sampling of kt-space for time-resolved cardiac MRI.

14:00 4373.   3D dynamic contrast enhanced imaging of liver at 250ms temporal resolution 
Bo Xu1,2, Pascal Spincemaille2, Mukta Agrawal2, Gang Chen3, Martin Prince2, and Yi Wang1,2
1Biomedical Engineering, Cornell University, New York, NY, United States, 2Weill Cornell Medical College, New York, NY, United States, 3Polytechnic Institute of New York University, New York, NY, United States

A high temporal resolution dynamic 3D spiral MR acquisition method is presented which allows the retrospective selection of the optimal arterial phase and its subphases for enhanced detection and characterization of liver lesions and function.

14:30 4374.   Parallel Reconstruction for Cartesian Golden Step MRI with Arbitrary Temporal Resolution, Field-of-view and Acceleration Rate. 
Haris Saybasili1, J. Andrew Derbyshire1, Liheng Guo2, Ozan Sayin2, Annette M. Stine1, Robert J. Lederman1, and Daniel A. Herzka2
1National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States, 2Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, United States

This work describes a fully auto-calibrated GRAPPA approach for the reconstruction of Golden-step Cartesian MRI data. Golden-step Cartesian MRI advances the phase encoding gradients in steps of the golden fraction of the k-space support region. The resulting data sets are non-uniformly sampled in the phase encode direction and have advantageous properties for real-time imaging, permiting arbitrary and retrospective selection of temporal resolution, FOV and parallel imaging acceleration rate. In our approach the Golden-step MRI data are mapped onto the nearest Cartesian grid position using 1D SC-GROG. GRAPPA is then applied to estimate missing lines prior to a standard FFT reconstruction.

15:00 4375.   Image Reconstruction from Highly Undersampled (k, t)-space Data with Joint Partial Separability and Sparsity Constraints 
Bo Zhao1, Justin Haldar1, Anthony Christodoulou1, and Zhi-Pei Liang1
1Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States

Sparse sampling is emerging as an effective tool to further accelerate MRI. Previous work has shown that partial separability and sparsity constraints are each able to individually reduce sampling requirement below the Nyquist rate. In this abstract, we present a new reconstruction method that enables using partial separability and sparsity constraints jointly. The joint use of these constraints enables high resolution reconstruction from sparsely sampled data.

Wednesday May 11th
  13:30 - 15:30 Computer 115

13:30 4376.   Cardiac Perfusion Imaging Using a Combination of CAIPIRINHA and Compressed Sensing 
Daniel Stäb1, Tobias Wech1, Christian Oliver Ritter1, Dietbert Hahn1, and Herbert Köstler1
1Institute of Radiology, University of Würzburg, Würzburg, Bavaria, Germany

A combination of CAIPIRINHA simultaneous multi-slice imaging with Compressed Sensing is presented. A technique is generated, accelerating the imaging procedure in slice and phase encoding direction. In the reconstruction process, Compressed Sensing is used to eliminate incoherent artifacts, while a parallel imaging reconstruction separates the simultaneously excited slices. The technique was applied for high resolution myocardial perfusion imaging with extended anatomic coverage. Different sparsifying transforms for the Compressed Sensing reconstruction were examined in terms of systematic and statistical errors.

14:00 4377.   k-t ISD: Dynamic Cardiac Imaging Using Compressed Sensing with Iterative Support Detection 
Dong Liang1, Edward V. R. DiBella2, Rong-Rong Chen3, and Leslie Ying1
1Department of Electrical Engineering and Computer Science,University of Wisconsin – Milwaukee, MIlwaukee, WI, United States, 2Department of Radiology,University of Utah, Salt Lake City, UT, United States, 3Department of Electrical and Computer Engineering,University of Utah, Salt Lake City, UT, United States

We study how to obtain and exploit the additional prior information on the support of sparse signals in compressed sensing (CS) reconstruction. We propose a k-t Iterative Support Detection (k-t ISD) method for dynamic cardiac MRI to iteratively learn and utilize the support knowledge in x-f space to improve CS reconstruction. The learned support is incorporated in CS reconstruction by excluding part of the signal at the known support from the cost function in the constrained minimization process. Experiments demonstrate k-t ISD improves the reconstruction quality over the basic CS method in which support information is not exploited.

14:30 4378.   Accelerating Phase Contrast MR Angiography by Simplified Skipped Phase Encoding and Edge Deghosting with Array Coil Enhancement (S-SPEED-ACE) 
Zheng Chang1, Xiang Qing-San2,3, Hao Shen4, Jim Ji5, and Fang-Fang Yin1
1Department of Radiation Oncology, Duke University, Durham, NC, United States, 2Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada, 3Department of Radiology, University of British Columbia, Vancouver, BC, Canada, 4Applied Science Laboratory, GE Healthcare, Beijing, China, People's Republic of,5Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, United States

The parallel imaging method of Skipped Phase Encoding and Edge Deghosting with Array Coil Enhancement (SPEED-ACE) has been simplified with enhanced acceleration for imaging sparse objects and is termed S-SPEED-ACE. As demonstrated previously with a computer simulated study, S-SPEED-ACE partially samples k-space with multiple coils in parallel and yields a deghosted image based on a least-square-error solution. Without differential filtering and full central k-space sampling, S-SPEED-ACE uses more straightforward reconstruction and achieves further scan time reduction as compared with SPEED-ACE. In this work, S-SPEED-ACE is further developed to accelerate real human 3D phase-contrast MR angiography.

15:00 4379.   Improved Compressed Sensing reconstruction in dynamic contrast enhanced MR Angiography by means of Principal Component Analysis (PCA) 
Felix A Breuer1, Andre Fischer1, Nicole Seiberlich2, Philipp Ehses1, Martin Blaimer1, Daniel Neumann1, Peter M Jakob1,3, and Mark A Griswold2
1Research Center Magnetic Resonance Bavaria, Würzburg, Germany, 2Radiology, Case Western Reserve University, Cleveland, Ohio, United States, 3Experimental Physics 5, University of Würzburg, Würzburg, Germany

In this work we demonstrate that the concept of Principal Component Analysis (PCA) can significantly improve Compressed Sensing (CS) reconstructions of highly undersampled contrast enhanced MR Angiography (MRA) data. In contrast to conventional CS, in this approach, each CS step operates in a heavily compressed basis. After PCA the dynamics are modeled within a few PCs exhibiting very high SNR, resulting in more accurate CS reconstruction results. In addition, the new method employs an iterative update of the principal components (PCs) after each CS step and thus is self-calibrating and does not require any prior knowledge about the contrast dynamics.

Thursday May 12th
  13:30 - 15:30 Computer 115

13:30 4380.   k-t Sparse GROWL: A Fast and Accurate Algorithm for Highly Accelerated Dynamic Imaging 
Feng Huang1, Wei Lin1, George Randy Duensing1, and Arne Reykowski1
1Invivo Corporation, Gainesville, Florida, United States

The combination of partially parallel imaging (PPI) and compressed sensing (CS) has shown great potential for dynamic MRI. In this work, a self-calibrated PPI technique GROWL is combined with CS in k-t space for fast and accurate reconstruction with highly accelerated dynamic imaging. The proposed method is called k-t sparse GROWL. By using golden angle radial trajectory, real time speech MRI with flexible temporal resolution can be achieved by using 16 radial projections for each time frame. The reconstruction for a low artifact image using a 256multiplication sign16 multiplication sign16 data set needs less than 10 seconds in Matlab.

14:00 4381.   Fast functional imaging using interleaved data acquisition and compressed sensing 
Thimo Grotz1, Benjamin Zahneisen1, Maxim Zaitsev1, and Jürgen Hennig1
1Dept. of Radiology - Medical Physics, University Medical Center Freiburg, Freiburg, BW, Germany

It has been demonstrated that strongly undersampled single shot trajectories combined with multi channel arrays can be used to speed up functional imaging while maintaining good spatial resolution. Spatial resolution of dynamic imaging methods can be improved by employing an interleaved data acquisition scheme and by using information from several interleaves to reconstruct a time frame. We demonstrate that using a 3d radial single shot trajectory, combination of k-space data from adjacent interleaves according to KWIC (k-space weighted image contrast) and compressed sensing image reconstruction can improve spatial resolution for fast functional imaging and maintain a high temporal resolution.

14:30 4382.   High resolution structural free-breathing cardiac MRI using k-t SLR 
Yue Hu1, Sajan Goud Lingala2, and Mathews Jacob2
1Electrical and Computer Engineering, University of Rochester, Rochester, NY, United States, 2Biomedical Engineering, University of Rochester, Rochester, NY, United States

We consider the problem of free-breathing high-resolution structural cardiac MRI. To overcome the limitations with conventional navigator pulses, we propose to reformulate the structural problem as a dynamic one by recovering a 2D+time dataset from under-sampled k-t data. We use our recently proposed k-t SLR scheme to estimate the principal temporal bases of the data, which enables data sharing between heartbeats and facilitate high-resolution dynamic dataset recovery. The structural image at any respiratory phase can be obtained from the recovered dynamic data. Experiments on free-breathing cardiac MRI data showed the feasibility of the proposed scheme in obtaining high fidelity reconstructions.

15:00 4383.   A Model-Based Compressed Sensing Method for Fast Cardiac T1 Mapping in Small Animals 
Wen Li1,2, Mark Griswold1,3, and Xin Yu1,3
1Biomedical Engineering Department, Case Western Reserve University, Cleveland, OH, United States, 2Case Center for Imaging Research, Case Western Reserve University, Cleveland, OH, United States, 3Radiology Department, Case Western Reserve University

A model-based compressed sensing method was developed for fast cardiac T1 mapping (<1.5 min) in small animals. Simulation and MRI studies on phantom and in vivo mouse heart were performed to evaluate the acceleration capability under various experimental conditions using different reconstruction approaches.


Electronic Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the video presentation.
The Many Faces of Image Reconstruction

Monday May 9th
Exhibition Hall  14:00 - 16:00 Computer 116

14:00 4384.   Bloch Equation Based Algebraic Reconstruction for MRI using Frequency-Modulated Pulses 
Naoharu Kobayashi1, Steen Moeller1, Jang-Yeon Park2, and Michael Garwood1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, 2School of Biomedical Engineering, College of Biomedical and Health Science, Konkuk University, Chungju, Korea, Republic of

A Bloch equation based algebraic reconstruction method applied to concurrent dephasing and excitation (CODE) with frequency-modulated (FM) pulse excitation is introduced. Compensation of the quadratic phase generated by FM excitation has been performed based on a linear approximation of the spin system. However, the actual spin system has non-linearity in its time evolution that is described by the Bloch equation. Therefore, incorporation of the non-linearity into the reconstruction method should improve the image quality. Here, we show the computer simulation and reconstructed images of experimental data acquired on a 16.4 T MRI system.

14:30 4385.   Correcting K-trajectory by Using Multiple Function Models of Gradient Waveform for Ultrashort TE(UTE) 
Masahiro Takizawa1, Hikaru Hanada1, Kuniharu Oka1, and Tetsuhiko Takahashi1
1MRI system division, Hitachi Medical Corporation, Kashiwa, Chiba, Japan

The UTE sequence, based on radial sampling, acquires echo signal from central to outer parts of k-space. For this kind of sequence, K-trajectory error caused by gradient system response becomes a major problem. For clinical use of UTE it is important to be able to change imaging conditions and parameters for a general oblique imaging plane without causing K-trajectory errors. Even if there are errors on the gradient output, the K-trajectory can be estimated by calculating the error strictly. In this study, the multiple function models are used for correcting the total error of the gradient system response.

15:00 4386.   A wavelet fusion approach to the reconstruction of isotropic-resolution MR images from anisotropic orthogonal scans 
Iman Aganj1, Christophe Lenglet2, Essa Yacoub2, Guillermo Sapiro1, and Noam Harel2
1Electrical Engineering, University of Minnesota, Minneapolis, MN, United States, 2Center for Magnetic Resonance Research, University of Minnesota, United States

Hardware, timing, and SNR considerations restrict the slice-selection and the in-plane resolutions differently, generally resulting in thicker acquisition slices and therefore anisotropic voxels. This non-uniform sampling can be problematic, especially in image segmentation and clinical examination, since the image will be missing high frequencies in the slice-selection direction. High-resolution MR volumes with isotropic voxels are acquired at the cost of requiring the subject to be motionless for a clinically unreasonably long time, hence increasing the risk of motion artifacts. This can be alleviated by dividing the acquisition into (two or) three separate scans, with thicker slices yet complementary resolutions. Every scan will then have a shorter acquisition time and a lower chance of undergoing motion-related distortion. Misalignment between the three scans can be corrected by employing a variety of available registration techniques, and the high-resolution image is eventually reconstructed from the three scans. In this work, we adopt a non-iterative wavelet-based approach, which takes into account the actual system response of the MR scanner. We show results from three orthogonal Susceptibility-Weighted Imaging datasets acquired at 7T, and compare them with a high resolution ground truth dataset.

15:30 4387.   MR Based Limited-field-of-view SPECT Image Reconstruction 
Keumsil S Lee1,2, Werner W Roeck1,3, Grant T Gullberg4, and Orhan Nalcioglu1,3
1Tu & Yuen Center for Functional Onco-Imaging, University of California, Irvine, Irvine, CA, United States, 2Department of Electrical Engineering and Computer Science, University of California, Irvine, Irvine, CA, United States, 3Department of Radiological Sciences, University of California, Irvine, Irvine, CA, United States, 4Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA, United States

In nuclear imaging, a limited field of view (LFOV) system is more practical due to the fact that the ROIs are usually a lot smaller than the whole subject and the detectors to build a gamma camera are expensive. However, image reconstruction for the projections acquired by LFOV imaging systems have been done using standard full-field-of-view algorithm. The work presented here proposes a LFOV image reconstruction method named Keyhole SPECT (K-SPECT) that uses anatomical a priori information of ROI determined by high-resolution MR images and radioactivity distribution from SPECT image reconstructed without any a priori information. The simulation results indicate that K-SPECT reconstruction improved the image quality and the accuracy.

Tuesday May 10th
  13:30 - 15:30 Computer 116

13:30 4388.   Lesion and Deep Grey Matter Visualization in Phase Images Using a Local Polynomial Filter with Moving Window 
Sarah E. Riske1, Amir Eissa1, Sandra M. Meyers1, and Alan H. Wilman1
1University of Alberta, Edmonton, Alberta, Canada

A means to perform phase filtering in susceptibility images is introduced and applied to MS patients for lesion visualization and for deep grey matter. The method is based on local polynomial fitting using a moving window and provides improved lesion and deep grey matter contrast.

14:00 4389.   Improved Interleaved Single-shot z-shim EPI via Spatial and Temporal Encoding 
W. Scott Hoge1, Hong Pan1, Huan Tan2, Emily Stern1, and Robert A. Kraft2
1Radiology, Brigham and Women's Hospital, Boston, MA, United States, 2Virginia-Tech Wake Forest School of Biomedical Engineering, Winston-Salem, NC, United States

Echo planar imaging often suffers from signal dropout in regions with high susceptibility. This is particularly problematic for fMRI studies of the brain near the nasal sinuses. Z-shim methods are one approach to recover this lost signal, where a z gradient is employed prior to the EPI readout to counter phase accumulation in the signal dropout region. Single-shot z-shim methods give improved temporal resolution, but with a cost of longer echo trains, which increases geometric distortion. Here, we employ parallel MR imaging (pMRI) to shorten the EPI echo train in a single-shot z-shim method. Temporal encoding complements the approach, to counter Nyquist ghost effects and improve the pMRI calibration. Temporal signal stability is shown to be comparable to a two-shot z-shim method.

14:30 4390.   Rapid Sample Density Estimation for 3D Trajectories 
Nicholas Ryan Zwart1, and James Grant Pipe1
1Neuroimaging Research, Barrow Neurological Institute, Phoenix, Arizona, United States

The reconstruction of non-cartesian k-space trajectories often requires the estimation of non-uniform sampling density. Particularly for 3D, this calculation can be computationally expensive. The method proposed in this work is the combination of a fast, previously proposed, iterative algorithm with a previously proposed optimized convolution kernel.

15:00 4391.   Correction of EPI Nyquist Ghosts via GESTE with Spatial Calibration 
W. Scott Hoge1, Huan Tan2, Zhikui Xiao3, and Robert A. Kraft2
1Radiology, Brigham and Women's Hospital, Boston, MA, United States, 2Virginia-Tech Wake Forest School of Biomedical Engineering, Winston-Salem, NC, United States,3Global Applied Science Laboratory, GE Healthcare, Beijing, China, People's Republic of

GESTE is a robust method of ghost correction that employs temporal encoding with parallel imaging. In this work we demonstrate that the temporal encoding requirements can be applied across the slice dimension in a single volume acquisition. Working from the assumption that the signal changes slowly across slices, this enables accurate GRAPPA parameters to be estimated and used in a GESTE-style image reconstruction pipeline. The method is shown to be effective in in-vivo brain EPI images, with only minimal errors introduced compared to a standard GESTE reconstruction.


Electronic Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the video presentation.
Parallel Imaging

Monday May 9th
Exhibition Hall  14:00 - 16:00 Computer 117

14:00 4392.   Through-Time Spiral GRAPPA for Real-Time Cardiac Imaging 
Nicole Seiberlich1, Gregory Lee1, Philipp Ehses2, Jeffrey Duerk1,3, and Mark Griswold1,3
1Radiology, University Hospitals of Cleveland, Cleveland, OH, United States, 2Research Center for Magnetic Resonance Bavaria (MRB), Wuerzburg, Germany, 3Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States

Through-time non-Cartesian GRAPPA has recently emerged as a technique for real-time MRI, where images acquired using an undersampled radial trajectory could be reconstructed to yield a temporal resolution better than 50 ms/image. This through-time GRAPPA method has been extended to the more efficient variable density spiral trajectory in order to scan at a higher frame rate with a lower acceleration factor than with radial. Using through-time spiral GRAPPA and highly undersampled spiral data (R=12), short axis cardiac SSFP images can be generated with a temporal resolution of 17.9ms/image (a frame rate of 56 images/s) without any echo sharing.

14:30 4393.   3D Radial Parallel imaging for bandwidth limited acquisitions. 
Steen Moeller1, Curtis A Corum1, Djaudat Idiyatullin1, and Michael Garwood1
1University of Minnesota, Minneapolis, 55455, United States
Parallel imaging has been combined with the 3D radial SWIFT sequence and applied to reduced FOV imaging for increased spatial resolution. With a 2 channel coil, an R=2 reconstruction has been demonstrated.

Yuchou Chang1, Dong Liang1, and Leslie Ying1
1Electrical Engineering, University of Wisconsin - Milwaukee, Milwaukee, Wisconsin, United States

We improve the convolution model in GRAPPA using a kernel approach. We map the acquired k-space data through a nonlinear transform to a high-dimensional space and then linearly combine the transformed data to estimate the missing k-space data. Both polynomial and Gaussian kernels are investigated for the nonlinear transform. The proposed kernel model characterizes the system noise in reconstruction more accurately. Experimental results using in vivo data demonstrate that the proposed kernel GRAPPA method can significantly suppress the noise in conventional GRAPPA without introducing artifacts.

15:30 4395.   CS-GRAPPA: Improving GRAPPA Using Cross Sampling 
Haifeng Wang1, Dong Liang1, Kevin F. King2, Gajanan Nagarsekar1, and Leslie Ying1
1Department of Electrical Engineering and Computer Science, University of Wisconsin-Milwaukee, Milwaukee, WI, United States, 2Global Applied Science Lab, General Electric Healthcare, Waukesha, WI, United States

A cross sampling method is proposed to acquire the ACS lines orthogonal to the reduced lines for GRAPPA. This cross sampling method increases the amount of calibration data along the direction that the k-space is undersampled and thus improves the calibration accuracy, especially when a small number of ACS lines are acquired. Both phantom and in vivo experiments demonstrate that the proposed method, named cross-sampled GRAPPA (CS-GRAPPA), can effectively reduce the aliasing artifacts of GRAPPA when high acceleration is desired.

Tuesday May 10th
  13:30 - 15:30 Computer 117

13:30 4396.   IMPATIENT MRI: Illinois Massively Parallel Acceleration Toolkit for Image reconstruction with ENhanced Throughput in MRI 
Xiao-Long Wu1, Jiading Gai2, Fan Lam1,2, Maojing Fu1,2, Justin P. Haldar1,2, Yue Zhuo2,3, Zhi-Pei Liang1,2, Wen-Mei Hwu1,2, and Bradley P. Sutton2,3
1Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 2Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 3Bioengineering Department, University of Illinois at Urbana-Champaign, Urbana, IL, United States

Despite advances in acquisition and reconstruction technologies, typical clinical scans rely on Cartesian acquisitions and limited reconstruction routines. Requirements for significant computational resources and specialized expertise are a barrier to widespread use of algorithms that combine efficient non-Cartesian trajectories, field inhomogeneity correction, parallel imaging, and image regularization. We present a parallel implementation of such a reconstruction utilizing manycore graphics processing cards to speed reconstruction to acceptable levels, even for large matrix sizes and multiple coil acquisitions. We compare reconstruction times with parallel C-code and a common approximation method, showing that the proposed code is faster without using interpolation operators.

14:00 4397.   Parallel imaging using a non-uniform undersampling trajectory 
Yu Li1, and Charles L. Dumoulin1
1Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States

This work introduces a novel parallel imaging technique that uses a non-uniform k-space undersampling trajectory to accelerate Cartesian data acquisition for MRI. In this technique, a non-uniform undersampling trajectory is formed from multiple uniform sub-trajectories with higher undersampling factors. A modulation model is used to separate non-uniformly undersampled data into aliasing and real image data in k-space. A set of linear filters is used to pass real image and block aliasing for reconstruction. In high-resolution brain imaging, it is demonstrated that a non-uniform trajectory gives better performance in parallel imaging with high acceleration factors than a uniform trajectory.

14:30 4398.   Hadamard Encoded Time-Dependent Phase Constraint Parallel Image Reconstruction 
Jacob R. Hoberg1, and Nan-Kuei Chen1
1BIAC, Duke University, Durham, NC, United States

The use of the multi-band parallel imaging along the slice-select direction in fMRI can increase the throughput without signal reduction resulting from k-space undersampling as in conventional parallel acceleration along the phase-encoding direction. However, the multi-band parallel imaging is still susceptible to noise amplification due to non-ideal sensitivity profile. The existing methods may not improve the SNR when the simultaneously excited bands are not spatially far apart. The purpose of this work is to present a novel method that integrates Hadamard slice encoding and time-domain phase constrained reconstruction, to eliminate the noise amplification of multi-band parallel.

15:00 4399.   Simultaneous acquisition of image and navigator slices using CAIPIRINHA 
Zarko Celicanin1, Frank Preiswerk2, Patrik Arnold2, Philippe Cattin2, Klaus Scheffler1, and Francesco Santini1
1Radiological Physics, University of Basel Hospital, Basel, Switzerland, 2Medical Imaging Analysis Center, University of Basel, Basel, Switzerland

Respiratory organ motion is a complicating factor in many treatments. Novel respiratory correlated MR imaging method was recently purposed that acquires a full 2D sagittal navigator image and builds 4D-MRI organ model. Image and navigator slices were acquired interleaved. Since the navigator image is used to estimate the exact organ position and shape, a time lag could lead to discrepancy in images and to incorrect models. We describe a new approach to image and navigator acquisition based on multislice CAIPIRINHA, which allows a true simultaneous acquisition with consequent decrease of lag and increase of temporal resolution.

Wednesday May 11th
  13:30 - 15:30 Computer 117

13:30 4400.   The Accuracy of Noise Covariance Estimation and Its Relationship with Signal-to-noise Ratio in Parallel Magnetic Resonance Imaging 
Yu Ding1, Yiu-Cho Chung2, and Orlando Simontetti3
1The Ohio State University, Columbus, OH, United States, 2Siemens Medical Solutions, 3The Ohio State University

Image based parallel magnetic resonance imaging (pMRI) techniques (SENSE or its variants) use the best linear unbiased estimation (BLUE) to reconstruct image. Mathematically, the signal-to-noise-ratio (SNR) of images reconstructed by BLUE is better or equal to the SNR of the simple least square solution, depending on the accuracy of the noise covariance matrix used. Hence, the accuracy of the noise covariance matrix estimation affects the SNR performance of pMRI. In this study, we use volunteer study to quantify the how the errors of covariance matrix estimation affect image SNR, and propose a guideline for accurate covariance matrix estimation.

14:00 4401.   Theoretical signal-to-noise penalty in parallel ultra-low-field magnetic resonance imaging 
Fa-Hsuan Lin1,2, Panu Vesanen3, Jaakko O. Nieminen3, John W. Belliveau2, and Risto J. Ilmoniemi3
1Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan, 2Martinos Center, Massachusetts General Hospital, Charlestown, MA, United States,3Department of Biomedical Engineering and Computational Science (BECS), Aalto University, Espoo, Finland

In ultra-low-field (ULF) magnetic resonance imaging (MRI), a readily available sensory array consisting of up to hundreds of detectors can be used for simultaneous data acquisition. Such a parallel data acquisition immediately allows the application of the parallel MRI principle to reduce the data acquisition time, which critically depends on the number of magnetization polarization steps in ULF-MRI. In this study, we investigate the theoretical signal-to-noise ratio (SNR) penalty based on the Sensitivity Encoded (SENSE) MRI at various acceleration rates using the optimized MEG array with different channels of pick-up coils.

14:30 4402.   G-factor as Regularization Parameter in Regularized SENSE Reconstruction 
Hammad Omer1, and Robert Dickinson2
1Imperial College London, London, London, United Kingdom, 2Imperial College London

Parallel MRI is a technique to reduce the scan time for MRI image acquisition but this comes at the cost of noise amplification during the process of image reconstruction. A method based on the use of g-factor as a regularization parameter in Tikhonov regularized SENSE reconstruction is proposed. The results show a considerable improvement in the reconstructed image as compared to contemporary methods. It has been shown that the g-factor map effectively acts as a spatially adaptive regularization parameter providing very good reconstruction at much less computational cost.

15:00 4403.   Suppression of Residual Noise and Artifact in Parallel Imaging by Iterative Noquist 
Lei Hou Hamilton1, Sumati Krishnan2, Senthil Ramamurthy2, David Moratal3, and Marijn Brummer2
1School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States, 2School of Medicine, Emory University, Atlanta, GA, United States, 3Center for Biomaterials and Tissue Engineering, Universitat Politècnica de València, Valèncian, Spain

A simplified variant of the PINOT method is presented, which combines parallel imaging and iterative Noquist (iNoquist) sequentially to greatly accelerate the reconstruction speed. Compared with parallel imaging alone with the same reduction factor, this approach reduces noise and residual artifacts. Compared with original PINOT with the same reduction factor, it has the advantage of alleviating computational burden, albeit at some penalty in image quality. Furthermore, although illustrated here only for SPACE-RIP, we note that iNoquist can be used as a post processing method following any parallel imaging methods to suppress residual noise and artifacts.

Thursday May 12th
  13:30 - 15:30 Computer 117

13:30 4404.   Optimized RX Field Homogeneity for SENSE Imaging in Parallel Transmit MR 
Hanno Homann1, Tim Nielsen2, Kay Nehrke2, Ingmar Graesslin2, Olaf Dössel1, and Peter Börnert2
1Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Karlsruhe, Germany, 2Philips Research Europe, Hamburg, Germany

Most transmit (TX) arrays used in parallel transmission can also be used as receive (RX) arrays, raising the question of optimal signal combination to recover RX field homogeneity. In this study, different approaches to signal combination are compared, using an 8-channel TX/RX body coil at 3T. The possibility to combine the signals of the individual channels in the image space resulted in greatly improved homogeneity compared to a single channel birdcage coil.

14:00 4405.   Temporal Filtering Effects in Dynamic Parallel MRI: Comparing Radial and Cartesian Sampling 
Irene Paola Ponce Garcia1, Martin Blaimer2, Felix Breuer2, Peter M Jakob1,2, Mark A Griswold3, and Peter Kellman4
1Experimental Physics 5, University of Würzburg, Würzburg, Bavaria, Germany, 2Research Center Magnetic Resonance Bavaria e.V (MRB), Würzburg, Bavaria, Germany,3Department of Radiology, University Hospitals of Cleveland and Case Western Reserve University, Cleveland, Ohio, United States, 4Laboratory of Cardiac Energetics, National Institutes of Health, National Heart, Lung and Blood Institute, Bethesda, Maryland, United States

In Auto-calibrated Dynamic Parallel Magnetic Resonance Imaging (pMRI), such TSENSE or kt-SENSE, the missing information is reconstructed using the spatial sensitivities of multiple receiver coils. The coil sensitivities are derived from the full FOV temporal average image (a.k.a direct current, DC) that is obtained by averaging the undersampled time frames. In Cartesian sampling, the averaging leads to aliasing artifacts and therefore to errors in the coil sensitivities estimates. As a result, the reconstructed images exhibit temporal filtering effects. In this work, we demonstrate that these temporal filtering effects are not significantly present in accelerated dynamic parallel MRI experiments using Radial sampling.

14:30 4406.   Time-resolved MRA with Data-Driven Parallel Imaging Using Calibration Over Multiple Time-Frames and Interleaved Variable Density Cartesian Acquisition 
James H Holmes1, Kang Wang2, Philip J Beatty3, Reed F Busse4, Frank R Korosec5, Lauren A Keith2, Christopher J Francois6, Scott B Reeder5, and Jean H Brittain7
1Global Applied Science Laboratory, GE Healthcare, Madison, WI, United States, 2Medical Physics, University of Wisconsin-Madison, Madison, WI, 3Global Applied Science Laboratory, GE Healthcare, Thornhill, ON, Canada, 4MR Research, GE Healthcare, Waukesha, WI, 5Radiology, University of Wisconsin-Madison, Madison, WI, 6Radiology, University of Wisconsin-Madison, Madision, WI, 7Global Applied Science Laboratory, GE Healthcare, Madison, WI

An interleaved variable density (IVD) Cartesian acquisition combined with a constrained reconstruction (HYCR) and data-driven parallel imaging has been demonstrated for improved MRA temporal resolution. There are several potential methods for calibrating the parallel imaging including using mask data, mask data subtracted from the time-frame, and data from multiple time-frames. In this work, we present results from these different calibration methods and demonstrate the advantages of using multiple calibration data sources to address data inconsistencies and maintain high temporal resolution with time-resolved MRA.

15:00 4407.   Adaptive Self-Calibrating in k-Space Parallel Magnetic Resonance Imaging using Kalman Filter 
Suhyung Park1, Jin-Suck Suh1,2, and Jaeseok Park2
1Medical Science, Yonsei University, Seoul, Korea, Republic of, 2Radiology, Yonsei University, Seoul, Korea, Republic of

It is challenging to estimate accurate convolution kernel in k-space based parallel imaging. This work suggest adaptive self-calibrating method designing static calibration region into dynamic calibration region using the Kalman filter